Respiration Flashcards
what are the 4 stages of respiration?
1) glycolysis (in cytoplasm)
2) Link Reaction in mitochondrial matrix
3) Krebs cycle mitochondrial matrix
4) ETC cristae of mitochondria
what do aerobic prokaryotes use their cell membrane for
to perform oxidative phosphorylation which uses oxygen
in anaerobic only glycolysis is produced
what is the function of the outer membrane of the mitochondria
contains transport proteins that enable the shuttling of pyruvate from the cytosol
what is the function of the inner membrane of the mitochondria
contains the ETC and ATP synthase for oxidative phosphorylation
what is the function of the cristae on the inner membrane?
arranged in folds to increase the SA:V ratio
more space for ETC
what is the function of the interembrane space
membranes maximises hydrogen gradient upon proton accumulation
what is the function of the matrix
cavity that contains appropriate enzymes and a suitable pH for the Krebs cycle to occur.
why is the intermembrane space very small?
maximises more rapid generation of a proton motive force/ quickly accumulate protons
what does the matrix contain
appropriate enzymes and a suitable pH for the Krebs cycle
In Glycolysis:
what is the reactant
glucose (6C compound)
In Glycolysis:
ATP reacts with glucose to make an unstable compound which immediately spilts into what?
and what is the name of the unstable 6C compound
(phosphorylation)
hexose bisphosphate is unstable
splits into 2 3C molecules called triosphosphate
what is the ATP molecule at the start of glycolysis acting as
a coenzyme (carries a group)
what are the products of glycolysis
x2 ATP
x2 NADH+ H+
x2 Pyruvate
what is the phosphorylation stage of glycolysis
hexose sugar is phosphorylated by two molecules of ATP. this forms hexose bisphosphate which is less stable and more reactive.
this prevents diffusion out of cell
ATP primes the process
what is the lysis stage of glycolysis
the hexose bisphosphate 6C sugar is split and further phosphorylation occurs from inorganic phosphate ions (P i) (in the cytosol)
two triose phosphates 3C sugars formed
what is the oxidation/dehydrogenation phase of glycolysis
the 3rd stage of glycolysis
hydrogen atoms are removed from the 3C sugars via oxidation/dehydrogenation to reduce NAD+ to NADH(H+)
x2 NADH produced in total from the two triose phosphates
what is the ATP formation stage of glycolysis
some energy released from sugar intermediates is used to directly synthesise ATP
this is called substrate level phosphorylation
x4 molecules ATP made during glycolysis
what is substrate level phosphorylation
doesnt use oxygen but uses substrate glucose instead
bonds are providing the energy for reaction, (not from protons being pumped across a membrane through a ATP synthase pump)
what is the net gain of ATP after glycolysis
2 as 4 are made but 2 were used at the start
availability of oxygen affects what happens to the pyruvate following glycolysis:
if aerobic…..
if anaerobic….
aerobic- aerobic respiration continues and further ATP production continues (34 ATP)
anaerobic respiration/fermentation occurs no ATP is produced (pyruvate without oxygen)
where does the link reaction occur in prokaryotes
cytoplasm and eventually moves to membrane
what is the process that occurs in the Link reaction
oxidative decarboxylation
the link reaction is the first aerobic stage in aerobic respiration
how does pyruvate get from the cytosol into the mitochondiral matrix?
by active transport via carrier proteins on the membrane
when oxygen is available what does it cause in the link reaction
further oxidation of the sugar molecules for a greater yield of ATP
what is removed from the pyruvate in the link reaction and what does it form
what happens to this product
Carbon atom removed
forms CO2`
diffused away as metabolic waste or used by autotrophs in photosynthesis
how many carbon atoms remain in link reaction after CO2 removed
2C which forms an acetyl group
what is removed in the link reaction by oxidation involving the acetyl group
what is the product of this
Acetyl group loses a hydrogen atom
this reduces NAD+ to NADH + H+
how is acetyl coenzyme A formed and what does it do
the acetyl group combines with coenzyme A to form Acetyl CoA
how many times does the link reaction occur and why
twice
as it occurs once per molecule of glucose formed in glycolysis (two pyruvate are formed from glycolysis)
what is the Krebs Cycle aka
the citric acid cycle
where does the Krebs cycle occur
in the mitochondrial matrix
how is a 6C molecule made at the start of the krebs cycle
acetyl CoA loses its acetyl group which becomes citrate
coenzyme A is released and can be returned to the link reaction
what are the different reactions in the Krebs cycle
decarboxylation - two carbon atoms are released to form two molecules of CO2
oxidation - reactions result in reduction of hydrogen carriers (3x NADH+H+ ; 1x FADH2)
substrate level phosphorylation - one molecule of ATP produced directly
what are the products of the Krebs cycle
x4 CO2
x2 ATP
x6 NADH+ H+
x2 FADH2
why does the Krebs cycle occur twice
because two molecules of acetyl CoA produced in link reaction (one from each pyruvate)
the Krebs cycle includes an addition of a 2C molecule to a _C molecule
4C
the 2C is the acetyl group and they join to form a 6C molecule
what is the function of NAD and FAD
to carry electrons from one enzyme controlled reaction to another
which coenzymes are involved in respiration?
CoA
ATP
NAD
FAD
which of NAD/FAD is only involved in the Krebs cycle
FAD
NAD in all stages
which one of NAD/FAD accepts two hydrogens?
FAD
NAD accepts 1 hydrogen
which one of NAD/FAD is oxidised at the start of the electron transport chain
NAD
FAD is oxidised further along
which one of NAD/FAD produces 2 ATP
FAD
NAD produces 3
which reaction does the ETC cause in terms of ATP
allows ATP production by chemiososmosis
ETC releases the energy stored within the reduced hydrogen carriers (NAD and FAD) to synthesise ATP
this is called OXIDATIVE PHOSPHORYLATION
(energy from hydrogen carriers synthesises ATP)
The steps of Oxidative Phosphorylation
- proton pumps create an electrochemical gradient
- ATP synthase uses the diffusion of protons(chemiosmosis) to produce ATP
- oxygen accepts electrons and protons and forms water
what is the purpose of the final electron acceptor
needed at the end of the ETC so oxygen needed for other processes can happen
the final electron acceptor is oxygen
it:
»»prevents the chain getting blocked by removing de-energised electrons
»»also binds with free protons/hydrogen to form water removing matrix protons to maintain a hydrogen gradient
in the absense of oxygen what stops aerobic respiration being able to occur
hydrogen carriers cannot transfer energised electrons to the ETC and ATP production is halted
(no electron acceptor so ETC chain stops)
»>this means everything after glycolysis stops
what is cytochrome C
a component of the ETC
the haem group of it accepts electrons from bq1 complex and transfers to complex IV
what is the function of complex IV / enzyme cytochrome c oxidase
large transmembrane protein complex found in bacteria and the mitochondrion of eukaryotes
last enzyme in the respiritory ETC
as the electrons pass through the ETC they ____energy which is used to….
lose
to pump protons/ H+ from the matrix
what process do protons move back into the matrix from the intermembrane space
proton motive force
