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Cell > Membrane Structure and Composition > Flashcards

Membrane Structure and Composition Flashcards

1
Q

what are three components of a membrane structure

A

glycoprotein, sterol, cytostolic leaflet

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2
Q

what do glycoproteins do

A

sorting signal and aid in stability

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3
Q

what do sterols do in membrane

A

maintain integrity of cell

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4
Q

what to cytostolic leaflets do in membrane

A

half of the phospholipid bilayer

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5
Q

what are the two parts of the phospholipid bilayer

A

cytostolic leaflet and extracellular leaflet

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6
Q

how is the lipid bilayer semi fluid

A

permits the movement of both lipids and proteins

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7
Q

what are some functions of the membranes

A 
boundary/permeabiltiy barrier
organization and localization
transport
signal detection
cell-to-cell interactions
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8
Q

what are three components of the membrane

A

lipids, proteins, and carbohydrates

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9
Q

what are the types of sterols

A

low-density: bad kind

high-density: good kind

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10
Q

how is the membrane a fluid mosaic model

A

fluid: lipids and proteins can move
mosaic: made of many components; lipids, proteins, carbohydrates

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11
Q

what are phospholipids and what are different types

A
  • the most abundant lipid in membranes
  • glycerol-based and spingosine-based sphingolipids
  • glycolipids: carbohydrate + lipid
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12
Q

what are fatty acids and what is their function

A
  • they are essential to membrane structure and function
  • components of all membrane lipids except sterols
  • they are a barrier to diffusion of polar solutes
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13
Q

how do lipids move in their monolayer?

A

freely

  • rotation and lateral diffusion (phospholipid)
  • rapid and random movement
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14
Q

how is the membrane asymmetrical?

A
  • lipids are distributed unequally between the 2 monolayers

- there are different kinds and varying degrees of saturation of the fatty acids in the phospholipids

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15
Q

what is freeze-fracture microscopy

A

a bilayer is frozen and then hit sharpely with a diamond kinfe to allow the plane between the 2 layers of membrane lipids to be visible

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16
Q

what state do membrane function in? what affects this state

A

fluid, changes with temperature

17
Q

what is Tm? how is it affected

A

when the lipid becomes fluid

- disrupted when there is an increase in temperature; increases fluidity

18
Q

what is diffusion

A

molecules move from high concentration to low concentration

19
Q

what is osmosis

A

the movement of water across a semi permeable membrane (low to high solute concentration)

20
Q

what is an electrochemical gradient

A

when there is a high concentration of a positively charged ion on the outside of the cell, negatively charged ions will be attracted to it

21
Q

what are lipid rafts and how are they formed

A
  • membrane microdomains that stay together as a unit

- need cholesterol and actin cytoskeleton

22
Q

what are ion electrochemical gradients and what do they need

A

need ion pumps to transport ions across the gradient (require a lot of ATP)

23
Q

what is passive transport and what does it require

A

powered by diffusion along chemical or electrochemical gradient
- requires channel proteins and transporter proteins

24
Q

what is the difference between a chemical and electrochemical gradient

A

chemical: the difference of solute across a membrane
electrochemical: the difference of charge across a membrane

25
Q

what are channel proteins

A

pores lined with polar amino acids, outside of the channel is lined with hydrophobic groups that interact with the lipid bilayer

26
Q

what are transporter proteins

A

proteins that change shape during transport across lipid bilayer
- conformational change

27
Q

what is the permeability of a membrane influenced by: 4 things

A
  • saturated/unsaturated fatty acid chains
  • temperature
  • amount of sterols
  • length of fatty acids
28
Q 
what makes the membrane more fluid
saturated/unsaturated
poly/mono unsaturated
long/short fatty acid
more/less sterols
A
  • unsaturated
  • poly
  • short
  • less

Cell (6 decks)

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