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The human cell > Lecture 7 and 8 > Flashcards

Lecture 7 and 8 Flashcards

1
Q

Membrane lipids are ______/

A

Amphiphilic

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2
Q

How thick is the lipid membrane?

A

5nm (50 angstrom)

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3
Q

What name is given to the carboxl and methyl end of a fatty acid?

A

Delta and omega (respectively)

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4
Q

Give an example of a glycerophospholipid

A

Phosphatidyl-choline

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5
Q

What is the structure of phosphatidyl-choline?

A

Choline, phosphate, glycerol, hydrocarbon tails

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6
Q

Why do membrane lipids favor a bilayer of two leaflets over a micelle?

A

Cylindrical shape

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7
Q

What do membrane sheets favour the formation of?

A

Liposomes (membrane lipid balls, energetically favorable)

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8
Q

What are exosomes and what do they do?

A

Liposomes released by cells, cell to cell communication

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9
Q

Membranes can be split into glycerophospholipids and ________

A

Sphingolipids (S for serine linker)

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10
Q

What three lipid components can comprise a membrane?

A

Phosphoplipids, glycolipids, cholesterol

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11
Q

Name two categories of phospholipids.

A

Amino and choline phospholipids

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12
Q

Name 4 glycerophospholipids

A 
Phosphatidyl:
- Inositol
-Athanolamine
-Serine
Choline
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13
Q

What are the three coponents of cholesterol?

A

Polar head group
Rigid steroid ring structure
Nonpolar hydrocarbon tail

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14
Q

How do cholestrol interact with glycerophospholipid?

A

Associates with head the lipid, it becomes more densely packed, less fluid, less permeable

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15
Q

How do cholesterol interact with sphingolipids?

A

Sphingolipids have longer, straighter chains, cholesterol reduces packing density and keeps membrane fluid

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16
Q

Where are cholesterol enriched sphingolipids found?

A

Membrane invaginations (Caeolae and clathrin-coated pits)

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17
Q

What is cholesterol an important starting molecule for?

A

Bile salts
Vitamin D
Steroids (cortisol and aldosterone)
Sex hormones (progesterone, oestrogen and testosterone)

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18
Q

Where are fat droplets originating from?

A

Endoplasmic reticulum, bound in monolayer (contents hydrophobic)

19
Q

What are glycolipids based on?

A

Ceramide

20
Q

What glycolipid is the receptor for the cholera toxin?

A

GM1 ganglioside

21
Q

What do glycolipids do?

A

Protect from the environment, cell to cell contact, important in lipid raft generation function

22
Q

What membrane proteins bind sugars and contain glycolipids?

A

Lectins

23
Q

Why are hepatocytes enriched with phsophatidylcholine?

A

Secrete PC into the bile

24
Q

Why is the ER low in cholesterol and high in glycerophospholipids?

A

Makes it more fluid for protein insertion

25
Q

Myelin is enriched in what type of lipid?

A

Glycolipids- insulate nerve axon

26
Q

What are some limitations to the fluid mosaic model?

A
  • Some proteins are anchored or tied to extracellular/intracellular matrix/cytoskeleton
    Lipids can be signalling molecules
    Lipids modules membrane protein activity
27
Q

What % of coding capactiy of the human genome is for membrane proteins?

A

26%

28
Q

What % drug targets are for membrane proteins?

A

60%

29
Q

Name a membrane channel.

A

Channel CFTR (chloride channel. Mutations lead to cystic fibrosis)

30
Q

Name a transporter protein.

A

Transporter ABCB1 (drug efflex plump, causes multidrug resistance)

31
Q

Name an adherent gap junction between cochlear cells.

A

Connexin 26

32
Q

Name a receptor.

A

Receptors FGFR3 _FGF

33
Q

What does FGFR3 + FGF do?

A

Changes gene expression, decreased poliferation of bone cells

34
Q

Name a membrane enzyme

A

Phospholipase C

35
Q

How is glucose uptaken into a cell?

A

SGLT1 symporter

Na+ driven glucose symport

36
Q

How is cellular sodium kept low in intestinal epithelial cells?

A

Na+K+ ATPase (primary active pump) pumps out 3 sodium and in 1 pottasium ion

37
Q

What protein facilitates glucose diffusion into the extracellular fluid?

A

GLUT2

38
Q

What three active transporters were identified to cause progressive familiar intrahepatic cholestasis?

A

ATP8B1
ABCB4
ABCB11

39
Q

What is a dominant disease caused by deficiency in receptor-mediated endocytosis?

A

Familiar hypercholesterolaemia

40
Q

What domain is deleted in familial hypercholesterolameia?

A

Clathrin interaction domain, affects 1 in 500 UK popn.

41
Q

What does CFTR do?

A

Releases Cl- to induce flow of Na+ and water to reduce viscocity of surface mucous

42
Q

What drug helps as a chemical chaperone to help delta F508 fold to treat CF?

A

Lumacaftor

43
Q

What is Ivacaftor an example of?

A

A potentiator- increases ability of channel to open for G551D patients

The human cell (10 decks)

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