Lecture 4: Membrane Structure and Function Flashcards Preview

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Flashcards in Lecture 4: Membrane Structure and Function Deck (36):
1

Most abundant membrane lipids are ____

phospholipids

2

Membranes are held together by ___ interactions

noncovalent

3

What two structures do lipids form?

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4

What lipid types have a cylinder shape?

Normal phospholipids, PC, PS, PI, PG, sphingomyelin

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5

What types of lipids have an inverted cone shape?

Lysolipids, acyl-CoAs, detergents

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6

Which lipids have a cone shape?

Diacylglycerol, Phosphatidic acid, unsaturated PE, fatty acids, ceremide

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7

What are the four types of lipid movements in a membrane?

Lateral diffusion, flexion, rotation, flip-flop

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8

Name typical membrane proteins.

  • Glycerophospholipids 

        – PS, PE, PC, PI

 • Sphingolipids 

      – Sphingomyelin (SM) 

• Cholesterol

• Glycolipids

9

How does cholesterol affect membranes?

• Presence decreases fluidity of nearby lipids (less permeable) 

• Inhibits crystallization (lowers phase transition temperature) 

10

What's the structure of cholesterol?

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11

How does cholesterol pack in lipids?

It packs between fatty acid tails of the hydrophobic core of a bilayer.

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12

Glycolipids

  • Special sugar-containing lipids
  • Found exclusively on noncytosolic side 
  • Tend to self-associate (lipid rafts) 

13

Functions of glycolipids

  • protection of cell surface 
  • electrical effects 
  • cell recognition and adhesion 

14

Glycolipid structure

They have a short carbohydrate chain covalently attached and this is exposed on the outer surface of the cell.

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15

What are phospholipases?

A phospholipase is an enzyme that hydrolyzes phospholipids into fatty acids and other lipophilic substances.

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16

Lipid Rafts

• often rich in sphingolipids and cholesterol 

• longer, saturated chains of sphingolipids cause membrane thickening 

• arrangement recruits particular proteins and facilitates their transport or function as a group

17

How are lipid droplets formed?

Storage form of lipids, usually triacylglycerol cores and cholesterol esters surrounded by a monolayer with a few proteins. They are thought to form from a “swelling” of the ER. 

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18

Phospholipid assymetry

  • SM, PC, and glycolipids in outer leaflet (nuetral)
  • PE and PS in inner leaflet (charged, net negative)

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19

What type of membrane protein is this?

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Peripheral membrane proteins

20

What type of membrane protein is this?

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PIG tail (GPI anchor)

21

What type of membrane protein is this?

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Covalent lipid attachment

22

What type of membrane protein is this?

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antipathic  α-helix 

23

What type of membrane protein is this?

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β-barrel

24

What type of membrane protein is this?

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Multipass α-helix 

25

What type of membrane protein is this?

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Single pass α-helix

26

Name three post-translational attachments to the membrane

Myristoyl anchor (14 carbons)

Palmitoyl anchor (16 carbons)

Farnesyl anchor (15 carbons)

27

Which residues are preferentially hydrophobic?

Preferentially hydrophobic residues: Leu, Ile, Val, Ala, Phe 

28

Where are membrane-spanning beta barrels usully found in the cell?

bacterial, chloroplast, and mitochondrial membranes

29

What are some common detergents?

SDS, Triton X-100, ß-octylglucoside

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30

What does CMC stand for?

Critical micellar concentration

31

How do detergents dissolve membranes?

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32

Solubilization and reconstitution of a membrane protein 

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33

___ create diffusion barriers for lipids, creating cells  ____ membranes on different sides of the cell

Tight junctions, asymmetrical

ex- epithelial cells

34

How does this protein shape the membrane?

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Hydrophobic region of protein wedges into membrane, displacing lipid head groups and causing curvature

35

How does this protein shape the membrane?

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protein is curved and can bind to lipid head groups causing membrane to curve with it

36

How does this protein shape the membrane?

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protein binds to and therefor clusters lipids with big head groups, this induces curvature