Respiration- module 5 Flashcards
what are the adaptations of mitochondria
-Folded inner membrane (cristae)- increase surface area to maximise respiration
-Matrix- contains enzymes for Krebs cycle and link reaction
-Inner mitochondrial membrane contains electron transport chains and lots of ATP synthase
4 stages of respiration
1)Glycolysis
2)Link reaction
3)Krebs cycle
4) Oxidative phosphorylation
The hydrolysis of ATP
Energy can be immediately available to cells by the hydrolysis of ATP to ADP and Pi
ADP is also hydrolysed into AMP and then hydrolysis can occur again to produce adenosine
Energy is released with each hydrolysis
glycolysis
-function is to produce Pyruvate from glucose
-Takes place in cytoplasm as glucose can’t cross outer mitochondrial membrane
-Doesn’t require oxygen so takes pklace in anaerobic respiration
-Involves a sequence of reactions catalysed by different enzymes and a coenzyme NAD
what is NAD
coenzyme derived from vitamin B3
responsible for transfer of hydrogen to hydrogenase enzyme
what are the 2 stages of glycolysis
Phosphorylation
Oxidation
Process of phosphorylation
1)ATP molecule is hydrolysed to release phosphate group
2)Phosphate group attached to glucose at carbon 6
3)molecule is now called hexose phosphate
4)Another ATP molecule is hydrolysed
5)phosphate is attached to hexose phosphate
6)molecule now called hexose bisphosphate
7)This addition activates the hexose sugar, but also prevents it from being transported out of the cell
8) Each molecule of hexose 1,6-bisphosphate is now split into two molecules of triose phosphate
Process of Oxidation (glycolysis)
1)triose phosphate molecules are dehydrogenated (2 hydrogen atoms removed)
2)they now have been oxidised
3)This is catalysed by dehydrogenase enzymes
4)require coenzyme NAD to combine with hydrogen atoms to become reduced NAD or NADH
Two molecules of NAD are produced per glucose molecule
Two ATP molecules are also produced in phosphate-level phosphorylation
Enzyme catalysed reactions convert triose phosphate into pyruvate (3C compound)
Two more ATP molecules are produced by phosphorylation of ADP
Link reaction does
Links anaerobic glycolysis to the aerobic steps of respiration
Pyruvatev is actively transported to the Matrix of the mitochondria via special carrier proteins
The pyruvate is converted into acetyl coenzyme A (acetyl Coa)
Products of link reaction per glucose
-2 acetyl CoA
- 2CO2
- 2NADH
Process of link reaction
-pyruvate actively transported into matrix of mitochondria
-pyruvate decarboxylated (CO2 removed)
-then dehydrogenated by NAD to produce NADH
THIS produces Acetate
Coenzyme A forms with Acetate to form acetyl coenzyme A
This is then transported to the krebs cycle
Process of Krebs cycle
1)Acetyl CoA (2C) combines with oxaloacetate (4C) to form Citrate (6C) - > CoA goes back to the link reaction
2) Citrate is converted to a 5C compound by decarboxylation + dehydrogenation forming reduced NAD
3) Regeneration of Oxaloacetate forms 5C compound by decarboxylation, dehydrogenation forming 2 x reduced NAD, reduced FAD and substrate - level phosphorylation to make ATP
Respiratory quotients
When an organism respires a specific respiratory substrate, the respiratory quotient (RQ) can worked out.
This is the volume of CO2 produced when that substrate is respired divided by the volume of O2 consumed in a set time.
The answer tells us which molecule is being respired.
average energy value of the respiratory substrate carbohydrates (KJ g^-1)
15.8
average energy value of the respiratory substrate Lipids (KJ g^-1)
39.4
average energy value of the respiratory substrate proteins (KJ g^-1)
17.0
RQ value of Lipids
0.7