The link reaction and Krebs cycle Flashcards
What is the link reaction
Converts pyruvate to acetate
Nad is reduced
What is the Krebs cycle
Oxidises acetate to carbon dioxide
Nad and fad are reduced
ATP is made by substrate level phosphorylation
Where do both these reaction take place
Mitochondrial matrix
How is pyruvate from glycolysis transported to matrix
Across the inner and outer mitochondrial membrane
What is pyruvate changed into during link reaction
2 carbon compound acetate
When is acetate oxidised
During Krebs cycle
Talk about what happens in the link reaction
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
What is the equation for the link reaction and Krebs cycle
Check book
Why are there 2 molecules of pyruvate in the equation
Because 2 come from one glucose molecule
Is ATP produced in link reaction
No
So what in link reaction helps make ATP
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
Where does the Krebs cycle take place
Mitochondrial matrix
Intro to Krebs cycle
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
1st step of Krebs cycle
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
Step 2 of Krebs cycle
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
Step 3 of Krebs
5c compound is decarboxylated and dehydrogenated to form a 4c compound and another molecule of reduced nad
Stop 4 of Krebs cycle
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
Step 5 of Krebs cycle
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
Step 6 of Krebs cycle
3rd 4c compound is dehydrogenated and regenerates oxaloacetate.
Another molecule of nad is reduced
How many turns for cycle of Krebs for each pyruvate
One turn of cycle for each molecule of acetate made from pyruvate
Turns of cycles from glucose
2 for each glucose molecule
Products of link reaction and numbers
Reduced nad 2 Reduced fad 0 CO2 2 ATP 0
Products of Krebs cycle and numbers
Reduced nad 6 Reduced fad 2 CO2 4 ATP 2
