5.2 (12) - Respiration Flashcards
What is the balanced symbol equation for aerobic respiration?
C6H12O6 + 6O2 > 6CO2 + 6H2O
What are the 3 coenzymes that respiration uses?
What do they carry?
NAD and FAD carry electrons and hydrogen
Coenzyme A carries acetate
What are the 4 stages of aeorbic respiration?
- Glycolysis
- Link reaction
- Krebs cycle
- Oxidative phosphorylation
Where does glycolysis take place?
Cytoplasm of cell
Where does the link reaction take place?
Matrix of mitochondria
Where does the Krebs cycle take place?
Matrix of mitochondria
Where does oxidative phosphorylation take place?
Inner membrane of mitochondria
Describe the stages of glycolysis
1) Glucose is phosphorylated (using energy from the hydrolysis of 2 ATP into 2 ADP + 2 Pi) into glucose phosphate
2) Glucose phosphate is a highly unstable molecule, causing it to split into 2 molecules of TP
3) TP is oxidised - NAD accepts its hydrogens (produces NADH)
4) TP is dephosphorylated (the 2 phosphates combine with 2 ADP > 2 ATP)
5) 2 molecules of pyruvate are formed
Describe the stages of the link reaction
1) 1 molecule of pyruvate is oxidised - NAD accepts its hydrogens (produces NADH)
2) Pyruvate is decarboxylated and CO2 is lost as a waste product
3) Acetate is formed
4) Acetate combines with coenzyme A
5) Acetylcoenzyme A is formed
6) If 1 molecule of glucose is used in glycolysis, the link reaction happens twice, since it produces 2 molecules of pyruvate
Describe the stages of the Krebs cycle
1) Acetylcoenzyme A combines with a 4-carbon molecule to form a 6-carbon molecule
2) Coenzyme A is released
3) The 6-carbon molecule is decarboxylated (CO2 lost as a waste product) and oxidised (produces NADH), resulting in a 5C molecule
4) The 5C molecule is decarboxylated and oxidised, forming a 4-carbon compound
5) The 4C molecule temporarily combines with coenzyme A, causing ATP to be produced from ADP + Pi (substrate-level phosphorylation)
6) The 4C molecule is oxidised (produces FADH)
7) The 4C molecule is oxidised (produces NADH)
8) The 4C molecule can now be combined with acetylcoenzyme A again - the cycle starts again
9) For 1 turn of the cycle, the products are 3 NADH, 2 CO2, 1 FADH and 1 ATP
Describe the stages of oxidative phosphorylation
1) In the matrix, there is a low concentration of protons. In the intermembrane space, there is a high concentration of protons
2) In the matrix, NADH and FADH donate their electrons to the first molecule of the ETC
3) The electrons pass down the ETC, losing energy
4) This energy is used to actively transport the protons across the inner mitochondrial membrane
5) They diffuse across the membrane through ATP synthase
6) When protons diffuse through ATP synthase, it undergoes a conformational change and spins
7) This kinetic energy allows many ADP + Pi to couple, creating many ATP
8) The electrons from the ETC and the protons bond to create hydrogen molecules
9) The hydrogen molecules bond to oxygen, creating water
What are the 5 main stages of oxidative phosphorylation?
- NADH and FADH donate their electrons and protons
- Electrons move down the ETC
- Protons actively transported across membrane
- Protons diffuse through ATP synthase, generating ATP
- Protons, electrons and oxygen bind, making H2O
What are some examples of alternative respiratory substrates?
Lipids and proteins
How are lipids used as a respiratory substrate?
1) Lipids are hydrolysed into glycerol and fatty acids
2) Glycerol is phosphorylated and converted to TP
How are proteins used as a respiratory substrate?
1)
2)
3)
