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My Packs: (WIZEPREP) (BIO 2382) > Chapter 3: 3.5 Receptor-mediated Endocytosis > Flashcards

Chapter 3: 3.5 Receptor-mediated Endocytosis Flashcards

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Biology 101 flashcards
1
Q

Define:

Endocytic Pathway

A

Proteins or other molecules entering the cell by endocytosis
* Substances are engulfed by cell into vesicles

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2
Q

In endocytic pathway:

What are the three basic processes?

A
  1. Phagocytosis
  2. Pinocytosis
  3. Receptor-mediated endocytosis
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3
Q

Define:

Phagocytosis

A

Ingestion of food in large vesicles

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4
Q

Define:

Pinocytosis

A

Ingestion of fluids in tiny vesicles

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5
Q

Define:

Receptor-mediated endocytosis

A

Receptors bind to molecules outside the cell and bring them in inside a vesicle (very specific)

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6
Q

In receptor-mediateed endocytosis:

What molecules bind to receptors that are brought inside by vesicles?

A
  • Lipoproteins (LDL: low density lipoproteins)
  • Transferrin
  • Hormones
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7
Q

Define:

Lipoproteins

A

Transport lipids
* Made up of a monolayer of phospholipids, cholesterol, and apoproteins

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8
Q

Where are lipoproteins made?

A

Made in either the intestine or liver

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9
Q

Lipoproteins travel through the ———– providing ——

A
  1. Bloodstream
  2. Energy
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10
Q

True or False:

Any remaining lipoproteins are recycled in the intestine

A

False, they are recycle in the liver

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11
Q

Describe the structure of:

Lipoproteins

A
  • Amphipathic shell: Lipids
  • Apolar core: Made of hydrophobic cholesterol esteres
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12
Q

What types of lipoproteins are there?

A
  1. Chylomicrons
  2. LDL
  3. HDL
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13
Q

Define and give examples of:

Chylomicrons

A

Made in the small intestine
* Contain TAGs and apoprotein 48

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14
Q

Define and give examples of:

LDL

A

Made in liver
* Contains ApoB100
* Lipoprotein lipase hydrolizes TAGs to produce HDL and LDL

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15
Q

Define and give examples of:

HDL

A

Brings cholesterol and CEs back to the liver for breakdown
* The “good cholesterol” - Picks up cholesterol esters via LCAT enzyme

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16
Q

Describe:

LP uptake by Endocytosis

A

LDL receptors on liver cells bind lipoproteins

17
Q

How many domains do receptors of liver cells have? List them

A

3
1. C-terminus sorting segment
2. N-terminus ligand binding domain
3. Beta-propeller domain

18
Q

Lipoprotein is surrounded by what at the surface?

A

ApoB proteins

19
Q

Describe:

Receptor and ApoB interactions under normal pH

A

Ligand binding domain binds to ApoB

20
Q

Describe:

Receptor and ApoB interactions under acidic pH

A
  • Beta-propeller binds to ligand binding domain
  • Releases it from ApoB
  • Releases lipoprotein into lysosome or endosome
21
Q

Where does acidic pH normally occur?

A

Inside lysosomes etc.

22
Q

How does Receptor-Mediated Endocytosis occur?

A

Occurs via clathrin-coated vesicles

23
Q

Which clathrin-coated vesicles does receptor-mediated endocytosis occur through?

A
  1. Clathrin AP1 adaptor from Golgi
  2. Clathrin AP2 from PM
24
Q

LP get fused with ——— and get —— —-

A
  • Lysosomes
  • Broken down
25
Q

True or False:

In LP Uptake by Endocytosis, the receptors are recycled

A

True

26
Q

What happens if there are mutations in during the receptor recycling process?

A

Can increase cholesterol levels

27
Q

Define:

Transferrin

A

Secreted protein that scavenges and collects iron from the environment
* Once bound to iron, it brings it back to the cell

28
Q

Describe:

The 6 step process that transferrin takes part in

A
  1. Transferrin bound to iron (ferrotransferrin) binds to transferrin receptors on the surface of the cell
  2. Clathrin coat proteins mediate vesicle formation
  3. Coat proteins dissociate off to form an early endosome
  4. Endosome is acidified and matures to late endosome
  5. Iron is released in the acidified environment
  6. Transferrin is recycled back to the PM and released
29
Q

What are the two types of autophagy?

A
  1. Macroautophagy
  2. Microautophagy
30
Q

Define:

Macroautophagy

A

Forms a vesicle around material needed to be recycled

31
Q

What surface proteins are involved in mediating macroautophagy?

A

Atg 12, 5, 6, 8

32
Q

Define:

Microautophagy

A

Directly recycle material by transferring it to a lysosome

My Packs: (WIZEPREP) (BIO 2382) (20 decks)

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