Ch 24 Bio Exam 4

Question 1

A transport system called the ______ carries fatty acids into the mitochondria from the cytosol.

______ catalyzes the transfer of a fatty acyl group to the hydroxyl group of carnitine to produce fatty acyl carnitine.

Answer 1

• carnitine shuttle
• Carnitine acyltransferase

Fatty acyl carnitine then passes through the inner mitochondrial membrane into the matrix.

Question 2

Fatty acids in the cytosol are transported through the inner mitochondrial membrane to ______ in the matrix.

Answer 2

• undergo β oxidation

Question 3

Bile salts break fat globules into smaller particles called ______ in the small intestine.

Answer 3

• micelles

Question 4

Pancreatic lipases ______ ester bonds to form monoacylglycerols and fatty acids, which recombine in the intestinal lining.

Answer 4

• hydrolyze

Question 5

phospholipids and proteins coat the fats, forming ______, which are transported to the cells of heart, muscle, and adipose tissues.

Answer 5

• chylomicrons

Question 6

Lipases hydrolyze triacylglycerols, forming _____ and free fatty acids, which are oxidized to acetyl CoA molecules for ATP synthesis.

Answer 6

• glycerol

Question 7

• the process of fat utilization is stimulated.
• the hormones glucagon and epinephrine are secreted into the bloodstream, where they bind to receptors on the membrane of adipose tissue.
• a hormone-sensitive lipase within the fat cells catalyzes the hydrolysis of triacylglycerols to glycerol and free fatty acids.
• glycerol and fatty acids diffuse into the bloodstream and bind with plasma proteins to be transported to the tissues, muscles, and fat cells.

Answer 7

• When blood glucose is depleted and glycogen stores are low,

Question 8

• adds a phosphate from ATP to form glycerol-3-phosphate.
• undergoes oxidation of the —OH group to dihydroxyacetone phosphate.
• becomes an intermediate in glycolysis and gluconeogenesis.

Answer 8

Glycerol from fat digestion

Question 9

What helps add a phosphate group to Glycerol?

What helps oxidize Glycerol -3-phosphate to Dihydroxyacetone phosphate?

Answer 9

• Glycerol kinase

- Glycerol-3-phosphate dehydrogenase

Question 10

How is glycerol utilized?

Answer 10

• Glycerol adds a phosphate and is oxidized to an intermediate of the glycolysis and gluconeogenesis pathways.

Question 11

• a fatty acid is combined with CoA to yield a high-energy fatty acyl CoA.
• energy is released by the hydrolysis of ATP to AMP and used to drive the reaction.

Answer 11

• Fatty acid activation

Question 12

A large amount of energy is obtained when fatty acids undergo oxidation in the mitochondria to acetyl CoA.

________, which removes two-carbon segments containing the alpha and beta carbon from the of the fatty acid.

Answer 12

• beta oxidation (β oxidation)

- carboxyl end

Question 13

After the fatty acyl carnitine is transferred by the carnitine shuttle into the mitochondria matrix what does carnitine acyltransferase do?

Answer 13

• catalyzes the reverse reaction that transfers the fatty acyl group to CoA to reform fatty acyl CoA.
• releases the carnitine and returns to the cytosol.

Question 14

What is produced in reaction one of beta oxidation?

Answer 14

• trans-Enoyl CoA and FADH2
• acyl CoA dehydrogenase catalyzes the transfer of hydrogen atoms from the α and β carbons of the activated fatty acid.
• a trans C = C bond is formed between α and β carbons, and the reduced coenzyme FADH2 is produced.

Question 15

• a hydration reaction catalyzed by enoyl CoA hydratase adds the components of water to the trans double bond.
• a hydroxyl group (—OH) attaches to the β carbon of the fatty acid, and a hydrogen atom attaches to the α carbon.

Answer 15

• beta-oxidation reaction 2

Question 16

• the secondary hydroxyl group on the β carbon (carbon 3) is oxidized by 3-hydroxyacyl CoA dehydrogenase to yield a ketone.
• the hydrogen atoms removed in the oxidation are transferred to NAD+ to yield a β keto or 3-keto group and the reduced coenzyme NADH.

Answer 16

• beta-oxidation reaction 3

Question 17

• the Cα — Cβ bond is cleaved by β-ketoacyl CoA thiolase to yield a two-carbon acetyl CoA and a new fatty acyl CoA that is shortened by two carbon atoms.
• the shorter fatty acyl CoA repeats the four steps of the β- oxidation cycle until the original fatty acid is completely degraded to two-carbon units of acetyl CoA.

Answer 17

• beta-oxidation reaction 4

Question 18

Odd-numbered fatty acids go through the same four steps of β oxidation until the final cycle, in which the remaining fatty acyl CoA is cleaved to yield a_____ group and an acetyl CoA.

Answer 18

• propionyl CoA (C3)

Question 19

For one cycle of beta-oxidation how many molecules of NADH, FADH, and acetyl CoA are produced and where are they produced?

Answer 19

• 1 FADH in reaction 1
• 1 NADH in reaction 2
• Acetyl CoA in reaction 4

Question 20

Some fats from our diets contain unsaturated fatty acids, which have one or more cis double bonds.
An isomerase converts a cis double bond to a trans double bond between the ______ so the fatty acid can undergo hydration. It forms a product that enters β oxidation at reaction 2, so the energy released by the β oxidation of an unsaturated fatty acid is slightly less because no _____ is produced in that cycle.

Answer 20

• α and β carbons

- FADH2

Question 21

How many ATP does it take to activate Fatty acid beta-oxidation?

Answer 21

• 2 ATP

Question 22

____ is a protoxin that is metabolized to become an inhibitor of acyl CoA dehydrogenase, the first enzyme in the b oxidation pathway.

Answer 22

• Hypoglycin A

Question 23

If carbohydrates are not available

Answer 23

fatty acids break down to meet energy needs.

acetyl CoA molecules combine to form ketone bodies.

Question 24

Where do high levels of acetyl CoA accumulate?

Answer 24

• Liver

acetyl CoA molecules combine in a pathway known as ketogenesis to form compounds called ketone bodies.

Question 25

During reaction 1 of ketogenesis ( condensation), what do two molecules of acetyl CoA combine to form?

Answer 25

• Acetoacetyl CoA

this condensation is in the opposite direction of the last step of β oxidation

Question 26

• in cases of diabetes, diets high in fat, and starvation.
• as ketone bodies accumulate.
• when acidic ketone bodies lower blood pH below 7.4 (acidosis).

Answer 26

• Ketosis occurs

Question 27

Hydrolysis reaction 2 of ketogenesis:

Acetoacetyl CoA undergoes hydrolysis to form what?

Answer 27

• Acetoacetate

Question 28

______ can undergo either a hydrogenation or a decarboxylation (reactions 3 and 4) to produce other ketone bodies.

Answer 28

• Acetoacetate

Question 29

Acetoacetate is reduced by 2H from NADH + H+ to _____, which is considered a ketone body even though it does not contain a keto group.

Answer 29

• β-hydroxybutyrate

Reaction 3

Question 30

Acetoacetate can also undergo ____ to yield acetone, a ketone body, and CO2.

Answer 30

• decarboxylation

Reaction 4

Question 31

where does lipogenesis occur?

Answer 31

• In the cytosol

Question 32

Lipogenesis occurs in the cytosol using the reduced coenzyme _____ instead of occurring in the mitochondria, where oxidation takes place using FAD and NAD+.

Answer 32

• NADPH

Question 33

What activates the Acyl compounds for fatty acid synthesis?

Answer 33

• acyl carrier protein