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BMB 402 Final > Final: Chapter 9 Glycolysis > Flashcards

Final: Chapter 9 Glycolysis Flashcards

1
Q

What does flux refer to?

A

The rate that substrates and products (metabolites) are interconverted

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2
Q

What two primary factors determine flux?

A

Level of enzyme activity and bioavailability of substrates

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3
Q

When might reactions be coupled?

A

When the overall Gibbs free energy is unfavorable/nonspontaneous (positive)

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4
Q

What is the structure of a monosaccharide?

A

One sugar containing an aldehyde (aldoses) or a ketone (ketoses)

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5
Q

What are epimers?

A

Two monosaccharides that differ in the -OH position around one chiral carbon

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6
Q

Simple sugars go through an intramolecular reaction to form what two types of rings?

A

Pyranose or furanose rings which increase structural stability

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7
Q

What determines whether a simple sugar is oxidized or reduced?

A

Their functional groups

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8
Q

What are reducing sugars?

A

Carbohydrates that react with oxidizing agents to promote oxidation

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9
Q

What are disaccharides?

A

Two monosaccharides linked together through an O-glycosidic bond

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10
Q

What type of reaction forms disaccharides?

A

Condensation reaction

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11
Q

What are the three most common disaccharides?

A

Lactose, sucrose, and trehalose

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12
Q

What’s one reason why shared intermediates are used effectively in coupled reactions?

A

Some metabolic enzymes are components of large multiprotein complexes. This is a type of close physical interaction that limits product diffusion and functions to “channel” shared intermediates from one enzyme to the next

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13
Q

What are nonreducing sugars?

A

Sugars that cannot reduce Cu2+. Examples include sucrose and trehalose

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14
Q

What is lactase?

A

A hydrolytic enzyme that is expressed in high levels in infants to aid in the digestion of lactose. Levels of lactase decline in adults

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15
Q

Under what conditions does glycolysis generate ATP?

A

Anaerobic conditions

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16
Q

In general, what is glycolysis?

A

The “splitting” of 1 molecule of glucose into 2 molecules of pyruvate

17
Q

How many enzymatic reaction comprise glycolysis?

A

10 reactions
(1-5) ATP investment
(6-10) ATP production

18
Q

What is the first step of glycolysis and what enzyme is involved?

A
  • Glucose is phosphorylated by hexokinase or glucokinase to form glucose-6-P
  • Mg2+ required
  • ATP converted to ADP (ATP hydrolysis)
  • Hexokinase is for all cells (broad range of substrate specificities), glucokinase (specific for glucose in the liver and pancreas)
19
Q

What enzyme is used for glucose monitoring?

A

Glucokinase

20
Q

What is the second step of glycolysis and what enzyme is involved?

A

Glucose-6-P undergoes isomerization using phosphoglucoisomerase to form fructose-6-P

21
Q

What is the third step of glycolysis and what enzyme is involved?

A
  • Fructose-6-P is phosphorylated by phosphofructokinase-1 to form fructose-1,6-BP
  • ATP hydrolysis
  • This is the rate-limiting step!
22
Q

What is the fourth step of glycolysis and what enzyme is involved?

A
  • Fructose-1,6-BP is cleaved with aldolase to form dihydroxyacetone-P
  • Uses Schiff base as an intermediate
23
Q

What is the fifth step of glycolysis and what enzyme is involved?

A

DHAP (dihydroxyacetone-P) undergoes isomerization using triose phosphate isomerase to form glyceraldehyde-3-P . This is the end of the ATP investment stage.

24
Q

What is the sixth step of glycolysis and what enzyme is involved?

A
  • Glyceraldehyde-3-P uses glyceraldehyde-3-P dehydrogenase (GAPDH) to transfer a phosphoryl group to it and form 1,3-biphosphoglycerate
  • Produces 2 NADH
25
Q

What is the seventh step of glycolysis and what enzyme is involved?

A
  • Phosphoglycerate kinase phosphorylates (substrate-level phosphorylation) 1,3-biphosphoglycerate to form 3-phosphoglycerate
  • 2 ATP produced
26
Q

What is the eight step of glycolysis and what enzyme is involved?

A

Phosphoglyceromutase is used which causes a phosphoryl shift in 3-phosphoglycerate to form 2-phosphoglycerate

27
Q

What is the ninth step of glycolysis and what enzyme is involved?

A

Enolase dehydrates 2-phosphoglycerate to form phosphoenolpyruvate

28
Q

What is the tenth step of glycolysis and what enzyme is involved?

A
  • Pyruvate kinase phosphorylates (substrate-level phosphorylation) phosphoenolpyruvate to form pyruvate
  • Produces 2 ATP
29
Q

How is phosphofructosekinase-1 regulated?

A
  • AMP and ADP indicate low energy charge in the cell, ATP indicates high energy charge of the cell (if there is high ATP levels, then glycolysis is not needed)
  • Citrate inhibits this enzyme when there is high levels of citrate (indicates that glycolysis is not needed right now to produce pyruvate)
30
Q

What is the relationship between glucose levels and production of insulin?

A

When glucose levels are high, insulin is released

31
Q

What are the three ways pyruvate is metabolized depending on availability of oxygen?

A

Aerobic conditions: ATP production (Citrate Cycle and ETC)
Anaerobic conditions: Production of lactate and ethanol production

32
Q

Why is NAD+ regenerated and where is it regenerated?

A
  • NAD+ is required to maintain flux through GAPDH (enzyme in the step of glycolysis that produces 2 NADH)
  • Regenerated in the cytoplasm
33
Q

Why are NAD+ levels inadequate in someone who has lactate dehydrogenase deficiency?

A

Lactate dehydrogenase is an enzyme that converts pyruvate to lactate and also converts NADH to NAD+. If this enzyme is deficient, the enzyme is not functional and therefore, lower levels of NAD+

34
Q

An example of an anabolic pathway is _____________.

A) smaller amino acids being linked together to make a protein
B) the tendency to gain or lose weight
C) the burning of fat by exercise
D) a protein being broken down into smaller amino acids
E) none of the above

A

A) smaller amino acids being linked together to make a protein
*anabolic is building :)))

35
Q

Tarui’s disease is a disorder in which
phosphofructosekinase-1 deficiency occurs.
Which of the following would most likely be
observed in patients with this disorder?

A) Fructose-6-P levels increase.
B) Fructose-1,6-P levels decrease.
C) ATP levels increase.
D) A and B
E) A and C

A

A and B

BMB 402 Final (6 decks)

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