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Microanatomy > SM01 Mini1 > Flashcards

SM01 Mini1 Flashcards

1
Q

Prokaryote

A

no nuclear membrane

no organelles

has cell wall b/c no cytoskeleton

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2
Q

Eukaryote

A

no cell wall

Organelles: membraneous nucleus, mitochondira, endoplasmic reticulum (rough & smooth), Golgi body, Ribosomes, Lysosomes, Peroxisomes, cytoskeleton (plants only: chloroplasts & rigid cell wall)

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3
Q

Nuclear Envelope

A

2 membranes surrounding eukaryotic cell nucleus

continuous at nuclear pore complexes (3000 on average)

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4
Q

Plasma Membrane

A

phospholipid bilayer surrounding cell

selective barrier for protection

also contains proteins & cholesterol

all membranes 7.5-10nm thick

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5
Q

Cytoplasm

A

everything inside the plasma membrane except nucleus

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6
Q

Cytosol

A

intracellular gelatinous fluid

everything outside organelles, but inside the cell

cytoskeleton, free protein, organic molecules, fatty acids, sugars, amino acids, salts & H2O

contains non-membrane bound organelles (ribosomes, proteosomes)

70% cell volume

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7
Q

Organelle

A

intracellular membrane bound body with a specific task

distinct structure, macromolecular composition, & function

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8
Q

Extracellular Fluid

A

fluid of the environment

outside of cell

composition: [Na+]0=145mM, [K+]0=4.5mM,

[Ca2+]0=10-3M, [Cl-]0=102mM, [protein]= 1mM

pH=7.4

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9
Q

Phosopholipid

A

outer & inner leaflets create plasma membrane

Parts: polar head group, glycerol, fatty acid chain (saturated or unsaturated)

types: 1. phosphatidylethanolamine (ethanolamine + phosphate), 2. phosphatidylcholine, 3. sphingomyelin (has choline), 4. phosphatidylserine, 5. phosphotidylinositol

free lateral & rotational movement, VERY RARE flipping

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10
Q

Antibiotic

A

water soluble substance derived from a mold or bacterium that inhibits the growth of other microorganisms

Either attack cell wall biosynthesis enzymes or enzymes whose bacterial counterparts are vastly different than our own

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11
Q

Functions of Plasma Membrane

A
  1. Physical barrier
  2. Selective permeability
  3. Electrochemical gradient
  4. Communication: molecular signaling
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12
Q

Cholesterol

A

steroid, lipid soluble, amphiphilic -OH head group

readily flips sides of membrane (smaller head group)

synthesized in ER

precursor to ALL steroids

function: immobilize first few hydrocarbons of phospholipids (decreases membrane permeability) & prevents crystallization of hydrocarbons at low T (only applicable to cold-blooded animals)

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13
Q

Membrane Fluidity

A

viscosity of lipid bilayer of membrane

influence by: T (increase with T), lipid composition (unsaturated, more fluid), cholesterol composition (more cholesterol, less fluid [except at very low T])

Purpose: change shape for bud off and fusing w/vesicle

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14
Q

Endocytosis

A

import material from outside to inside by surrounding and pinching off membrane around said material

creation of vesicle

*membranes retain orientation during transfer between cellular components

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15
Q

Exocytosis

A

exportation of material by surrounding and pinching off of membrane around said material

releasing of vesicle

*membranes retain orientation during transfer between cellular components

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16
Q

Membrane Proteins

A

types: transmembrane, monolayer associated, lipid-linked, & protein attached (peripheral- removed w/high salt)

all others removed with organic detergent

mobile & fluid throughout membrane, restricted by tethers intra- or extracellularrly or binding to protein on another cell surface (desmosome)

