Cell biology II Flashcards Preview

Year 1 Cell Biology > Cell biology II > Flashcards

Flashcards in Cell biology II Deck (54):
1

What is the contribution, in percentage, of proteins to the plasmalemma?

25-75%

2

Beta-amyloid precursor protein is important in what (five) cellular processes?

1) Neuronal migration during development2) Synaptic formation and repair3) Cell signaling4) Long-term potentiation5) Cell adhesion

3

What is the causative molecule involved in Creutzfeld-Jakob disease?

A variant prion protein

4

What is the normal prion protein (PrP) involved in, normally?

Cell surface, glycosylated GPI anchor within lipid rafts

5

What does the variant prion protein do in Creutzfeld-Jakob disease?

Crosslinks filaments that are resistant to proteolysis and accelerates formation of other variants of the same form

6

Normal prion proteins are implicated in what cellular processes?

1) Neuroprotective against ischemia2) Control Circadian rhythms3) Serve to organize myelin sheath

7

What do carrier proteins do?

Transport one or two chemicals in one direction, or two molecules in opposite directions without energy expenditure

8

What are protein pumps?

Transport proteins requiring the direct expenditure of energy

9

What does the Na/K pump do?

1) Cleaves ATP to transport three Na out of the cell and two K into the cell2) Functions to regulate intracellular volume

10

What does digoxin do?

Partially inhibits Na/K pump, leading to decreased activity of Ca/Na transporter. Result is an increase in sarcoplasmic [Ca]

11

What are multidrug resistant transporters (MDRs)?

Subfamily of primary transporter proteins that are ATPases

12

Where is MDR-1 expressed?

1) Kidney2) Intestine3) Liver4) BBB

13

What does overexpression of MDR cause?

Causes some cancer cells to become resistant to cytotoxic drugs

14

How is MDR-1 overexpression combatted pharmacologically?

1) RNA interference2) Pharmacological inhibitors

15

What does MDR-2 transport?

Direct bilirubin

16

Which transporter is responsible for direct bilirubin?

MDR-2

17

Which protein is defective in Dubin-Johnson Syndrome?

MDR-2

18

A defect in MDR-2 leads to what disease?

Dubin-Johnson Syndrome

19

Where is MDR-3 expressed?

Liver

20

What is the function of MDR-3?

Flippase of phosphatidylcholine - flips it to the the outer canalicular membrane of hepatocytes so that it may be excreted into bile

21

What are aquaporins?

Protein channels for water

22

What are the protein channels for water called?

Aquaporins

23

How many isoforms of aquaporins are there?

12

24

Aquaporin-2 is expressed by what type of cell?

Renal collecting tubule cells

25

Renal collecting tubule cells express what protein channel, specifically?

Aquaporin-2

26

What induces translocation of aquaporin receptors to the plasma membrane of collecting tubule cells?

Vasopressin

27

What does the translocation of aquaporin receptors to the plasma membrane of collecting tubule cells do to water reabsorption across their apical domain?

Increases reabsorption

28

Nephrogenic diabetes insipidus results from mutation of both ________ genes

Aquaporin-2

29

Mutations in both genes of aquaporin-2 results in what disease?

Nephrogenic diabetes insipidus

30

What kind of channel is CFTR?

Chloride channel

31

What does CFTR regulate in addition to chloride?

Na and HCO3-

32

Na and HCO3- is regulated by what channel?

CFTR

33

Where are glycolipids found, exclusively?

Noncytosolic lipid monolayer (also found in some intracellular membranes)

34

What glycolipid serves as a receptor for cholera toxin?

Ganglioside Gm1

35

Ganglioside Gm1 serves as a receptor what what toxin?

Cholera toxin

36

What does cholera toxin do once it binds to ganglioside Gm1 receptor?

Ramps up synthesis of cAMP, leading to efflux of Na and water into intestinal lumen

37

Carbohydrates in the plasmalemma have what charge?

Negative

38

What are the five pathways for endocytosis?

1) Macropinocytosis2) Clathrin-mediated endocytosis3) Non-coated-mediated endocytosis4) Caveolae-mediated endocytosis (Simian virus 40)5) Phagocytosis

39

Where does macropinocytosis occur?

Thyroid cells as they take up thyroglobulin and dendritic cells for immune surveillance

40

Macropinocytosis relies on what type of cytoskeletal element?

Actin

41

Is macropinocytosis specific or nonspecific for its substrate?

Nonspecific

42

What molecule is required to pinch off the vesicle in clathrin-mediated endocytosis?

Dynamin (GTPase)

43

Can clathrin-mediated endocytosis be mediated by receptors?

Yes

44

What are two examples of receptor-mediated clathrin-mediated endocytosis?

1) Cholesterol (in LDL form) 2) Protein hormones

45

Where are cargo receptors located in clathrin-mediated endocytosis?

Coated pits

46

What molecule associates with the intracellular portion of the cargo receptor in clathrin-mediated endocytosis?

Adaptin

47

What is the role of adaptin in clathrin-mediated endocytosis?

Associates with the intracellular portion of the cargo receptor

48

What condition occurs when there is a decrease or defect in LDL receptors?

Atherosclerosis

49

Recycling of synaptic vesicles is performed by what type of endocytosis?

Clathrin-mediated endocytosis

50

Cholera and Shiga toxins enter the cell via what endocytotic mechanism?

Non-coated-mediated endocytosis

51

Is phagocytosis receptor-mediated?

Yes, generally (zipper-mediated)

52

Phagocytosis is dependent on what type of cytoskeletal component?

Actin

53

Does phagocytosis require clathrin?

No

54

What do phagosomes fuse with?

Lysosomes