Cellular Respiration
| English | Chinese | Pinyin |
|---|---|---|
| cellular respiration | 细胞呼吸 | xì bāo hū xī |
| glycolysis | 糖酵解 | táng jiào jiě |
| aerobic respiration | 有氧呼吸 | yǒu yǎng hū xī |
| anaerobic respiration | 无氧呼吸 | wú yǎng hū xī |
Releasing energy from food
- Glucose holds a lot of energy, but a cell cannot use it directly.
- It must unlock that energy in small steps and store it as ATP.
- This controlled release of energy from food is cellular respiration.
- It runs in every one of your cells, every second of your life.
The overall reaction
- Cellular respiration 细胞呼吸 breaks glucose down using oxygen.
- $\text{C}_6\text{H}_{12}\text{O}_6 + 6\text{O}_2 \rightarrow 6\text{CO}_2 + 6\text{H}_2\text{O} + \text{ATP}$.
- The energy released is captured as ATP.
- Carbon dioxide and water leave as waste.
What is the purpose of cellular respiration?
Cellular respiration breaks down glucose to release energy as ATP.
Stage 1: glycolysis
- Glycolysis 糖酵解 splits glucose in the cytoplasm.
- It makes two smaller molecules (pyruvate) and a little ATP.
- This first step needs no oxygen.
- If oxygen is present, the pyruvate goes on to the mitochondria.
The stages of respiration
Step through respiration — glucose is split, then broken down fully in the mitochondrion to release lots of ATP.
The first stage, splitting glucose in the cytoplasm, is called ____.
Glycolysis splits glucose into two pyruvate molecules and makes a small amount of ATP.
With or without oxygen
- Aerobic respiration 有氧呼吸 uses oxygen in the mitochondria to finish breaking glucose down.
- It releases a large amount of ATP.
- Anaerobic respiration 无氧呼吸 has no oxygen, so glucose is only partly broken down.
- It releases much less ATP and leaves a waste product.
Which type of respiration releases the most ATP?
Aerobic respiration fully breaks down glucose in the mitochondrion, releasing far more ATP than anaerobic.
Anaerobic respiration releases much less ATP than aerobic respiration.
Without oxygen, glucose is only partly broken down, so far less ATP is released.
Select all true statements about respiration.
Building glucose from CO₂ is photosynthesis — the opposite of respiration. The other three are correct.
Anaerobic respiration gives far less ATP than aerobic. Without oxygen, glucose is only partly broken down, so a cell forced to respire anaerobically gets only a small fraction of the energy — and cannot keep it up for long.
Why hard exercise makes muscles ache:
- During a sprint, your muscles run out of oxygen.
- They switch to anaerobic respiration, which builds up lactic acid.
- That is the burning feeling — and why you keep breathing hard afterwards, repaying the "oxygen debt".
Cellular respiration releases energy from glucose as ATP. It starts with glycolysis in the cytoplasm (no oxygen needed). With oxygen, aerobic respiration finishes the job in the mitochondria and releases a lot of ATP; anaerobic respiration (no oxygen) releases far less. Respiration is the reverse of photosynthesis.