What happens when there is not enough oxygen: glycolysis alone, lactate in muscles, alcohol and carbon dioxide in yeast, and the ATP sums when the oxygen is partial.
Step 1 of 7 · Cut off
Step 1 of 7
Cut off
In a sprint the muscles use ATP faster than the blood can bring them oxygen. Oxygen is the last acceptor of the chain’s electrons. What happens when it runs short?
Step 2 of 7
How many times more
Respiration with oxygen is called aerobic respiration. When there is no oxygen, cells switch to fermentation: in our muscles the pyruvate becomes lactate (lactic acid), and in yeast alcohol and carbon dioxide. Fermentation itself makes no ATP; it only lets glycolysis keep going.
Step 3 of 7
Half the oxygen
Oxygen supply is the share of the oxygen the cell needs that actually reaches it. When only part arrives, only that share of the pyruvate is burned in the mitochondria, and the rest becomes lactate.
Step 4 of 7
Twenty-six
Oxygen supply is free, starting from zero.
Step 5 of 7
Lactate
The lactate that builds up in a muscle does not stay there: the blood carries it to the liver, where, once there is oxygen again, it is turned back into glucose. That is part of why you keep panting for a while after a sprint.
Step 6 of 7
Yeast
Yeasts are single-celled fungi. With oxygen they respire as we do; without it they ferment. People have used that fermentation for thousands of years, in bread, wine and beer.
Step 7 of 7
The currency
ATP ties together everything in this Unit: photosynthesis stores the energy of light in sugar, and respiration moves it from the sugar into ATP, which the cell can spend.
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Each step sets up the Scene for you, and a control marked “fixed” stays put for that step.
Practice · Predict, then look
With plenty of oxygen each glucose gives 32 ATP. We will cut off the oxygen supply completely. How many ATP will each glucose give?
Practice · Predict, then look
With plenty of oxygen each glucose gives 32 ATP. We will cut off the oxygen supply completely. How many ATP will each glucose give?
Practice · Calculate
The supply is full. How many times more ATP does a glucose give by respiration with oxygen than without?
Practice · Calculate
The supply is full. How many times more ATP does a glucose give by respiration with oxygen than without?
Practice · Calculate
The muscle gets only half the oxygen it needs, so only half the pyruvate is burned in the mitochondria. How many ATP does each glucose give, on average?
Practice · Calculate
The muscle gets only half the oxygen it needs, so only half the pyruvate is burned in the mitochondria. How many ATP does each glucose give, on average?
Practice · Reach the target
Change Oxygen supply until each glucose gives 26 ATP, then press Check.
Practice · Reach the target
Change Oxygen supply until each glucose gives 26 ATP, then press Check.
Practice · Calculate
At half the oxygen, how many lactate molecules form from each glucose, on average? (A glucose splits into two pyruvates.)
Practice · Calculate
At half the oxygen, how many lactate molecules form from each glucose, on average? (A glucose splits into two pyruvates.)
Practice · Choose
Dough with yeast rises in a covered bowl, even after its oxygen has run out. What puffs it up?
Practice · Choose
Dough with yeast rises in a covered bowl, even after its oxygen has run out. What puffs it up?
Practice · Choose
Which statement about ATP is true?
Practice · Choose
Which statement about ATP is true?
Lesson complete. Every practice question here is done.