The link reaction and Krebs cycle

Question 1

What is the link reaction

Answer 1

Converts pyruvate to acetate

Nad is reduced

Question 2

What is the Krebs cycle

Answer 2

Oxidises acetate to carbon dioxide
Nad and fad are reduced
ATP is made by substrate level phosphorylation

Question 3

Where do both these reaction take place

Answer 3

Mitochondrial matrix

Question 4

How is pyruvate from glycolysis transported to matrix

Answer 4

Across the inner and outer mitochondrial membrane

Question 5

What is pyruvate changed into during link reaction

Answer 5

2 carbon compound acetate

Question 6

When is acetate oxidised

Answer 6

During Krebs cycle

Question 7

Talk about what happens in the link reaction

Answer 7

Pyruvate dehydrogenase removes hydrogen atoms from pyruvate

Pyruvate decarboxylase removes a carboxyl group, which eventually becomes carbon dioxide from pyruvate

The coenzyme Nad accepts the hydrogen atoms

Coenzyme a accepts acetate, to become acetyl coenzyme a and it’s function is to carry acetate to Krebs cycle

Question 8

What is the equation for the link reaction and Krebs cycle

Answer 8

Check book

Question 9

Why are there 2 molecules of pyruvate in the equation

Answer 9

Because 2 come from one glucose molecule

Question 10

Is ATP produced in link reaction

Answer 10

No

Question 11

So what in link reaction helps make ATP

Answer 11

Fact that each reduced nad will take a pair of hydrogen atoms to the inner mitochondrial membrane and they will be used to make ATP during oxidative phosphorylation

Question 12

Where does the Krebs cycle take place

Answer 12

Mitochondrial matrix

Question 13

Intro to Krebs cycle

Answer 13

A series of enzyme controlled reactions

Oxidise the acetyl group of acetyl CoA to 2 molecules of CO2

Produced one molecule of ATP by substrate level phosphorylation

Reduced 3 molecules of nad and one molecule of fad

These reduced coenzymes have the potential to produce more ATP during oxidative phosphorylation

Question 14

1st step of Krebs cycle

Answer 14

Acetate is offloaded from coenzyme a (which can collect more acetate) and joins with a 4 carbon compound called oxaloacetate to form a 6 carbon compound called citrate

Question 15

Step 2 of Krebs cycle

Answer 15

Citrate is decarboxylated and dehydrogenated to form a 5 carbon compound

The pair of hydrogen atoms is accepted by a molecule of nad which then becomes reduced

Question 16

Step 3 of Krebs

Answer 16

5c compound is decarboxylated and dehydrogenated to form a 4c compound and another molecule of reduced nad

Question 17

Stop 4 of Krebs cycle

Answer 17

4c compound changed to another 4c compound

During which a molecule of ADP is phosphorylated to produce a molecule of ATP. This is substrate level phosphorylation

Question 18

Step 5 of Krebs cycle

Answer 18

Second 4c compound is changed again to a diff 4c compound

A pair of hydrogen atoms is remove dad accepted by coenzyme fad which is reduced

Question 19

Step 6 of Krebs cycle

Answer 19

3rd 4c compound is dehydrogenated and regenerates oxaloacetate.
Another molecule of nad is reduced

Question 20

How many turns for cycle of Krebs for each pyruvate

Answer 20

One turn of cycle for each molecule of acetate made from pyruvate

Question 21

Turns of cycles from glucose

Answer 21

2 for each glucose molecule

Question 22

Products of link reaction and numbers

Answer 22

Reduced nad
2
Reduced fad
0
CO2
2
ATP
0

Question 23

Products of Krebs cycle and numbers

Answer 23

Reduced nad 6
Reduced fad
2
CO2
4
ATP
2