Chapter 17

Question 1

What are the advantages of using fats over polysaccharides for energy ?

Answer 1

• fatty acids carry more energy per carbon b/c they are more reduced
• they carry less water b/c they are nonpolar

Question 2

What emulsifies dietary fats in the small intestine, forming mixed micelles

Answer 2

bile salts

Question 3

What do intestinal lipases degrade triacylglycerols into ?

Answer 3

triacylglycerols are degraded into free fatty acids and monoacylglycerols

Question 4

What are spherical aggregates of apolipoproteins and lipids ?

Answer 4

lipoprotein particles

Question 5

What are Chylomicrons

Answer 5

Lipoprotein particles consisting of (main component is apolipoprotein B-48) as well as triacylglycerols, cholesterol and other apoliporoteins

function is to transport lipids from the intestine to adipose tissues

Question 6

Where are fatty acids converted into triacylglycerols

Answer 6

liver

Question 7

What two molecules trigger lipases

Answer 7

glucagon and epinephrine

Question 8

What does serum albumin do?

Answer 8

it is a blood protein that non-covalently binds and transports free fatty acids to target tissues

Question 9

What are proteins in their lipid free form that eventually bind lipids to form lipoproteins ?

Answer 9

Apolipoproteins

Question 10

What is the primary protein component of chylomicrons

Answer 10

apolipoprotein B-48

Question 11

What is the protein picked up from high-density lipoprotein particles by chylomicrons?

Answer 11

Apolipoprotein C-II

Question 12

Name the family of proteins that coat the surface of lipid droplets to restrict access to lipid droplets

Answer 12

Perilipins

Question 13

In the metabolism of glycerol, what is glycerol converted to ?

Answer 13

Glyceraldehyde-3-phosphate

Question 14

Through what enzyme are fatty acids converted into fatty acyl coA ?

Answer 14

via fatty acid acyl coA synthetase

Question 15

What are fats degraded into in the cytoplasm of adipocytes ?

Answer 15

fatty acids and glycerol

Question 16

Where does the Beta oxidation of fatty acids occur ?

Answer 16

in the mitochondria

Question 17

What type of fatty acids can freely diffuse across mitochondrial membranes ?

Answer 17

the less common small (<12 carbon) fatty acids

Question 18

What type of fatty acids are transported into the mitochondria using a transporter?

Answer 18

large fatty acids (which is most fatty acids)

Question 19

What is the name of the antiporter that transports larger fatty acids across the mitochondrial membrane ?

Answer 19

Acyl-carnitine / carnitine transporter

Question 20

What is being shuttled in and out of the acyl-carnitine / carnitine cotransporter ?

Answer 20

Acyl-carnitine in shuttled into the matrix as carnitine is shuttled out

Question 21

What are the roles of the two different carnitine acyl-transferases (CAT 1 and CAT 2)

Answer 21

CAT 1: catalyzes the transesterification b/w fatty acyl-CoA and carnitine (on the cytosolic side of the outer mitochondrial membrane)
CAT 2: catalyzes the transesterification b/w fatty acyl-carnitine and coA (on the matrix side of inner mitochondrial membrane)

Question 22

What is the rate-limiting step for the oxidation of fatty acids in the mitochondria ?

Answer 22

carnitine mediated entry

Question 23

What molecule inhibits CAT 1

Answer 23

malonyl-coA inhibits CAT 1 to prevent simultaneous breakdown/synthesis

Question 24

When oxaloacetate is depleted, acetyl-coA is converted into what ?

Answer 24

Ketone bodies

Question 25

Under what circumstances does the accumulation of acetyl-coA accelerate the formation of ketone bodies ?

Answer 25

during starvation and in untreated diabetics

Question 26

What is ketosis, what is ketoacidosis

Answer 26

ketosis - high levels of ketone bodies in the blood + urine ketoacidosis - ketosis + acidosis (lowered blood pH)

Question 27

During peroxisomal oxidation, fats can be oxidized to generate _____?_____

Answer 27

heat

Question 28

What are the two potential fates of acetyl-coA formed in the liver ?

Answer 28

Acetyl-coA can either be oxidized via the citric acid cycle or converted to ketone bodies that serve as fuels for other tissues

Question 29

In the metabolism of glycerol, glycerol is converted into what?

Answer 29

glycerol ----> D-Glyceraldehyde-3-phosphate (D-G3P)

Question 30

What causes the release of glycerol

Answer 30

the action of lipases on TAGs

Question 31

What are lipases

Answer 31

enzymes that breakdown fats in food

Question 32

Basic relationship b/w lipid & carbohydrate metabolism?

Answer 32

1. acetyl-coA is the linking molecule 2. glucose, glycerol and fatty acids all degrade into acetyl-coA

Question 33

What is the role of **Glycogen Phosphorylase **in glycogenolysis

Answer 33

glycogen phosphorylase breaks the alpha 1-4 linkages by adding Pi to the first carbon, transforming glycogen into glucose-1-phosphate it keeps going until it reaches 4 glucose away from an alpha 1-6 branch

Question 34

What is the role of the **debranching enzyme** in glycogenolysis ?

Answer 34

the debranching enzyme grabs the 3 glucose residues and attaches them to a non-reducing end (transferase activity)

Question 35

What is the role of **phosphoglucomutase** in glycogenolysis?