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17
Q

Transmembrane Protein

A

can work on both sides of membrane

approximately 20aa alpha helix to cross once

removed by organic detergent

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18
Q

Monolayer-associated Proteins

A

anchored to cytosolic leaflet by amphipathic alpha helix

removed by organic detergent

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19
Q

Lipid-linked Protein

A

attached to either leaflet by a lipid

cytosolic- fatty acid chain or prenyl group

extracellular- GPI anchor on phosphotidylinositol

removed by organic detergent

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20
Q

Protein-attached Proteins

A

don’t penetrate membrane, but on both sides

not covalently linked to any membrane components

ionic interactions with membrane components

removed with high salt concentration, doesn’t disrupt membrane integrity

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21
Q

Microscopy visualization

A

minimum naked eye= 0.2mm= 2000nm

light microscope= 200nm-2000nm

electron microsope=0.2nm-200nm

mitochondria=2000nm=2 micrometers

average human single cell= 10-20 micrometeres

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22
Q

Lipid Raft

A

lipid domains with different composition that bind or travel together trough membrane

interaction/aggregation of sphingomyelin, glycolipids, & cholesterol (proteins with longer transmembrane domains & GPI-linked)

more ordered & tightly packed that bilayer

compartmentilize cellular processes, some form caveolae

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23
Q

Glycosylation

A

addition of carbohydrate to protein or lipid

occurs in lumen of ER & Golgi

if membrame destined, carbohydrate always found on outer leaflet

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24
Q

Permeability of Membrane

A

synthetic model

all hydrophobic molecules: O2, N2, CO2, benzene

some small uncharged polar: H2O, urea, glycerol

few large uncharge polar molecules: glucose, sucrose

NO ions!

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25
Q

Intracellular Fluid

A

aka cytosolic fluid

composition: [Na+]0=15mM, [K+]0=120mM,

[Ca2+]0=10-7M, [Cl-]0=20mM, [Protein]= 4mM

pH=7.2

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26
Q

Plasma Membrane Protein Function

A
  1. transport
  2. anchor
  3. receptor (communication)
  4. enzyme
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27
Q

Ribosome

A

large & small subunits made of protein & RNA

perform RNA translation to protein (1º structure)

found in the cytosol & on ER

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28
Q

Cytoplasmic Inclusions

A

nonmolite

no membrane

composed of accumulated metabolites

mainly: fat droplets, glycogen granules, & lipfuscin granules

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29
Q

Fat Droplet

A

no membrane, spheroid

type of cytoplasmic inclusion

accumulation of lipid molecules

mostly found in adipocytes, adrenal cortex cells, liver

often in association with smooth ER (where lipids are made)

clear in EM picture

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30
Q

Gylcogen Granules

A

aka rosettes

type of cytoplasmic inclusion

stored energy source

no membrane

aggregates of glycogen

mostly in liver & skeletal muscle

dense, dark no clear shape in EM picture

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31
Q

Lipfuscin Granules

A

type of cytoplasmic inclusion, but sometimes has membrane

small, pigmented golden-brown in LM

accumulated waste product

occur with age in stable non-dividing cells ie. neurons & muscle

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32
Q

Cytoskeleton

A

network of protein filaments criss-crossing the cell

constantly assembling & disassembling

cell shape, movement of intracellular material, motility of cell

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33
Q

Microtubules

A

Subunit: Tubulin (alpha & beta heterodimers)

functions: intracellular organelle transport, form cilia & flagella, form mitotic spindle

beta points to + end; alpha to - end

grows & shrinks at + end

bound to GTP, conversion to GDP signals tubulin breakdown

13 protofilaments form hollow tube

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34
Q

Microfilaments

A

aka Actin (after subunit)

function: shape at cell’s surface, rearranging powers locomotion, form contractile ring during mitosis

2 standed helix add at + end

G actin: free globular actin monomers

F actin: assembled in filaments

treadmilling: subunit travels through filament & falls off - end, occurs when rate of addition= rate of falling off

