Exam 2 Study Guide - Lipids

Question 1

Fatty acids – know the basic structure.

Answer 1

Carboxylic acids with hydrocarbon tails ranging from 4 to 36 carbons long

Question 2

Be familiar with the common fatty acids.

Answer 2

Palmitic, linoleic, and arachidonic acid

Question 3

Saturated vs unsaturated fatty acids.

Answer 3

Saturated fats (unbranched) are solid at room temperature, whereas unsaturated fats (branched) are liquid at room temperature

Question 4

Delta system.

Answer 4

Chain length and number of double bonds, separated by a colon; positions of double bonds are indicated by  and superscript number

Question 5

Omega system.

Answer 5

Labeled omega and by double bond between most distant carbon

Question 6

What is the difference between cis and trans bonds

Answer 6

• Cis bonds have hydrogen atoms on same side of double bond, resulting in a bent shape
  -Trans bonds have hydrogen atoms on opposite sides of double bond

Question 7

Triacylglycerols: Know the basic structure

Answer 7

Three fatty acids, each in ester linkage with a single glycerol (non-polar, hydrophobic)…provide energy storage and insulation

Question 8

Waxes: Basic structure

Answer 8

Esters of long-chain saturated and unsaturated fatty acids with long-chain alcohols

Question 9

Where are waxes found.

Answer 9

Bee honeycomb, leaves of plants, feathers

Question 10

Properties of waxes.

Answer 10

Higher melting point than triacylglycerols, water-repellant, firm consistency

Question 11

Biological membranes: Structure

Answer 11

• A double layer of lipids that act as a barrier to polar molecule and ions
• Amphipathic (one end is hydrophobic, the other hydrophilic), Hydrophobic (regions associate with each other), Hydrophilic (regions associate with water)

Question 12

Phospholipids: Composition

Answer 12

Have hydrophobic regions composed of two fatty acids joined to glycerol or sphingosine

Question 13

Phospholipids: Basic structure

Answer 13

Two fatty acids are attached in ester linkage to the first and second carbons of glycerol, and a highly polar group is attached through phosphodiester linkage to the third carbon

Question 14

Sphingolipids: Composition

Answer 14

Have a polar head group and two nonpolar tails, no glycerol, one molecule of the long-chain amino alcohol sphingosine

Question 15

Sphingolipids: Role in blood types

Answer 15

Human blood groups (O, A, B) are determined by the oligosaccharide head groups of sphingolipids

Question 16

Glycolipids: Role in chloroplasts

Answer 16

Oxygenic photosynthesis (thylakoid membrane); lipid bilayer matrix for photosynthetic protein cofactor complexes and support the ETC (electron transport chain)

Question 17

Archaeal tetraether lipids: General composition

Answer 17

Have two very long alkyl chains ether-linked to glycerol at both ends

Question 18

Sterols: Basic structure

Answer 18

Rigid system of four fused hydrocarbon rings; planar and rigid

Question 19

Cholesterol: Role in membranes

Answer 19

Structural components of eukaryotic membranes

Question 20

Cholesterol: Hormone example

Answer 20

estradiol

Question 21

Bile acids: What are they?

Answer 21

Polar derivatives of cholesterol that emulsify dietary fats in the intestine to make them more readily accessible to digestive lipases

Question 22

Intracellular signaling

Answer 22

Regulate cell structure and metabolism

Question 23

Intercellular signaling

Answer 23

• Ex. Eicosanoids: paracrine hormones that act only on cells near the point of hormone synthesis instead of being transported in the blood
• Reproductive function, inflammation, fever, pain, regulation of blood pressure, etc.

Question 24

Steroid hormones

Answer 24

Oxidized derivatives of sterols (lack alkyl chain attached to D ring in cholesterol) move through the bloodstream to target tissues

Question 25

Explain why glycerophospholipids make good membrane components.

Answer 25

Glycerophospholipids are membrane lipids in which two fatty acids are attached in ester linkage to the first and second carbons of glycerol, and highly polar group is attached through a phosphodiester linkage to the third carbon. They can vary in the fatty acid content and the composition of the polar head group. Having a polar head group, allows this membrane lipid to arrange themselves into a membrane bilayer; thus, providing stability. Lastly, the head group can bear a negative, neutral, or positive charge. These characteristics make them amphipathic (hydrophobic and hydrophilic region) allowing for permeability and fluidity in the membrane.