Lipid and Amino Acid Metabolism

Question 1

Mechanical

Digestion:

Answer 1

Mechanical digestion of lipids occurs primarily in the

mouth and stomach.

Question 2

How does the Chemical Digestion occur

Answer 2

Chemical digestion of lipids occurs in the small intestine
and is facilitated by bile, pancreatic lipase, colipase, and
cholesterol esterase

Question 3

Explain how does Emulsification occurs

Answer 3

Upon entry into the duodenum, emulsification occurs,
which is the mixing of two normally immiscible liquids;
in this case, fat and water. (A common example of an
emulsion is oil-and-vinegar salad dressing). This
increases the surface area of the lipid, which permits
greater enzymatic interaction and processing.

Question 4

what is Emulsification aided by

Answer 4

Bile Salts

Question 5

Micelles

Answer 5

Water-soluble spheres with a lipid-soluble interior.
Digested lipids may form micelles to be carried to the
intestinal epithelium where they are absorbed across
the plasma membrane.

Question 6

Short-chain fatty acids

Answer 6

are absorbed across the intestine

into the blood.

Question 7

Long-chain fatty acids

Answer 7

are absorbed as
micelles and assembled into chylomicrons for release
into the lymphatic system.

Question 8

Lipid

Mobilization:

Answer 8

Lipids are mobilized from adipocytes by hormone-sensitive
lipase. Lipids are mobilized from lipoproteins by lipoprotein
lipase.

Question 9

Chylomicrons:

Answer 9

Transport dietary triacylglycerols, cholesterol, & cholesteryl
esters from intestine to tissues. Uses the lymphatic system.

Question 10

Lipoproteins:

Answer 10

The transport mechanism for lipids.
Very-low-density: Liver ® tissues.
Intermediate-density: Transition particle. VLDL ® IDL ® VLDL
Low-density: Bad. Moves cholesterol ® tissues.
High-density: Good. Moves cholesterol ® liver, exits body

Question 11

Apolipoproteins

Answer 11

Form the protein component of lipoproteins. They are

receptor molecules that control interactions between

Question 12

how can Cholesterol be obtained

Answer 12

Cholesterol may be obtained through dietary sources or through de novo
synthesis in the liver

Question 13

HMG-CoA

Reductase:

Answer 13

Synthesizes mevalonate. This is the rate limiting step of

cholesterol synthesis

Question 14

LCAT

Answer 14

Catalyzes the formation of cholesteryl esters for transport

with HDL

Question 15

CETP

Answer 15

Catalyzes the transition of IDL to LDL by transferring

cholesteryl esters from HDL

Question 16

Fatty Acids:

Answer 16

Carboxylic acids with a long chain

Question 17

Fatty Acids Saturated

Answer 17

No double bonds

Question 18

Fatty Acids Unsaturated

Answer 18

One or more double bonds

Question 19

Fatty Acid

Synthesis

Answer 19

Synthesized in cytoplasm from acetyl-CoA transported out of
the mitochondria. Five steps: Activation, bond formation,
reduction, dehydration, and a second reduction.

Question 20

Fatty Acid

Oxidation:

Answer 20

Oxidation occurs in the mitochondria following transport by the
carnitine shuttle. b-oxidation uses cycles of oxidation,
hydration, oxidation, and thiolysis cleavage. The fatty acid
chain is shortened by two carbon atoms. FADH2, NADH, and
acetyl CoA are generated.

Question 21

Ketogenesis:

Answer 21

Ketone bodies form via ketogenesis due to excess acetylCoA in the liver during a prolong

Question 22

Ketolysis:

Answer 22

Regenerates acetyl-CoA for use as an energy source in

peripheral tissues

Question 23

Energy Source:

Answer 23

The brain can derive up to 2/3 of its energy from ketone

bodies during prolonged starvation

Question 24

Protein Catabolism

Answer 24

Protein digestion occurs primarily in the small intestine. Catabolism of
cellular proteins occurs only under conditions of starvation. Amino acids
released from proteins usually lose their amino group through deamination.
The remaining carbon skeleton can be used for energy.

Question 25

Glucogenic

Amino Acids:

Answer 25

Can be converted into glucose through gluconeogenesis.

All but leucine and lysine.