6. Respiration Flashcards
What is respiration ?
A series of chemical reactions that convert energy from glucose into ATP.
Name 5 uses of energy (ATP) for cellular processes?
- Muscle cell contraction
- Cell division
- Transmission of nerve impulses
- Protein synthesis
- ACTIVE TRANSPORT
What does ATP stand for?
Adenosine Tri Phosphate
What is ATP made up of ?
1x adenosine + 3 x Inorganic phosphates
Why is ATP important?
ATP is the way a cell ‘transfers’ energy from one place to another. The more ATP, the more energy available.
ATP is a very high energy molecule
Energy is releases each time the bond of the 3rd phosphate is broken
What are the 2 types of respiration ?
- Aerobic Respiration
- Fermentation
What is meant by aerobic?
Requires oxygen
When will cells follow a fermentation pathway?
When oxygen is absent
How many stages does aerobic respiration occur in?
2 stages
How many molecules of ATP does aerobic respiration generate in total per molecule of glucose?
38ATP per glucose
2 from stage 1
36 from stage 2
You do not need to remember the exact amount. Stage 1 releases 2 ATP and stage 2 lots!!!
What is the equation for aerobic respiration?
glucose+oxygen —–> carbon dioxide+water (+38ATP)
What is the organelle involved in aerobic respiration?
mitochondria
What is stage 1 of aerobic respiration called?
Stage1: Glycolysis = The breakdown of glucose
Where does Stage 1 (glycolysis) of respiration take place?
In the cytoplasm
What does stage 1 (glycolysis) of resiration not require?
It doesn’t require oxygen
How much ATP is generated during Stage 1(glycolysis)?
2ATP
Describe Stage 1 (glycolysis) using a diagram and a word equation?
- The 6 Carbon glucose is split into 2 x 3 carbon molecules called pyruvate, producing 2xATP
- Glucose ——-> Pyruvate + 2ATP
- This is an enzyem dependant reaction
This requires no oxygen and takes place in the cytoplasm
What is the second stage of aerobic respiration known as?
Stage 2 is the complete breakdown of pyruvate
Also known as the Kreb’s cycle
Where does Stage 2 of respiration take place?
In the Mitochondria
What is required for Stage 2 of respiration (Kreb’s cycle) to proceed?
Oxygen must be present
How much ATP is generated during Stage 2 of aerobic respiration?
36ATP (18 per pyruvate)
At Nat 5 it is acceptiabe to say lots!
Describe Stage 2 of respiration (Kreb’s Cycle) using a diagram and a word equation?What is the equation for Kreb’s cycle?
- If oxygen is present, aerobic respiration takes place, and each pyruvate is broken down to carbon dioxide and water, releasing enough energy to yield a large number of ATP molecules.
- Pyruvate + Oxygen -> carbon dioxide + water + ATP
This takes place in the mitochondria
What is the mitochondria?
A organelle which ist he site of aerobic respiration
What do cells that need a lots of energy have?
A large number of mitochondria
Give examples of cells that have a lots of mitochondria and need lots of energy? (3)
Sperm cells
Muscle cells
Nerve cells
Explain why muscle cells need many mitochondria. (2 marks)
Muscle cells need energy to do mechanical work and respond quickly. Thus a higher number of mitochondria are present in muscle cells to produce many ATP so that they have the energy required for movement.
What is the name given to the apparatus which measures the rate of respiration?
A respirometer
Explain why there is a chemical to
absorb carbon dioxide.
This experiment measures the respiration rate in germinating peas.
This neutralizes the carbon dioxide and excludes it from affecting the respirometer.
Why will the coloured liquid start to rise as respiration occurs in the peas?
This experiment measures the respiration rate in germinating peas.
As germinating peas start to grow, they need more ATP, do cellular respiration more, and consequently consume more oxygen compared to non-germinating peas. This changes the volume of gas in the tube (more space now) which causes the liquid to be sucked up.
Describe what fermentation is?
- This is how living cells produce ATP when oxygen is NOT AVAILABLE.
- Fermentation is not as efficient as aerobic respiration. It does not produce as much ATP.
- The breakdown of each glucose molecule via the fermentation pathway yields only 2 molecules of ATP.
Why do organisms need fermentation?
Fermentation is still needed by organisms, for example when the lungs can’t provide enough oxygen during exercise or when a plant is growing in waterlogged soil.
Describe fermentation in animal cells with the word equation.
- In animal cells, stage 1 happens as normal, but in the absence of oxygen the pyruvate molecules are converted to LACTATE (incomplete breakdown of glucose)
- Word equation: Glucose <–> lactate + 2 ATP
- This is reversible meaning if the oxygen debt is repaid lactate can be converted back to puruvate and aerobic respiration could proceed as normal.
- Occurs in cytoplasm
- Ineffificient 2 ATP are produced from stage 1 only.
What effect does a build up of lactate have on muscles?
Makes them feel sore and fatique and eventually cramp
Describe fermentation in plant (yeast) cells with the word equation.
- In plant and yeast cells stage 1 happens as normal, but in the absence of oxygen the pyruvate molecules are converted to CARBON DIOXIDE and ETHANOL. (incomplete breakdown of glucose)
- Word equation:
Glucose –> carbon dioxide + ethanol + 2ATP - This is IRREVERSABLE even if the oxygen became available once ethanol is made, it is permanent and CANNOT be converted back to lactate.
- Occurs in cytoplasm
- Ineffificient 2 ATP are produced from stage 1 only.
Compare aerobic respiration and fermentation in humans. (4 marks)
- Aerobic respiration requires oxygen to take place, fermentation does not require oxygen.
- Both processes use glucose to produce ATP but aerobic respiration produces a lot more ATP.
- Both processes make pyruvate, this is converted to lactate in fermentation but carbon dioxide and water are produced in aerobic respiration.
- Fermentation takes place in the cytoplasm, however, aerobic respiration occurs mainly in the mitochondria.
Describe 2 differences between fermentation in plant or yeast cells and animal cells
- The end product of fermentation in animal cells is lactate for plant or yeast cells the end products are Ethanol and carbon dioxide.
- Fermentation in animal cells produces lactate but the reaction is reversible, so if the oxygen debt is repaid lactate can ve converted back to pyruvate and enter the aerobic pathway. In plants or yeast once ethanol and Carbon dioxide is made this is irreversable/permanent.
Name product S and waste product T.
Look at the diagram which shows fermentation in plant cells.
S = Pyruvate
T = Ethanol
Identify which of the two stages releases the larger quantity of ATP.
STAGE 1 Releases 2 ATP, Stage 2 yields none.
