2.2 Cellular Respiration Flashcards
What is the purpose of cellular respiration?
To generate ATP from chemical energy
State the two uses of ATP
- Transfers energy to cellular processes which need energy
- Phosphorylating other molecules
Define ‘phosphorylation’
Adding a phosphate group to a molecule
What are the two types of cellular respiration?
- Aerobic respiration
- Fermentation
Describe the condition that causes aerobic respiration to happen instead of fermentation?
Aerobic respiration needs oxygen and fermentation does not.
State the three stages of aerobic respiration
- Glycolysis
- Citric Acid Cycle
- Electron Transport Chain
Define ‘glycolysis’
the breakdown of glucose to pyruvate in the cytoplasm
Where does glycolysis take place?
Cytoplasm
What is the respiratory substrate used in glycolysis?
Glucose
What is the net gain of ATP molecules in glycolysis?
4 ATP molecules made and 2 ATP molecules used.
Net gain = 2 ATP
Describe the energy investment stage of glycolysis?
2 ATP molecules are used up to phosphorylate glucose and intermediates
Describe the energy payoff stage of glycolysis?
4 ATP molecules are synthesised from the energy released
State the function of dehydrogenase enzyme
removes hydrogen ions and electrons and passes them to coenzyme NAD forming NADH
You need both parts
What is the purpose of NAD?
Coenzyme NAD carries hydrogen ions and electrons to the electron transport chain.
Describe the steps of glycolysis
- Occurs in the cytoplasm
- Breakdown of glucose into two molecules of pyruvate.
- Net gain of 2 ATP molecules.
- 2 ATP molecules are used up to phosphorylate glucose and intermediates = energy investment stage.
- 4 ATP molecules are synthesised from the energy released = energy pay-off stage.
- Dehydrogenase enzyme removes hydrogen ions and electrons and passes them to coenzyme NAD forming NADH.
State the location of fermentation
Cytoplasm
Describe the process of fermentation in animal cells
Glucose becomes 2 Pyruvate and 2 ATP are also made. 2 Pyruvate becomes Lactate.
pyruvate is converted to lactate in a reversible reaction.
Describe the process of fermentation in yeast and plant cells
Glucose becomes 2 Pyruvate and 2 ATP are also made. 2 Pyruvate becomes Ethanol and Carbon dioxide.
ethanol and CO2 are produced in an irreversible reaction
Describe what happens to pyruvate before the citric acid cycle?
- Pyruvate enters the mitochondria
- Pyruvate is broken down to acetyl group
- Acetyl group combines with coenzyme A
- Forming acetyl coenzyme A
Define ‘citric acid cycle’
A circular metabolic pathway that generates more hydrogen ions and electrons.
State where the citric acid cycle takes place
Matrix of mitochondria
Full answer needed
Describe the steps of the citric acid cycle
- Occurs in matrix of mitochondria.
- Acetyl group from Acetyl coenzyme A combines with oxaloacetate to make citrate.
- During a series of enzyme-controlled steps citrate is gradually converted to oxaloacetate.
- This results in generation of ATP and release of CO2.
- During this cycle dehydrogenase enzyme removes H ions and electrons and passes them to coenzyme NAD which carries them to the electron transport chain in the form of NADH.
Which enzyme removes hydrogen ions and electrons from the citric acid cycle?
Dehydrogenase enzyme
Where does hydrogen ions and electrons removed from the citric cycle go?
Carried by NADH to the electron transport chain
