Histology block I Flashcards

Question

what does chromium or silver stains stain?

Answer 1

used to stain some extracellular fibers and some cells in the nervous system and endocrine system

Answer 2

Periodic Acid Schiff staining (PAS technique)

Answer 3

Periodic acid cleaves some of the carbon-carbon bonds in sugars and changes to aldehyde groups which bind the Schiff reagent and stain bright pink. Thus good for some carbohydrates and basement membranes

Answer 4

Examples: Orcein’s elastic stain (brown); Weigert’s elastic stain (blue); Wright and Giemsa

Answer 5

differentiate different types of blood cells

Answer 6

Specimen fixed with glutaraldehyde (crosslinks proteins by aldehyde groups) followed by Osmium metal (fixes lipids) 2.Dehydration of specimen with alcohol or acetone series 3.Infiltration and embedding of specimen with a polymerizable plastic 4.Cutting of section with a microtome with either a glass or diamond knife. The sections are much thinner than for light microscopy (0.1 micron) 5.Mounted on 3 mm diameter copper grid and stained with electron dense heavy metals (uranyl acetate and lead citrate) 6.Examined in electron microscope

Answer 7

1. freeze-fracture 2. Quick-freeze deep-etch technique

Answer 8

1. Specimen infiltrated with a cryo-protective agent such as glycerol to help prevent ice crystal formation and then rapidly frozen by plunging into liquid nitrogen 2. Frozen specimen mounted in a freeze-fracture unit at a temperature of -110 to -120 degrees under vacuum and cleaved (fractured) with steel knife 3. A metal (platinum) replica of fracture face surface is made 4. The specimen is removed and warmed to room temperature and the tissue dissolved away 5. The cleaned metal replica of surface is examined in the transmission electron microscope

Answer 9

for examining membrane structure

Answer 10

TEM; intestinal epithelium cells

Answer 11

1. In this procedure the sample is rapidly frozen (-10,000 degrees/sec) without the use of cryo-protective agents. At this speed of freezing water is solidified without the formation of ice crystals which would disrupt structure. 2. Freeze-fracture of the specimen is performed under vacuum maintaining the specimen temperature below -110 to -120 degrees centigrade. 3. The specimen temperature is then raised to -100 degrees for a short time. At this temperature the water at the surface changes to the vapor phase and is removed from the specimen, thus exposing surface detail by etching away the surrounding water. 4. The specimen is rotary shadowed with platinum to form a replica which is cleaned and examined in the transmission electron microscope.

Answer 12

Quick-freeze deep-etch technique

Answer 13

has the advantage of allowing a more three-dimensional imaging of cells and tissues.

Answer 14

Electron microscope; 1. Golgi complex 2. mitochondria 3. Rough eR 4. Smooth eR 5. secretory Vesicles

Answer 15

Membranes compartmentalize biochemical functions of the cell and form closed compartments within which biochemical reactions take place with minimal interference from reactions in adjacent compartments of the cell.

Answer 16

Electron microscope; mitocondria (ATP production); rough endoplasmic reticulum (protein synthesis)

Answer 17

1. Selective permeability 2. structural scaffolding 3.vesicular transport 4. division of labor

Answer 18

can tightly control the environment such as pH or substrate concentrations within an organelle or region of the cell and thus influence the equilibrium or nature of the biochemical reactions taking place in that organelle; electron transport reaction, H+ act to drive prodcution of ATP, [protons]

Answer 19

for enzyme and receptor attachment; hormone receptors

Answer 20

Forming vesicles to move large particles between cellular compartments

Answer 21

In eukaryotic, the concept that cells use membranes to divide their functions into specific compartments for better efficiency

Answer 22

Fluid Mosaic Model of Membrane Structure; lipids arranged as a bilayer and proteins floating within the bilayer. Carbohydrate groups (green) are attached to both the lipids and the proteins primarily on the extracellular surface (non-cytoplasmic side) of the membrane

Answer 23

primarily phospholipids with some sphingomyelin and glycolipids) are arranged as a continuous bilayer with their polar head groups on surfaces and fatty acid chains in interior of bilayer

Answer 24

Proteins float in the lipid bilayer like icebergs. Are present as peripheral proteins loosely attached at surface and integral proteins deeply embedded in bilayer

Answer 25

Carbohydrate (2 – 5% by weight) is attached on non-cytoplasmic surface to lipids and proteins

Answer 26

is fluid like a thick oil with many (~50%) of both lipids and proteins able to move in plane of membrane as a mosaic like arrangement.

Answer 27

Cholesterol molecule, hydrophobic fatty acid chain, hydrophilic polar (charged) head, non-polar non charged hydrophobic.

Answer 28

arranged to maximize contact of their polar groups (hydrophilic - water loving groups) with water, and to sequester their non- polar groups (hydrophobic - water hating groups) away from water (amphipathic structure)

Answer 29

higher temperature = more fluidity lower temp = less fluidity

Answer 30

reduces fluidity

Answer 31

phospholipid composition, fatty acid chain length, saturation or desaturation of the fatty acid chains, temperature, and cholesterol

Answer 32

Double bond promotes fluidity

Answer 33

glycophospholipids, lipid raft, carbohydrates, peripheral protein, peripheral proteins, integral protein

Answer 34

a permeability barrier

Answer 35

simple difussion

Answer 36

some gases such as O2 and CO2, small polar molecules such as H2O Etanol, small lipid-soluble molecules and some hydrophobic molecules such as benzene

Answer 37

require integral proteins in the form of channels or carrier proteins to pass across the membrane either by facilitated diffusion (no ATP or additional energy required) or active transport (ATP or other energy expenditure required).

Answer 38

Charged molecules such as most ions, sugars, amino acids, and nucleotides

Answer 39

can be ungated, but often are either voltage- or ligand-gated to open or close

Answer 40

Simple difussion; carrier protein; channel protein; the presence of both carrier proteins and channel proteins to facilitate movement of large polar molecules across the membrane

Answer 41

1. Peripheral proteins 2. Integral proteins

Answer 42

are loosely bound to surface of membrane by electrostatic bonds.

Answer 43

yes, Easily removed with high ionic strength solutions

Answer 44

Includes some cytoskeletal proteins that anchor to the membrane and are involved in shape determination and membrane stability

Answer 45

are tightly bound to the lipid bilayer

Answer 46

require membrane destruction (lipid solvents or detergents) for removal.

Answer 47

1. Transmembrane proteins 2. Lipid anchored proteins

Answer 48

the amino acid sequences at the membrane surfaces are hydrophilic and those in bilayer are hydrophobic.

Answer 49

covalently linked to lipids but do not extend thru bilayer core

Answer 50

integral membrane proteins peripheral membrane proteins lipid anchored proteins

Answer 51

major proteins which act as, ion or carrier protein pumps, ion channels, receptors and signal transducing proteins (such as the G-proteins), structural linkers between cytoskeleton and extracellular matrix, enzymes, and structural proteins

Answer 52

Diagram illustrating the important role played by integral membrane proteins which can act as channels, pumps, receptors, linker-proteins, enzymes, and structural proteins

Answer 53

Mainly present on the external surface of the plasma membrane bound to some of the integral proteins and phospholipids as the cell coat or glycocalyx

Answer 54

They often act as key recognition sequences or receptor components for: 1. Enzymes 2. Hormone binding 3. Virus binding (HIV) 4. cell recognition/diferentiation (for example differences in the carbohydrate groups present on the surface of red blood cells differentiate the A, B, AB, and O blood types)

Answer 55

extracellular surface, cytoplasmic surface; Diagram of modified fluid mosaic model of membrane showing the extracellular location of membrane-associated carbohydrates

Answer 56

EM of microvilli on intestinal epithelial cells showing the glycocalyx or cell coat

Answer 57

Larger stable regions where some of the proteins and associated lipids are arranged

Answer 58

contain higher concentrations of glycosphingolipids and cholesterol and are present as thicker regions of the membrane.

Answer 59

These lipid rafts tend to localize together groups of proteins or lipids involved in a common function

Answer 60

They may be involved in cholesterol transport, endocytosis, and especially signal transduction.

Answer 61

signal receptor and effector proteins and enzymes may be located together to receive and convey specific signals more efficiently.

Answer 62

1. Thin sections in EM 2. Freeze-fracture replicas in EM

Answer 63

1. plasma membrane and zonula occludens cell junction 2. Thin section EM image of intestinal epithelial cell

Answer 64

1. region of the plasma membrane and zonula occludens 2. Freeze-fracture EM image

Answer 65

membranes have a trilaminar structure = two dense outer layers separated by an electron translucent central layer

Answer 66

7.5 - 10 nm thick for plasma membrane & 6 - 7.5 nm thick for cytoplasmic membranes

Answer 67

Thin-section EM showing the trilaminar appearance of the plasma membrane on intestinal microvilli

Answer 68

Electron dense, electron translucent, electron dense; trilaminar structure of plasma membrane,

Answer 69

charge distribution contributes to the trilaminar appearance of the membrane as seen in thin section EM

Answer 70

1. tissue is rapidly frozen (vitreous state – no ice crystals) in cryogen and cleaved with knife edge 2. Half of the tissue is cleaved away and removed in this process 3. The surface of the remaining tissue is coated with a heavy metal to form a replica of the surface 4. The remaining tissue is removed by bleach and the replica examined in the TEM

Answer 71

the fracture plane tends to preferentially move along and split membranes along the central plane of the bilayer between the phospholipid fatty acid chains with the fracture plane passing around the integral proteins.

