UNIT 6: LIPIDS

Question 1

What are 3 main roles of lipids?

Answer 1

• energy source
• signalling
• precursor to hormones

Question 2

A molecule with detergent characteristics means the _____ zone is strong. What does a detergent do?

Answer 2

hydrophilic zone strong of a amphipathic molecule

• destroys lipid structures to form emulsions
• destroys cell systems

Question 3

What has a lower melting point?

Short chain FA or long chain FA

Answer 3

• short chain FA have lower melting points

Question 4

What has a lower melting point?

saturated or unsaturated FA?

Answer 4

Unsaturated have lower melting points

saturated - straight chain - low fluidity - high melting point

Question 5

Delta system nomenclature starts on which end?

Omega system?

Answer 5

Delta
- carbonyl (=O)

Omega
- methyl end (-CH3)

Question 6

What are the only 2 essential fatty acids?

Answer 6

• Linoleic acid (LA, n-6)

- Alpha-linoleic acid (ALA, n-3)

Question 7

Linoleic acid is metabolized to ____

Answer 7

Arachidonic acid (AA)

Question 8

Alphalinoleic acid is metabolized to ____

Answer 8

eicosapentanoic acid (EPA)
docosahexaenoic acid (DHA)

Question 9

Linoleic acid and Alpha-linoleic acid can synthesize longer omega6 and omega 3 fatty acids via ___ and ___

Answer 9

desaturation and elongation, (and desaturation)

• products are AA, EPA, DHA

Question 10

Increase in ______ increases fluidity of membranes

Answer 10

unsaturation

Question 11

Eicosanoid signalling is essential in some endocrine pathways. What is eicosanoid formed from?

Answer 11

AA (essential eicosanoids)

EPA (nonessential eicosanoids)

Question 12

What is the first step of eicosanoid signalling?

Answer 12

Enzyme phospholipid A-2 activtaes and release a free fatty AA (arachidonic acid) and EPA (eicosapentaenoic acid) from phospholipid membrane
= free fatty acid pool, important for synthesizing more eicosanoids and endocrine

Question 13

What are the roles of free arachidonic acid (FFA) and eicosapentaenoic acid (EPA)?

Answer 13

• eicosanoid forming enzymes like lipoxygenases and cycloxygenases
• responses: disease resisting, wound healing,, inflammation

Question 14

Proinflammatory events are catalyzed by what enzyme?

Answer 14

5-lipoxygenase

Question 15

Prostoglandins that increase and decrease blood clotting, increase perception of pain/fever, asthma, incr. BP, catalyzed by what enzyme?

Answer 15

cycloxygenases COX

Question 16

Eicosanoids are 20C metabolites of AA and EPA and have functions for:

Answer 16

inflammation, platelet aggregation

blood pressure

Question 17

We ingest and store lipids mostly as ____?

Answer 17

Triglycerides (TG)

90% of dietary fats

Question 18

What are the 3 classifications of lipids?

Answer 18

• triglycerides
• phospholipids
• sterols

Question 19

Phospholipids are amphipathic, like triglycerides; but do not have _____ properties.

Answer 19

detergent

Question 20

Do triglycerides have detergent properties?

Answer 20

• only the intermediate forms do
• monoacylglycerol MAG (1glycerol + 1FA)
• diacyglycerol DAG (1 glycerol + 2FA)

Question 21

Phospholipids in the small intestine can become detergents for digestion by which process?

Answer 21

• clip sn-1 (the first) fatty acid (unsaturated)
• leaves the 2 (saturated) and 3 with phosphate
  = 2-lysophospholipid (2lysoPL)
  = now a detergent
• but it needs to be converted back to a phospholipid once inside cells

Question 22

What is the most prevalent phospholipid in the body?

Answer 22

phosphatidylcholine
PC
- choline attached to the phosphate at sn-3

Question 23

What is a steroid nucleus?

Answer 23

the 4 ringed core structure that characterizes sterols and steroids

Question 24

Most sterols are from diet than produced in the body. True / False

Answer 24

False. 60% endogenous, 40% diet

Question 25

What vitamin is a sterol?

Answer 25

Vitamin D