Week 7 - Membrane Structure Flashcards

1
Q

Define Cytoplasm.

A

Contents of the cell outside of the nucleus (includes other organelles).

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

Define Cytosol.

A

Aqueous part of the cytoplasm; does NOT include membrane bound organelles - DOES include ribosomes and cytoskeleton

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

Define Lumen.

A

Insides of organelles.

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

What are the 6 cell functions at the membrane?

A
  1. Compartmentalization
  2. Scaffold for biochemical activities
  3. Selectively permeable barrier
  4. Transporting solutes
  5. Responding to external signals
  6. Interactions between cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Membrane lipid bilayers have what properties?

A
  1. Amphipathic (hydrophilic/polar head groups and hydrophobic tails)
  2. Have 2 layers (leaflets)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the fluid mosaic model?

A

Of the membrane bilayer; Lipids are FLUID and some Proteins are MOBILE; MOSAIC of many different lipids and proteins

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

Membrane lipids structure?

A
  • polar, hydrophilic head group

- 2 hydrocarbon, hydrophobic tails

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

In an aqueous environment, phospholipids spontaneously self-associate into what?

A

Spontaneously self-associate into a bilayer

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

Hydrocarbon tails of membrane lipids interact with what?

A

Other hydrocarbon tails

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

What is in artificial lipid bilayers?

A

liposomes

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

Experimental uses of a Liposome? (3)

A
  1. Study lipid properties
  2. Membrane protein properties
  3. Drug delivery into cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Most energetically favourable structure of a liposome?

A

Spherical sealed compartment formed by phospholipid bilayer

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

Types of membrane lipids?

A
  1. Phospholipid (i.e. Phosphoglyceride)
  2. Sphingolipids (less abundant)
  3. Steroids (i.e. Cholesterol in animal cells)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the Phosphoglyceride structure?

A
  • Variable head group (R)
  • phosphate group
  • glycerol group
  • 2 hydrocarbon tails.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Hydrocarbon tails have what structure properties?

A
  • saturated or unsaturated (the latter with a kink from a cis double bond)
  • 14-24 carbons in length
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the Steroid (cholesterol) structure?

A
  • polar head group
  • rigid steroid ring structure (like a wedge)
  • 1 non-polar hydrocarbon tail
17
Q

The 1;1; ratio of cholesterol to phospholipids can decrease what?

A
  • decrease mobility of phospholipid tails

- decrease plasma membrane permeability

18
Q

Phospholipids diffuse and move in what directions?

A
  • laterally
  • within each leaflet
  • rotationally
  • with flexion (often)
19
Q

Phospholipids RARELY diffuse in what way?

A

transversely (flip-flopping) without other influences

20
Q

At lower temperatures, lipid bilayers become what?

A

become rigid (gel)

21
Q

The presence of cis-double bonds allows the membrane to remain what?

A

remain fluid at lower temperatures

22
Q

Kinks in hydrocarbon tails allow for what?

A

Kinks in hydrocarbon tails allow for more space and less hydrophobic interactions

23
Q

Shorter hydrocarbon tails increase what?

A

Shorter hydrocarbon tails increase fluidity at lower temperatures (the tails interact less)

24
Q

Phospholipid translocators catalyze what?

A

They catalyze the rapid flip-flop of phospholipids from one leaflet to the other

25
Why is it necessary to have some phospholipid flip-flopping?
Phospholipids are synthesized in the cytosolic leaflet of the endoplasmic reticulum but are needed on both the cytosolic and exoplasmic faces
26
What are the 2 leaflets of the lipid bilayer of one membrane?
Cytosolic and exoplasmic
27
What does the inner membrane of the nucleus have?
The inner membrane has a cytosolic face that faces into the nucleus. It is continuous and bends around the nuclear pore.
28
What does the outer membrane of the nucleus have?
The outer membrane has an "exoplasmic face", although it faces inter membrane space
29
What organelles have 2 membranes?
The nucleus and mitochondria
30
Where does the exoplasmic face of the mitochondria face?
It faces inter membrane space.
31
Where does the cytosolic face of the mitochondria face?
It faces the matrix of the mitochondria, and it is discontinuous.
32
What are the bilayers of the vesicles like?
They are continuous and stay consistent.
33
Is the lipid bilayer symmetrical or asymmetrical?
Asymmetrical
34
Glycolipids and glycoproteins found on the exoplasmic leaflet are formed by what?
Formed by adding sugar groups.
35
Glycolipids and glycoproteins protect what?
They protect the membrane from harsh environments.
36
Phospholipids are distributed in what manner?
Asymmetrically
37
Phospholipids can bind to what?
Some can bind to cytosolic proteins.