B12. Respiration (DONE) Flashcards
What are the conditions for aerobic respiration and its product?
Requires presence of Oxygen; Produces carbon dioxide, H2O and high amounts of ATP
What are the conditions for anaerobic respiration and its products?
Requires the absence of Oxygen; Produces lactate in animals or ethanol and carbon dioxide in plants and fungi; Produces little ATP as well
What are the stages of aerobic respiration and what are the general mechanisms?
Glycolysis - Glucose to pyruvate; Link reaction - Pyruvate to Acetyl Coenzyme A; Krebs cycle - Acetyl CoA to 2H; Oxidative phosphorylation - 2H to H2O, O is terminal molecule
Describe the mechanism of glycolysis.
Glucose phosphorylated by 2 ATP forming fructose bisphosphate; Fructose bisphosphate split into 2 triose phosphate; Oxidation of 2 triose phosphate by 2 NAD forming 2 NADH; 2 Triose phosphate dephosphorylated by substrate linked phosphorylation forming 4 ATP; Converted into 2 pyruvate ,
What is the net product yield from glycolysis?
2 ATP, 2 NADH, 2 Pyruvate
Describe the mechanism of the link reaction.
Pyruvate oxidised by NAD producing NADH and decarboxylated producing CO2, forming acetate; Acetate combines with Coenzyme A forming Acetyl Coenzyme A; Per molecule
What is the net product yield from the link reaction?
2 Acetyl coenzyme A; 2 NADH; 2 CO2
Describe the general mechanism of the Krebs cycle.
AcetylCoA (2C) combines w/ Oxaloacetate (4C) intermediate forming citrate; Citrate is oxidised by NAD forming NADH, decarboxylated forming CO2; Produced 5C intermediate, decarboxylated forming CO2, oxidised by NAD, FAD then NAD forming FAD2 and 2 NADH and dephosphorylated by substrate linked phosphorylation forming ATP; Reforming to oxaloacetate
What is the net product yield from the Krebs cycle per molecule of AcetylCoA?
1 ATP, 2 CO2, 3 NADH, 1 FADH2
Why is the krebs cycle significant?
Breaks down macromolecules into smaller ones, pyruvate broken into CO2; Produces H atoms carried by NAD to ETC & provide energy for oxidative phosphorylation; Regenerates 4C intermediate; Source of intermediate compounds used by the cell for important substances, fatty acids, amino acids, chlorophyll
What is the importance of phosphorylation of glucose in glycolysis and where does it come from?
Increases molecule reactivity and lowers activation energy for enzyme controlled reactions; phosphate molecules come from hydrolysis of ATP;
Describe the structure of mitochondria.
Organelle found in eukaryotic cells; 2 phospholipid membranes; Outer - smooth. permeable to several small molecules; Inner - folded, cristae. less permeable, site of ETC and ATP synthase; Intermembrane space - low pH due to high H+ conc. conc gradient occurs across inner membrane; Matrix - Aq solution within inner membrane. contains ribosomes, enzymes and circular mitochondrial DNA.
Which stages produces the most ATP?
Oxidative phosphorylation
Define aerobic respiration.
Process of breaking down a respiratory substrate in order to produce ATP using oxygen
What’s the equation of glucose respiration?
C6H12O6 + 6O2 => 6CO2 + 6H2O + ATP
What are autotrophs?
Organisms that are able to synthesise their own usable carbon compounds from carbon dioxide in the atmosphere through photosynthesis
Describe how mitochondria are specialised in active cells.
High conc in in metabolically active cells eg. Muscle, liver and epithelial; Mitochondria have more densely packed cristae, provides greater surface area for proteins and enzymes.
Describe the mechanism of oxidative phosphorylation.
NADH & FADH2 donate e- of H atoms to the ETC; e- passed along chain of electron transfer carriers, series of Oxidation-reduction reactions; Energy released as e- flow along chain causes active transport of H+ across inner mitochondrial membrane into inter-memerbanal space; H+ accumulate before they diffuse back into matrix through ATP synthase channels; Chemiosmosis; End of ETC e- combine with oxygen to form H2O
What is the importance of oxygen in respiration?
Acts as final acceptor; Terminal molecule
What would happen if there was no oxygen during oxidative phosphorylation?
H+ and e- would back up along chain process of respiration would stop due to H+ ions not being removed at the end of the chain
Why is energy released in stages during respiration?
The greater the energy that is released in a single step, more of it is released as heat; As energy released slowly, more of it can be harvested for benefit of the organism
What are the alternative respiratory substrates to sugars?
Lipids and proteins
Describe the mechanism for respiration of lipids.
Lipids are hydrolysed to glycerol and fatty acids; Glycerol then phosphorylated and converted to triose phosphate, entering the glycolysis pathway; Fatty acid is broken down into 2C fragments which are then converted to AcetylCoA and many Hydrogen atoms
Why do lipids produce more energy than sugars during respiration?
Large quantity of Hydrogen atoms produced from Fatty acids being converted into AcetylCoA are used to produce ATP during oxidative phosphorylation
Describe the mechanism for respiration of proteins.
Hydrolysed to its constituent amino acids. These are deaminated before entering pathway at different points depending on carbon number. 3C - pyruvate; 4 & 5C - intermediates for Krebs.
What is the general definition of deamination?
Removal of amino groups of amino acids
How do cells respire in low oxygen conditions?
Anaerobic respiration
Describe ethanol fermentation.
Pyruvate is decarboxylated to ethanal producing CO2; Ethanal is hydrogen acceptor; NADH is oxidised, forming NAD; Ethanal is reduced to ethanol by the enzyme alcohol dehydrogenase; Ethanol cannot be further metabolised, waste product
Describe lactate anaerobic respiration.
Pyruvate is hydrogen acceptor; NADH is oxidised forming NAD by pyruvate; Pyruvate reduced to lactate by enzyme lactate dehydrogenase; Final product lactate cannot be further reduced
Describe the metabolisation of lactate
Oxidised back to pyruvate; Channelled into kreb cycle; Needs extra oxygen; Can be converted into glycogen for storage in the liver
Why do animals breathe heavier after exercise?
Oxygen debt; Extra oxygen is needed to metabolise, oxidise lactate into pyruvate
What is the equation for respiratory quotient?
CO2 produced / O2 consumed
What is the respiratory quotient of glucose?
1.0
