respiration Flashcards
what is aerobic respiration?
- respiration which requires oxygen and produces carbon dioxide, water and ATP
what is anaerobic respiration?
-takes place in absence of oxygen, and produce lactate in animals, or ethanol and carbon dioxide in plants and fungi
-does not produce a lot of atp
what are the four stages of aerobic respiration?
- glycolysis
- link reaction
- krebs cycle
- oxidative phosphorylation
where does glycolysis occur?
- in the cytoplasm of the cell
where does the link reaction occur?
in the matrix of the mitochondria
where does the krebs cycle occur?
in the matrix of the mitochondria
where does oxidative phosphorylation happen in aerobic respiration?
in the membrane of the cristae of the mitochondria
what are coenzymes?
complex organic molecules needed for some enzymes to function, which accept or donate hydrogen
how are the stages of aerobic respiration linked?
- carrier molecules transfer substrates between the three pathways
- NAD used as a hydrogen acceptor
- reduced NAD used as hydrogen donator for last stage where most ATP synthesised
what is glycolysis?
- first stage of aerobic and anaerobic respiration
- splitting of glucose
describe what happens in glycolysis
- phosphorylation of glucose;
2x phosphate molecules from hydrolysis of ATP, produces 1x glucose phosphate and 2x ADP - glucose phosphate split into 2x triose phosphate
- oxidation of triose phosphate;
triose phosphate added to 2x ADP and 1x NAD, produced 2x ATP 1x reduced NAD and 1x pyruvate per triose phosphate
what is the net production from glycolysis?
- 2 ATP
- 2 reduced NAD
- 2 pyruvate
what is the purpose of the link reaction?
- to link glycolysis to the krebs cycle
how does pyruvate move from glycolysis?
- actively transports from cytoplasm to matrix of mitochondria
what happens in the link reaction?
- pyruvate oxidised to produce acetate;
pyruvate loses a carbon molecule and 2x hydrogen, forms a molecule of carbon dioxide and 1x reduced NAD - acetate combines with coenzyme A to produce acetylcoenzyme A
- acetylcoenzyme A moves onto Krebs cycle
- happens 2x per glucose molecule
what is net production per glucose molecule at the end of the link reaction?
- 2x acetylcoenzyme A
- 4x reduced NAD
- 2x carbon dioxide
what happens in the Krebs cycle?
- Acetylcoenzyme A combines with 4c compound oxaloacetate, coenzyme A released
- produces 6c compound citrate which enters Krebs cycle
- series of redox reactions cause this molecule to lose carbon dioxide and hydrogen to result in oxaloacetate which can restart the cycle
what are the products of the Krebs cycle?
- 1x ATP
- 3x reduced NAD
- 1x reduced FAD
- 2x carbon dioxide
what is the way of making ATP in the krebs cycle called?
substrate level phosphorylation
what is the net production of one glucose molecule after the krebs cycle?
- 6x carbon dioxide
- 4x ATP
- 10x reduced NAD
- 2x reduced FAD
what is the significance of the krebs cycle?
- breaks macromolecules into smaller ones (pyruvate to CO2)
- produces hydrogen for coenzymes for oxidative phosphorylation for ATP production
- regenerates oxaloacetate
how many molecules of carbon in pyruvate?
3
how many molecules of carbon are in acetate?
2
what happens in oxidative phosphorylation?
- coenzymes deposit hydrogen molecules to the electron transport chain
- energy from electrons within hydrogen atoms converted to ATP
describe the oxidation phosphorylation stage of aerobic respiration
- reduced NAD and FAD donate electrons of hydrogen atoms to first molecule of ECT (first electron carrier; cytochrome)
- electrons pass along the chain in a series of redox reactions, releasing energy as they are passed
- this energy is used to actively transport the protons across the inner mitochondrial membrane into the inner space
- protons accumulate and then diffuse back into the inner membrane through ATP synthase, synthesising the production of ATP
- electrons reach end of chain and combine with oxygen and protons to form water
what is the final electron acceptor of the electron transport chain in aerobic respiration?
- oxygen
how many molecules of ATP are released per one molecule of reduced NAD and reduced FAD?
- reduced NAD: 3x ATP
- reduced FAD: 2x ATP
what is the net production of ATP per glucose molecule?
38
what are the alternative respiratory substances?
- proteins
- lipids
how are lipids used as respiratory substances?
- hydrolysed to glycerol and fatty acids
- glycerol phosphorylated and converted to TP which enters glycolysis pathway
- fatty acid broken down into 2 carbon fragments and converted to acetate and enter Krebs cycle
- oxidation of lipids produce 2 carbon fragments and many hydrogen atoms
- release more than 2x energy of carbs at same mass
how are proteins used as respiratory substances?
- hydrolysed to amino acids
- amino group removed and enter respiration at different points depending on amount of carbon atoms they have
how is respiration measured?
- rate of exchange of oxygen and/or carbon dioxide
describe the process by which rate of respiration is measured
- oxygen taken up
- carbon dioxide absorbed by potassium hydroxide
- pressure in capillary tube decreases
- drop of coloured liquid moves towards the organism
what measurements do you need to perform the calculation to find the rate of respiration?
- distance drop moves and time
- mass of organism
- diameter of tube
describe how anaerobic respiration happens in plants and some microorganisms
- glycolysis occurs as normal
- pyruvate from glycolysis loses 1x CO2
- reduced NAD is oxidised
- one hydrogen atom is passed to pyruvate (reduced)
- creates ethanol
what are the products of anaerobic respiration in plants and microorganisms?
- ethanol
- carbon dioxide
why do animals respire anaerobically?
- strenuous exercise
- respiration rate increases, unable to sufficiently supply cells with enough oxygen
- oxygen debt occurs
describe the process of anaerobic respiration in animals
- glucose partially broken down
- reduced NAD is oxidised
- each pyruvate receives 2x hydrogen
- becomes lactate
- lactate conc increases
what is the consequence of anaerobic respiration in animals?
- lactate concentration increases
- lowers PH; highers acidity
- proteins denature
what happens to lactate once oxygen is available again?
- lactate oxidised back to pyruvate
- enters link reaction and krebs cycle
