respiration Flashcards
what is the main purpose of respiration?
to produce ATP
respiration is split into 4 stages, what are they?
1- glycolysis
2- link reaction
3- krebs cycle
4- oxidative phosphorylation
where does glycolysis occur?
in the cytoplasm of the mitochondria
where does the link reaction occur?
in the mitochondrial matrix
where does the krebs cycle occur?
in the mitochondrial matrix
where does oxidative phosphorylation occur?
in the cristae
is glycolysis an aerobic or anaerobic process? and why?
its an anaerobic process, as it doesn’t require oxygen
what happens during glycolysis?
ATP IS USED TO PHOSPHORYLATE GLUCOSE TO TRIOSE PHOSPHATE. THEN TRIOSE PHOSPHATE IS OXIDISED, RELEASING ATP.
- phosphorylation of glucose to glucose-phosphate from a molecule of ATP.
- this creates 1 molecule of glucose-phosphate and 1 molecule of ADP.
- ATP is then used to add another phosphate, forming hexose bisphosphate
- hexose bisphosphate is then split into 2 molecules of triose phosphate
- triose phosphate is oxidised (loses hydrogen), forming 2 molecules of pyruvate
- NAD collects the hydrogen ions, forming 2 reduced NAD
- 4 ATP are produced, but 2 were used up in stage one, so there’s a net gain of 2 ATP.
- there’s a net gain of 2 reduced NAD
what happens during the link reaction?
PYRUVATE IS CONVERTED INTO ACETYL COENZYME A.
- pyruvate is decarboxylated (one carbon atom is removed from pyruvate in the form of CO2)
- pyruvate is oxidised to form acetate and NAD is reduced to form reduced NAD
- acetate is combined with coenzyme A (CoA) to form acetyl coenzyme A (acetyl CoA)
- no ATP is produced in this reaction
what happens during the krebs cycle?
THE KREBS CYCLE PRODUCES REDUCED COENZYMES AND ATP.
- acetylcoenzyme A reacts with a four-carbon molecule, releasing coenzyme A and producing a six-carbon molecule that enters the Krebs cycle
- in a series of oxidation-reduction reactions, the Krebs cycle generates reduced coenzymes and ATP by substrate-level phosphorylation, and carbon dioxide is lost
what happens during oxidative phosphorylation?
THE PROCESS BY WHICH THE ENERGY CARRIED BY ELECTRONS, FROM REDUCED NAD AND REDUCED FAD, IS USED TO MAKE ATP.
- H atoms are released from reduced NAD and reduced FAD as they’re oxidised to NAD and FAD. the H atoms split into protons (H+) and electrons (e-)
- the e- move down the ETC made up on electron carriers, losing energy at each carrier.
- this energy is used by the electron carriers to pump protons from the matrix to the intermembrane space
- the concentration of protons is now higher in the intermembrane space than in the matrix, this forms an electrochemical gradient (a concentration gradient of ions)
- protons then move down the gradient back across the membrane and into the matrix via ATP synthase.
- this movement drives the synthesis of ATP from ADP + Pi
- in the matrix at the end of the ETC, the protons, electrons and O2 (from the blood) combine to form water
- oxygen is said to be the final electron acceptor
how many times does the link reaction and krebs cycle occur for every glucose molecule?
twice for every glucose molecule
in the link reaction, per glucose molecule, what is made?
what are they used for ?
- 2 molecules of acetyl CoA (go into the krebs cycle)
- 2 CO2 molecules are released (as a waste product of respiration)
- 2 molecules of reduced NAD are formed (they go to the last stage, oxidative phosphorylation)
what are the products from 1 krebs cycle, and what are they used for?
- 1 CoA (reused in the next link reaction)
- oxaloacetate (regenerated for use in the next krebs cycle)
- 2 CO2 (released as a waste product)
- 1 ATP (used for energy)
- 3 reduced NAD (goes to oxidative phosphorylation)
- 1 reduced FAD (goes to oxidative phosphorylation)
how many ATP can be made from one glucose molecule?
32 ATP
