Metabolism/Glycolysis Review (57/58)

Question 1

Liver: fuel preference

Answer 1

fatty acids, glucose, amino acids

Question 2

Skeletal muscle: fuel preference (at rest)

Answer 2

fatty acids

Question 3

Skeletal muscle: fuel preference (exertion)

Answer 3

glucose

Question 4

Heart muscle: fuel preference

Answer 4

fatty acids

Question 5

Brain: fuel preference (fed state)

Answer 5

glucose

Question 6

Brain: fuel preference (starvation)

Answer 6

ketone bodies/glucose

Question 7

Carbs: kcal/g (dry)

Answer 7

4

Question 8

Protein: kcal/g (dry)

Answer 8

4

Question 9

Fat: kcal/g (dry)

Answer 9

9

Question 10

Threshold for hypoglycemia, fasting conditions

Answer 10

60 mg / 100 mL

Question 11

Insulin promotes what, in relation to glucose?

Answer 11

Glycogenesis (glucose → glycogen)
Glycolysis (glucose → lactate (into CAC))

Fed states

Question 12

Glucagon / epinephrine promote what, in relation to glucose?

Answer 12

Glycogenolysis (glycogen → glucose)
Gluconeogenesis (lactate → glucose)

Fasting states

Question 13

Hexokinase location in tissue

Answer 13

Present in all cell types

Question 14

Inhibitor of hexokinase

Answer 14

Glucose-6-phosphate (G6P); feedback inhibition

Question 15

Levels of hexokinase

Answer 15

Constant, non-inducible

Question 16

Is hexokinase saturated at low glucose concentrations

Answer 16

Yes

Question 17

Glucokinase location in tissue

Answer 17

Liver and pancreas

Question 18

Inhibitor of glucokinase

Answer 18

Fructose-6P; translocates glucokinase to the nucleus (inactive)

Question 19

Active/inactive locations of glucokinase

Answer 19

Nucleus: inactive
Cytosol: active

Question 20

Up-regulator of GK activity?

Answer 20

Glucose (promotes translocation to nucleus)

Question 21

Chronic hyperglycemia level

Answer 21

110+ mg / 100 mL (leads to insulin resistance and beta cell dysfunction)

Question 22

Glucose utilization of brain, per day

Answer 22

120 g glucose / day

Question 23

Glucose utilization of muscle tissue, per day

Answer 23

40 g glucose / day

Question 24

Glycolysis end product (anaerobic)

Answer 24

Lactate

Question 25

Glycolysis end product (aerobic)

Answer 25

CAC (pyruvate (in mitochondria) → acetyl CoA → lactate)

Question 26

Stages of glycolysis

Answer 26

``` Priming stage (ATP investment) Splitting stage (fructose 1,6 bisphosphate can be converted to 2 molecules, further generating pyruvate) Oxidoreduction - phosphorylation stage (ATP earnings; happens twice because of splitting stage) ```

Question 27

NAD+ conversion to NADH happens at which stage of glycolysis

Answer 27

Immediately after splitting stage

Question 28

What does the NAD+ conversion to NADH catalyze?

Answer 28

Conversion of glyceraldehyde 3-phosphate to 1,3-bisphosphoglycerate

Question 29

Participates in NAD+ conversion to NADH

Answer 29

Dehydrogenase

Question 30

Key, irreversible enzymes for glycolysis/gluconeogenesis

Answer 30

Hexokinase/glucokinase PFK-1 Pyruvate kinase

Question 31

Levels of glucokinase

Answer 31

Inducible; synthesis is increased by insulin

Question 32

Glucokinase affinity (Km)

Answer 32

Low; not saturated at physiological glucose concentrations

Question 33

Pyruvate carboxylase genetic deficiency

Answer 33

Increased levels of alanine, lactate, and pyruvate

Question 34

PDH genetic deficiency

Answer 34

Increased circulatory levels of pyruvate and lactate

Question 35

NAD+ must be regenerated to maintain __________

Answer 35

Glycolytic flux Functions as coenzyme in oxidation reaction

Question 36

Anaerobic respiration replenishment of NAD+

Answer 36

Lactate dehydrogenase Reduction reaction, leading to lactate or EtOH production

Question 37

Aerobic respiration replenishment of NAD+

Answer 37

Metabolite shuttle system (NADH cannot pass mitochondrial membrane)

Question 38

Two types of NAD+ shuttles for regeneration

Answer 38

Malate-asparate shuttle | Glycerol-phosphate shuttle

Question 39

Function of pyruvate dehydrogenase (PDH)

Answer 39

Catalyzes conversion of pyruvate and CoASH (coenzyme A) to AcCoA (acetyl CoA)

Question 40

Vitamin cofactors required to activate PDH

Answer 40

Thiamine (B1): PDH-E1 and Thiamine PPi Riboflavin (B2): Dihydrolipoyl dehydrogenase E3 and FAD Niacin (B3): Dihydrolipoyl dehydrogenase E3 and FAD Pantothenate (B5): Dihydrolipoyl transacetylase E2 and lipoate CoA

Question 41

Lactate dehydrogenase A deficiency (LDHA)

Answer 41

Insufficient levels of lactate dehydrogenase leads to lower levels of NAD+, limiting flux through the glyceraldehyde-3-P dehydrogenase reaction

Question 42

Glycolysis net gain (ATP)

Answer 42

2 ATP, 2 pyruvate

Question 43

Lactate formation is favored in _________

Answer 43

anaerobic conditions

Question 44

Low levels of NADH leads to ________

Answer 44

Decreased lactate formation

Question 45

Galactosemia is caused by a deficiency in one of these two enzymes

Answer 45

Galactokinase | Galactose 1-phosphate uridyltransferase (classic, most common, most severe)

Question 46

Deficiency in aldolase B

Answer 46

Hereditary fructose intolerance