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?

4

What lipid types have a cylinder shape?

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

5

What types of lipids have an inverted cone shape?

Lysolipids, acyl-CoAs, detergents

6

Which lipids have a cone shape?

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

7

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

Lateral diffusion, flexion, rotation, flip-flop

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?

11

How does cholesterol pack in lipids?

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

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.

15

What are phospholipases?

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

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. 

18

Phospholipid assymetry

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

19

What type of membrane protein is this?

Peripheral membrane proteins

20

What type of membrane protein is this?

PIG tail (GPI anchor)

21

What type of membrane protein is this?

Covalent lipid attachment

22

What type of membrane protein is this?

antipathic  α-helix 

23

What type of membrane protein is this?

β-barrel

24

What type of membrane protein is this?

Multipass α-helix 

25

What type of membrane protein is this?

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

30

What does CMC stand for?

Critical micellar concentration

31

How do detergents dissolve membranes?

32

Solubilization and reconstitution of a membrane protein 

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?

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

35

How does this protein shape the membrane?

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

36

How does this protein shape the membrane?

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