Lecture 13

Question 1

What are lipids

Answer 1

diverse group of compounds characterized by INSOLUBILITY in aqueous fluids and solubility in organic solvents

Question 2

What are the 4 classes of lipids

Answer 2

1. Fats and oils (Triglycerides)
2. Waxes
3. Phospholipids
4. Steroids

Question 3

Describe the Fats and Oils (triglycerides) classes of lipids

Answer 3

esters of glycerol and 3 fatty acids
at room temperature fats are solid but oils are liquids

Question 4

Describe Waxes

Answer 4

Esters of LONG-CHAIN alcohols and long chain fatty acids
protects plants and insects against water loss
Cerumen (ear wax) protects ear

Question 5

describe phospholipids

Answer 5

glycerol bonded to 2 fatty acids and a phosphate group
structure of plasma membrane
functional group (R)

Question 6

Describe Steroids

Answer 6

Phenanthrene Ring
Synthesized from isoprenoidW units via squalene
Cholesterol is the parent molecule for many hormones

Question 7

What are the structural and Functional role of lipids in the body

Answer 7

1. biological membranes
2. energy storage
3. waterproofing
4. signaling

Question 8

how does energy storage occur in lipids

Answer 8

undergoes β-oxidation

Question 9

How do lipids do waterproofing

Answer 9

Cerumen: cuticle of arthropods and plants

Question 10

describe signaling in lipids

Answer 10

20C polyunsaturated lipid (Arachidonic Acid: source of eicosanoids)

Question 11

What is Arachidonic acid

Answer 11

precursor or prostaglandins & Thromboxanes

Question 12

What do prostaglandins do

Answer 12

contribute to pain perception
-mediate inflammation, pain, and contraction of smooth muscle
Nonsteroidal anti-inflammitory drug (NSAID) Drugs (asprin, ibuprofin) inhibits prostaglandin synthesis

Question 13

What is Anandamide

Answer 13

The bliss molecule
regulates mood, appetite, pain perception, memory, pleasure
part of the endocannabinoid system of the brain

Question 14

What does phospholipase A do

Answer 14

cleaves a fatty acid from the membrane

Question 15

What is cyclooxyegenases (COX-1, COX-2)

Answer 15

key enzymes in the conversion of arachidonic acid to postaglandins and other lipid mediators
celebrex inhibits COX2

Question 16

What are eicosanoids

Answer 16

lipid signaling molecules synthesized on demand (inducible) at their site of action

Question 17

What do Corticosteroids do

Answer 17

suppress immune reaction by inhibiting biosynthesis of eicosanoids

Question 18

What is the relation between fatty acid chain length, saturation, and melting point

Answer 18

longer the chain, more saturated, higher melting point

Question 19

What essential lipids are polyunsaturated

Answer 19

linoleic acid (ω-6)
linolenic acid (ω-3)

Question 20

what is beta-oxidation

Answer 20

catabolism of lipids for energy
4 repeating enzymatic steps that lead to stepwise breakdown of a fatty acid
Yield:
1. 1 reduced coenzyme FADH
2. 1 reduced coenzyme NADH
3. 1 One molecule of Acetyl CoA

Question 21

How does Acetyl CoA enter the mitochondrial matrix

Answer 21

carnitine shuttle system

Question 22

Where does fatty acid activation occur

Answer 22

in the cytosol

Question 23

what is the first step of beta-oxidation

Answer 23

pyrophosphate cleavage of ATP

Question 24

How many cycles in beta-oxidation

Answer 24

N/2 - 1
n= #carbon atoms in fatty acid

Question 25

Where does B-oxidation take place

Answer 25

Mitochondrial matrix

Question 26

How does the carnitine shuttle system work?

Answer 26

Activated fatty (Acyl-CoA) and carnitine are combined using Carnitine Palmetto transferase I in the cytosol Acyl-carnitine diffuses into the mitochondrial matrix and through the inner mito-membrane through an anti-port translocase with carnitine Inside mito, converted back into Acyl-CoA + Carnitine by Carnitine Palmitoyl transferase II Carnitine passively diffuses through both membranes back into the cytosol

Question 27

What are the products of the Krebs cycle?

Answer 27

1 ATP/GTP 3NADH 2 CO2 1 FADH2

Question 28

Where does electron transport occur?

Answer 28

Inner membrane of mitochondria

Question 29

What is the net ATP yield from complete oxidation of one molecule of palmitic acid? (16C)

Answer 29

129

Question 30

what is the net ATP yield from metabolism of a 16:0 fatty acid for B-oxidation, TCA, and fatty acid activation

Answer 30

B-oxidation: 7NADH + 7FADH2 + 8 acetyl CoA TCA: 24 NADH + 15 FADH2 + 8 ATP from substrate level phos. Fatty acid conv: NADH= 2.5 ATPs ; FADH2=1.5 ATP NET: 106