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Flashcards in Cytology Deck (91):
1

Importance of Compartmentalization

Allows for organelles with specific chemical micro environments

2

Membrane Composition

Composed of lipids, proteins, and carbohydrates

(Lipids make up trilaminar membrane, proteins are within or attached to membranes, carbohydrates congregate to form a fuzzy coat)

3

Lipid Bilayer

Lipids that makeup the bilayer are amphipathic ( have hydrophilic heads and hydrophobic tails) results in a trilaminar appearance to the membrane. Having hydrophobic core allows for an anchoring spot for membrane proteins

4

Membrane Permeability

Membrane is permeable to small uncharged molecules. These are allowed to passively diffuse through the membrane

5

Integral Membrane Protein

Embedded in the hydrophobic region of the lipid membrane (Does not pass all the way through the membrane)

6

Transmembrane Protein

Embedded in hydrophobic core of the lipid membrane and passes all the way through the membrane

7

Peripheral Membrane Proteins

Non-embedded. Attach to integral proteins or to the hyrdophilic lipid heads

8

Transport Protein Classes

1.) Channels
2.) Carriers
3.) Pumps

9

Channel Proteins

Type or transport protein that allows for SELECTIVE passage of small charged molecules (ions) via passive diffusion

Example: Gap Junctions between adjacent cells

10

Carrier Proteins

Type of transport protein that drags a molecule across the membrane by hiding it in its cleft (Facilitated diffusion)

11

Pumps

Type of transport protein that requires ATP (active transport) to pump ions across the membrane

EX: Na/K pump

12

Receptor Proteins

Type of transmembrane protein that binds a molecule resulting in a conformational change of the protein that sends a signal for the cell to respond

13

Structural Proteins

Attach the cell to its surroundings by linking their skeletal elements to extracellular proteins

Example: Focal adhesion and Hemidesomosomes

14

Carbohydrates and the Lipid Membrane

Attach to extracellular domains of membrane proteins and lipids (forms oligoprotein and oligolipid) resulting in the appearance of a fuzzy coat

15

Glycolax

Fuzzy coat formed by carbohydrates on the lipid membrane

16

Role of Particles and Inclusions in the cell

Synthesis and storage

Ex: Ribosomes and glycogen particles

17

Ribosome

Catalyze protein synthesis ( link mRNA to tRNA to form a polypeptide)
Large and Small subunit

18

Where are the majority of proteins synthesized

Free Ribosomes

19

What proteins are synthesized in RER

Golgi proteins
Lysosomal proteins
Secretory proteins
Plasma membrane Proteins

20

Mitochondrial Protein synthesis

20% are synthesized by Mitochondrial Ribosomes

Others are synthesized by free ribosomes in the cytoplasm (nuclear transcribed)

21

Polysomes

Chain of ribosomes attached to an mRNA

22

Glycogen Particles

Storage form of polysaccharides

23

Smooth Endoplasmic Reticulum (SER)

No ribosomes
Tubular appearance

1.) Lipid and Steroid metabolism
- lipids for the cell membrane (Membrane
synthesis and recycling)
2.) Detoxification (mostly in Liver)
3.) Glycogen metabolism
4.) Calcium storage (sacoplasmic reticulum or muscle cells)

24

Rough Endoplasmic Reticulum (RER)

Ribosomes
Cisternae
Protein Secretion
- Golgi, Lysosomes, Membrane, Export

25

Golgi Apparatus Function

Modify, sort, and transport proteins

"Mailing center"

26

Areas of the Golgi

Cis Golgi (closest to RER ---> Receives protein)
Medial Golgi (middle)
Trans Golgi (closest to plasma membrane---> sends protein out)

27

Posttranslational Modification of proteins

Adding or removing sugar residues, sulfates or phosphate groups.