Answer 72

the P-face and the E-face are produced

Answer 73

associated with the inner leaflet of the membrane adjacent to the cytoplasm (protoplasm).

Answer 74

associated with the outer leaflet of the membrane adjacent to the extracellular space outside the membrane

Answer 75

An important feature seen on the fracture faces is the present of bumps which represent the integral proteins in the membrane

Answer 76

top: E-face bottom: P-face

Answer 77

In general see more IMPs on the P-face than E-face. This probably correlates with ~50% of membrane proteins being anchored in place by attachment to cytoskeletal structures or other proteins in the cytoplasm

Answer 78

The vesicles and their associated proteins play a major role in the transport of substances into and out of the cell at the plasma membrane, and between organelles in the cytoplasm

Answer 79

Endocytosis Exocytosis Intracellular transport

Answer 80

Is the uptake (internalization) of material by cell from the outer membrane into the cytoplasm

Answer 81

Is the release of material out of the cell by secretion

Answer 82

Transport & sorting of proteins or other molecules between the organelles and plasma membrane.

Answer 83

Exocytosis and endocytosis

Answer 84

Mechanism for bulk movement of fluids, proteins, or even whole structures such as bacteria into the cell

Answer 85

Pinocytosis Receptor mediated endocytosis Phagocytosis

Answer 86

bulk intake of extracellular fluid, typically not highly specific

Answer 87

highly specific uptake of required substance and usually requires specific receptors for the substance and involves a protein called clathrin

Answer 88

Intake of particles larger than 250 nm in diameter such as bacteria. It can be either relatively non-specific or highly specific

Answer 89

Pinocytosis

Answer 90

Rceptor mediated edocytosis

Answer 91

phagocytosis

Answer 92

(“cell drinking”) is a process for the non-specific (random) uptake of extracellular fluid and material in solution into pinocytotic vesicles at the cell surface

Answer 93

cell drinking

Answer 94

Micropinocytosis Macropinocytosis

Answer 95

Micropinocytosis

Answer 96

Macropinocytosis

Answer 97

Em of endothelial cell showing pinocytosis including macropinocytosis

Answer 98

process for uptake of water and substances into vesicles less than 150 nm diameter. Constitutive (continual) process

Answer 99

uptake into vesicles greater than 200 nm diameter. Allows the maximum uptake of fluid and solutes of any of the endocytotic mechanisms

Answer 100

In many cells there is a continuous (constitutive) non-specific formation of small vesicles (less than 150 nm in diameter) which pinch off from the plasma membrane and carry small amounts of fluid & proteins into the cell.

Answer 101

non-specific

Answer 102

Does not require specific receptors in the plasma membrane for the ligand and does not involve the coating-protein clathrin

Answer 103

involves lipid rafts with the proteins caveolin or flotillin

Answer 104

EM of continuous capillary with micropinocytic vesicles

Answer 105

Caveolin 1 and 2

Answer 106

except neurons and white blood cells

Answer 107

caveolin 3

Answer 108

flotillin 1 and flotillin 2

Answer 109

Caveolin forms complexes of 14 – 16 monomers that aid in causing curvature of the membrane to form the vesicle.

Answer 110

No, clathrin-independent

Answer 111

Is a gtpase mechanoenzyme involved in the pinching off of the vesicles allowing vesicles to be free

Answer 112

Rearrangement of actin microfilaments of the cytoskeleton is not required

Answer 113

No, clathrin and actin - independent

Answer 114

Non-specific

Answer 115

actin-filament rearrangements

Answer 116

to form membrane-ruffles or folds which fold-back to trap large pockets of fluid with the formation of large vesicles greater than 200 nm diameter.

Answer 117

No (clathrin-independent but actin-dependent)

Answer 118

is used by cells to endocytose large amounts of fluid and trapped solutes. And In particular, it is used by cells of the immune system such as macrophages and dendritic cells to trap antigenic material to be processed to initiate immune responses

Answer 119

growth factors such as macrophage colony-stimulating factor, epidermal growth factor, and platelet-derived growth factor

Answer 120

a highly specific process for the movement of needed substances into the cell

Answer 121

by way of binding to specific plasma membrane receptors for that substance and the formation of structures called clathrin coated- vesicles

Answer 122

bind to recognition sequences of amino acids on the cytoplasmic domain of the receptor (1), and clathrin molecules in turn bind to clathrin-binding sites on the adaptin protein (2).

Answer 123

Diagram of receptor-mediated endocytosis

Answer 124

acts to provide the force for bending the membrane into the shape of first a clathrin coated pit (2) which deepens and then pinches off with the help of GTPase dynamin (3) as a clathrin coated vesicle free in the cytoplasm

Answer 125

Clathrin & adaptin are released (5 and 6) and the vesicle fuses with early endosomal compartment of the cell

Answer 126

TEM image of plasma membrane prepared by quick-freeze deep-etch technique showing forming clathrin coated pits and vesicles

Answer 127

TEM images of thin sections showing stages in formation of a clathrin coated vesicle

Answer 128

Familial Hypercholesterolemia; It is characterized by extremely elevated levels of cholesterol in the blood which can lead to the development of cardiovascular diseases such as atherosclerosis, heart attacks, and valve pathologies which may be fatal. Men with this condition untreated have a ~50% probability of dying from cardiovascular problems by age 50; and women a 30% probability by age 60.

Answer 129

1) complete loss of the receptor protein 2) or may involve defective binding of the LDL-protein particles at the LDL protein binding site 3) or may result from a mutation in the NPxY binding site for adaptin in the cytoplasmic domain of the protein thus blocking the binding to adaptin and clathrin and internalization by receptor mediated endocytosis

Answer 130

Used for intake of particles such as bacteria which are greater than 250 nm in size

Answer 131

Primarily used by cells of the mononuclear phagocytic System (MPS) such as macrophages and certain white blood cells to uptake bacteria and other antigenic material

Answer 132

by the binding of antibodies or complement fragments to the bacterial surface

Answer 133

Phagocytosis can also be triggered by the presence of pathogen-associated recognition patterns (PAMPs) commonly found on the surface of bacteria or other pathogens

Answer 134

yes, material such as carbon, particles, glass particles, and asbestos fibers

Answer 135

Diagram of phagocytosis for (a ) bacteria and other antigenic material which may be facilitated by binding of antibodies or complement fragments to the surface of the particle and (b) phagocytosis of non-biological particles which does not involve the binding of antibodies or complement fragments

Answer 136

by cytoplasmic pseudopod-like processes to form a vesicle containing the particle which is called a phagosome

Answer 137

requires rearrangement of actin, phagocytosis is said to be actin-dependent

Answer 138

The phagosome fuses with a vesicle containing lysosomal enzymes to form a phagolysosome & the particle is broken down by lysosomal enzymes.

Answer 139

Phagocytosis of non-biological particles such as glass, carbon particles, asbestos crystals is similar but does not involve the recognition of antibodies, complement fragments, or PAMPs on their surface

Answer 140

is the process involved in either the release of secretory material at the plasma membrane or for transport to the endosome

Answer 141

This generally involves the formation of proteins in the rough endoplasmic reticulum (RER) which are transported to the Golgi complex in vesicles where the protein can be modified (glycosylation and sulfation or other modifications) and packaged into vesicles for transport either to the plasma membrane or to endosomes

Answer 142

Light micrograph of pancreatic cells showing secretory granules in their apical cytoplasm ready for secretion by exocytosis

Answer 143

constitutive secretion Regulated secretion

Answer 144

the vesicles carrying molecules for secretion move continuously from the trans-Golgi membranes to the plasma membrane with no storage in cytoplasm and no signal for release required

Answer 145

collagen and immunoglobulin antibody secretion

Answer 146

the vesicles carrying the molecules for secretion move from the trans-Golgi to the apical region of the cell where they are stored until secretion is stimulated by a hormone or other factor causing local movement of calcium into cell.

Answer 147

the release of most hormones and pancreatic enzyme release which require specific signals for the secretion

Answer 148

endosome and plasma membrane

Answer 149

Proteins for movement are made in the rER, then go to the golgi stacks, pinch off into a vesicle into another sac. Then , into the trans golgi network, packed and move to the cell surface.

Answer 150

in terms of its cytoplasmic and non-cytoplasmic domains is established during the insertion of the protein into the membranes of the rough endoplasmic reticulum. This orientation of the protein is maintained through-out the entire process of vesicular transport of the membrane protein to the plasma membrane.

Answer 151

SNARE mechanism of membrane vesicle fusion which may also provide part of the mechanism for ensuring the vesicles fuse with the appropriate target membranes

Answer 152

the major mechanism for fusion of a vesicle to a target organelle or the plasma membrane and may help targeting to the correct organelle for fusion

Answer 153

Soluble NSF Attachment Receptor protein

Answer 154

a small class of at least 30 - 40 proteins associated both with the vesicle (v-SNARE proteins) and the target organelle membrane (t-SNARE proteins).

Answer 155

They can interact specifically with each other to facilitate docking of the vesicle to the specific target organelle or plasma membrane and catalyze fusion of the membranes

Answer 156

1. Formation by receptor mediated endocytosis of a plasma membrane vesicle with a v-SNARE protein (synaptobrevin or other VAMP proteins) associated with the membrane 2. As the vesicle approaches the endosome, a tethering protein will bind to the vesicle and draw it close to the endosome, where Rab GTPase on the vesicle and its receptor on the endosome membrane and the v-SNARE protein on the vesicle and t-SNARE proteins (such as SNAP-25 and syntaxin) on the endosome membrane will specifically interact to form a trans-SNARE docking complex. 3. This docking complex will draw the vesicle and endosome membrane close enough to each other to initiate and catalyze fusion of the membranes at a fusion pore. Once fusion is initiated the SNARE complex will be referred to as a cis-SNARE complex and allow the recruitment of the general fusion proteins NSF and alpha SNAP to the docking complex to disassembly the cis-SNARE complex

Answer 157

SNARE mechanism. Diagram of steps in vesicle formation, targeting, docking, and fusion of a transport vesicle with the early endodome

Answer 158

is a V-SNARE protein in the synaptic vesicle membrane which binds with the T-SNARE proteins syntaxin and SNAP-25 to form the zipper-like SNARE complex to target and bind the synaptic vesicle to the pre-synaptic terminal membrane

Answer 159

Fusion of the vesicle and release of its contents occurs

Answer 160

functions to unzip (disassociate the cis SNARE complex) allowing recycling of the vesicle

Answer 161

1. The botulinum toxin from Clostridium botulinum is endocytosed into the cytoplasm of the presynaptic neuron at the synapse at the neuromuscular junction where it cleaves synaptobrevin (VAMP) a V-SNARE protein and the T-SNARE proteins Syntaxin and SNAP-25 2. This blocks the fusion of the synaptic vesicle with the pre-terminal synaptic membrane thus blocking transmission at the neuronal synapse 3. Tetanus toxin from Clostridium tetani is similar, but is transported to the spinal cord where it translocates to the pre-synaptic terminal of inhibitory neurons where it blocks their ability to inhibit and regulate the activity of the large motor neurons which innervate the skeletal muscles thus leading to the sustained contraction of the skeletal muscles found in tetanus

Answer 162

Eucrhomatin, heterochromatin, nucleolus, nuclear envelope

Answer 163

nuclear material containing DNA and various nuclear proteins (e.g. histones).

Answer 164

Site of rRNA synthesis and contains regulat ory cell cycle proteins

Answer 165

two membrane system perforated by nuclear pores.

Answer 166

nuclear content other than chromatin nucleolus.

Answer 167

Nerve cell top, bottom inactive cell (lymphocyte)

Answer 168

Loosely arranged (dispersed) chromatin so that DNA can be read and transcribed.

Answer 169

Highly condensed chromatin. Transcriptionally inactive.

Answer 170

highly repetitive sequences of DNA, packaged in the same regions in different cells. Usually near the centromeres and telomeres.

Answer 171

: is not repetitive, location is different for different cell types. It may undergo active transcription in certain cells, under specific conditions.

Answer 172

Marginal Chromatin

Answer 173

Discrete bodies of chromatin irregular in size and shape and size that are found throughout the nucleus.

Answer 174

Nucleolar associated chromatin

Answer 175

Beads on a string

Answer 176

Chromatin isolated from interphase nucleus appears in EM as a thread 30nm thick.

Answer 177

Chromatin that has been experimentally unpacked and show the nucleosomes “beads on a

Answer 178

are the smallest units of chromatin and represent the first level of chromatin folding.

Answer 179

about 100,000 times longer than the nuclear diameter.

Answer 180

8 histone molecules (octamer)

Answer 181

the principal structural proteins of chromosomes. They form a core structure of 2 units of each of the four types of histones (H1 H4).

Answer 182

Entire length of DNA (2.5 billion base pairs) packed in all chromosomes. Each region of

Answer 183

Each region of the DNA helix that produces a functional RNA molecule

Answer 184

The end of each chromosome is the telomere which shortens with each cell division

Answer 185

Telomere length plays an important role in the lifespan of cells.

Answer 186

neutrophil from a female blood smear, Barr body

Answer 187

discovered in nerve cells of female cats, looks like a drum stick, can tell the sex

Answer 188

Trisomy 21 (Down’s): leads to mental retardation and congenital malformations. Abnormalities in sex chromosomes Kleinfelter’s Syndrome (XXY): Male phenotype and no secondary sex characteristics. Turner’s Syndrome ( XO):

Answer 189

Special fluorescence probes (FISH technique ) for in situ hybridization are used. A single fluorescent DNA or a mixture of different probes is used to produce different colors in each chromosome.

Answer 190

Chromatin condensation; protamines replace histones in tightly compacted chromatin

Answer 191

Chromatin condensation; protamines replace histones in tightly compacted chromatin

Answer 192

nucleolin and nucleostemin , which are shuttling proteins that relocalize from the nucleolus to the nucleoplasm.

Answer 193

Nucleostemin is a p53 (tumor supressing protein) binding protein found within the nucleolus that regulates the cell cycle and influences cell differentiation

Answer 194

Fibrillar centers, fibrillar material, granular material

Answer 195

contain DNA loops of five different chromosomes (13, 14, 15, 21, and 22) that contain rRNA genes, RNA polymerase I, and transcription factors.

Answer 196

(pars fibrosa) contains ribosomal genes that are actively undergoing transcription and large amounts of rRNA.

Answer 197

(pars granulosa): represents the site of initial ribosomal assembly and contains densely packed preribosomal particles.

Answer 198

the network formed by the granular and fibrillar materials .Genes for the ribosomal subunits are localized in the interstices of this network.

Answer 199

Membrane barrier that separates the nucleoplasm from cytoplasm (encloses chromatin)

Answer 200

Separated by a perinuclear cisternal space , which is continuous with cisternal space of the rough endoplasmic reticulum

Answer 201

nuclear pores , which mediate the active transport of proteins between nucleus and cytoplasm.

Answer 202

Support the nucleus

Answer 203

Electron micrograph of a portion of the nuclear lamina from a Xenopus oocyte. It is formed by intermediate filaments (lamins) that are arranged in a square lattice. The nuclear lamina is a meshwork of intermediate type filaments.

Answer 204

intermediate filaments lamins and lamin associated proteins. Mainly composed of Lamin A nad lamin C

Answer 205

orthogonal lattice. Attached via lamin B protein to the inner nuclear membrane through its interactions with lamin receptors: nurim (binds lamin); emerin (binds lamin A and B; lamin B receptor (binds lamin B)

Answer 206

Fibrous lamina (nuclear lamina)

Answer 207

during mitosis

Answer 208

The nuclear lamina appears to serve as scaffolding for chromatin, chromatin associated proteins, nuclear pores, and the membranes of the nuclear envelope. * Essential for many nuclear activities including DNA replication and transcription, it is involved in nuclear organization, cell cycle regulation, differentiation, and gene expression. Lamins disassemble during

Answer 209

Mutations of lamin and their associated (receptor) proteins cause various diseases called laminopathies. These are tissue specific diseases that affect striated muscle, nerve or skeletal development, and premature aging.

Answer 210

Emery Dreifuss muscular dystrophy EDMD Hutchinson Gilford Progeria Syndrome (HGPS),

Answer 211

associated with mutations in either lamins or lamin receptors, characterized by muscle weakness and wasting in the upper and lower limbs and cardiomyopathy (weakening of heart muscle). The X linked recessive form of EDMD caused by mutations of emerin , whereas autosomal dominant form of EDMD caused by mutations in lamin A/C proteins.

Answer 212

One of the most severe laminopathies, Hutchinson Gilford Progeria Syndrome (HGPS), which is caused by aberrant splicing of the gene encoding for A type lamins and is associated with premature aging.

Answer 213

nuclear pores

Answer 214

Array of “openings” (70 to 80 nm) through the nuclear envelope formed from the merging of the inner and outer membranes.

Answer 215

composed of multidomain proteins collectively referred to as nucleoporins. Regulate the passage of proteins between the nucleus and cytoplasm. * Ribosomal subunits exported from nucleolus to the cytoplasm. Nuclear proteins imported from cytoplasm to nucleus.

Answer 216

Nuclear Pore Complex with Freeze Fracture

Answer 217

Nuclear Pore Complex Negative Staining Techniques

Answer 218

NPC is composed of a central cylindrical body placed between inner and outer octagonal rings, each consisting of 8 protein particles.

Answer 219

CET is a version of electronmicroscopy where 3D reconstruction ofa sample (i.e., electron tomogram) is created from 2D images obtained from freeze fracture methods.

