Respiration Flashcards
Is glycolysis aerobic or anaerobic?
Anaerobic
What are the overall products of glycolysis?
2 Pyruvate
2 NADP
2 ATP
Steps of glycolysis
1) Glucose is phosphorylated by two phosphates to form hexose biphosphate
2) It splits into two molecules of triose phosphate
3) A phosphate is added to each TP
4) TP are oxidised by dehydrogenation to form two pyruvate molecules. NAD accept the hydrogens to form NADP
What is glycolysis an example of?
Substrate level phosphorylation
What is substrate level phosphorylation?
Formation of ATP without the involvement of an ETC. ATP is formed from the transfer of a phosphate group from a phosphorylated intermediate to ADP.
Where does glycolysis occur?
Cytoplasm
Where does the link reaction take place?
Mitochondrial matrix
Is the link reaction aerobic or anaerobic?
Aerobic
What are the steps of the link reaction?
1) Pyruvate undergoes decarboxylation as a carbon dioxide is removed and oxidation as a hydrogen is removed. This results in a two carbon acetyl group.
2) Hydrogen atoms are accepted by NAD to form NADH.
3) The acetyl group combines with coenzyme A to form acetylcoenzyme A.
Is removal of a hydrogen oxidation or reduction?
Oxidation
What is the NADH produced in the link reaction used in?
The oxidative phosphorylation to synthesise ATP.
Where does the krebs cycle take place?
Mitochondrial matrix.
What does the krebs cycle involve?
Decarboxylation
Dehydrogenation
Substrate level phosphorylation
The products of the krebs cycle include reduced coenzymes NAD and FAD, what are their uses?
Used in oxidative phosphorylation.
What are the steps of the krebs cycle?
1) Acetylcoenzyme A delivers an acetyl group to the krebs cycle.
2) The 2 carbon acetyl group combines with a 4 carbon oxaloacetate.
3) This forms a 6 carbon citrate.
4) The citrate undergoes decarboxylation and dehydrogenation to give a 5 carbon molecule, carbon dioxide and one reduced NAD.
5) The 5 carbon compound undergoes further decarboxylation and dehydrogenation to regenerate oxaloacetate. The cycle continues producing more carbon dioxide, two more reduced NADs and one reduced FAD. ATP is produced by substrate level phosphorylation.
Why are coenzymes needed in respiration?
- Transfer protons
- Transfer electrons
- Transfer functional groups
between enzyme catalysed reactions
What are the differences between FAD and NAD?
1) NAD accepts one H atom, FAD accepts two.
2) NAD takes part in all stages of respiration, FAD only takes part in the krebs cycle.
3) NADH is oxidised at the start of the ETC, FADH oxidised further along the chain.
4) NADH results in the synthesis of 3 ATP molecules, FADH results in 2 ATP
What are the steps of oxidative phosphorylation?
1) H atoms from reduced coenzymes are delivered to the ETC.
2) H atoms dissociate into H ions and electrons.
3) High energy electrons are used in the synthesis of ATP in chemiosmosis.
4) Energy is released during redox reactions as electrons flow along the ETC.
5) Energy is used to create a proton gradient leading to the diffusion of protons through ATP synthase channels.
6) At the end of the ETC electrons combine with H ions and oxygen to form water.
What is the final electron acceptor in the ETC?
Oxygen
Where does oxidative phosphorylation occur?
Cristae of the mitochondria
Why was aerobic respiration not possible when life began?
No oxygen in atmosphere
How much ATP is formed per molecule of glucose?
38
How many ATPs are formed from fermentation?
2
Which is more efficient at producing ATP, aerobic or anaerobic?
Aerobic
What are obligate anaerobes?
Cannot survive in presence of oxygen. Prokaryotes and some fungi.
What are facultative anaerobes?
Synthesise ATP by aerobic respiration if oxygen is present but can switch to anaerobic respiration if no oxygen is present e.g. yeast.
What are obligate aerobes?
Can only synthesise ATP in presence of oxygen e.g. mammals.
What is fermentation?
Process by which complex organic compounds are broken down into simpler inorganic compounds without use of oxygen or the ETC.
How is the ATP produced in fermentation?
By substrate level phosphorylation alone
Why does fermentation produce a lot less ATP than aerobic?
Organic compounds are not fully broken down.
Where does alcoholic fermentation occur?
Yeast
What are the products of alcoholic fermentation?
Carbon dioxide and ethanol
Where does lactate fermentation occur?
Animals
What are the products of lactate fermentation?
Lactate
What is the process of lactate fermentation?
1) Pyruvate acts as an H acceptor taking the H from NADH, catalysed by lactate dehydrogenase.
2) Converted to lactate and NAD is regenerated.
Where is lactate converted back to glucose?
Liver
Why is there oxygen debt after exercise?
To convert lactate to glucose oxygen is needed.
Why can’t lactate fermentation occur indefinitely?
- Lactic acid causes a fall in pH leading to proteins denaturing.
- Reduced quantity of ATP produced would not be enough to maintain vital processes for a long period of time.
Which of lactate fermentation and alcoholic fermentation is a reversible reaction?
Lactate fermentation
What are the main steps of alcoholic fermentation?
1) Pyruvate is converted to ethanal, catalysed by decarboxylase.
2) Ethanal accepts a H atom from NADH to form ethanol.
What does the regenerated NAD do from the alcoholic fermentation?
Acts as a coenzyme and glycolysis can continue.
What is the difference in relative energy values of carbohydrates, lipids and proteins as respiratory sustances?
Lipids store and release twice as much as carbohydrates. Proteins are equivalent to carbohydrates.
How is the respiratory quotient (RQ) calculated?
Carbon dioxide produced/ Oxygen consumed
Why do lipids produce more ATP than carbohydrates in respiration?
Lipids contain a greater proportion of C-H bonds.
What is the RQ during anaerobic respiration?
Increases above 1.0
