Brainscape's Knowledge GenomeTM

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


See full index

CORE Block 4 > Membranes I > Flashcards

Membranes I Flashcards

1
Q

Why are cell memranes essential?

A

Act as biological barrier and compartmentalize processes.

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

What cell structure makes signaling possible?

A

Cell membrane. Allows for separation of genes from gene products for regulation.

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

WHat is the average fatty acid tail chain length?

A

C18

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

What is the major lipid component of the cell wal;?

A

Glycerophospholipid

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

Describe glycerophospholipids.

A

glycerol-3-phosphate esterified to fatty acids and polar alcohol

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

which part of the phospholipid allows for its packing in the membrane?

A

The fatty acid tail

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the order of the components of phosphatidylcholine?

A

Choline - phosphate - glycerol - hydrophobic tails

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

How do sphingolipids differ from phospholipids?

A

Also major components of then cell membrane, but they are based on lipophilic amino alcohol (sphingosine) rather than glycerol.

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

What is the main sphingolipid in cell membranes?

A

Sphingomyelin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How are sphingolipids similar to phosphatidylcholine and phosphatidylethanolamine?

A

They have similar conformations and charge distributions.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

In what cell type is sphingomyelin highly present?

A

Myelin sheath around nerve cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is a ceramide?

A

A sphingosine attached to a fatty acid.

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

How do cerebrocides, galactocerebrocides, and gluccocerebrosides differ?

A

They are all sphingolipids that comprise a ceramide group with different sugars on the head group.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are the most complex sphingolipids?

A

Gangliosides

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Describe gangliosides.

A

They are ceramide oligosaccharides that have sugar groups and at least one sialic acid residue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are the functions of gangliosides?

A
  1. primary components of cell surface membranes
  2. constitute 6% of all brain lipids
  3. act as receptors for certain pituitary glycoprotein hormones
  4. act as receptors for certain bacterial cell toxins
  5. specific determinants of cell-cell recognition
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How does cholesterol affect membrane fluidity?

A

More cholesterol, less fluid (bc less space between phospholipids)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What are the functions of cholesterol?

A
  1. substrate used to make steroid hormones (progesterone aldosterone, testosterone)
  2. substrate used to make vitamin D
  3. Precursor to bile salts
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

How is cholesterol classified?

A

As a sterol due to its branched alipathic side chain (hydrophobic with hydroxy group – branch other than entirely aromatic)

20
Q

Describe melting point of cell membrane.

A

Tm. Acyl chains become more flud and disordered, allowing motion.

21
Q

At what temperature are cell membranes in a gel-like state?

A

It is gel-like, restricting motion

22
Q

How can lipids move in the cell membrane?

A

Laterally (rapid), transverse (slow, facilitated by enzymes flippases)

23
Q

What factors affect membrane fluidity?

A
  1. degree and type of acyl chain unsaturation (double bonds are kinked and allow more fluidity)
  2. acyl chain length (longer chains are less fluid)
  3. cholesterol content (rigid ring structure reduces lateral movement – less fluidity)
24
Q

What is the general composition of biological membranes?

A

Complex mixture of proteins and lipids, of which varies between cell types and organelle types.

25
Q

What are the two main classes of memrbane proteins?

A

Integral and peripheral proteins

26
Q

How are membrane proteins classified?

A

Based on how they are separated from the membrane.

27
Q

Describe integral membrane proteins.

A

Require detergent to be separated form the membrane

28
Q

Describe peripheral membrane proteins:

A

Loosely associated with the membrane and can be easily removed by changing pH or ionic strength

29
Q

What type of interactions keep integral membranes in the membrane?

A

Via hydrophobic interactions

30
Q

Which types of interactions predominate

A

electrostatic interactions predominate (ionic and hydrogen). Binding to polar lipid heads or integral proteins.

31
Q

How do some peripheral membranes go to and from the membrane?

A

Reversibly attached lipid anchor.

32
Q

Describe lipid anchors.

A

They are proteins covalently linked to lipids. Some can be reversibly attached from the protein.

33
Q

What is a lipid anchor switching device?

A

It alters the affinity of a protein for the membrane, a role in signal transduction pathways in eukaryotes

34
Q

What are the three main types of lipi anchors?

A

Prenylation, fatty acylated, glycosylphosphatidylinositol.

35
Q

Describe prenylation.

A

iso-prenoid groups attached to protein via thoester linkage (eg. Rab proteins act as taxi cabs)

36
Q

Describe fatty acyl lipid anchors.

A
  • Myristic acid: myristoylated to N-term gly by amide linkage
  • palmitic acid: palmitoylated to cys via thioester linkage and is reversible (e.g. Ras GTPase)
37
Q

Why are glycosylphosphatidylinositol lipid anchors so complex?

A

They are involved in cell signaling.

38
Q

Describe glycosylphosphatidylinositol lipid anchors.

A

Phosphatidylinositol core is linked to sugars and forms phosphoester bond to phosphoethanolamine which is amide linked to proteins.

39
Q

How do we know that membranes are more patchy than fluid?

A
  • we have more knowledge of the oligomeric nature of membrane protein structue
  • we know pure lipid mixtures form non homogenous patches within vesicles
40
Q

What is responsible for the assymetry of lipid membranes?

A

Specific lipid transporter proteins such as flippases

41
Q

What is the importance of membrane microdomains?

A

They are important in signaling

42
Q

In what are lipid rafts enriched.

A

Cholesterol and sphingolipids.

43
Q

What types of proteins are lipid rafts enriched in?

A

Signaling proteins

44
Q

Why might membranes in lipid rafts differ in thickness?

A

They might warp the membrane

45
Q
A

CORE Block 4 (8 decks)

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