Answer 220

Cryoelectron Tomography (CET)

Answer 221

The Nuclear Pore Complex

Answer 222

Large molecules containing a nuclear localization amino acid sequence (NLS , Pro Lys Lys Lys Arg Lys Val), can be imported into the nucleus. * Labeled NLS proteins destined to nucleus binds to cytosolic nuclear importin receptors that directs them to the NPC in a GTP dependent fashion controlled by Ran Ras like nuclear GTPase signaling.

Answer 223

Proteins that posses the nuclear export sequence (NES) bind in the nucleus to exportin and to a Ran GTP molecule. * The exportin Ran GTP complexes pass through the NPC into cytoplasm where GTP is hydrolyzed and the NES protein is released. * The NPC transports proteins, all forms of RNA, as well as ribosomal subunits in their fully folded configurations.

Answer 224

Export (Nuclear Pore Complex) * Proteins that posses the nuclear export sequence (NES) bind in the nucleus to exportin and to a Ran GTP molecule. * The exportin Ran GTP complexes pass through the NPC into cytoplasm where GTP is hydrolyzed and the NES protein is released. * The NPC transports proteins, all forms

Answer 225

Import (Nuclear Pore Complex)

Answer 226

Material enclosed by the nuclear envelope exclusive of the chromatin and the nucleolus.

Answer 227

Nuclear alterations in dying cells Pyknosis : condensation of chromatin leading to shrinkage of the nuclei (dense basophilic masses). * Karyorrhexis : is the destructive fragmentation of the nucleus of a dying cell whereby its chromatin is distributed irregularly throughout the cytoplasm * Karyolysis : disappearance of nuclei proteins due to complete dissolution of DNA (increased DNAase).

Answer 228

Exposure to physical or chemical environment that causes acute cellular injury and damage to the plasma membrane

Answer 229

This damage may also be initiated by viruses, or proteins called perforins

Answer 230

Rapid cell swelling and lysis are two characteristic features of this process

Answer 231

Occurs during normal embryologic development or physiologic processes, such as follicular atresia in the ovaries Cells

Answer 232

Cells can initiate their own death through activation of an internally encoded suicide program Apoptosis

Answer 233

Apoptosis is characterized by controlled autodigestion, which maintains cell membrane integrity thus, the cell dies without spilling its contents and damaging its neighbors

Answer 234

necrosis left apoptosis right

Answer 235

This electron micrograph shows an early stage of apoptosis in a lymphocyte. The nucleus is already fragmented, and the irreversible process of DNA fragmentation is turned on. Note the regions containing condensed heterochromatin adjacent to the nuclear envelope b. Further fragmentation of DNA. The heterochromatin in one of the nuclear fragments (left) begins to bud outward through the envelope, initiating a new round of nuclear fragmentation. Note the reorganization of the cytoplasm and budding of the cytoplasm to produce apoptotic bodies. c. Apoptotic bodies containing fragments of the nucleus, organelles, and cytoplasm. These bodies will eventually be phagocytosed by cells from the mononuclear phagocytic system. (Courtesy of Dr. Scott H. Kaufmann.)

Answer 236

This photomicrograph taken with light microscopy of intestinal epithelium from the human colon shows apoptotic bodies (AB) within a single layer of absorptive cells.

Answer 237

Breast cancer cell Orange: Microtubule marker Purple: Actin microfilament marker marker

Answer 238

The cytoskeleton is a network of protein filaments and tubules in the cytoplasm composed of 3 types of non-membranous filamentous organelles

Answer 239

microfilaments intermediate filaments microtubules

Answer 240

6-8 nm diameter & actin is the main protein

Answer 241

are 10 nm diameter & are composed of intermediate filament proteins (several classes of proteins

Answer 242

24 nm diameter & tubulin (α and β tubulin) is the main protein

Answer 243

cell shape determination and motility

Answer 244

Fluorescently light micrograph with the distribution of intermediate filaments in fetal lung fibroblasts cells in culture/ Red=vimentin (intermediate filaments) green=actin

Answer 245

Fluorescent staining of microtubules with (green) and nucleus in blue. gren= immunostaining for microtubules (tubulin)

Answer 246

movement: of whole cell, organelles, cilia, chromosomes (spindle formation) (mt), and the processes of cytokinesis (mf), endocytosis, exocytosis, cytoplasmic streaming [release of vesicles]

Answer 247

involvement in cell shape determination; shape of cilia and microvilli

Answer 248

Micrograph of non-distended transitional bladder epithelium. Note top balloon-shaped (umbrella or dome) cells or columnar/cuboidal-like shape cells in the bottom

Answer 249

EM micrograph of intestinal microvilli supported by actin microfilaments.

Answer 250

Tracheal epithelium showing cilia on apical surface supported by microtubules forms these motile cilia

Answer 251

tubulin in cilia helps maintain the long linear shape of the cilium but also plays a key role in the movement of the cilia

Answer 252

tubulin maintains the shape of the colium in this oviduct and helps with the moevment of ciclia to move the oocyte along the oviduct

Answer 253

Micrograph of cerebellum showing the very asymmetrical shaped Purkinje cells with dendrites

Answer 254

EM image of a mature myelinated axon showing microtubules in the cytoplasm

Answer 255

cytoskeleton plays a role both in maintaining very asymmetric shape of Purkinje neurons in cerebellum (structural function), but also within axons plays a key role in fast axonal transport of molecules and organelles to axon terminal (motor function)

Answer 256

G-actin (Globular), while in its polymerized form (the filament) it is called F-actin (Filamentous

Answer 257

double helical arrangement

Answer 258

Electron micrograph of actin (negative stain)

Answer 259

computer filtered image of actin filament, and diagram of double helical structure of actin filament

Answer 260

Anchorage and movement of membrane proteins = focal adhesion point Formation of the structural core of microvilli and stereocilia * Locomotion of cells – thought to involve a reversible gelation - solation of cytoplasm & may involve myosin II (thick filaments) and or myosin I * Extension of cell processes – filopodia & lamellipodia * Vesicular transport and movement of organelles (myosins I, II, Va, Vb, VI, VIIa, IXa, X) * Cytokinesis * Morphogenetic movements of tissues during embryology e.g. shaping of epithelia into tubes and etc

Answer 261

Points where you have actin filaments intercating with integrins and integrins interacting with the extracellular matrix; scaffolds for signaling pathways

Answer 262

There is a large pool of G-actin in the cell in equilibrium with the F-actin. This allows microfilaments to be polymerized and depolymerized in specific areas of the cell as necessary for function

Answer 263

requires the hydrolysis of ATP

Answer 264

depends on the local concentration of G-actin (binds to ATP) & other actin-binding proteins.

Answer 265

The polymerization occurs as a polarized process in which G-actin molecules with bound ATP bind preferentially at the (+)-end of the filament. After a short time the bound ATP is hydrolyzed to bound ADP, and eventually the actin with bound ADP is lost by depolymerization at the (-) end of the filament. This is an ongoing process which has certain proteins to stop it.

Answer 266

Polymerization of actin filaments

Answer 267

the name given to this process in which new actin molecules add preferentially to (+) end filament, while other actin molecules are lost at (-) end thus giving a continuous flow actin from (+) end to (-) end

Answer 268

Pulse-Chase Experiment Showing Treadmilling. Labeled actin molecules (green) add at the plus end of microfilament and after a short period of time the labeled molecules in solution are replaced with non-labeled actin and the patch of labeled actins can be seen to move along the filament

Answer 269

in motility

Answer 270

Cytochalasins B and D; Phalloidin

Answer 271

These drugs bind (+) end of microfilament & block addition of new actin molecules. Thus the drugs can block cellular activities that require polymerization of the microfilaments, such as cell movement and cytokinesis

Answer 272

This drug stabilizes microfilament structure & prevents depolymerization. Thus blocks cell activities requiring reversible polymerization & depolymerization such as cell movement and cytokinesis

Answer 273

These drugs disrupt the equilibrium between G-actin and F-actin. Because drugs block mitosis by inhibiting cytokinesis they may have anti-tumor use. The drugs also inhibit such cellular activities as lymphocyte migration, phagocytosis

Answer 274

As a loose meshwork of crosslinked filaments or as bundles of parallel filaments

Answer 275

typically found immediately under and attached to the plasma membrane or as a loose meshwork throughout the cytoplasm.

