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Flashcards in Membrane Composition and Structure Deck (36):
1

Membranes are composed of lipids, proteins, and carbohydrate containing molecules. The carbohydrate portions are covalently bound to either ____ or ____

proteins (glycoproteins) or lipids (glycolipids)

2

Compounds soluble in organic solvent are called ___

lipids

3

True or false? the relative amounts of protein and lipid varies from membrane to membrane

true

4

A membrane that has a high protein to lipid ratio would be found where?

mitochondrial inner membrane

5

A membrane that has a low protein to lipid ratio would be found where?

myelin

6

All of the membrane lipids are "amphipathic". Explain what this means.

one part is hydrophilic: phosphate, amino acid derivatives, and carbohydrate
the other part is hydrophobic: the fatty acid

7

The head group in membrane lipids is ___, while the hydrocarbon tail is ___

polar; nonpolar

8

What is different about the hydrocarbon tails in saturated fatty acids than in unsaturated fatty acids?

saturated: tails are straight
unsaturated: tails have kink

9

Membrane lipids can spontaneously form "____" which are similar to a membrane

liposomes

10

____ proteins require detergents to separate them from the membrane

integral

11

Integral proteins interact extensively with the ____ ___ of the membrane

hydrophobic core

12

Integral proteins usually span the membrane. The membrane spanning domains may also be in the form of ____.

Beta-sheets

13

___ proteins do not require detergents to separate them from the membrane

peripheral

14

Plasma membrane is characterized by the greatest amount of ____

cholesterol

15

Cardiolipin is restricted to ____ membrane

mitochondrial

16

Plasma membrane phospholipids are found randomly in the membrane. True or false?

false; are not found randomly

17

PC and sphingomyelin are located primarily in the ____ ____ of the plasma membrane

outer leaflet

18

___ and ____ are located primarily in the inner leaflet of the plasma membrane

PS; PE

19

Lateral movement of phospholipids is common, but movement from one leaflet to the other occurs only rarely.. There are enzymes that catalyze the movement of lipid from one leaflet to the other. These enzymes are responsible for maintaining the lipid ____ of the plasma membrane

asymmetry

20

The _____ portion of glycolipids extends only into the extracellular space. Therefore these lipids are restricted to the outer leaflet of the plasma membrane

carbohydrate

21

Protein orientation is greatly associated with the ____ of the protein

function

22

True or false? Proteins in membranes may be anchored by interaction with other cellular elements either outside or inside of the cell.

true

23

Various regions of a membrane may be associated with a specialized function. These regions may not only have a specific protein composition, but may have a ____ composition which differs measurably from the rest of the membrane

lipid

24

Bilayer lipids under most physiological conditions can exist in either a _______ phase or in a ___ phase

liquid-crystalline; gel

25

For any given composition of lipids, there is a temperature at which this phase transition occurs, called the ___ temperature

transition

26

The lipid bilayer is ___ permeable to small molecules when in the gel phase

less

27

Unsaturated fatty acids have a ____ melting temperature

lower

28

Increasing the unsaturated fatty acids in phospholipids ____ the membrane fluidity

increases

29

One function of cholesterol appears to be to modulate the ____ of the membrane.

fluidity

30

At temperatures below the Tm, cholesterol ___ the fluidity, and at temperatures above the Tm, it ____ the fluidity

increases, limits

31

Membrane permeability is simple diffusion, non mediated. This means it is restricted to what type of molecules? give examples

hydrophobic molecules or small uncharged, polar molecules
ex: H2O, O2, CO2, Urea

32

A channel protein with a water-filled pore is an example of what type of diffusion?

simple

33

Channel proteins display exquisite ____ in the molecule they allow through the pore

selectivity

34

Describe facilitated diffusion

proteins do not form pores, but interact with the transported molecule and due to some change in the molecule-protein complex, release the molecule on the opposite side of the membrane

35

Mediated transport may be classified as electroneutral or electrogenic. Explain each one.

electroneutral: transport results in no difference in charge
electrogenic: transport results in charge difference across membrane

36

The Na+, K+ ATPase is responsible for transporting ___ Na+ out of the cell, as it transports ___ K+ into the cell at the expense of 1 ATP

3; 2