Respiration Flashcards
define substrate level phosphorylation
the formation of ATP via direct phosphorylation of ADP
when do you get substrate level phosphorylation? (3)
- 1,3-Bisphosphate to 3-Phosphoglycerate
- Phosphoenolpyruvate to Pyruvate
- from GDP to GTP
Describe Structure of Mitochondria.
outer membrane
intermembrane space
inner membrane
matrix
cristae
mitochondria DNA
ribosomes
ATP synthase
DRAW OUT GLYCOLYSIS, LINK REACTION AND TCA WITH MAIN ENZYMES
Where does Glycolysis, Link Reaction, TCA cycle and Oxidative Phosphorylation Occur?
cytoplasm
3x Mitochondria
What is the NET ATP of Aerobic Respiration?
Glycolysis = 2ATP
TCA = 2ATP
ETC = 28ATP
= 32ATP
What is OIL RIG?
oxidation is loss of electrons
reduction is gain of electrons
What are the 3 Main Carriers?
ATP - Phosphate
NADH,NADPH,FADH2 - electrons and hydrogens
Acetly CoA - acetyl group
How is Energy Created under Anaerobic Conditions?
Fermentation of Yeast
- cannot do TCA or ETC
- pyruvate is produced but needs to be metabolised to balance NADH
= pyruvate - acetaldehyde - ethanol
= oxidation
- stops when too much ethanol created = toxic
What Happens if an Aerobic Respiration turns Anaerobic?
- shortage of oxygen
- TCA stops when it runs out of NAD and FAD
- leads to lactic acid fermentation
Can other Sugars other than Glucose be Used?
Yes - galactose and fructose from adipose or liver
but efficiency is poor
What are the 4 Types of Regulation Mechanisms for Enzymes in Metabolism?
allosteric regulation
- enzyme activity can be inhibits
covalent modification
- phosphorylation
sequestration
- compartmentation or isolation of enzymes in specific parts of the cell
association with regulatory protein
How is Hexokinase Regulated?
allosteric regulation
- if there is too much glucose being converted to G-6P
- gets inhibits
- glucose stores as glycogen
How is Phosphofructokinase Regulated? (3)
allosteric reglation
- ATP binds to allosteric site and inhibits conversion of fructose-6-phopshate into fructose-1,6-bisphosphate
- to increase affinity back up
- PFK is activated by fructose-2,6-bisphosphate
- reduces affinity to ATP
- glycolysis continues
- sensitivity to pH
- if its too low, it reduces activity
- prevents lactic acid formation
How is Pyruvate Kinase Regulated?
allosteric regulation and covalent modificaiton
- catalyse phosphophenolpyruvate into pyruvate
- activated by fructose-1,6-bisphosphate
too much energy, phosphorylates pyruvate kinase and makes it less active
How is Pyruvate Dehydrogenase Regulated?
allosteric regulation and covalent modificaiton
- convertes pyruvate to acetyl CoA
limiting sites
- limited by Acetyl CoA = E2 Transacetylase
- limited by NADH = E3 Dihydrolipodehydrogenase
- phosphorylation switches off activity
How is Isocitrate Dehydrogenase from TCA Regulated?
- inhibited by ATP and NADH
- activated by ADP
How is a-Ketoglutarate Dehydrogenase from TCA Regulated?
- inhibited by ATP, succinyl CoA and NADH
What are the Main Enzymes in Glycolysis?
hexokinase
phosphofructokinase
pyruvate kinase
pyruvate dehydrogenase
What are the Main Enzymes in TCA?
citrate synthase
isocitate dehydrogenase
a-ketoglutarate dehydrogenase
what is isocitrate dehydrogenase, activated and inhibited by?
activated by ADP
inhibited by ATP and NADH
what is a-ketoglutarate dehydrogenase inhibited by?
ATP, NADH, succinyl CoA
What is the purpose of the ETC?
to reoxidise the co-enzymes used in glycolysis and TCA by transferring electrons
Why cannot Electrons go Directly to the Electron Acceptors?
- too much energy is released at once
What happens at each Electron Transport Chain complex?
energy is used to push H+ across the inter membrane space, creating a gradient to the mitochondrial matrix
Define Redox Potential, What Happens if the Value is Higher?
the measure of the tendency of a redox pair to lose a pair of electrons.
- higher the positive value, higher the attraction to electron
What is the Order of Electron Transporters and Why?
- NADH-Q Reductase Complex
- Succinate Dehydrogenase Complex
- Cytochrome C Reductase Complex
- Cytochrome C Oxidase Complex
- increasing standard redox potential
describe what happens in ETC
1) a FMN molecule accepts electrons from NADH = NAD+
- electrons pass through Fe-S complexes
===== 4 H+ into inner membrane space
2) succinate binds to a binding site bound to a FAD
- accepts electrons
- electrons pass through 3 Fe-S complexes
- FAD2-FAD
All electrons go to coenzyme q
3) transfer electrons from CoQ to cytochrome C
===== 4+ into inner membrane space
4) contains 2 copper centres and 2 haem groups
- 1st cytochrome c releases electrons and reduces 1st copper centre
- this in turn, reduces the 2nd copper centre
- a 2nd cytochrome c releases electrons and reduces iron groups
== 2 reduced complexes
- iron binds to oxygen = peroxide iron
Fe-O-O
- a peroxide bridge forms between Fe-O-O-Cu
- a 3rd cytochrome c release electrons and cleave O-O w/ H+
- a 4th cytochrome c releases electrons and reduces Fe w/ H+
= oyxgen is the final electron acceptor
- uses 2 extra H+
- forms 2H20
What is the Final Electron Acceptor?
oxygen
