Biochemistry Chapter 11: Lipid and Amino Acid Metabolism

Question 1

Where does mechanical digestion of lipids primarily happen?

Answer 1

stomach

Question 2

Where does chemical digestion of lipids occur?

Answer 2

the small intestine and is facilitated by bile, pancreatic lipase, colipase and cholesterol esterase

Question 3

Digested lipids can be:

Answer 3

form micelles for absorption or be absorbed directly

Question 4

Short-chain fatty acids are absorbed

Answer 4

across the intestine into the blood.

Question 5

Long-chain fatty acids are absorbed

Answer 5

as micelles and assembled into chylomicrons for release into the lymphatic system

Question 6

Lipids are mobilized from adipocytes by

Answer 6

hormone-sensitive lipase

Question 7

Lipids are mobilized from lipoproteins by

Answer 7

lipoprotein lipase

Question 8

Chylomicrons

Answer 8

the transport mechanism for dietary triacylglycerol molecules and are transported via the lymphatic system.

Question 9

VLDL

Answer 9

transports newly synthesized traacylglycerol molecules from the liver to peripheral tissues in the bloodstream.

Question 10

IDL

Answer 10

A VLDL remnant in transition between triacylglycerol and cholesterol transport; it picks up cholesteryl esters from HDL.

Question 11

LDL

Answer 11

primarily transports cholesterol for use by tissues.

Question 12

HDL

Answer 12

involved in the reverse transport of cholesterol.

Question 13

Apoproteins

Answer 13

control interactions between lipoproteins

Question 14

Cholesterol can be formed from:

Answer 14

dietary sources or through de novo synthesis in the liver

Question 15

The key enzyme in cholesterol biosynthesis

Answer 15

HMG-CoA reductase

Question 16

LCAT

Answer 16

catalyzes the formation of cholesteryl esters for transport with HDL

Question 17

CETP

Answer 17

catalyzes the transition of IDL to LDL by transferring cholesteryl esters from HDL

Question 18

Fatty acids

Answer 18

carboxylic acids with a (usually) single long chain, although they can be branched.

Question 19

Saturated fatty acids

Answer 19

have no double bonds between carbons

Question 20

Unsaturated fatty acids

Answer 20

have one or more double bonds

Question 21

Fatty acids are synthesized in___

Answer 21

the cytoplasm from acetyl-CoA transported out of the mitochondria

Question 22

What are the five steps of fatty acid synthesis?

Answer 22

activation
bond formation 
reduction
dehydration
2nd reduction

(Repeated, ex. 8 times to get palmitic acid)

Question 23

What is the only fatty acid that humans can synthesize?

Answer 23

palmitic acid

Question 24

Where does fatty acid oxidation occur?

Answer 24

in the mitochondria following transport by the carnitine shuttle

Question 25

Beta oxidation uses cycles of:

Answer 25

oxidation, hydration, oxidation & cleavage

Question 26

What types of fatty acids require special enzymes?

Answer 26

branched and unsaturated

Question 27

Unsaturated fatty acid enzymes

Answer 27

isomerase and an additional reductase

Question 28

When do ketone bodies form?

Answer 28

during a prolonged starvation due to excess acetyl-CoA in the liver

Question 29

Ketolysis

Answer 29

regenerates acetyl-CoA for use as an energy source in peripheral tissues

Question 30

Where does the brain get its energy during starvation?

Answer 30

from ketone bodies (up to 2/3 of energy)

Question 31

Where does protein digestion generally occur?

Answer 31

small intestine

Question 32

When does catabolism of cellular proteins occur?

Answer 32

conditions of starvation.

Question 33

How can amino acids be used for energy?

Answer 33

through either gluconeogenesis or ketone body formation.