RESPIRATION 2 - GLYCOLYSIS, LINK REACTION AND KREB CYCLE

What is respiration?

"Respiration is the process whereby the energy stored in complex organic molecules is used to make ATP"

What happens during the link reaction?

● Mitochondria actively transport pyruvate from the cytoplasm into the mito. matrix.
● Pyruvate is converted to acetate (C2) by removal of CO2 (decarboxylation) + removal of H atoms (dehydrogenation).
● Acetate combines with coenzyme A (CoA) to make acetylcoenzyme A
● H atoms combines with NAD, making reduced NAD.

What is produced by the link reaction?

2 reduced NAD + 2CO2

What happens during the 2nd stage of glycolysis?

Hexose Bisphosphate splits into two Triose Phosphates

● Hexose bisphosphate splits into two triose phosphates
● Each triose phosphate is a 3C sugar containing one phosphate group

What happens during the 3rd stage of glycolysis?

● Each triose phosphate is dehydrogenated to make pyruvate.
● Dehydrogenase enzymes remove 2H atoms from each triose phosphate
● Each pair of H atoms combines with coenzyme NAD, making reduced NAD.
● During the process 2ATP are made from each triose phosphate.

What is substrate level phosphorylation?

the energy from substrate molecules in respiration has been released to add phosphate to ADP molecules to make ATP.

What happens during the 1st stage of the krebs cycle?

● Acetylcoenzyme A (2C) combines with a 4C compound to make a 6C compound
● Coenzyme A is recycled (so is now free to collect more acetate in the link reaction).

What happens during the 2nd stage of the krebs cycle?

● Each 6C compound is converted to a C5 compound and then to a 4C compound by removal of two CO2 (decarboxylation) + removal of 8H atoms (dehydrogenation).
● Three pairs of H atoms combine with NAD, making three reduced NAD.
● One pair of H atoms combines with FAD, making one reduced FAD.
● 1 ATP is made per "turn" of the cycle (by substrate-level phosphorylation)

What is oxidative phosphorylation?

H atoms (carried by reduced NAD) are used from the first 3 stages are used to make ATP

Where does glycolysis happen?

cytoplasm

Where does the Krebs cycle happen?

matrix of mitochondria

Where does the link reaction happen?

matrix of mitochondria

Where does oxidative phosphorylation happen?

inner mitochondrial membrane

What is produced by glycolysis?

2ATP (net) + 2 reduced NAD

What is produced by the krebs cycle?

2ATP + 6 reduced NAD +2 reduced FAD+ 4CO2

What is acetlycoenzyme A?

is coenzyme A attached to the acetate group removed from pyruvate
(this now goes off the KREBS

What happens during the 1st stage of glycolysis?

Phosphorylation of Glucose to make Hexose Bisphosphate

● Glucose is made reactive by phosphorylation 🡪 adding phosphate ions, which are released by hydrolysis of ATP.
● Addition of one phosphate to glucose produces glucose phosphate.
● Addition of a second phosphate produces hexose bisphosphate