5.2 Respiration Flashcards
What are the 4 stages of respiration?
- Glycolysis
- Link reaction
- Krebs cycle
- Oxidative phosphorylation
Where does glycolysis occur?
Cytoplasm
Is glycolysis an aerobic or anaerobic process?
Anaerobic
What is the first step in glycolysis?
Phosphorylation of glucose to glucose phosphate, using ATP
What is the second step in glycolysis?
Glucose phosphate -> 2 x triose phosphate
What is the third step in glycolysis?
Triose phosphate is oxidised to produce pyruvate
How is glucose phosphorylated to glucose phosphate?
2ATP -> 2ADP + 2Pi
How is glucose phosphate converted to 2 x triose phosphate?
Glucose phosphate is very unstable, and therefore splits (lysis)
What is glucose phosphate also known as?
Fructose 1,6 bisphosphate
How is triose phosphate converted into pyruvate?
- NAD is reduced to NADH
- 2 ADP –> 2ATP
What are the net products of glycolysis?
2 pyruvate, 2 ATP, 2 NADH
Where does the link reaction happen?
Mitochondrial matrix
What happens for the link reaction to happen?
Pyruvate and NADH are actively transported from the cytoplasm into the mitochondrial matrix
What is the first step of the link reaction?
Pyruvate is oxidised to acetate
What is the second step of the link reaction?
NAD is reduced (NAD + H+) and forms NADH
What is the third step of the link reaction?
Acetate combines with coenzyme A to produce acetylcoenzyme A
How does pyruvate become acetate?
Carbon dioxide is released
NAD is reduced to NADH
How many times does the link reaction occur for each glucose molecule?
Twice - once for each pyruvate produced in glycolysis
What are the net products of the link reaction PER glucose molecule?
2 acetylcoA
2 CO2
2 NADH
Where does the Krebs cycle happen?
Mitochondrial matrix
How many carbons are in acetyl coenzyme A?
2
What is the first thing that happens in the Krebs cycle?
AcetylcoA reacts with a 4 carbon molecule, releasing coenzyme A, and producing a 6 carbon molecule
What are the net products of the Krebs cycle PER glucose?
6 NADH
2 FADH
2 ATP
4 CO2
Where does oxidative phosphorylation occur?
Inner mitochondrial membrane
What stage of respiration is most ATP made in?
Oxidative phosphorylation
What is oxidative phosphorylation catalysed by?
ATP synthase
What is the first step of oxidative phosphorylation?
Hydrogen atoms are released from NADH and FADH to form NAD and FAD
What is the second step of oxidative phosphorylation?
The hydrogen atoms split into electrons and H+ ions
What is the third step of oxidative phosphorylation?
Electrons move down the electron transport chain, losing energy at each carrier
What is the fourth step of oxidative phosphorylation?
The energy from the electrons is used to pump protons into the intermembrane space of the mitochondria - creating an electrochemical gradient
What is the fifth step of oxidative phosphorylation?
Protons move down the gradient into the matrix via the ATP synthase
What is the sixth step of oxidative phosphorylation?
Protons, electrons and oxygen are combined to form water
When does anaerobic respiration occur?
When there is no oxygen
Where does anaerobic respiration occur?
In the cytoplasm
When does the anaerobic respiration process differ?
After pyruvate has been formed in glycolysis
In anaerobic respiration in ANIMALS, what happens after a pyruvate has been formed?
- Pyruvate is reduced to form lactate
- By gaining a hydrogen from reduced NAD, which oxidises NADH, forming NAD.
What is the benefit of NAD being formed again?
It can be reused in glycolysis to ensure more ATP is continued to be produced
In anaerobic respiration in PLANTS & FUNGI, what happens after a pyruvate has been formed?
- Pyruvate is reduced to form ethanol and carbon dioxide
- By gaining a hydrogen from reduced NAD, which oxidises NADH, forming NAD.
Is ethanol formed immediately?
No - ethanAl is formed first, and is then reduced to form ethanOl
Which is more efficient: aerobic or anaerobic?
Aerobic
In theory, how many molecules of ATP are produced in aerobic respiration?
38
In theory, how many molecules of ATP are produced in anaerobic respiration?
2
Describe the process of glycolysis.
- Glucose is phosphorylated using ATP
- Triose phosphate is oxidised to pyruvate
- Net gain of ATP
- NAD is reduced to form NADH
Explain why malonate would decrease the uptake of oxygen in a respiring cell.
- Less NADH
- Oxygen is the final electron acceptor
Explain why aerobic respiration produces more ATP per molecule of glucose than anaerobic respiration.
- Oxygen is terminal electron acceptor (combines with electrons + protons)
- In aerobic respiration there is oxidative phosphorylation
- Anaerobic respiration only glycolysis occurs
Describe how acetyl coenzyme A is formed in the link reaction.
- Pyruvate is oxidised, and CO2 is released
- Addition of coenzyme A
Explain why converting pyruvate to lactate allows the continued production of ATP during anaerobic respiration.
- Oxidises reduced NAD
- NAD used in glycolysis
In muscles, some of the lactate is converted back to pyruvate when they are well supplied with oxygen. Suggest one advantage of this.
- Pyruvate used in aerobic respiration
- Lactate is toxic
