Lipids and Membranes Flashcards

1
Q

Amphiphilic

A

Containing both polar and nonpolar regions

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

4 major classes of lipids

A

Fatty acids
Phospholipids
Glycosphingolipids
Isoprenoids

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

Simplest class of lipids

A

Fatty acids

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

Fatty acid nomenclature

A

Carboxyl group is C-1
Main chain is named as usual
Unsaturations: delta^n (n= carbon where double bond is located)

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

Effects of unsaturations in fatty acid chains

A

Increased flexibility: looser packing

Lowered melting point

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

Triacylglycerols

A

3 fatty acids esterified with one molecule of glycerol
Hydrophobic storage form of fatty acids
Most abundant lipid form

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

Metabolism of triacylglycerols

A

Broken down in small intestine by lipases

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

Glycerophospholipids

A
Compose majority of membranes
Amphiphilic molecules (polar head, nonpolar tail)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Phosphatidates

A

Form of glycerophospholipids
Have glycerol backbone, fatty acids at C-1 and C-2 and phosphate at C-3
Present in small amounts (rather rare)

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

Phospholipases

A

Class of enzymes that catalyze cleavage of esters in phospholipids

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

Plasmalogens

A

Form of glycerophospholipid with C-1 substituent linked by vinyl ether linkage
Found in CNS as well as peripheral nerve and muscle tissue

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

Sphingolipids

A

Sphingosine backbone

Particularly abundant in CNS cells

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

Ceramide

A

Precursor of all other sphingolipids

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

Sphingomyelins

A

Class of sphingolipid
Phosphocholine at C-1
Major component of myelin sheath

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

Cerebrosides

A

Class of sphingolipid
Monosaccharide attached through beta-glycosidic bond
Abundant in nerve tissue and myelin sheaths
Different subclasses, depending on ID of sugar

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

Gangliosides

A

Class of sphingolipid
Linked to complex oligosaccharide containing N-acetylneuraminic acid
Used in cell-surface signaling

17
Q

Steroids

A
Classified as isoprenoids
Shared fused, four-ring structure
Derived from squalene
Hydrophobic
Precursor of steroid hormones and bile salts as well as component of certain membranes
18
Q

Waxes

A

Nonpolar esters of long-chain fatty acids and long-chain monohydroxylic alcohols

19
Q

Functions of biological membranes

A

Separation of cellular components
Generation and maintenance of ion and small molecule gradients
Assistance of biosynthesis and delivery of transmembrane proteins

20
Q

Formation of lipid bilayers

A

Spontaneous formation: hydrophobic interactions

21
Q

Lipid-to-protein ratio of biological membranes

A

25-50% lipid
50-75% protein
<10% carbohydrate

22
Q

Fluid-mosaic model

A

Membranes are dynamic structures in which lipids and proteins can rapidly rotate and diffuse

23
Q

Flippase and floppase

A

Enzymes which catalyze transverse diffusion of certain phospholipids

24
Q

Factors affecting membrane fluidity

A

Increased temp- increased fluidity
Unsaturated fatty acids- increased fluidity
Cholesterol: decreased fluidity at high temps, increased fluidity at low temps (fluidity buffer)

25
Liposomes
Synthetic vesicles composed of lipid bilayers that enclose an aqueous compartment Great method for solubilizing certain drugs and delivering them within the body
26
Integral membrane proteins
Span the bilayer completely (hydrophobic middle) | Includes pores and channels used in passive and active transport
27
Peripheral membrane proteins
Associated with one face of membrane through charge-charge interactions and/or H-bonding with integral membrane proteins or polar head groups
28
Lipid-anchored membrane proteins
Tethered to membrane through covalent bond to lipid anchor
29
Membrane transport depends on...
Concentration gradient | Charge gradient
30
Passive transport
Movement of solute down its concentration gradient without expenditure of energy Continues until concentration gradient is equalized
31
Active transport
Requires energy to move molecule up its concentration gradient Usually uses ATP as energy source
32
2 types of active transport
Primary active transport: powered by direct source of energy | Secondary active transport: uses ion concentration gradient to power second transport process