Unit 1 KA7 - Cellular respiration Flashcards
What are the final products when one molecule of glucose is passed along the glycolytic pathway?
Two molecules of pyruvate, two molecules of ATP, and two hydrogen ions on carrier molecules (as NADH).
what is cellular respiration?
a series of metabolic pathways that brings about the releases of energy from a foodstuff and the regeneration of the high-energy compound adenosine triphosphate (ATP).
what are the three stages of cellular respiration?
glycolysis, citric acid cycle and electron transport chain.
what does ATP stand for and what is it made of?
adenosine triphosphate is made of adenosine and three inorganic phosphate groups.
ATP is synthesised in a ………….. reaction from …….. and …… (…………. and …………..)
reversible, ADP, Pi, adenosine diphosphate, phosphate.
the …………… of ATP to ADP and ………… …………….. energy.
breakdown, phosphate, releases.
the ……….. of ATP from ADP and ………. uses the energy released from ……….. …………..
regeneration, phosphate, cellular respiration.
what is phosphorylation?
an enzyme-controlled process in which a phosphate group is added to a molecule.
give an example of phosphorylation.
ADP + Pi to produce ATP.
why is phosphorylation important?
often, a step in a pathway can only occur if a reactant is phosphorylated and energised.
name the two stages of glycolysis.
energy investment stage and energy pay off stage.
where do the three stages of cellular respiration take place?
glycolysis - cytoplasm.
citric acid cycle - matrix of the mitochondria.
electron transport chain - inner mitochondrial membrane.
describe glycolysis.
involves the breakdown of glucose to pyruvate.
it occurs in the cytoplasm and no oxygen is required.
describe the energy investment stage of glycolysis.
2 ATP are used to phosphorylate glucose and intermediates.
1st phosphorylation produces an intermediate which can move to other integrated metabolic pathways.
2nd phosphorylation is an irreversible reaction that can only lead to glycolysis pathway.
describe the energy pay off stage of glycolysis.
4 ATP are produced causing a net gain of 2 ATP per molecule of glucose.
hydrogen ions and electrons are released from intermediates.
H+ ions and electrons are passed onto the co enzyme NAD to form NADH.
describe the citric acid cycle.
occurs in the matrix of the mitochondria in the presence of oxygen.
1. pyruvate is broken down to an acetyl group.
carbon dioxide is released as well as h+ ions and electrons which bind to NAD to form NADH.
2. acetyl group combines with coenzyme A to form acetyl coenzyme A.
3. acetyl coenzyme A combines with oxaloacetate to form citrate.
coenzyme A leaves to find another acetyl group.
4. several enzyme controlled steps of the citric acid cycle regenerate oxaloacetate while;
- ATP is regenerated from ADP and Pi
- coenzyme and NAD is reduced to NADH as dehydrogenase enzymes remove Hydrogen ions and electrons from intermediates.
- carbon dioxide is released.
describe the electron transport chain.
occurs in the inner mitochondrial membrane.
- NADH releases the electrons to the electron transport chain where they cascade down the chain, releasing energy.
- the energy is used to pump H+ ions across the inner mitochondrial membrane.
- the return flow of H+ ions drives ATP synthase and produces the bulk of the ATP generated by cellular respiration.
- the final electron acceptor is oxygen, which then combines with hydrogen ions and electrons to form water.
what is fermentation and where does it occur??
the breakdown of glucose in the absence of oxygen, occurs in the cytoplasm.
describe fermentation.
glycolysis occurs as normal, and in the absence of oxygen, the pyruvate undergoes fermentation, becoming lactate.
what is ATP synthase and where is it found?
the enzyme that catalyses the synthesis of ATP from ADP and phosphate, found in membranes in the cell.
what is the role of dehydrogenase enzymes?
remove hydrogen ions and electrons and passes them to the coenzyme NAD, forming NADH.
used in both glycolysis and citric acid cycle.
what is the role of ATP?
used to transfer energy to cellular processes which require energy.