Answer 276

Filamin and spectrin

Answer 277

fimbrin or villin

Answer 278

Electron micrograph (EM) showing microvilli at apical surface of cell as finger-like projections with a core consisting of a bundle of actin filaments (terminal web)

Answer 279

A higher magnification micrograph (EM) showing microvilli at apical surface of cell as finger-like projections with a core consisting of a bundle of actin filaments

Answer 280

core bundle; loose meshwork; EM of cell prepared by quick-freeze deep-etch technique showing microvilli with core bundle of actin filaments and actin filaments as a loose meshwork in cytoplasm below microvilli

Answer 281

Distribution of actin filaments in pulmonary artery cells in culture. Green= imunostaining of actin stress fibers (bundles of crosslinked microfilaments) red=imunostaining of mitochondria

Answer 282

Actin is extremely conserved in its amino acid sequence

Answer 283

crosslink filaments into loose gel (filamin) * fragment filaments (gelsolin) * bundle filaments into bundles (villin, fimbrin, espin) * interact with actin to produce motion including vesicular transport (myosins I, II, Va, Vb, VI, VIIa, IXa, X) * cap filament ends (example gelsolin) [prevent filament from linking polymerization or shortening length by depolymerization] * attach filaments to cell membrane (spectrin, myosin I, ezrin) * sequester actin monomers to prevent filament formation (profilin & thymosin)

Answer 284

myosin II; involved in muscle contraction; however there are approximately 35 of unconventional myosins invovled in vesicular transport and movement of other cargo such as organelles

Answer 285

myosins V and VI

Answer 286

it moves in a retrograde direction towards the (-) end of the actin filament unlike all other known myosins. Thus bidirectional transport by myosins on actin filaments is possible

Answer 287

transports long distances

Answer 288

often short-range motion, such as under the plasma membrane

Answer 289

24 nm in diameter. Play a role in both cytoskeletal and cytomotor functions

Answer 290

EM micrograph of microtubules in the mitotic spindle of a dividing cell.

Answer 291

microtubule associated proteins involved in many functions

Answer 292

Intracellular vesicular transport and organelle movement– for example as in fast axonal transport * Maintenance of cell shape * Movement of cilia and flagella * Cell elongation and movement (cell migration) * Chromosome movement (spindle formation and pulling chromosomes to poles) * Maintenance of position of ER and intermediate filaments (if disrupt microtubules, then get a shift in position of both endoplasmic reticulum and intermediate filaments)

Answer 293

Composed of tubulin  -  dimers arranged in 13 -15 protofilaments.

Answer 294

cold, pressure, or high levels of calcium

Answer 295

yes, in the cytoplasmic microtubules

Answer 296

align in a head to tail conformation along the protofilaments. Thus the two ends of the microtubule are different

Answer 297

polar with tubulin dimers with bound GTP preferentially binding at the plus end of the microtubule and loss of the tubulin dimers being promoted when the tubulin has bound GDP.

Answer 298

Capping proteins and other bound proteins

Answer 299

dynamic equilibriuk (dynamic stability) between assembly and disassembly.

Answer 300

the state of the nucleotide bound to the tubulin dimer with bound GTP = assembly at plus end and bound GDP = dissociation)

Answer 301

Colchicine, Taxol, Vinblastin & vincristine

Answer 302

binds tubulin dimers & blocks their addition to tubule end causing rapid depolymerization of the microtubules. Is used for treatment of some cancers and gout arthritic symptoms. For gout it acts by blocking the movement and function of immune cells in the areas of inflammation in the joints.

Answer 303

binds to tubulin in the intact microtubule & stabilizes the microtubule. Is used in therapy for breast cancer (very toxic)

Answer 304

bind microtubule dimers and increase their binding to each resulting in the formation of paracrystalline deposits of the dimers thus reducing the ability of microtubules to polymerize. Are used in the treatment of leukemia and various types of lymphomas in particular. (stabilizes too much, if you stabilize too much or destabilize it affects either way)

Answer 305

used as anti-mitotic and anti-proliferative drugs in cancer therapy because they can block mitotic activity through their action on the polymerization and depolymerization of microtubules (can be highly toxic)

Answer 306

There is polarity in the arrangement of the ends of the microtubule in the cell.

Answer 307

In most cells the (-) end of the tubule is associated with the mitotic organizing center (centrioles) near nucleus & microtubules grow & radiate out with (+) end toward cell periphery. The exception is that in dendrites of neurons they may have opposite orientation. In axons these have a typical orientation.

Answer 308

near the nucleus

Answer 309

Immunolabeled microtubules growing outwards from mitotic organizing center (centrioles) with (-) end at center and (+) end peripherally

Answer 310

important in determining how cytomotor proteins bind microtubules and produce movement.

Answer 311

(kinesins) move toward the (+) end & others (cytoplasmic dyneins) toward the (-) end

Answer 312

bidirectional movement

Answer 313

kinesins (40 types in 14 classes) and dyneins (9 heavy chain classes)

Answer 314

represent families of proteins with many distinct members and are involved in a variety of movements including fast axonal transport, chromosome movement during mitosis and meiosis, movement of cilia and flagella.

Answer 315

Immunostaining showing the presence of a kinesin (Eg5 – red staining) which interacts with polar spindle fibers from the two mitotic poles to help separate the chromosomes. Dynein (not stained) also acts by binding at kinetochores and drawing chromosomes towards poles; chromosomes are shown in the middle

Answer 316

Rabiesvirus is transmitted through direct contact (such as through broken skin or mucous membranes in the eyes, nose, or mouth) with saliva or brain/nervous system tissue from an infected animal. People usually getrabiesfrom the bite of a rabid animal. Herpes simplex virus may use retrograde transport

Answer 317

Evidence has been shown that the rabies virus is transmitted along neuronal axons from near the site of the bite to the brain by retrograde transport involving binding of the P protein from rabies virus to the dynein light chain protein LC8. In the brain, rabies causes acute inflammation of the brain leading to extremely aggressive and violent behavior and death if not treated

Answer 318

provide a cytoskeletal (structural, support). They provide mechanical strength and control cytoplasmic stiffness in individual cells, provide mechanical strength to layers of cells, help to control cell shape, and may play a role in the positioning of organelles in the cell

Answer 319

EM showing hemidesmosomes at the base of an epidermal cell. The filaments are Keratin-containing Intermediate filaments

Answer 320

EM showing a desmosomal junction (intercellular) with intermediate filaments (arrows [zonula occludens]

Answer 321

Keratins (epithelia) –tonofilaments

Answer 322

Vimentin & vimentin-like proteins including desmin (muscle) & glial fibrillary acidic protein (glial cells in nervous system) & several less well known proteins

Answer 323

Neurofilament protein (neurons)

Answer 324

Lamins (nucleus - all eucaryotic cells)

Answer 325

Beaded filaments – (eye lens fiber cells)

Answer 326

Antibody labeling of the different classes of intermediate filament proteins (particularly the different subclasses of cytokeratins

Answer 327

For example this image shows astrocytes, a type of glial cell (supporting cell) in the brain immunostained for glial fibrillary acidic protein (GFAP) in their intermediate filaments. A tumor in which the intermediate filaments of the cells are immuno-stained with GFAP would suggest the tumor is of glial cell origin. Similarly, immunostaining of the intermediate filaments with an antibody to keratins would suggest an epithelial origin. Section of brain immuno-stained for glial fibrillary acidic protein (GFAP) showing astrocytes (a type of glial supporting cell) stained because their intermediate filaments contain GFAP

Answer 328

assembled from a pair of helical monomers that twist around each other to form coiled-coil dimers. Intermediate filaments are assembled in a dense ring around the nucleus and then radiate out toward the cell periphery.

Answer 329

No polarity, it is difficult for a protein to walk into a direction due to no polarity no (+) end

Answer 330

Intermediate filaments are assembled from a pair of helical monomers that twist around each other to form coiled-coil dimers. Two of these dimers then assemble with each other in antiparallel fashion (parallel but pointing in opposite directions) to generate a staggered tetramer of two coiled-coil dimers, thus forming the non-polarized unit of the intermediate filaments. Each tetramer then binds to other tetramers staggered relative to each other along the axis of the filament to form a protofilament, 8 of which are crosslinked to form the intermediate filament

Answer 331

they attach at cell junctions such as hemidesmo-somes and desmosomes and extend as bundles across the cytoplasm from junction to junction

Answer 332

Intermediate filaments

Answer 333

Although previously thought to be stable structures, they are now considered to be dynamic structures which form filamentous linkages between the cell surface and the nucleus that change depending upon the mechanical stresses on the cell.

Answer 334

important regulators of the intracellular changes in cytoplasmic mechanics that accompany various physiological activities such as cell contraction, migration, proliferation, and organelle positioning

Answer 335

They provide stiffness and strength to individual cells and help the cells resist and respond to environmental stresses. maintain location of organelles within the cell

Answer 336

help to strengthen an entire layer of cells. Thus providing a mechanism in which tension or pulling forces on the cells are shared by all the cells thus providing strength to the layer.

Answer 337

How IF provide strength to the nuclear envelope

Answer 338

No; due to their lack of a polar structure which hinders cytomotor proteins binding to them and moving along the filaments in only one direction.

Answer 339

rearranged during cell motility & may be involved in controlling directionality of the movement of the cell, and may play a role in the formation and directionality of cytoplasmic processes in cells such as astrocytes.

