Respiration Flashcards
Where does glycolysis occur
Cytoplasm
Where does link reaction occur
Mitochondrial matrix
Where does the Krebs cycle occur
Mitochondrial matrix
Where does oxidative phosphorylation occur
Mitochondrial inner membrane-cristae
What are the three main steps of glycolysis
Phosphorylation glucose to glucose phosphate (using ATP)
production of triose phosphate
Oxidation of trios phosphate to produce pyruvate with net gain of ATP and reduced NAD(coenzyme)
What are the products of glycolysis
2x pyruvate
Net gain of 2 ATP
2x NADH
What happens to pyruvate and NADH after glycolysis
Actively transported from cytoplasm into the mitochondrial matrix
Explain what happens in the Link Reaction
The pyruvate made in glycolysis is oxidised further to form acetate
Acetate loses a hydrogen
Hydrogen picked up by NAD = NADH
Acetate is a 2 carbon molecule because CO2 is formed in the reaction
Acetate then combined with coenzyme A = ACETYLCOENZYME A
link reaction occurs twice for every glucose molecule - for every glucose molecule formed there is:
2x acetyl CoA
2x CO2 released
2x NADH
Formed
What is the job of coenzyme A
To deliver Acetyl-CoA to the 4 carbon compound
Released once used to be reused in Link reaction
What happens in the Krebs Cycle?
Acetyl CoA reacts with 4 carbon molecule, releasing coenzyme A and producing a 6 carbon molecule that enters the Krebs Cycle
In series of Redox reactions, the Krebs cycle generates REDUCED COENZYMES and ATP by substrate-level phosphorylation + CO2 is lost
What r the products of Krebs Cycle per cycle AND per glucose molecule ?
Per cycle:
3x reduced NAD
1x reduced FAD
1x ATP
2x CO2
Per glucose molecule:
6x reduced NAD
2x reduced FAD
2x ATP
4x CO2
Where is most of the ATP produced in respiration?
Oxidative phosphorylation
What happens during oxidative phosphorylation?
In mitochondrial matrix, all of reduced coenzymes produced release their hydrogens = protons + electrons
Electrons transported along electron transport chain = energy
Energy used to actively transport protons from matrix to Inter membrane space
Creates electrochemical gradient
=protons move my facilitated diffusion DOWN con gradient through ATP SYNTHASE
Atp synthase phosphorylates ADP = ATP (34)
END of electrontransfer chain - electrons picked up my oxygen
Also picks up protons that have passed though
= WATER
(Final electron acceptor = O2)
What is anaerobic respiration and what happens during it?
Absence of oxygen respiration occurs anaerobically - CYTOPLASM
Pyruvate produced in glycolysis is reduced to form ethanol and CO2 (plants and microbes)
OR
Lactate, remaining in cytoplasm, (animals) by pyruvate gaining the hydrogen immediately from NADH
This oxidises NAD = reused in glycolysis and ensure more ATP is continued to be produced
describe the process of glycolysis (3)
phosphorylation of glucose to triose phosphate (using ATP)
oxidation of triosephosphate to form pyruvate
withnet gain of ATP and NADH
what is the importance of oxygen in respiration
oxygen is the final electron acceptor
- if didn’t accept electrons = no more electrons move down chain
- protons wouldn’t be transported across membrane
= no gradient = no ATP made
why does NAD become ‘reduced’ when gaining a hydrogen
hydrogen made up of a proton and electron
- gains proton and electron
why id NADH oxidised during anaerobic respiration
do NAD can be reused in glycolysis and make sure ATP is continued to be produced
and glycolysis can continue
why can’t anaerobic respiration go on for long periods of time
either lactate or ethanol will denature enzymes involved in glycolysis
= respiration will stop
explain the efficiency of aerobic respiration
one molecule of glucose
= 38 molecules of ATP
= 32% efficiency (not high)
because:
- oxidative phosphorylation, protons move through ATP synthase by F. diffusion - BUT some can leak across mitochondrial membrane
- ATP used to actively transport pyruvate and NADH into matric
- some energy lost as heat
explain why anaerobic respiration is less efficient than aerobic respiration
for every 1 glucose molecule (not fully broken down)
= 2 ATP molecules produced
what does dehydrogenase enzyme do
occurs in yeast
- catalyses reactions involved in removing H from coenzymes and carbon compounds
how do we track how quickly dehydrogenase enzyme catalyses reactions (indicator of rate of respiration)
add artificial hydrogen acceptor (TTC)
TTC = redox indicator
- when oxidised it is colourless
- when picks up hydrogen and reduced = red precipitate
what is the hypothesis used in yeast required practical
the yeast and TTC will turn red faster, indicating a faster rate of reaction, as the temp increases
