BY4 - Respiration Flashcards
Where does the link reaction and the Kreb’s cycle take place?
In the matrix of the mitochondria
Where does glycolysis take place?
In the cytoplasm of the cell
Where does the electron transport chain take place?
At the cristae of the mitochondria
Give three roles of ATP
Metabolic processes Active transport Movement Nerve transmission Secretion
Define activation energy
The minimum energy required to start a chemical reaction
Define phosphorylation
The addition of phosphate (Pi) and ADP
What are the three forma of phosphorylation?
Oxidative phosphorylation
Substrate-level phosphorylation
Photophosphorylation
Give the uses and advantages of ATP
Hydrolysis of ATP to ADP is a single reaction that releases immediate energy
Only one enzyme required to release energy
Energy released in small amounts
Is the universal energy currency in organisms
Why is ATP described as the universal energy currency?
Universal because it is a common source of energy for all reactions in all cells
Energy currency because it transfers small packets of energy from the place of release to energy requiring reactions
Give the disadvantages of glucose as an energy source
Requires many enzymes to release energy
Has many intermediates to release energy
Takes a long time to release energy
Releases a large amount of energy that may not be needed immediately
Release large amounts of heat energy that can damage the cell and enzymes
What is oxidation?
Is the loss of electrons/hydrogen
Catabolism
Exergonic
What is reduction?
The gain of electrons/hydrogen
Anabolism
Endergonic
Give the two coenzymes and their reactions
NAD and FAD
NAD + 2H+ + 2e- —-> NADH/H+
FAD + 2H+ + 2e- —-> FADH2
What is the role of coenzyme A?
Transports the acetyl group to the next stage of reaction as acetyl coenzyme A
Define dehydrogenation
The removal of hydrogen
Define carboxylation
The removal of carbon dioxide
What is the Chemiosmotic theory?
A model to explain the synthesis of ATP. It proposes that the energy for ATP synthesis originates from the electrochemical gradient of protons across a membrane.
What is referred to as the final electron acceptor?
Oxygen
During anaerobic respiration what acts as the final hydrogen acceptor in animals? Consequently what is it converted to?
Pyruvate is the final hydrogen acceptor. It is reduced to lactic acid.
What is the final hydrogen acceptor in plants? What is it converted into?
(Pyruvate is decarboxylated to produce ethanal). Ethanal is the final hydrogen acceptor. It is then reduced to form ethanol. This process is called fermentation.
Define a respiratory substance
Organic molecules that can be respired to release energy to make ATP
How can lipids be used as a respiratory substance?
It is hydrolysed into glycerol and fatty acids. The glycerol is then converted into a three carbon sugar which enters glycolysis via triose phosphate, this yields ATP molecules. The fatty acid chains are split into two carbon fragments which enter the pathway as acetyl coenzyme A. Very large molecules of ATP can be built up depending on the hydrocarbon chain length of the fatty acids. 1g of fat releases 2x more energy than carbohydrates.
When are proteins used as a respiratory substance?
Only when an individual is suffering from starvation. Usually only when reserves of carbohydrates and lipids have been used up.
How can proteins be used as a respiratory substance? Where does it take place?
Protein is hydrolysed into its amino acids. Amino acids are deaminated to form urea and residue. Urea is excreted. The residue is then converted into acetyl coA or pyruvate to enter the Krebs Cycle.
This takes place in the liver.
