Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Cell Biology and Biochemistry > 9 Membranes and Membrane Transport > Flashcards

9 Membranes and Membrane Transport Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

Give a quick recap on what we know about membranes

A
  • fluid mosaic model
  • thin film of lipids and proteins held together by non covalent attractions
  • lipid bilayer
  • impermeable to polar/water soluble molecules
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

give a quick recap on what we know about fatty acids

A
  • long hydrocarbon chains
  • carboxyl group at the end
  • forms ester bond with glycerol in condensation reaction
  • unsaturated when contain double bonds
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

describe the overall structure of a phospholipid

A
  • 2 fatty acids covalently bonded to a glycerol
  • 1 fatty acid is saturated and the other is unsaturated
  • the third hydroxyl group of the glycerol is bonded to a phosphate group
  • the phosphate bonds to either a choline/serine/ethanol amine group
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

how many types of phospholipids are there? and whats the difference between them

A
  • 3 types

- whether the phosphate is bonded to a choline, serine or ethanol amine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What other structures are there that are similar to phosphlipids

A
  • sphingomyelin and sphingosine
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Describe the structure of sphingomyelin

A
  • 2 fatty acid tails, one very long unsaturated and one regular and pretty much unsaturated
  • sphingosine instead of glycerol
  • phosphate head
  • choline group bonded to the phosphate
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

describe the structure of sphingosine

A
  • one long fatty acid chain

- and a sphingosine body

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

explain how membrane lipids are amphipathic

A
  • The are partly hydrophobic and partly hydrophilic

- having a polar hydrophilic head and nonpolar hydrophobic tail

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what determines polarity

A
  • how well covalently bonded atoms share electrons, the more equal the sharing the less polar the molecule
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

how do polar molecules and non-polar molecules interact with water

A
  • water is a very polar molecules so interacts favourably with other polar molecules
  • so its energetically favourable for polar molecules to dissolve in water
  • non-polar molecules do not interact like water and oil
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

how do micelles form

A
  • hydrophobic tails cluster together disorderly exposing only the hydrophilic heads to water
  • the overall system is more disordered so this is energetically favourable and happens naturally
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What happens to cell membranes if they become dameged?

A

the smooth ER traffics phospholipids to the damaged site

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Describe why the membrane is so fluid and dynamic

A
  • the phospholipids are free to move
  • phospholipids can move along laterally (lateral diffusion)
  • phospholipids can rotate a full 360
  • the tails of the phospholipids can move freely (flexion)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

In which direction can phospholipids not travel

A
  • Across to the other side of the membrane
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How does temperature effect membrane fluidity

A
  • at low temperatures the lipid bilayer undergoes a phase transition and becomes closely packed and rigid
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what factors prevent the membrane becoming packed and rigid

A
  • cholesterol in the membrane bilayer

- c=c double bonds in the fatty acid chain of the phospholipids space out the phospholipids

17
Q

How do membranes with lots of double bonds in the fatty acid tails compare to a membrane with phospholipids that are unsaturated

A
  • the c=c double bonds put kinks in the fatty acid tails
  • this means the membrane is thinner but the fatty acids are harder to pack together so resist a phase transition due to low temps
18
Q

Describe the structure of cholesterol

A
  • polar region with interacts with the phosphate head

- rigid steroid region which interacts with the phospholipid tails stiffening them

19
Q
  • What role does cholesterol play in the lipid bilayer
A
  • cholesterol stiffens up the upper region of the fatty acid tail which prevents phospholipids packing together tightly
  • stiffening the tail reduces fluidity and lateral movement but reduced packing increases fluidity by more
  • overall increase in fluidity
20
Q

Describe a lipid raft and how it forms

A
  • a lipid raft is a region of the membrane with a high concentration of sphingolipids
  • Sphingolipids have extra long fatty acid tails, as a result the van der vaals forces are much stronger and hold adjacent molecules together as a lipid raft
21
Q

What is a glycocalyx

A
  • This is a protective layer of glycoproteins and glycolipids situated on the outer surface of a cell membrane, this is a coat
22
Q

What is the purpose of a glycocalyx

A
  • this layer is used for protection and more importantly recognition
23
Q

Where do glycoproteins and glycolipids get synthesised in the cell

A

Glycoproteins: proteins which are glycosylated in the RER and Golgi
Glycolipids: lipids from the SER and are glycosylated in the Golgi

24
Q

What catagories can membrane proteins be put under?

A
  • Integral/transmembrane proteins (through the lipid bilayer)
  • peripheral membrane proteins (on 1 layer of the lipid bilayer)
  • single pass (passes through the membrane once)
  • multipass (passes through the membrane more than once)
25
Q

How well do non-polar, small polar, large polar and ions travel across the cell membrane

A
  • non-polar diffuse across the cell membrane easily
  • small polar molecules can travel through the membrane but very slowly
  • large polar molecules mostly cant and need a transporter
  • All ions cannot travel through the cell membrane without a specialised mechanism
26
Q

give some examples of molecules that can travel through the membrane easily

A
  • non-polar molecules

- eg O2, CO2, hormones, steroids

27
Q

can glucose and sucrose travel through the cell membrane

A
  • they are large polar molecules so no without a transporter
28
Q

what factors contribute to how well molecules diffuse through the cell membrane

A
  • the more polar the molecule the less likely it is to diffuse across
  • the larger the molecule the less likely it is to diffuse across the membrane
29
Q

describe the structure of all transport proteins

A
  • transmembrane
  • multi-pass
  • either alpha helix or b-sheet/barrel shaped
30
Q

What 2 types of transport proteins are there

A
  • carrier proteins

- channel proteins

31
Q

how do carrier proteins work

A
  • they bind to a solute and undergo a conformational change to transfer the solute
32
Q

How so channel proteins work

A
  • they interact very weakly with the solutes forming an aqueous pore that solutes can pass through
33
Q

what factors determine facilitated diffusion

A
  • the concentration gradient

- the electrochemical gradient

34
Q

What are the 2 main mechanisms behind active transport

A

ATP driven pumps - primary active transport

Coupled carriers - secondary active transport

35
Q

What proteins mediate coupled transport

A
  • symporter proteins

- antiporter proteins

36
Q

What is the difference between primary active transport and secondary active transport

A
  • Primary active transport uses energy such from things like ATP hydrolysis to pump molecules against the concentration gradient
  • secondary active transport uses coupled carriers and as one molecule passes down its concentration gradient, this provides energy to pump another ion against its electrochemical gradient
37
Q

Describe the mechanism behind how Sodium-Potassium-ATPase pumps work

A
  • 3Na+bind to the protein pump, ATP is hydrolysed releasing energy causing a conformational change spitting the 3Na+ out the cell
  • 2K+ from outside bind to the open protein pump which is kept open by the phosphate released from ATP hydrolysis, once both the K+ have bound the phosphate dissociates spitting K+ into the cell
38
Q

Give another example of where ATPase pumps are used

A
  • on lysosomes to pump H+ ions into the lysosome to reduce the pH for the enzymes inside
39
Q

channel proteins form pores on cell membranes, are these selective? name a few types

A

yes

  • voltage gated
  • ligand gated
  • mechanically gated

Cell Biology and Biochemistry (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions