Lipids and Membranes Flashcards Preview

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Flashcards in Lipids and Membranes Deck (32)
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1
Q

Amphiphilic

A

Containing both polar and nonpolar regions

2
Q

4 major classes of lipids

A

Fatty acids
Phospholipids
Glycosphingolipids
Isoprenoids

3
Q

Simplest class of lipids

A

Fatty acids

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)

5
Q

Effects of unsaturations in fatty acid chains

A

Increased flexibility: looser packing

Lowered melting point

6
Q

Triacylglycerols

A

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

7
Q

Metabolism of triacylglycerols

A

Broken down in small intestine by lipases

8
Q

Glycerophospholipids

A
Compose majority of membranes
Amphiphilic molecules (polar head, nonpolar tail)
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)

10
Q

Phospholipases

A

Class of enzymes that catalyze cleavage of esters in phospholipids

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

12
Q

Sphingolipids

A

Sphingosine backbone

Particularly abundant in CNS cells

13
Q

Ceramide

A

Precursor of all other sphingolipids

14
Q

Sphingomyelins

A

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

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

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
Q

Liposomes

A

Synthetic vesicles composed of lipid bilayers that enclose an aqueous compartment
Great method for solubilizing certain drugs and delivering them within the body

26
Q

Integral membrane proteins

A

Span the bilayer completely (hydrophobic middle)

Includes pores and channels used in passive and active transport

27
Q

Peripheral membrane proteins

A

Associated with one face of membrane through charge-charge interactions and/or H-bonding with integral membrane proteins or polar head groups

28
Q

Lipid-anchored membrane proteins

A

Tethered to membrane through covalent bond to lipid anchor

29
Q

Membrane transport depends on…

A

Concentration gradient

Charge gradient

30
Q

Passive transport

A

Movement of solute down its concentration gradient without expenditure of energy
Continues until concentration gradient is equalized

31
Q

Active transport

A

Requires energy to move molecule up its concentration gradient
Usually uses ATP as energy source

32
Q

2 types of active transport

A

Primary active transport: powered by direct source of energy

Secondary active transport: uses ion concentration gradient to power second transport process