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Cell biology > Lecture 7 > Flashcards

Lecture 7 Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

receptor mediated endocytosis

A

Cells take in macromolecules

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2
Q

endocytic pathway

A
  • Membrane-bound compartments

- Early endosomes, Late endosomes and Lysosomes

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3
Q

early endosomes

A

-recycling and sorting

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4
Q

receptors release ligands at

A

low pH. change # of protons. conformational change of receptor allows release of ligand

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5
Q

Vacuolar ATPase (or proton pump)-

A
  • ATP is hydrolyzed and changes structure. Protons going against gradient
  • proton pump maintains low pH in lysosomes
  • production of nutrients for cell
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6
Q

what are located in lysosomes?

A

acid hydrolases- only work at low pH.

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7
Q

Ph 4.5 in lysosome, 5.5 early endosome, 6.5 late endosome. Why diff pH if theres proton pump in all 3?

A

You have more proton pumps in different areas.

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8
Q

Binding of ligand to a receptor (LDL)-

A
  • LDL (low density lipoprotein) binds and transports cholesterol to cells
  • Atherosclerosis (plagues in bloodstream)
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9
Q

bad

A

LDL

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10
Q

LDL
HDL
Triglycerides

A

-too much in blood can lead to plaques. Carries cholesterol from liver to other tissues.
HDL - carries cholesterol back to liver where it is passed from body
Triglycerides - fat made in body (high levels signal problems)

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11
Q

cholesterol binds to

A

LDL, LDL bound to LDL receptor. Bound to adaptin and clathrin. Then you make clathrin coated pit then transported

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12
Q

ways it can get messed up

A
  1. cholesterol doesnt bind to LDL
  2. LDL doesnt bind to LDL receptor
  3. LDL receptor doesnt bind to adaptins
  4. cholesterol stays out of cells
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13
Q

YXX(PSI)

A

signal peptide for CCP

psi-hydrophobic aa

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14
Q

NPVY

A

in LDL receptor

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15
Q

Receptor recycles for additional rounds of endocytosis

A

lifespan 20 hours, can make the trip 700 times

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16
Q

transferrin

A

soluble protein that transports iron in blood

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17
Q

Transferrin w iron-

A

transferrin receptor

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18
Q

In the blood stream if you have transferrin without iron-

A

APOtransferrin. why doesnt it bind? structure isnt correct

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19
Q

Receptor at what pH?

A

7 ish

20
Q

When transferrin binds to receptor, it will be taken to early endosome. It will release something-

A

could release iron, transferrin w iron, or nothing.

21
Q

ferritin

A

stores iron and releases at appropriate times

22
Q

Around neutral pH,

A

receptor has high affinity for transferrin w/ iron. Gets taken through CCP to CCV to EE, protons pumped in and pH lowers to 6.5, iron is released. Now apotransferrin bound to receptor. When it gets recycled back out to plasma membrane (by Rab4), apotransfferin comes off at pH 7. apotransferrin is bound at lower pH, but when we go back to neutral pH, apotransferrin gets released. We only get binding again if apotransferrin gets bound to iron.

23
Q

Ligand binds to receptor

what kind of bond is it?

A

It is a noncovalent bond.

24
Q

growth factors

A

too much, cancer. too little, death. bind to receptors and these receptors are in a class of proteins called RTK’s

25
Q

RTK

A

receptor tyrosine kinases. Only work as dimers.

26
Q

So ligands bind to receptors, what gets activated?

A

activates signaling cascade. This activates this activates this…

27
Q

apoptosis

A

cells need to die and if they don’t then cancer.

28
Q

epidermal growth factor receptors (Erbs)

A

some called HER

ErbB2-bad. associated w breast and ovarian cancer bc of diff trafficking of this isoform

29
Q

Epidermal growth factor receptors -4 flavors

A

ErbB1, ErbB2, ErbB3, ErbB4

30
Q

isoform

A

forms of same receptor (bind the same ligand), but slightly different.

31
Q

When ligands bind they get taken into CCP. what about ErbB2?

A

ErbB2 does not bind to ligand, it can bind to receptor. Ligands bind and two receptors brought close enough together to activate endocytosis. Get dragged into CCP. On the inside part of these receptors, there is tyrosine kinase activity. When they get close enough, they cross phosphorylate each other. Recruitment of SH2 domains causes signaling (growth, differentiation, adhesion). If you don’t stop signaling, you get uncontrolled growth.

32
Q

activated receptors (ligand bound, dimers)

A

keep signaling. only in MVB in cytosol they dont signal. ErbB1, 3, and 4 do this.

33
Q

ErbB2 does not get taken in intraluminar vesicle. Why?

A

Different than the rest. Doesn’t get transported to LE. Recycled back to plasma membrane.

34
Q

proteins are imported into ER as they’re being translated and modified?

A

contranslational import

35
Q

receptor down regulation

A

decreasing the signaling

-transport to lysosomes

36
Q

protein ubiquitination

A

sorting signal for internalization into internal vesicles within MVB

37
Q

CBL recognizes the tyrosine residues getting cross phosphorylation, then CBL

A

adds individual ubiquitin onto tails of receptors.

38
Q

why do we want to make the mvb’s?

A

to turn off signaling.

39
Q

calveolae

A

specialized lipid raft structure

  • protein found: caveolin
  • flask like structures
40
Q

pinocytosis

A

cell drinking

-macrophages ingest 100% of their membrane every 1/2 hr

41
Q

macrophages

A

part of immune system. in tissues. they eat and send signals.

42
Q

neutrophiles

A

white blood cell that goes to site that have been cut or infected. They kill everything in the area.

43
Q

phagocytosis

A

endosomes called phagosomes

44
Q

things can get in the cell by

A
  1. calveolae
  2. phagocytosis
  3. pinocytosis
  4. receptor mediated endocytosis
45
Q

polarized cells

Transcytosis

A

transport from one side to the other - apical (top) to basolateral (bottom) or vice versa. have 2 sets of early endosomes.

Cell biology (15 decks)

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