Glycolysis And The Krebs Cycle Flashcards

1
Q

What is the name of ATP and what is its function?

A

Adenosine triphosphate.
It is an energy carrier. The phosphate bonds are high energy and will release this energy when broken.

In simple terms:
ATP — energy used in metabolic process — ADP + Pi — energy produced in respiration — ATP…

ATP — ADP + Pi

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2
Q

What do kinase enzymes do?

A

Also involved in the movement of phosphate

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3
Q

Overall what does glycolysis produce?

A

1 molecule of glucose:
2 molecules of ATP
2 NADH
2 molecules of pyruvate

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4
Q

What is the job of co-enzymes?

A

In many metabolic pathways they transfer electrons in oxidation and reduction reactions.
They can also go on to be used in ATP production

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5
Q

What does glucose form in the first step of glycolysis?

A

Glucose — Glucose-6-phosphate

Using hexokinase in most the body and glucokinase in the liver

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6
Q

What does Glucose-6-Phosphate form in the second step of glycolysis?

A

Glucose—phosphate forms Fructose -6-Phosphate
Using Phosphoglucose isomerase

Reversible reaction

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7
Q

Fructose-6-phosphate forms…

A

Fructose-1,6-bisphosphate

Using phosphofructokinase-1

This is also the rate limiting step of glycolysis and hence controls the mechanism.

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8
Q

What does fructose-1,6-bisphosphate form…

A

Both Glyceraldehyde-3-phosphate and dihydroxyacetone phosphate

Using enzyme adolase

Triose phosphate isomerase also converts dihydroxyacetone phosphate into glyceraldehyde-3-phosphate

Favoured as G-3-P is used up

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9
Q

You now have 2 glyceraldehyde-3-phosphate molecules which produce…

A

2 (1,3-bisphosophoglycerate) and 2 NADH

Using 2pi and 2 NAD

Uses the enzyme Glyceraldeyde-3-phosphate dehydrogenase

Also reversible

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10
Q

2(1,3-Bisphosophoglycerate) is converted into….

A

2(3-phosphoglycerate)
Using phosphoglycerate kinase

2 ADP— 2 ATP

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11
Q

2 (3-phosphoglycerate) is converted into…

A

2 (2-phosphoglycerate)
Using phosphoglyceromutase

Reversible

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12
Q

2 (2-phosphoglycerate) is converted into…

A

2 (phosphoenolpyruvate)

Using enolase and H20 is produced

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13
Q

2 (phosphoenolpyruvate) is converted into…

A

2 pyruvate molecules
Using pyruvate kinase
ADP-ATP

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14
Q

Overall glycolysis equation:

A

Glucose + 2NAD + 2Pi + 2ADP — 2 Pyruvate + 2 NADH + 2H + 2ATP + 2H20

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15
Q

Pyruvate is converted into… during anaerobic respiration.

A

Into Lactate, using lactate dehydrogenase

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16
Q

Regulators of glycolysis?

A

AMP and ATP can bind to a site away from is active site and cause the change in shape of PFK-1 (non-competitive inhibitors)

In low ATP conditions its rate increase, in high it is inhibited
In low AMP conditions its rate is inhibited, in high its increased
Citrate may also play a role in PFK-1 inhibition

17
Q

2 ADP — AMP + ATP using which enzyme?

A

Adenylate Kinase

18
Q

What are all the names for the krebs Cycle?

A

Citric acid cycle and TCA cycle

19
Q

Overview of the Krebs Cycle…

A

Pyruvate is transported into the mitochondria and converted into Acetyl-CoA (link reaction)

The Acetyl-CoA is then used in the Krebs cycle. It is added to Oxaloacetate to form citrate and the cycle continues.

Overall:
Acetyl-CoA + 3NAD + FAD + GDP + Pi + 2H20 — 2CO2 + 3NAD + FADH2 + GTP + 3H* + CoA

20
Q

What is the links reaction:

A

Pyruvate + CoA +NAD — Acetyl-CoA + CO2 + NADH + H*

Main point produces Acetyl-CoA and a NADH

21
Q

Citrate forms…

A

Isocitrate

Using aconitase

22
Q

Isocitrate forms…

A

Ketoglutarate

Using isocitrate dehydrogenase

Also forms NADH and CO2

23
Q

Ketoglutarate forms…

A

Succinyl-CoA

Using a-Ketoglutarate

Also forms NADH + H*

24
Q

Succinyl-CoA forms…

A

Succinate
Using succinyl CoA thiokinase
Also forms GTP from GDP

25
Succinate is converted into...
Fumarate | Using succinate dehydrogenase
26
Fumarate is converted into...
Malate | Using fumarase
27
Malate is converted into...
Oxaloacetate Using Malate dehydrogenase And the cycle starts again, with a new molecule of Acetyl-CoA
28
What are the three enzymes that regulate the Krebs cycle?
Isocitrate DH a-Ketogluterate DH Citrate synthase (converts Acetyl - CoA + oxaloacetate into Citrate)
29
How does Isocitrate DH regulate the Krebs cycle?
An increase in isocitrate dehydrogenase leads to an increase in citrate synthase reaction rate increased.
30
How does a-ketoglutarate DH regulate the Krebs cycle.
It is inhibited by its products NADH and succinyl-CoA Also inhibited by GTP, ATP Activated by Ca2+ - useful in generating ATP during intense muscle excerice
31
How does citrate synthase regulate the Krebs cycle?
ATP and NADH, allosterically inhibit citrate synthase. Hence reduces rate of reaction. Succinyl Co-A ( a Krebs cycle product), competitively inhibits citrate synthase. It competes for binding to the active site of citrate synthase with its substrates.