Answer 340

During embryological movement epithelial cells undergo a process called the epithelial-mesenchymal transition in which the epithelial cells undergo a change to a more mesenchymal-like cell morphology. A key feature of this process is that the intermediate filament composition changes from cytokeratin-containing intermediate filaments to vimentin-containing intermediate filaments and the breakdown of desmosomal and hemidesmosomal junctions. The cells then assume a more mesenchymal – fibroblast-like morphology and become motile. The clinical significance of this is the finding that epithelial cells becoming cancerous typically recapitulate this epithelial-mesenchymal transition to become motile and metastatic. Evidence has been shown for example that vimentin expression is required for the invasive behavior and metastasis of both prostate and breast cancer cells

Answer 341

Filaggrin Plectin family of proteins Plakins Lamin-Associated Proteins

Answer 342

binds keratin filaments into bundles

Answer 343

bind microfilaments, microtubules, and intermediate filaments into 3-D networks

Answer 344

involved in binding of intermediate filaments to hemidesmosomes and desmosomes. They also bind actin filaments to the neurofilaments in sensory neurons. Includes desmoplakins, desmoplakin-like proteins, and plakoglobulins

Answer 345

Emerin, lamin B receptor, nurim, and other lamin-associated polypeptides [serve to form the fibers coding on the inner surface of nuclear envelope]

Answer 346

Schematic of 3D structure of the G-actin with ribbon representation

Answer 347

slender cytoplasmic projections that extend beyond the leading edge of lamellipodia in migrating

Answer 348

cytoskeletal protein actin projections that occur at the leading edge of the migratory cells.

Answer 349

filopodia, lamellopodia

Answer 350

apical is to the outside and basal is close to the base or connective tissue.

Answer 351

Membrane bound closed system of anastomosing tubules and broad flat saccules called cisternae

Answer 352

the outer membrane of the nuclear envelope

Answer 353

principal organelle involved in detoxification and conjugation of noxious substances. It is particularly well developed in the liver and contains a variety of detoxifying enzymes related to cytochrome P450 into sER plasma membranes.

Answer 354

They modify and detoxify hydrophobic compounds such as pesticides, barbiturates and carcinogens converting them into water-soluble conjugated products that can be eliminated from the body

Answer 355

-lipid and steroid metabolism, -glycogen metabolism, and calcium homeostasis. -membrane formation and recycling

Answer 356

hydrolases, methylases, glucose-6-phosphatase, ATPases

Answer 357

The ER Network

Answer 358

Heat shock protein 90 B-1 antibody (green): HSP90B1, ER protein resident required for the folding of numerous signaling proteins

Answer 359

Consists of short anastomosing tubules that are not associated withribosomes.

Answer 360

cytoplasmic eosinophilia (acidophilia) when viewed in the light microscope.

Answer 361

Abundant smooth ER in a steroid-hormone-secreting cell. This electron micrograph is of a testosterone-secreting Leydig cell in the human testis. Can see the cisternae

Answer 362

Electron Microscopy (EM) image of abundant sER usually present in cells with active lipid synthesis. detoxyfication

Answer 363

sarcoplasmic reticulum a specialized ER

Answer 364

Its function is essential in the process of muscle contraction. In basal state (no contraction) it sequesters Ca+2 from the cytoplasm. for movement.

Answer 365

The sarcoplasmic reticulum is close to the plasma membrane invaginations that conduct the activating impulses, which trigger the release of Ca+2 and produce the contraction

Answer 366

Rough endoplasmic reticulum (rER). A region of the endoplasmic reticulum that is associated with ribosomes and is thus the organelle in which the synthesis of proteins takes place (proteins destined for export, to a specific organelle or to the plasma membrane)

Answer 367

The RNA in the ribosomes has basophilic staining. Therefore, the rER has a basophilic staining pattern.

Answer 368

Pancreatic acinar cells; lumen and basophilic staining rER; the clear part is acidophilic staining

Answer 369

ergastoplasm

Answer 370

Light micrograph of nerve cells (H&E) with Nissl bodies. Nerve cells have large basophilic bodies aclled nissl bodues (rER + many free ribosomes)

Answer 371

Electromyograph of nerve cells showing abundant rER

Answer 372

chief cell = secretory cell. Electron micrograph of rER in a chief cell of the stomach shows membranous cisternae “C” closely packed in “parallel arrays”. The particles attached to the exterior surface of the membrane are ribosomes

Answer 373

the protein making machine

Answer 374

Small particles 15 to 20 nm in diameter and contain ribosomal RNA and protein (made in nucleoulus)

Answer 375

(40S): 1 RNA molecule + 33 proteins

Answer 376

(60S) binds to membrane of rER: 3 RNA molecules + 49 proteins

Answer 377

associating with mRNA

Answer 378

polysomes = clusters of 10-20 ribosomes

Answer 379

synthetize proteins that remain in the cytoplasm.

Answer 380

spiral shaped polyribosomes. Electron micrograph of the rough endoplasmic reticulum (rER) and polyribosome complexes

Answer 381

The large spiral cytoplasmic assemblies (arrows) are chains of ribosomes that form polyribosomes that are actively engaged in translation of the mRNA molecule.

Answer 382

signal sequence (signal peptide SP)

Answer 383

signal recognition particle (SRP)

Answer 384

The first 15 to 60 amino acids on the amino-terminus forms a signal sequence (signal peptide SP) * The signal peptide interacts with a signal recognition particle (SRP) * The complex SRP–polyribosome arrests polypeptide synthesis and moves to the rER membrane * SRP binds to a docking protein of rER * Now, synthesis resumes with peptide going into lumen of rER. * Dissociation of the SRP–docking protein complex from the ribosome and rER membrane occurs * Protein synthesis continues towards the lumen of the rER

Answer 385

Electron micrograph of the rER and polyribosome complexes. We can see pores, nucleous, nuclear membrane, cisternae of rER

Answer 386

-Glycosylation – Disulfide-bond – Hydrogen-bond – Protein folding is achieved with the help of proteins called chaperones. they need more processing

Answer 387

Properly modified proteins are concentrated in a lumen of the rER to be delivered to the Golgi. Proteins secreted by the constitutive pathway, are delivered to the Golgi apparatus within minutes

Answer 388

a communication problem between rER and Golgi Apparatus. characterized by inability of rER to export a mutated protein to Golgi apparatus. In alpha1- antitrypsin (A1AT [gets accumulated in the rER without doing its function]) deficiency, one single amino acid substitution causes accumulation of defective A1AT within the rER cisterna of liver hepatocytes. The result is impaired liver function. Also the lack of enzyme contributes to cause emphysema in the lungs. (basically damages the alveolos of lung)

Answer 389

Electron micrograph of a hepatocyte from the liver of a child with α1-antitrypsin deficiency. The arrow shows the accumulation of α1-antitrypsin within the rER causing impaired function

Answer 390

Emphysema; alpha1- antitrypsin (A1AT) deficiency

Answer 391

in small transport vesicles

Answer 392

Electromyograph of hepatocyte showing rER and Golgi apparatus. also transport vesicles full of proteins to be transported to the golgi

Answer 393

the golgi apparatus

Answer 394

COP I nad COP II

Answer 395

mediates transport vesicles originating in the Golgi back to rER, as well as retrograde transport between Golgi cisternae. This retrograde transport returns proteins mistakenly transferred to the Golgi

Answer 396

coats the transport vesicles responsible for the anterograde transport that mediates transport of proteins from rER to Golgi.

Answer 397

Camillo Golgi's drawings of cells in spinal ganglia (1898).

Answer 398

In 1897 Camillo Golgi studying the nervous system with his “black reaction” (silver impregnation) described an intracellular structure called like that

Answer 399

Impregnated with silver or osmium (osmiophilic) appears as juxtanuclear structure

Answer 400

appeared unstained with most histological stains including hematoxylin or eosin (H&E). The term "negative Golgi” was used for that unstained region of the cytoplasm

Answer 401

parallel stacks of flattened closely apposed, membrane-bound saccules or cisternae, and associated vesicles

Answer 402

present in all cells and it is well developed in secretory cells

Answer 403

PLASMA CELLS (secretory cells that produce immunoglobulins) – “Negative Golgi”

Answer 404

Negative golgi, lack of staining in the apical region

Answer 405

Electron micrograph of Golgi Apparatus; cis-golgi network, rER; vesicles

Answer 406

Convex cisterna, osmiophilic, closest to rER. Mannose phosphorylation (M-6-P) occurs here (for proteins that go to the lysosomes). It stains in EM.

Answer 407

Nicotinamide adenine dinucleotide phosphatase (NADPase) * N-acetyl glucosamine transferase (agt)

Answer 408

Concave cisterna, stains for sialyl transferase and galactosyl transferase * Thiamine pyrophosphatase activity. * Site of condensing vacuoles and vesicles

Answer 409

The Golgi apparatus in a cultured fibroblast stained with a fluorescent antibody that recognizes a Golgi resident protein.

