ch 8 - lipids

Question 1

what is the common defining feature of lipids?

Answer 1

insoluble in water due to their hydrophobic or amphipathic characteristics

Question 2

what are the functional roles of lipids? (3)

Answer 2

• energy storage (fat in animals, oil in plants)
• structural component of membranes
• active roles (hormones, enzyme co factors, pigments)

Question 3

true or false: liquids are most likely to be unsaturated bonds, shorter in length

Answer 3

true

Question 4

what characteristics of lipids make them effective for long-term energy storage?

Answer 4

• low oxidation state: C atoms of fat tend to be linked to H or other C, not O
• low hydration state: lipids are hydrophobic with limited interaction with water making it more compact/dense

Question 5

what is made up of 3 fatty acids and a glycerol backbone? what variations are there?

Answer 5

• triaclyglycerols

- simple ones have the same 3 fatty acids and complex ones have different 3 fatty acids

Question 6

what are the characteristics of waxes?

Answer 6

• non-polar esters of long-chain fatty acids and long chain monohydroxylic alcohols
• insoluble in water
• high melting temperatures
• used in nature as waterproof coatings

Question 7

what is a glycerophospholipid?

Answer 7

• most abundant membrane lipid

- glycerol backbone with phosphate attached at C3 and two fatty acids

Question 8

how do plants conserve phosphate (limited resource) for where its essential?

Answer 8

• replace the phosphate groups of glycerophospholipids with a different, functionally equal, hydrophilic group
• sugars such as galactose used

Question 9

what are the 3 classes of sphingolipids?

Answer 9

• sphingomyelins: contain phosphocholine or phosphoethanolamine
• cerebrosides: glycosphingolipid. single sugar unit, no phosphate
• gangliosides: glycosphingolipid. more than 6 sugar units. contains N-acetylneuraminic acid (sialic acid)

Question 10

what 3 key membrane modifications do extremophiles have to live in those conditions?

Answer 10

• long chain hydrocarbons linked at either end of glycerol
• fatty acid chains join at the glycerol backbone rather than ester
• hydrocarbons often branched, giving resistance to oxidation

Question 11

what are sterols?

Answer 11

• structural membrane lipids serve as precursors for many biologically active products
• contain 4 fused ring systems (3-six carbon A,B,C ring and a 5 Carbon D ring)

Question 12

what is cholesterol?

Answer 12

• causes plaque associated with cardiovascular disease

- biological functions such as: mediate membrane fluidity, precursor for steroid hormones, precursor of bile salts

Question 13

what are eicosanoids and describe the 3 classes.

Answer 13

• paracrine hormones that are derivatives of the polyunsatturated fatty acid arachidonic acid
  Classes:
  1. Prostaglandins: constrict blood vessels (ex. fever, inflammation)
  2. Thromboxanes: blood clot formation
  3. Leukotrienes: smooth-muscle contaction/bronchial constriction (ex. asthma)