Metabolism 1 & 2

Question 1

Four fates of acetyl coA

Answer 1

Lipogenesis
Cholesterol synthesis
Formation of ketone bodies
TCA cycle

Question 2

What type of reaction is the TCA cycle?

Answer 2

Combustion reaction: produces H20, CO2, and ATP

Question 3

Where does beta-oxidation take place?

Answer 3

In the mitochondria

Question 4

What structures have the highest stores of glycogen?

Answer 4

Liver, heart/skeletal muscle

Question 5

How does amino acid metabolism lead to TCA cycle propagation?

Answer 5

Proteins can be broken down either to acetyl coA or to an intermediate in the TCA cycle

Question 6

Driving force for the coordination of metabolism

Answer 6

To provide the brain with glucose. (That and ketone bodies [during starvation] are the only source of fuel for the brain)

Question 7

Hydration status in stored macromolecules

Answer 7

Proteins and carbohydrates are stored in a hydrated state; lipids are stored in an anhydrous state

Question 8

Ratio of pancreatic amylase release to the amount of starch intake

Answer 8

There is a large excess of the enzyme released relative to the amount ingested

Question 9

Relative amounts of sucrase and lactase

Answer 9

Sucrase is generally in great excess; lactase is less abundant

Question 10

Products of bacterial breakdown of lactose left in the lumen

Answer 10

Lactic acid, methane, carbon dioxide, and hydrogen gas

Question 11

How many mutations of the LCT gene have been identified?

Answer 11

9

Question 12

Lactose anaphylaxis

Answer 12

Milk-induced allergic reaction in response to alpha S1 casein

Question 13

Secondary lactose intolerance

Answer 13

Present in children who have recently had gastroenteritis that caused damage to the epithelial lining of the gut; once the epithelial lining is healed, the symptoms resolve

Question 14

What long-term effects does insulin have on metabolism?

Answer 14

Glycolysis and glycogen synthesis

Question 15

Net products of glycolysis

Answer 15

2 pyruvate, 2 ATP, 2 NADH, and 2 water

Question 16

Daily glucose usage in the brain vs muscle

Answer 16

120 g vs 40 g

Question 17

Where are the only glucagon receptors located?

Answer 17

On the liver

Question 18

Fate of lysed glycogen in the liver

Answer 18

Once the glycogen is cleaved into G6P, the liver does not use it

Question 19

Products of the pentose phosphate pathway

Answer 19

NADPH and ribose-5-phosphate

Question 20

Red blood cell metabolism

Answer 20

They lack a nucleus and mitochondria, so they depend 100% on glycolysis

Question 21

Function of GLUT2 having lower affinity for glucose

Answer 21

All the other GLUT transporters are saturated at normal concentrations of glucose; this allows GLUT2 to be the “override” transporter that is present for excess glucose after a carbohydrate-rich meal

Question 22

Functional components of GLUT transporters

Answer 22

12 membrane-spanning helices with intracellular loop between 6th and 7th helices

Question 23

How much of glucose is metabolized in an insulin-independent manner?

Answer 23

70%

Question 24

Three mechanisms of regulation of regulatory enzymes in glycolysis

Answer 24

Allosteric in/activation, covalent modifications, and regulation of enzyme synthesis

Question 25

Three regulated enzymes in glycolysis

Answer 25

Hexokinase/glucokinase
PFK-1
Pyruvate kinase

Question 26

Glycolysis produces energy in the form of ___

Answer 26

NADH and ATP

Question 27

What can pyruvate be used for in the presence of sufficient energy?

Answer 27

Can be used in protein synthesis

Question 28

Significance of first phosphorylation step

Answer 28

Once glucose is phosphorylated, it is trapped inside the cell and will continue metabolism in one way or another

Question 29

Most highly regulated step of the glycoloysis pathway

Answer 29

Aldolase A (splits F16BP into dihydroxyacetone phosphate and glyceraldehyde 3 P)

Question 30

Deficiency of any of the glycolytic enzymes

Answer 30

Red blood cells become swollen and they burst, causing hemolytic anemia

Question 31

Substrate-level phosphorylation during glycolysis

Answer 31

Occurs during the step where 13BPG is converted to 3PG by phosphoglycerate kinase

Question 32

Glycolytic enzymes producing ATP

Answer 32

Pyruvate kinase and phosphoglycerate kinase

Question 33

Three stages of glycolysis

Answer 33

Stage 1: prepping stage
Stage 2: splitting stage
Stage 3: oxidoreduction/phosphorylation stage

Question 34

Allosteric regulation

Answer 34

Activates or inhibits enzyme activity; products of the enzyme will allosterically inhibit the enzymes in glycolysis, whereas substrates will activate them. Transient and easily reversible.

Question 35

Covalent modification

Answer 35

In/activation of an enzyme based on phosporylation

Question 36

Enzyme synthesis based on translation stability

Answer 36

Long-term control of enzyme activity