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35
Q

Intermediate Filaments

A

Subunit: several proteins

function: provide mechanical strength & form nuclear lamina

monomer → dimer (coiled together) → staggered tetramer → 8 tetramers twisted into ropelike filament

very tough, survive cell death

ex. hair, nails, outer layer of skin

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36
Q

Dyenin

A

protein motor on microtubules

transports material to - end (nucleus)

uses ATP

slides microtubule doublet past another to bend cilia or flagella

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37
Q

Kinesin

A

protein motor on microtubules

transports material to + end (cell periphery)

uses ATP

38
Q

Myosin

A

motor protein on actin that slides one filament across another

uses ATP

basis of contraction

39
Q

Cilia

A

beat back & forth to moe material past

short & numerous

made of microtubules (9+2 formation of doublets)

use of basal bodies instead of centrosome for nucleation

ex. respiratory tract

40
Q

Flagella

A

beat back & forth to move cell

long & few

made of microtubules (9+2 formation doublets)

use of basal bodies instead of centrosome for nucleation

ex. sperm tail

41
Q

Lamellipodia

A

thin foot

leading edge of cell during cell motility driven by actin polymerization

42
Q

Fillopodia

A

thread foot

slender cytoplasmic projections that extend beyond lamellipodia in migrating cells

form adhesions with substratum

sense cheomtropic cues & change direction

43
Q

Microvilli

A

formed by dense bundle of cross-linked actin filaments that are linked to terminal web

increase cell surace area for absorption, secretion, cellular adhesion, & mechanotransduction

44
Q

Desmosomes

A

link intermediate filament networks of adjoining cells to hold tissue together

45
Q

Types of Intermediate Filaments

A

Cytoplasmic: keratins (epithelia), vimemtin & related (connective tissue, muscle, & glial cells), neurofilaments (nerve cells)

Nuclear: nuclear lamins

46
Q

Nuclear Lamins

A

intermediate filament inside of nuclear envelope of all cells

control assembly of nuclear envelope & organization of perinuclear chromatin

47
Q

Centrosome

A

microtubule organizing center

1 in interphase, 2 in mitosis

anchors - end (alpha side) near nucleus in interphase or spindle poles in mitosis

2 centrioles at 90º from each other

48
Q

Centriole

A

nine triplets of microtubule with protein links between them

two together at 90º make up a centrosome

49
Q

Pericentriolar Matrix

A

PC

cloud of protein around centrioles in which their - ends are embedded

contain gamma-tubulin in rings= nucleating sites

50
Q

Basal body

A

made of two centrioles at 90º

but no Pericentriolar matrix with gamma-tubulin nucleating rings

51
Q

ARP

A

actin-related proteins

begin assembly of filaments, but don’t cap so monomers can still fall off

most frequently nucleated at or near plasma membrane

52
Q

Spectrin

A

stabilizes actin filaments that make up the terminal web

binds them to the apical cell membrane

53
Q

Taxol

A

chemotherapeutic drug that binds & stabilizes microtubules

thus inhibiting cell division

54
Q

Nucleus

A

organelle in eukaryotes, “brain of the cell,” houses DNA

functions: cellular regulation (genetic material) & production of ribosomal subunits

dense circle in cell on LM

most cells have one, but some have more (hepatocytes, skeletal muscle) & few have none (erythrocytes)

55
Q

Nuclear Lamina

A

composed of intermediate filaments (lamins)

functions: mechanical support, attachment site for chromatin to envelop, control nuceus disassembly during mitosis

56
Q

Chromatin

A

DNA & proteins (ie histones)

found in nucleus of eukaryotic cell

57
Q

Chromosome

A

structure of long DNA molecule & associated proteins that carry hereditary information of a human cell

46 in human

usually only seen during mitosis or meiosis

58
Q

Nucleosome

A

8 histone molecules: 2 each of H2A, H2B, H3, & H4

DNA wraps around it and is held on at Link DNA by H1 histone

59
Q

rRNA

A

ribosomal RNA

used to make ribosomes

transcribed & translated in nucleolus

knobs on top of 5 chromosomes code for these (13, 14, 15, 21, 22)

when knobs come together with cloud of assembling ribosomes, creates nucleolus (this is how you can have multiple)

60
Q

mRNA

A

messenger RNA

codes for proteins

transcribed & modified (splicing & 3’ polyadenylation) in nucleus, then transported to cytoplasm to ribosomes

