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Biochem > Glycolysis > Flashcards

Glycolysis Flashcards

1
Q

What is the end product of glycolysis?

A

2 molecules of pyruvate

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2
Q

Where does glycolysis occurs?

A

In the cytosol of all tissues/cells

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3
Q

T/F In the first five steps of glycolysis, ATP is consumed and none is produced.

A

True

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4
Q

When would glycolysis occur?

A

Glycolysis occurs when the body has high levels of energy or glucose.

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5
Q

What happens in the first step of glycolysis. Name the reactants, products, and enzyme.

A

In this step, glucose is phosphorylated into glucose-6-phosphate by hexokinase.

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6
Q

Which of the following is not true regarding the first step of glycolysis?
a) Glucose is phosphorylated into glucose-6P by hexokinase.
b) Hexokinase utilizes ATP to phosphorylate glucose thereby producing glucose-6P and ADP
c) Mg2+ is a cofactor required for the phosphorylation of glucose into glucose-6P
d) The phosphorylation of glucose into glucose 6-P is reversible.

A

d

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7
Q

What happens in the second step of glycolysis. Name the reactants, products, and enzyme.

A

Glucose 6P is converted into fructose 6P by phosphohexose isomerase

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8
Q

What happens in the third step of glycolysis. Name the reactants, products, and enzyme. What are the cofactor(s) of this step? Does it require ATP?

A

fructose 6P is converted into fructose 1,6-bisphosphate by phosphofructokinase (PKF-1)
Mg2+
Yes

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9
Q

What is the purpose of step 3 in glycolysis?

A

To make a symmetrical molecule by phosphorylating C1

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10
Q

What happens in the fourth step of glycolysis. Name the reactants, products, and enzyme.

A

fructose-1,6-bisphosphate is cleaved into dihydroxyacetone phosphate and glyceraldehyde 3-phosphate by aldolase

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11
Q

What happens in the fifth step of glycolysis. Name the reactants, products, and enzyme.

A

dihydroxyacetone phosphate is converted into glyceraldehyde 3-phosphate by triose phosphate isomerase.

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12
Q

T/F Glycolysis consist of two phases - one is the preparatory phase in which ATP is utilized and the other is the Pay-Off phase in which oxygen is produced.

A

True

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13
Q

What happens in step six of glycolysis. Name the reactants, products, and enzyme.

A

glyceraldehyde 3P is oxidized into 1,3-biphosphoglycerate by glyceraldehyde 3-phosphate dehydrogenase (GAPDH)

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14
Q

What is require in step 6 of glycolysis besides glyceraldehyde (the product) and glyceraldehyde 3-phosphate dehydrogenase (the enzyme)? What is produced besides 1,3-biphosphoglycerate?

A

This reaction requires the addition of an inorganic compound to glyceraldehyde via oxidation reaction. Meanwhile, NAD+ is reduced into NADH and H+. Meaning we form NADH besides 1,3-biphosphoglycerate

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15
Q

What happens in step seven of glycolysis. Name the reactants, products, and enzyme.

A

The one of the phosphate groups of 1,3-bisphosphoglycerate is transferred onto ADP to generate ATP and 3-phosphoglycerate by phosphoglycerate kinase

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16
Q

What happens in step eight of glycolysis. Name the reactants, products, and enzyme.

A

3-phosphoglycerate is converted into 2-phosphoglycerate by phosphoglycerate mutase.

17
Q

What else besides 3-phosphoglycerate (product) and phosphoglycerate mutase (enzyme) for the formation of 2-phosphateglycerate?

A

Mg2+. Although this reaction is reversible, Mg2+ is not required in the reverse reaction which converts 2-phosphoglycerate into 3-phosphoglycerate

18
Q

What happens in step nine of glycolysis. Name the reactants, products, and enzyme.

A

2-phosphoglycerate is converted into phosohoenolpyruvate through the loss of water by enolase

19
Q

What happens in step ten of glycolysis. Name the reactants, products, and enzyme.

A

the phosphate group of phosohoenolpyruvate is transferred by pyruvate kinase onto ADP to generate pyruvate and ATP

20
Q

What are the cofactors of the last step in glycolysis?

A

Mg2+ and K+

21
Q

What factor(s) regulate hexokinase?

A

concentration of glucose 6-phosphate (G6P). High concentration of G6P will inhibit hexokinase.

22
Q

How does high concentration of glucose 6-phosphate in the cell affects hexokinase?

A

it inhibits the activity of hexokinase. Meaning, glucose is not going to be phosphorylated into glucose 6-phosphate.

23
Q

What factors increase the activity of PFK-1?

A

F2,6BP, AMP, and ADP

24
Q

What factors decrease the activity of PFK-1?

A

ATP and citrate

25
Q

What factors increase the activity of pyruvate kinase?

A

F1,6BP and AMP

26
Q

What factors decrease the activity of pyruvate kinase?

A

ATP, Acetyl-CoA and Alanine

27
Q

Enzyme responsible for reducing pyruvate into L-lactate.

A

lactate dehydrogenase

28
Q

What is so special about reducing pyruvate into lactate?

A

The reduction reaction is coupled with the oxidation of NADH to NAD+, which allows the cell to reutilize NAD+ in glycolysis.

29
Q

How is pyruvate converted into ethanol in fermenting organisms?

A
  1. pyruvate undergoes decarboxylation to form acetaldehyde, which is catalyzed by pyruvate decarboxylation. This reaction requires TPP and Mg2+ as cofactors.
  2. acetaldehyde is reduced into ethanol by alcohol dehydrogenase, which is coupled with the oxidation of NADH into NAD+.
30
Q

A PET scanning, which is a tool used to diagnose tumors was performed on a patient. The patient’s results indicated that he was exhibiting the Warbug Effect. What does this means?

A

This means that tumor cells have high rate of glycolysis in which glucose is being fermented into lactate even in the presence of oxygen.

31
Q

What are two reasons in which the cell would want to send glucose 6-phosphate through the pentose phosphate pathway?

A
  1. When the cell requires 5-carbon sugar (or ribose sugar) needed for DNA/RNA or enzymatic synthesis.
  2. When the cell requires NADPH for fatty acid synthesis and lipid metabolism.
32
Q

Describe the steps of the pentose phosphate pathway

A

I. G6P will be oxidized into 6-phosphogluconate, which is coupled with the reduction of NADP+ into NADPH.
II. 6-phosphogluconate undergoes decarboxylation to form ribulose 5-phosphate. This reaction is also coupled with the reduction of NADP+ into NADPH.
III. R5P can be converted into ribose 5 phosphate (which will be use for nucleotide synthesis) or be recycled back into G6P by transketolase/transaldolase (when NADPH is highly required).

33
Q

Which two enzymes are helpful in reducing reactive oxygen species in the blood? Explain how.

A

glutathione reductase and glutathione peroxidase

Remember: glutathione peroxidase removes the peroxide species (that result from the oxidation of oxygen) and sends them to glutathione reductase. This enzyme reduces peroxide by transferring the protons onto NADP+ to generate NADPH.

Biochem (12 decks)

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