respiration 4 link and krebs

2 x 3C pyruvate

2 x 3C triose phosphate

6C hexose bisphosphate

Glucose (6C hexose)

Pyruvate actively pumped into mitochondrial matrix

2x NADH produced from NAD

4x ATP produced

2x ATP used

Glycolysis (cytoplasm)…

Glucose (6C hexose)

6C hexose bisphosphate

2 x 3C triose phosphate

2 x 3C pyruvatePyruvate actively pumped into mitochondrial

matrix

2x ATP used

4x ATP produced

2x NADH produced from NAD

Substrate Level Phosphorylation

• Formation of ATP from ADP and Pi during glycolysis and the Krebs cycle

http://www.northland.cc.mn.us/biology/biology1111/animations/glycolysis.html

http://www.science.smith.edu/departments/Biology/Bio231/glycolysis.html

The Link Reaction

• (i) state that the link reaction takes place in the mitochondrial matrix;

• (j) outline the link reaction, with reference to decarboxylation of pyruvate to acetate and the reduction of NAD;

• (k) explain that acetate is combined with coenzyme A to be carried to the next stage;

Key terms

Decarboxylation and dehydrogenation

• Decarboxylation – removal of a carboxyl group from a chemical compound, usually with hydrogen replacing it

• Dehydrogenation – removal of a hydrogen from a chemical compound

Draw the Link Reaction

• (i) state that the link reaction takes place in the mitochondrial matrix;

• (j) outline the link reaction, with reference to decarboxylation of pyruvate to acetate and the reduction of NAD;

• (k) explain that acetate is combined with coenzyme A to be carried to the next stage;

Pyruvate (3C)

Acetate (2C)

Acetyl CoA (2C)

CO2NAD+NADH

What enzymes are involved?

1. A hydrogen atom is removed from pyruvate

2. A carboxyl group is removed from pyruvate (the carboxyl group will eventually become carbon dioxide)

What type of substance are NAD and Coenzyme A?

The Krebs Cycle

• (l) state that the Krebs cycle takes place in the mitochondrial matrix;• (m) outline the Krebs cycle, with reference to the formation of citrate

from acetate and oxaloacetate and the reconversion of citrate to oxaloacetate (names of intermediate compounds are not required);

• (n) explain that during the Krebs cycle, decarboxylation and dehydrogenation occur, NAD and FAD are reduced and substrate level phosphorylation occurs;

Krebs Cycle

• http://highered.mcgraw-hill.com/sites/007352543x/student_view0/chapter8/how_the_krebs_cycle_works.html

Can You Remember?

6 5 4 4 4 4

NAD NAD ATP FAD NAD

Link Reaction and Krebs Cycle

• http://www.youtube.com/watch?v=KZYtwtNrAm8

• http://www.youtube.com/watch?v=ti6-57yK5RY

• Answer Stretch and Challenge Question P89

• Expand the table P89 to include glycolysis