Begins in cis golgi, continues in medial golgi and is finalized in the trans golgi)

28

Sorting and Packaging Proteins

Happens mainly in Trans golgi
proteins get a "stamp" that tells them what pathway to go down

1.) Secretory Pathway (clathrin coat)
2.) Lysosomal Pathway (Mannose 6- Phosphate)
3.) Constitutive Pathway (No stamp)

29

Secretory Pathway

Clathrin coat added around vesicle containing secretory contents. Sheds coat when it reaches destination in the cell. Secretory Vesicle remains in the cell until it receives a signal to move to membrane for secretion of contents

30

Lysosomal Pathway

Mannose 6 Phosphate tag destines it to be a lysosome

31

Lysosome Function

Involved in digesting material taken up by the outside of the cell and degrading senesant organelles
Low pH, hydrolytic enzymes (proteases, lipases, glucosidases)

32

I-cell Disease (Mucolipidosis)

Lysosomal Storage disease caused by mutations in the enzyme that places Mannose-6 P tag is mutated causing a shift to the constitutive pathway rather than lysosomal pathway

33

I-Cell Disease Clinical Presentation

-Abnormal skeleton (cartilage has to be destroyed for bones to grow)
- Restricted joints
- Hepatomegaly
- Splenomegaly

34

Classification of Lysosomes

1.) Primary: has not met target
2.) Secondary: Lysosome + Target
3.) Lipofuscin granules

35

Lipofuscin Granules

Occurs in cells with high turnover. Lysosome gets tired and shuts down. Seen as a yellowish color on preps

Ex: adrenal cortex

36

Peroxisomes

Organelle containing oxidative enzymes such as catalase- gets rid hydrogen peroxide (biproduct of oxidation reactions in the body)

- Responsible for breakdown of long-chain fatty acids

37

Consequences of abnormal functioning peroxisomes

1.) Zellweger Syndrome
2.) Adrenoluekodystrophy

38

Zellweger Syndrome

- Mutation that results in peroxisome enzymes not being transported from the cytoplasm to the peroxisome

Without these enzymes peroxisomes do not function properly

Impacts brain development (improper formation of the myelin sheath)

Fatal (die before 6 months of age)

39

Adrenoleukodystrophy

- X-linked disorder
- Caused by disruptions of very long chain f
fatty acids (accumulations of lipids in the
brain and adrenals)

Progressive brain damage
Failure of adrenal glands
Fatal

40

Mitochondria

Production of ATP through oxidation of pyruvate and fatty acids

Sensors of cell health

All cells except RBC and Terminal keratinocytes

41

Symbiotic Hypothesis of Mitochondria

Have 2 membranes
Have own genome
Multiply through division

42

Mitochondrial membrane components

1.) Outer Mitochondrial Membrane
2.) Inner Mitochondrial Membrane
3.) Intermembrane space
4.) Mitochondrial matrix

43

Outer Mitochondrial Membrane

Contains numerous pores to allow for the passage of ions and metabolites ( important for the production of ATP)

44

Inner Mitochondrial Membrane

Thinner layer folded into cristae

Contains enzymes involved in energy production

ATP is generated here

45

Intermembrane Space

Contain enzymes that use ATP that was generated in the inner membrane

46

Cytochrome C

Located in the intermembrane space of the mitochondria

Initiates apoptosis

47

Mitochondrial Matrix

Enclosed within the inner membrane

Contains soluble enzymes (for Krebs, DNA txn, et)

Contains mitochondrial DNA and mitochondrial ribosomes

Contains electron dense granules that store Ca2+

48

Mitochondrial Myopathies

Mutations in mitochondrial and nuclear genes

49

Mitochondrial gene mutations (Mitochondrial Myopathy)

Maternal inheritance (mito comes from oocyte)

May manifest with muscle weakness, neurologic symptoms, lactic acidosis, cardiomyopathy)
*** why? Mitochondria play important role in
muscles

50

Nucleus

contains the genome of the eukaryotic cell

51

Chromatin

DNA bound to proteins

1.) Heterochromatin (tight- nondividing cells)
2.) Euchromatin (loose- seen in dividing cells)

52

Nuclear envelope components

1.) Outer nuclear membrane
2.) Perinuclear space
3.) Inner nuclear membrane
4.) Nuclear Lamina
5.) Nuclear pores

53

Outer nuclear membrane

continuous with RER and has ribosomes attached to its surface

54

Perinuclear space

Between the inner and outer nuclear membranes and continuous with the lumen of the RER

55

Inner nuclear membrane

Can bind chromatin and lamins

Supported by network of intermediate filaments

56

Nuclear Lamina

Attached to inner nuclear membrane

"Skeleton" of nucleus

Specialized intermediate filament (Lamin) is able to disassemble during mitosis and reassemble when its done