61
Q

tRNA

A

transfer RNA

used during translation to carry and match up with amino acids

62
Q

Heterochromatin

A

dense black spots in nucleus on EM

highly condensed, transcriptionally inactive DNA

63
Q

Euchromatin

A

clear areas in nucleus on EM

less condensed, transcriptionally active DNA

64
Q

Telomere

A

caps the end of a chromosome so they don’t degrade

repeated nonsense DNA

65
Q

replication origin

A

when DNA or RNA polymerase binds & starts transcription

66
Q

Centromere

A

DNA location on sister chromatids that bind together

67
Q

Kinetochore

A

Proteins that bind to the centromere & link microtubules that form spindle fibers during mitosis

68
Q

NPCs

A

Nuclear Pore Complexes

VERY tightly regulated

controls movement of all macromolecules between nucleus & cytoplasm

ions, ATP & <50kDa proteins diffuse freely

69
Q

Targeting Signal

A

organelle specific proteins MUST have one to get to its corresponding organelle

made of a unique amino acid sequence & folded in a particular parttern: single discrete stretch or juxaposition after folding

70
Q

NLS

A

Nuclear Localization Signal (or Sequence)

signal for nuclear import

usually basic amino acids

71
Q

NES

A

Nuclear Export Signal (or Sequence)

singal for nuclear exportation

usually contains hydrophobis amino acids

72
Q

Importins

A

import carriers to nucleus

binds NLS-containing import cargo→ docks at NPC→ carries through NPC→ stimulated to release cargo by RAN protein inside nucleus→ recycles back to cytoplasm

73
Q

Exportins

A

export carriers from nucleus

binds NES-containing export cargo→ docks at NPC→ carries through NPC→ stimulated to release cargo by RAN protein outside nucleus→ recycles back to nucleus

74
Q

RAN

A

small GTPase that regulates binding and release of importins & exportins

regulated by GTP or GDP form

75
Q

DNA Structure

A

Phosphate- sugar backbone: 5’C one sugar- phosphate- 3’C next sugar

sugar is deoxyribose: 5C, 5 membered heterocyclic ring (5’ is NOT in ring)

nucleosides are attached at 1’ C: can be C, G, A, or T

guanine & cytosine form 3 H bonds, adenoine & thymine form only 2

in humans: antiparallel strands form double helix

76
Q

Requirements for Genetic Material

A
  1. carry information
  2. must replicate
  3. must be able to change, mutations
  4. must govern phenotype
77
Q

DNA Replication

A

semiconservative

occurs during S (synthesis) phase during interphase

78
Q

Initiation

A

proteins bind to DNA & open helix to prepare for complementary base pairing

79
Q

Elongation

A

proteins connect the correct sequence of nucleotides to extend the new strand of DNA

80
Q

Termination

A

proteins release the replication complex

81
Q

Rules of Replication

A
  1. semiconservative
  2. starts at “origin”
  3. bidirectional
  4. semi-discontinuous
  5. synthesized in 5’ → 3’ direction
  6. RNA primers required
82
Q

Semiconservative

A

in replication each strand is a template for a new daughter strand & stays with daugther strand wehn cell divides, so each new cell has 1 parent & 1 daughter

83
Q

Ori

A

origin of replication

where DNA replication starts

many on eukaryotes, approx. every 100,000bp

84
Q

Leading Strand

A

DNA fragment going toward the replication fork

synthesized continuously

85
Q

Lagging Strand

A

synthesized in fragments (Okazaki)

moves toward origin

86
Q

Okazaki Fragments

A

short fragments of new DNA form the lagging strand template

87
Q

DNA polymerase delta

A

synthesizes lagging strand

also has exonuclease activity to correct errors in 3’→5’ direction

88
Q

DNA polymerase epsilon

A

synthesizes leading strand of DNA

also has exonuclease activity to correct errors in 3’→5’ direction

89
Q

DNA polymerase alpha

A

primase that works as DNA & RNA polymerase

RNA polymersase part provides a base paired 3’ end as a starting point for delta/epsilon by creating approx. 10 nucleotide primers

b/c DNA polymerase delta/epsilon can only add to existing strand

90
Q

Telomerase

A

enzyme with integrated RNA template for the lagging strand of the telomere

sequence is tandem repeats

RNA-dependent DNA polymerase

Microanatomy (9 decks)

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