Answer 410

1. Posttranslational modification, sorting and packaging of secretory products synthesized in rER. 2. Synthesis of some carbohydrate components of complex glyco-proteins associated with glycosyl transferase. GAGs, glycoproteins, glycolipids, proteoglycans. 3. Trimming of oligosaccharides in glycolipids and glycoproteins 4. Transport and modification of membrane proteins and glycolcalyx 5. Mannose-6-phosphate is added to proteins destined for lysosomes (phosphorilation of proteins)

Answer 411

Condensing vacuole in formation for cytoplasm, secretory cell. This electron micrograph shows the extensive Golgi apparatus in a cell of the pancreas. The flattened membrane sacs of the Golgi apparatus are arranged in layers. The cis-Golgi network (CGN) is represented by the flattened vesicles on the outer convex surface, whereas the flattened vesicles of the inner convex region constitute the trans-Golgi network (TGN). Budding off the TGN are several condensing vesicles (vacuoles) (1). These vesicles are released (2) and eventually become secretory vesicles (granules)

Answer 412

attached to proteins, determine intracellular location/destine of the protein. Sorting signals can be linear polypeptide arrays or carbohydrate molecules

Answer 413

apical plasma membrane (mas sencillo) basolateral plasma membrane endosomes or lysosomes apical cytoplasm

Answer 414

Many extracellular proteins and membrane proteins are delivered to this site. The constitutive pathway most likely uses non-clathrin-coated vesicles

Answer 415

Proteins with specific sorting signal attached to them by the TGN. This constitutive pathway uses vesicles coated with unique proteins that bind to epithelium-specific adaptor proteins. The transported membrane proteins are continuously incorporated into the basolateral membranes. Present in most polarized epithelial cells.

Answer 416

The majority of proteins destined to organelles have specific signal sequences. Enzymes destined to lysosomes use Mannose-6-phosphate (M-6-P) markers and are delivered to early or late endosomes. occurs in the cis with specific signal

Answer 417

Proteins stored in large secretory vesicles undergo a maturation process and are retained within the vesicle. Eventually fuse with plasma membrane to release secretory product by exocytosis. Characteristic of secretory cells in exocrine glands. they have to live in the cytoplasm for a while until the signal arrived for them to be secreted.

Answer 418

apical plasma membrane (mas sencillo) basolateral plasma membrane endosomes or lysosomes apical cytoplasm

Answer 419

Light micrograph of pancreatic acinar cells (H&E). Apical region showing secretory granules

Answer 420

Electron micrograph of pancreatic acinar cells showing mature secretory granules (S)

Answer 421

Transfer Electron Microscopy (TEM) shows a system of cytoplasmic membrane-enclosed compartments associated with all endocytotic pathways. AN early endosome.

Answer 422

Describes early and late endosomes as stable cellular organelles connected by vesicular transport with the cell exterior and with the Golgi apparatus. Coated vesicles fuse only with the early endosomes because they have specific surface receptors

Answer 423

Early endosomes are formed de novo from endocytotic vesicles, their composition changes as some components are recycled between the cell surface and the Golgi. The maturation leads to the formation of late endosomes and then to lysosomes

Answer 424

to sort and recycle proteins internalized by endocytotic pathways

Answer 425

in early endosome is less acidic, more basic, in late endosome it turn more acidic and in lysosome is acidic in order to degrade . Each transport add a proton H+ to make the environment more acidic for degradation

Answer 426

Membrane-bound organelles, containing 50 or more hydrolytic enzymes. They are responsible for the degradation of macromolecules derived from endocytotic pathways and the cell itself

Answer 427

Present in all cells. Abundant cells of inflammatory pathways (macrophages and neutrophils)

Answer 428

sites of intracellular digestion

Answer 429

-Endocytosis: Macromolecules brought into the cell (cell “eating”) – Autophagy: Turnover of cellular components (cell “eating itself”)

Answer 430

Acid phosphatase staining: Histochemical method used to identify lysosomes. However eaarly endosome doesnt stain here.

Answer 431

Electron micrograph of phosphatase acid reaction staining in lysosome.

Answer 432

lysosomes, mitochondria; primary lysososme since it hasnt digested what its going to degrade.

Answer 433

In early and late endosomes, lysosomes and golgi

Answer 434

resistant to the hydrolytic digestion occurring in their lumen. *Unusual phospholipid structure: Cholesterol + lysobisphosphatidic acid

Answer 435

-Lysosome-associated membrane proteins (LAMPs) * Lysosomal membrane glycoproteins (LGPs) * lysosomal integral membrane proteins (LIMPs) * Proton H+ pumps, transport proteins.

Answer 436

Proteins secreted to the cell > surface > endocytosed > early endosomes > late endosomes > lysosomes.

Answer 437

Proteins exit the Golgi in clathrin-coated vesicles > late endosomes > lysosomes

Answer 438

are internalized by both receptor mediated endocytosis and pinocytosis (red arrows) -> endosome -> late endosome -> lysosome

Answer 439

such as bacteria and cellular debris are delivered via the phagocytotic pathway (blue arrows) -> phagosome -> late endosome -> lysosome

Answer 440

when the cell uses lysosomes to digest itself by creating a membrane from sER

Answer 441

-macroautophagy -microautiphagy -chaperone-mediated autophagy

Answer 442

a portion of the cytoplasm or an entire organelle is surrounded by an intracellular membrane of the endoplasmic reticulum to form a double-membraned autophagosome vacuole. After fusion with a lysosome they are degraded

Answer 443

cytoplasmic proteins are internalized into lysosomes by invagination of the lysosomal membrane

Answer 444

to lysosomes is the most selective process for degradation of specific cytoplasmic proteins. Participation of proteins called chaperones. The chaperone protein (hsc73) binds to the protein and transports it into the lysosomal lumen, and it is degraded.

Answer 445

Autophagosomes

Answer 446

Undigested residues from both autophagy and heterophagy form Residual bodies. Also called lipofuscin pigment when identified in neurons with light microscopy techniques

Answer 447

Yes, via proteosomes which destroy abnormal proteins misfolded, short-lived regulatory proteins, transcriptional factors.

Answer 448

ATP dependent

Answer 449

Ubiquitin 4 molecules

Answer 450

accumulation of tau protein (alzheimers); human papilloma virus

Answer 451

Provide energy for biosynthetic and motor activities of cells, mir=tochondrial DNA encodes 13 enzymes involved in oxidative phosphorilation, 2 rRNAs, 22 transfer (RNAs).

Answer 452

Chaperone proteins assist in translocation of proteins

Answer 453

Electron micrograph of skeletal muscle, showing abundant mitochondria in the intermyofibrillar spaces in striated muscle cells

Answer 454

Mitochondria

Answer 455

Fluorescent microscopy of cells were fixed and stained with phalloidin stain conjugated with fluorescein dye. Phalloidin binds and stabilizes actin filaments, preventing their depolymerization. Accumulation of actin filaments at the periphery of the cell just beneath the plasma membrane. These cells were also stained with two additional dyes: a mitochondria-selective dye (i.e., MitoTracker Red) that allows the visualization of mitochondria (red) in the middle of the cell and DAPI stain that reacts with nuclear DNA and exhibits blue fluorescence over the nucleus

Answer 456

Mitochondria within hair cells of a sensory system in fish. 3-D reconstructions of sensory hair cell patches with mitochondria labeled with Mito-Tracker in white. Scale Bar: 5um.

Answer 457

Permeable, voltage-dependent anion channels called porins. Posses TOM complexws for importing proteins into the intermembrane space. Also contains Acetyl CoA, phospholipase A2, monoamine oxidase, synthase

Answer 458

impermeable, has cristae for amplification of furcae area for efficiency of energy generation. Steroid metabolism, wich in phospholipid cardiolipin makes the membrane impermeable of ions.

Answer 459

Elementary particles, for oxidative phosphorilation, for ATP generation.

Answer 460

Space between the inner and outer membranes and contains specific enzymes that use ATP. These enzymes include creatine kinase, adenylate kinase, and cytochrome c. The latter is an important factor in initiating apoptosis

Answer 461

Surrounded by the inner mitochondrial membrane and contains the soluble enzymes of the citric acid cycle (Krebs cycle) and the enzymes involved in fatty-acid β-oxidation

Answer 462

Store Ca2+ and other divalent and trivalent cations. Mitochondria can accumulate cations and regulate the concentration of cations in the cell, a role they share with the sER. The matrix also contains mitochondrial DNA, ribosomes, and tRNAs

Answer 463

matrix granules

Answer 464

mitochondria dividing by fission

Answer 465

BCl2 regulates eprmeability adn leads to irreversible release of cytochrome c

Answer 466

1) The orthodox configuration, the cristae are prominent, and the matrix compartment occupies a large part of the total mitochondrial volume. This configuration is observed in healthy cells. 2) The condensed configuration is characterized by unfolded cristae that are not easily recognized and the intermembrane space increases to as much as 50% of the total volume of the organelle. These changes expose cytochrome c and facilitate its release from the mitochondria during apoptosis.

Answer 467

orthodox config and condensed config

Answer 468

Metabolically active tissues that use large amounts of ATP, such as muscle cells and neurons, are the most commonly affected. Myoclonic epilepsy with ragged red fibers (MERRF) * Is characterized by muscle weakness, seizures, and cardiac and respiratory failure. Microscopic examination of muscle tissue from affected patients shows aggregates of abnormal mitochondria. * MERRF is caused by mutation of the mitochondrial DNA gene encoding tRNA for lysine (to add a lysine amino acid). This defect affects the electron-transport chain of respiratory enzymes affecting ATP production

Answer 469

Small membrane bound organelles, containing more than 40 oxidative enzymes. Lack acid phosphatase (found in lysosome). H2O2 (hydrogen peroxide) is a product of oxidation reactions and it is a toxic substance. Excess hydrogen peroxide is destroyed by the enzyme catalase.

