Cellular Respiration Flashcards
1
Q
What is cellular respiration?
A
- A process by which organic molecules, (food) are broken down in the cells to release energy (ATP) for the cell’s activities
-It can release energy from glucose, amino acids, fatty acids and glycerol
2
Q
Nutrients- Organic compounds
A
- Molecules with a carbon chain
- Contain a hydrogen atom
- May include atoms of oxygen, nitrogen and sulfur
- E.g. carbohydrates, lipids, proteins, vitamins
3
Q
What are carbohydrates?
A
- Main source of energy
- Simple sugars e.g. glucose
- Made of carbon, hydrogen and oxygen
4
Q
What are lipids?
A
- Fats and oil
- Broken down into fatty acids and glycerol
- Glycerol can enter glycolysis pathway of cellular respiration
- Each lipid molecule consists of one molecule of glycerol and 1-3 fatty acid molecules
5
Q
What are proteins?
A
- Made of many amino acids
- Enzymes most important proteins for metabolism
- Can be used as source of energy but only if carbohydrates and lipids are not available
6
Q
What are vitamins?
A
- Coenzymes for many chemical reactions of metabolism
7
Q
Nutrients- Inorganic compounds
A
- Not based on a carbon chain
- E.g. water and minerals
- Important for metabolism because:
–> Water: fluid in which substances are dissolved, some cell’s chemical reactions occur in water
–> Minerals: May be part of enzymes, may function as cofactors, may be part of ATP
8
Q
Breakdown of glucose
A
- 60% of energy is released as heat
–> To maintain body temp
–> Rest makes ATP (energy) - C6H12O6 + 6O2 –> 6H2O + 6CO2 + up to 38 ATP
9
Q
Energy from cellular respiration
A
- ATP is formed when a phosphate is joined to an adenosine diphosphate or ADP
- Energy is held between the 2nd and 3rd phosphate
- When the high energy chemical bond between the ADP and third phosphate group is broken- energy is released and used within the cell
- ADP can then be reused to store energy later from cellular respiration, transferring energy to where it is required in the cell.
10
Q
Energy uses by the cell
A
- Cells need energy which is stored in ATP for a number of processes
11
Q
States of cellular respiration #1
A
- Glycolysis
- First phase in the breakdown of glucose
- No oxygen required
- 1 glucose molecule broken down into 2 pyruvate molecules (a 3 carbon acid)
- Results in production of 2 NET ATP
- Occurs in cytoplasm
12
Q
States of cellular respiration #2
A
2 options of what occurs next:
- Depends on if oxygen is available or not available
- 2a): No oxygen = anaerobic respiration
▪ Important during vigorous physical activity
- 2b): oxygen = aerobic respiration
13
Q
States of cellular respiration #2a
A
2a. Anaerobic respiration
- When no oxygen is available
- Pyruvate converted to lactic acid by fermentation
- No ATP produced- but still have 2 ATP produced from glycolysis
- Occurs in cytosol
- Important during vigorous activity- when unable to supply enough oxygen to meet energy demands
- Accumulation of lactic acid in muscles causes pain.
- This process can be summarised by the following equation
2a. Anaerobic respiration- Oxygen debt
- Lactic acid taken to liver via blood
- Recombines with oxygen to form glucose then glycogen
- This requires oxygen
- Thus incurring an oxygen debt
- This is why we breathe heavily for a short time after vigorous exercise
- Repays oxygen debt by converting lactic acid to glucose- known as recovery oxygen
14
Q
States of cellular respiration #2b
A
2b. Aerobic respiration
- Complete breakdown of glucose to carbon dioxide and water
▪ Following glycolysis the 2 pyruvate molecules breaks down into carbon dioxide and water - Requires oxygen
- Occurs in mitochondria, on the folds of the inner membrane (larger SA)
- Each pyruvate converted to acetyl CoA
-No ATP produced during this step - Each acetyl CoA enters citric acid cycle (krebs cycle)
- Releases CO2
- 2 ATP produced (1 per acetyl CoA) - Resulting molecules enter electron transport system/ oxidative phosphorylation where electrons pass between molecules.
- Each pyruvate converted to acetyl CoA
- Up to 34 ATP produced