(NOTE: most Intermediate filaments are not able to dessassemble)

57

Nuclear pores

Allow passage of small particles

Larger particles must be actively transported through the membrane

58

Euchromatin

Loosely packed and seen in metabolically/ transcriptionally active cells (eg: Neurons)
- DNA is stretched out to be read and
transcribed

Stain lightly

59

Heterochromatin

Densely packed chromatin and seen in metabolically inactive cells

Stains more intensely

60

Nucleolus

Area in the nucleus where Ribosomal RNA is processed and assembled into ribosomal subunits

61

Regions of the Nucleolus

1.) Fibrillar Component
2.) Dense Fibrillar Component
3.) Granular Component

62

Fibrillar Component

Region of the nucleolus

Contains DNA loops, rRNA genes, and txn factors

(getting all the pieces together)

63

Dense Fibrillar Component

Region of the nucleolus

Contains ribosomal genes being translated and large amounts of rRNA

(putting pieces together into bigger pieces)

64

Granular Component

Region of the nucleolus

Site for ribosomal assembly

65

Cytoskeleton Function

Shape, structural support, cell motility

66

Major types of Cytoskeleton

1.) Thin filaments (actin)
2.) Microtubules
3.) Intermediate Filaments

67

Actin Classification

G-actin (globular)
F-Actin (thin filament)- polarized

68

Actin (thin filament)

Form a sheath beneath the cytoskeleton called the cortex

69

Polarity of cytoskeletal filaments

Plus end (polymerizes faster )
Minus end (polymerizes slower)

70

Cell Cortex

Formed by F-actin (thin filaments)

Functions:
- resist deformation
- transmit forces
- resist organelle movement
- resist lateral movement of some mem. prot

71

What motor protein is associated with thin filaments?

Myosin

72

Microtubules

Present in all cells (except RBC)

Polymerized from alpha and beta tubulin (polarity)

Nonbranching

73

Microtubule polarity

minus end toward the nucleus

plus end toward the membrane

74

Microtubule functions

Intracellular transport

Mitotic spindle

Cilia/Flagella beating

75

Microtubule motor protein

Dyneins (move to minus--- move toward nucleus)

Kinesins (Move to plus --- move toward periphery)

76

Axoneme

Cilia and Flagella Core

- 9 microtubule doublets (one full one partial)
- Central pair of microtubules
- Dynein arms that interact with neighboring
doublet to bend it causing a swirling motion

77

Centriole (Basal Body)

Base of cilia or flagella

- 9 microtubule triplets
- NO central pair

During mitosis they replicate and migrate to form the mitotic spindle

78

Microtubule organizing center

Gives rise to all cellular microtubules

Made up of 2 centrioles

79

Intermediate Filaments

Strong but flexible polymers that provide support for the cell

No polarity --> No Motor protein

80

Classes of Intermediate Filament

1.) Lamins
2.) Keratins
3.) Vimentin
4.) Desmin
5.) Glial fibrillary acidic protein (GFAP)
6.) Neurofilaments

*** unique to the type of tissue they are found in (clinical significance= tumor testing)

81

Lamins

Intermediate filament

Found on innerside of nuclear envelope (support)

82

Keratin

Intermediate filament

Found mostly in epithelial cells (skin)

83

Vimentin

Intermediate filament

Found in fibroblasts of connective tissue

84

Desmins

Intermediate filament

Found in muscle cells

85

Glial fibrillary acidic protein (GFAP)

Intermediate filament

These are the glial cells ( neuron support cells)

86

Neurofilaments

Intermediate filaments

Found in neurons

87

Intermediate Filament functions

Spread tensile strength
Maintain architecture
Act as cacoon when cell is damaged
Anchor ion channel proteins

88

Hemotoxylin

Basic dye that turns acidic structures blue

89

Eosin

Acidic dye that turns basic structures pink

90

Structures that would be blue on a histo prep

Acidic structures

Nucleus
Ribosomes
Glucosaminoglycans

91

Structures that would be pink on a histo prep

Basic structures

Cytoplasm
Mitochondria
Collagen