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BIO130 > Week 7 - Membrane Structure > Flashcards

Week 7 - Membrane Structure Flashcards

1
Q

Define Cytoplasm.

A

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

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2
Q

Define Cytosol.

A

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

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3
Q

Define Lumen.

A

Insides of organelles.

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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
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5
Q

Membrane lipid bilayers have what properties?

A
  1. Amphipathic (hydrophilic/polar head groups and hydrophobic tails)
  2. Have 2 layers (leaflets)
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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

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7
Q

Membrane lipids structure?

A
  • polar, hydrophilic head group

- 2 hydrocarbon, hydrophobic tails

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8
Q

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

A

Spontaneously self-associate into a bilayer

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9
Q

Hydrocarbon tails of membrane lipids interact with what?

A

Other hydrocarbon tails

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10
Q

What is in artificial lipid bilayers?

A

liposomes

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11
Q

Experimental uses of a Liposome? (3)

A
  1. Study lipid properties
  2. Membrane protein properties
  3. Drug delivery into cells
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12
Q

Most energetically favourable structure of a liposome?

A

Spherical sealed compartment formed by phospholipid bilayer

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13
Q

Types of membrane lipids?

A
  1. Phospholipid (i.e. Phosphoglyceride)
  2. Sphingolipids (less abundant)
  3. Steroids (i.e. Cholesterol in animal cells)
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14
Q

What is the Phosphoglyceride structure?

A
  • Variable head group (R)
  • phosphate group
  • glycerol group
  • 2 hydrocarbon tails.
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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
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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
Q

Why is it necessary to have some phospholipid flip-flopping?

A

Phospholipids are synthesized in the cytosolic leaflet of the endoplasmic reticulum but are needed on both the cytosolic and exoplasmic faces

26
Q

What are the 2 leaflets of the lipid bilayer of one membrane?

A

Cytosolic and exoplasmic

27
Q

What does the inner membrane of the nucleus have?

A

The inner membrane has a cytosolic face that faces into the nucleus. It is continuous and bends around the nuclear pore.

28
Q

What does the outer membrane of the nucleus have?

A

The outer membrane has an “exoplasmic face”, although it faces inter membrane space

29
Q

What organelles have 2 membranes?

A

The nucleus and mitochondria

30
Q

Where does the exoplasmic face of the mitochondria face?

A

It faces inter membrane space.

31
Q

Where does the cytosolic face of the mitochondria face?

A

It faces the matrix of the mitochondria, and it is discontinuous.

32
Q

What are the bilayers of the vesicles like?

A

They are continuous and stay consistent.

33
Q

Is the lipid bilayer symmetrical or asymmetrical?

A

Asymmetrical

34
Q

Glycolipids and glycoproteins found on the exoplasmic leaflet are formed by what?

A

Formed by adding sugar groups.

35
Q

Glycolipids and glycoproteins protect what?

A

They protect the membrane from harsh environments.

36
Q

Phospholipids are distributed in what manner?

A

Asymmetrically

37
Q

Phospholipids can bind to what?

A

Some can bind to cytosolic proteins.

BIO130 (12 decks)

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