Two types of respiration
Aerobic respiration: the breakdown of glucose into energy involving oxygen.
glucose + oxygen → carbon dioxide + water + ATP
glucose + oxygen → carbon dioxide + water + ATP
Anaerobic respiration: the breakdown of glucose into energy without oxygen.
glucose → lactic acid + ATP (in animals only)
glucose → ethanol +carbon dioxide + ATP
glucose → lactic acid + ATP (in animals only)
glucose → ethanol +carbon dioxide + ATP
Stage 1: Glycolysis
Occurs in the Cytosol (the liquid part of the cytoplasm).
- Splits a glucose molecule into 2 - 3 Carbon molecules called PYRUVATE.
- Glucose → 2 pyruvate molecules.
- 2 ATP molecules are produced.
- Glycolysis is a process performed in the cells of all living things.
- Believed to be one of the earliest energy producing reactions to evolve.
Stage 2 - Option 1: Cellular respiration with oxygen
Also called "aerobic respiration"
Occurs in the Mitochondria
Occurs in the Mitochondria
- 2 Pyruvate → CO2 and water
- Produces 34 ATP.
- So there is a net total of 36 ATP per single glucose molecule.
- Happens via the Krebs Cycle and Electron Transport Chain (You'll learn these need year)
- Krebs Cycle Products: CO2 ATP, NADH, FADH
- ETC Products: 34 ATP, H2O
Stage 2 - Option 2: Cellular respiration without oxygen
![Picture](/uploads/1/2/5/9/125983434/published/beer.jpg?1563611161)
Also called "anaerobic respiration"
Occurs in the cytosol (NOT mitochondria)
The first energy releasing pathway to evolve (3.8 billion years ago) when there was very little oxygen in the atmosphere.
Two main types of fermentation:
ALCOHOL FERMENTATION:
glucose → ethanol + carbon dioxide + ATP
C6H12O6 → 2CH3CH2OH + 2CO2 + 2ATP
LACTIC ACID FERMENTATION:
glucose → lactic acid + ATP
C6H12O6 → 2CH3CH(OH)COOH + 2ATP
Occurs in the cytosol (NOT mitochondria)
The first energy releasing pathway to evolve (3.8 billion years ago) when there was very little oxygen in the atmosphere.
- Fermentation: the breakdown of glucose in the absence of oxygen.
Two main types of fermentation:
- Alcohol fermentation
- Lactic acid fermentation
ALCOHOL FERMENTATION:
glucose → ethanol + carbon dioxide + ATP
C6H12O6 → 2CH3CH2OH + 2CO2 + 2ATP
- This is a natural process performed by fungi and bacteria.
- Humans have taken advantage of it to produce products such as wine, beer, and bread.
- Ethanol is toxic to plants and yeast.
- Secret to making beer and wine is to not let the conditions become too anaerobic.
LACTIC ACID FERMENTATION:
glucose → lactic acid + ATP
C6H12O6 → 2CH3CH(OH)COOH + 2ATP
- An alternative to producing ethanol.
- This is the process in animals during short and intense physical activity such as sprints, weight lifting, jumping etc.
- Lactic acid is the substance that makes your muscles burn.
- Once strenuous exercise slows down, oxygen is now available and will convert lactic acid back to pyruvate.
Lactic acid not to blame Did you ever hear people say that a lactic acid build up is to blame for your sore muscles? Well, this misconception is a result of Nobel Prize winner Otto Meyerhof who discovered glycolysis. This discovery (and award) was inclusive of his conclusion that lactic acid "builds up" in the muscle causing pain and fatigue. Lactic acid was later discovered to burn faster than other fuels and turned out to be not a harmful byproduct of exercise but an extremely useful energy source. So what causes the pain after overdoing it on the treadmill? Scientists are still not 100% sure, but currently believe it is the result of many microscopic tears in the muscle tissue as well as inflammation. So quit blaming poor old lactic acid - its basically awesome! |
Now you should complete...
- Some exercise to observe the wonder that is anaerobic and aerobic cellular respiration.
- A written letter of apology to all lactic acid molecules gone-by.
- Oh... and Question Set 9.4 on page 236.
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