Answer 470

Abundant in liver and kidney, the number of peroxisomes increases in response to diet, drugs, and hormonal stimulation. In liver, peroxisomes are responsible for detoxification of ingested alcohol

Answer 471

crystalloid of urate oxidase

Answer 472

Peroxisomes; crystalloid of urate oxidase

Answer 473

Glycogen (alpha particles) in liver

Answer 474

Electron micrograph of skeletal muscle showing mitochondria and abundant amount of glycogen particles (beta)

Answer 475

lipid droplets, energy store abundant in sER

Answer 476

Melanin pigment

Answer 477

Lipofuscin pigment, brownish gold; wear and tear, cellular aging.

Answer 478

Lipofuscin is a aggregation of oxidized lipids, phospholipids, metals, and organic molecules that accumulate within the cells as a result of oxidative degradation of mitochondria and lysosomal digestion.

Answer 479

Electron micrograph of aneuron showing a group of neurofilaments and residual bodies (lipofuscin pigment in light microscopy

Answer 480

microvilli, brush border of small intestine

Answer 481

Epididymis with stereocilia

Answer 482

Tracheal epithelium with cilia

Answer 483

microvilli of intestinal "finger-like structures"

Answer 484

stereocilia

Answer 485

bundle of parallel microfilaments, striated border

Answer 486

absorption, increase surface area for better absorption.

Answer 487

periodic acid stain, stains carbohydrates due to glycocalyx in microvilli

Answer 488

microvilli

Answer 489

microvilli on intestinal cell showing central bundle of actin-containing microfilaments

Answer 490

microvilli with core bundle of actin filaments and actin filaments as a loose meshwork in cytoplasm below microvilli

Answer 491

Bundle of actin filaments in cross section in microvilli

Answer 492

cross-linked: fimbrin, fascin, espin attaches to plasma membrane: myosin I anchored at tip: villin terminal web: myosin II, spectrin, alpha-actinin

Answer 493

Found in male reproductive tract in the epididymis and vas deferens where they are involved in and regulate absorption of fluids from semen and in hair cells in the inner ear for perception of sound

Answer 494

Have actin bundle at core crosslink proteins: espin, fimbrin and fascin can be present villin is absent attachement to memebrane: ezrin instead of myosin I alpha-actinin can be cross-linked to other stem regions.

Answer 495

act as mechano-sensors of fluid movement in the ear which is perceived as different sounds, bending of hair cell causes calcium channels to open and depolarize the cel and stimulate adjacent auditory nerve.

Answer 496

scanning EM of stereocilia in the inner ear. (b) Espin labeled by fluorescent green marker can be seen adding at the tip of the stereocilia. (c) diagram showing the molecular mechanism for the addition of new actin molecules and crosslinking moleculesat the tip of the stereocilia

Answer 497

constant renewal of actin and crosslink proteins at the + tip, repair mechanism

Answer 498

Usher syndrome is characterized by hearing loss, visual impairment due to retinitis pigmentosa (RP), and in some cases, vestibular dysfunction. Usher syndrome is the most common cause of deaf-blindness and an important etiology underlying autosomal recessive deafness. Proteins encoded by Usher genes have been found to be particularly abundant in the stereocilia and the synaptic regions of hair cells and guide the cohesion and development of the hair bundles. Mutations in these proteins typically lead to deafness thus showing the importance of the stereocilia and the maintenance of their structure,

Answer 499

on the apical surface of many epithelial cells. They differ from both microvilli and stereocilia in having a core structure composed of an arrangement of microtubules and by their ability to move (in some types)

Answer 500

-Motile cilia which can move -primary cilia (monocilia, are imotile but have sensory function -nodal cilia (a type of monocilium that can move and its important for embryological development on te ventral node

Answer 501

commonly found on cells which are involved in moving material along their apical surfaces such as in the respiratory system (mucus) and oviduct (the oocyte), or in the form of flagella for moving the entire cell (sperm

Answer 502

motile citia

Answer 503

motile cilia in the trachea for movement of mucus.

Answer 504

motile cilia in the oviduct (thicker)

Answer 505

9+2 arrangement of microtubules

Answer 506

radial spokes

Answer 507

nexin-linking protein

Answer 508

9 triplet strcuture

Answer 509

the bending of cilia.

Answer 510

a-subfier (13 protofilamets) and b-subfiber (10-11 protofilaments)

Answer 511

basal bodies of motile cilia

Answer 512

Nexin link, radial spoke, a-subfiber, b-subfiber, dyenin arms

Answer 513

Requires ATP hydrolysis. This is the forward effective stroke. * The elastic recoil of the nexin and radial arm proteins then returns the cilium to original position (recovery stroke) * The adjacent cilia beat in a coordinated metachronal rhythm which is a wave of movement to rpopel fluid like trapped bacteria along the epithelium

Answer 514

either by duplication of existing centrioles (centriolar pathway) or by a denovo pathway (acentriolar pathway)

Answer 515

basal bodies, axoneme, basal foot, striated rootlet, transitional zone

Answer 516

basal bodies

Answer 517

have a 9 + 0 pattern of microtubule doublets, no dyenin arms; non-motile

Answer 518

Are present on most cells in epithelial, connective, muscle and nervous tissues

Answer 519

monocilia (primary cilia)

Answer 520

monitor fluid flow through the kidney tubules, biliary tubules, brain ventricles, and auditory system. * There presence has been found to be critical for function in the organs in which they are present

Answer 521

initiate signaling cascades within the cell by movement of fluid.

Answer 522

unique form of monocilium found on cells in the region of the ventral node in the developing embryo and are thought to be important for determining the left-right patterning of the embryo

Answer 523

+ 0 pattern of microtubule doublets like primary cilia but are motile since they have dynein arms. This distinguishes them from primary cilia (monocilia), only asingle ciliu present

Answer 524

This figure shows a scanning EM (A) of nodal cilia on the surface of nodal cells in the ventral node

Answer 525

Nodal cilia

Answer 526

In the region of the primitive node in the embryo they rotate in a clock-wise manner and generate a leftward or “nodal” fluid flow which is detected by sensory receptors on the left side of the embryo and helps to establish left-right symmetry of the organs.

Answer 527

cause “situs inversus” in which the heart and other organs appear on the wrong side of the body in approximately 50% of the patients with the defects

Answer 528

kinesin II; dyenin

Answer 529

provides precursor molecules to tip of cilia and removes old molecules

Answer 530

Mutations in genes encoding the proteins in the IFT-A and IFT-B complexes result in loss of cilia or result in ciliary dysfunctions. For instance, mutations in the genes for kinesin II the main anterograde transport protein in cilia (KIF3A/KIF3B/KAP3 trimeric complex) can result in either very short or absent cilia; resulting in ciliary disfunction related to a number of clinical conditions called ciliopathies.

Answer 531

* Autosomal dominant polycystic kidney disease (ADPKD) resulting in cysts in kidney leading to renal failure, and can also cause cysts in pancreas and liver * Chronic infections of the lungs & upper airways due to inability of the respiratory cells to move mucus along their surface. For example, Kartegener’s syndrome. * Situs Inversus with inversion of the side on which organs occur. As noted above this may be primarily related to defects in the nodal cilia * Infertility in males due to immotile sperm * An increased rate of ectopic pregnancy in affected females that cannot properly move the oocyte along the oviduct * Hydrocephalus internus (accumulation of fluid in the brain ventricles) may occur in patients due to defective motile cilia on the ependymal cells lining the cerebrospinal fluid-filled spaces in the brain

Answer 532

Autosomal dominant polycystic kidney disease (ADPKD) is the major type of polycystic kidney disease (PKD). It is characterized by formation of multiple fluid-filled cysts which destroy the renal cortex leading to more than half of patients progressing to renal failure. * ADPKD is associated with mutations in the Pkd1 and Pkd2 genes which encode for the proteins polycystin-1 (PC1) and polycystin-2 (PC2) in the membrane of the primary cilium. These proteins normally interact to form an ion channel complex that is necessary for signaling pathways and for the mechanosensory function of the primary cilium. The exact mechanism by which the mutations lead to formation of the cysts, however, is still unclear. * Individuals with ADPKD often exhibit other pathologies not associated with the kidney that are attributed to ciliary abnormalities. These include cysts in the pancreas and liver that are accompanied by an enlargement and dilation of the biliary tree system

Answer 533

Congenital abnormality typically involving absence of the motor protein dynein from motile cilia and nodal cilia Kartagener’s Syndrome can result in defects in ability of respiratory epithelial cells to transport mucus (mucociliary transport) in the tracheo-bronchial tree. This results in chronic respiratory disorders (bronchitis and sinusitis), otitis media (inflammation of middle ear), persistent cough, and asthma

Answer 534

Lack of dyenin arms, kartagener's syndrome