IB BIO TOPIC 3.7 : CELLULAR RESPIRATION Flashcards
1
Q
Define cell respiration
A
the controlled release of energy in the form of ATP from organic compounds in cells.
2
Q
State what occurs in cell respiration
A
glucose in the cytoplasm is broken down into pyruvate, with a small yield of ATP.
3
Q
Explain how pyruvates are converted during anaerobic cellular respiration
A
During anaerobic cell respiration, pyruvate can be converted in the cytoplasm into lactate, or ethanol and carbon dioxide, with no further yield of ATP.
4
Q
Explain anaerobic respiration:
A
- in the absence of oxygen, the pyruvate formed during glycolysis can’t be used to make more ATP; thus, glycolysis is the only source of ATP for cellular functions
- since glycolysis is the only source of ATP, it must be kept going
- however, glycolysis reduces NAD+ to NADH + H+, depleting the supply of NAD
- without NAD+, glycolysis will come to a halt
- therefore, NADH + H+ must be oxidized back to NAD+
- fermentation allows for the oxidation of NADH + H+ back to NAD+, by reducing pyruvate to either lactate or ethanol
- in animals, fermentation reduces pyruvate to lactate
- in yeast, fermentation reduces pyruvate to ethanol and carbon dioxide
- although fermentation does not produce ATP, it does regenerate NAD+, which allows for further glycolysis, providing the cell with additional ATP
5
Q
Explain that, during aerobic cell respiration, pyruvate can be broken down in the mitochondrion into carbon dioxide and water with a large yield of ATP.
A
- in the presence of oxygen, the pyruvate formed during glycolysis can be used to make as much as 36 more ATP
- thus, aerobic respiration is the main source of ATP for cellular functions in eukaryotes
- pyruvate from glycolysis diffuses from the cytosol into the mitochondrial matrix
- in the mitochondria a series of reactions (link reaction, Krebs cycle, electron transport system, oxidative phosphorylation) oxidize pyruvate to produce ATP
- by products of oxidation include carbon dioxide and water
