respiration Flashcards
What occurs during respiration?
Glucose is broken down, specifically the carbon-hydrogen bonds which releases energy. The energy released is used in chemiosmosis to synthesise ATP, the universal energy, which is used in energy requiring processes and reactions.
What is glycolysis, what does it produce and where does it occur?
Glycolysis is an anaerobic process and the first stage of respiration and is the splitting of glucose into two smaller pyruvate molecules.
It additionally produces 2 ATP and reduced NAD to synthesis more ATP later on.
It occurs in the cytoplasm within a mitochondrion
What is the difference between substrate level phosphorylation and oxidative phosphorylation?
Substrate level phosphorylation: Involves a phosphate molecule being added from an intermediate, occurs in glycolysis and krebs cycle
Oxidative phosphorylation: Requires an electron transport chain ( chemi-osmosis ), occurs during the last stage of photosynthesis
What is the link reaction, where does it occur?
The link reaction is the first stage of aerobic respiration which links glycolysis to aerobic respiration.
Occurs in mitocondrial matrix
Pyruvate enters the matrix by active transport and carrier proteins (requires ATP)
Will go through decarboxylation and oxidation producing CO2 and reduced NAD.
Acetyl group will bind with coenzyme A to form acetyl CoA which will deliver the acetyl group to the Krebs cycle,
What is the Krebs cycle? Where does it occur?
Krebs cycle occurs in the mitocondrial matrix and results in the break down of acetyl group.
Acetyl CoA delivers the acetyl group to the Krebs cycle.
The acetyl group will combine with oxaloacetate to form citrate.
Citrate will go through carboxylation and dehydrogenation producing reduced NAD and CO2.
The 5C compound produced will go through further decarboxylation and dehydrogenation regenerating oxaloacetate.
Produces reduced NAD, FAD , ATP and CO2
What is the difference between coenzyme NAD and FAD?
NAD is in all parts of cellular respiration whereas FAD only accepts H+ in the Krebs cycle
NAD will accept one H whereas FAD accepts two H
Reduced NAD is oxidised at the start of the electron transport chain whereas FAD is oxidised further along.
What is oxidative phosphorylation, where does it occur and what does it produce?
Oxidative phosphorylation takes place in the inner mitocondrial membrane and occurs via chemiosmosis where energy from electrons donated by reduced NAD and FAD cause H+ ions will flow by facilliated diffusion through ATP synthase.
This is an aerobic process therefore requires O2 to accept it to end the chain and form H2O.
What are obligate anaerobes, facultative anaerobes and obligate aerobes?
Obligate anaerobes: Cannot survive in the presence of O2
Facultative anaerobes: Synthesise ATP aerobically but will switch to anaerobic in the absence of oxygen e.g yeast cells
Obligate aerobes: Can only synthesise ATP when there is oxygen
What is fermentation?
Fermentation is when complex organic molecules are broken down into simple components without O2 or the electron transport chain which produce less O2 than aerobic respiration.
What is lactate fermentation and where does it occur and why?
Lactate fermentation occurs in animal cells when there is no O2 as it cannot act as the final acceptor in chemiosmosis meaning reduced NAD and FAD cannot be oxidised.
Pyruvate will accept the H+ , catalysed by lactate dehydrogenase and is converted into lactic acid and NAD is regenerated to allow glycolysis to produce a small amount of ATP.
What is alcoholic fermentation, where does it occur and why?
Alcoholic fermentation occurs in plants and yeast cells where pyruvate is converted to ethanal via decarboxylation and catalysed by pyruvate decarboxylase.
Ethanal can then accept a H+ atom from reduced NAD to become ethanol and produce NAD for glycolysis.
What is the respiratory quotient? What RQ values will carbohydrates, lipids and proteins?
Measured by a respirometer where CO2 is produced/O2 consumed
Glucose: 1.0
Lipids: 0.7
Proteins: 0.9
Why are proteins not commonly used for respiration?
Respiration of proteins requires deamination and conversion of a keto acid to pyruvate which requires ATP, lowering the net profit.
