Respiration Flashcards
Where does glycolysis occur?
Cytoplasm
What is the equation for aerobic respiration?
C6H12O6 + 6O2 -> 6CO2 + 6H2O
How many molecules of ATP are produced in aerobic respiration?
38 ATP
What happens to the respiratory substrate in respiration?
- it is oxidised
- addition of oxygen
- removal of hydrogen
- loss of electrons
First stage of glycolysis
- 2 phosphate molecules added to glucose
- phosphates are gained from 2 molecules of ATP (hydrolysed into 2xADP)
Second stage of glycolysis
- glucose is split into 2x triose phosphate
Third stage of glycolysis
- hydrogen is removed from each triose phosphate
- transferred to NAD
- NADH formed
Fourth stage of glycolysis
- triose phosphate converted to 2x pyruvate by enzyme reactions
- 2 molecules of ATP regenerated from ADP from triose phosphate molecules
Net production of ATP in glycolysis
-2 ATP + 4ATP = 2ATP
Net production of 2 ATP
Yields of glycolysis
2x pyruvate
2x NADH
2x ATP
Where does link reaction take place?
Matrix of mitochondria
What is the process of the link reaction?
- pyruvate (2x per glucose molecule) loses a CO2 and hydrogen atom, NADH formed
- oxidation of pyruvate forms acetate (2c)
- acetate combines with coenzymeA to form acetylcoenzymeA
Yield of link reaction
Per glucose molecule
2 acetyl coenzymeA
2 NADH
2 CO2
NO ATP PRODUCED
What are coenzymes?
- not actually enzymes
- some enzymes require them to function
- play important role in respiration - carry H+ from molecules
- e.g. NADH and coenzymeA
Where does the Krebs cycle take place?
Matrix of the mitochondria
Describe the process of the Krebs cycle
- acetylcoenzymeA becomes 2c molecule (coenzymeA leaves) and joins with 4c molecule to form 6c molecule
- CO2 lost, H+ lost, NADH formed
- 5c molecule formed
- CO2 lost, H+ lost, NADH formed
- ADP + Pi forms ATP
- FAD gains H+, FADH
- NAD gains H+, NADH
- 4c molecule formed
- cycle repeated
Yield of Krebs cycle
2x CO2
3x NADH
1x ATP
1x FADH
Per glucose x2 (2x pyruvate)
4x CO2, 6x NADH, 2x ATP, 2x FADH
Significance of the Krebs cycle
- breaks down macro to micro molecules
- produces hydrogen atoms that are carried to electrons transfer chain (energy for oxidative phosphorylation)
- regenerates 4 carbon atoms to combine with acetylCoA
- source of intermediate compounds for other substances e.g. fatty acids, aa and chlorophyll
Where does oxidative phosphorylation take place?
- cristae
- membrane between cristae and inter-membranal space
What is chemiosmosis?
- movement of ions across a semi-permeable membrane down electrochemical gradient
Stage one of NADH in electron transfer chain
- on cristae side
- NADH -> NAD + H+
- electrons into first electron carrier
- oxidation-reduction reaction, energy released for active transport of H+ as electron moves to next electron carrier
- hydrogen ion moves through electron carrier into ims
Stage two of NADH in electron transfer chain
- another oxidation-reduction reaction, electron moves to next electron carrier
- another H+ ion moves through electron carrier to ims
- H+ ion moves through last electron carrier
- oxygen is the final electron acceptor and a water molecule is formed with electrons
- a proton gradient is created and facilitated diffusion of H+ occurs through channel proteins
- H+ ions diffuse and ATP synthase catalyses formation of ATP
FADH in the electron transfer chain
- FADH -> FAD + H+
- H+ enters the first smaller electron carrier
- oxidation-reduction reaction, energy released for active transport of H+, electron transferred
- another H+ actively transported through next electron carrier
- oxidation-reduction reaction, electron enters last electron carrier
- another H+ actively transported
- molecule of water formed (oxygen as final electron acceptor)
- proton gradient created
- H+ ions facilitated diffusion across ATP synthase, ATP formed
Why do FAD and NAD make different numbers of molecules of ATP?
- only 2 H+ atoms released by one molecule of FAD so only 2 molecules of ATP formed
- NAD forms 3
How much ATP is made? (Per glucose)
Glycolysis: 2
Link reaction: 0
Krebs: 2
How much NAD is made?
Glycolysis: 2
Link reaction: 2
Krebs cycle: 6
How much FAD is made?
Glycolysis: 0
Link reaction: 0
Krebs: 2
How much FAD is made?
Glycolysis: 0
Link reaction: 0
Krebs: 2
How much ATP is from each part?
Glycolysis/link/Krebs: 4
NADH: 30
FADH: 4