Respiration

Question 1

define substrate level phosphorylation

Answer 1

the formation of ATP via direct phosphorylation of ADP

Question 2

when do you get substrate level phosphorylation? (3)

Answer 2

• 1,3-Bisphosphate to 3-Phosphoglycerate
• Phosphoenolpyruvate to Pyruvate
• from GDP to GTP

Question 3

Describe Structure of Mitochondria.

Answer 3

outer membrane
intermembrane space
inner membrane
matrix
cristae
mitochondria DNA
ribosomes
ATP synthase

Question 4

DRAW OUT GLYCOLYSIS, LINK REACTION AND TCA WITH MAIN ENZYMES

Question 5

Where does Glycolysis, Link Reaction, TCA cycle and Oxidative Phosphorylation Occur?

Answer 5

cytoplasm

3x Mitochondria

Question 6

What is the NET ATP of Aerobic Respiration?

Answer 6

Glycolysis = 2ATP
TCA = 2ATP
ETC = 28ATP

= 32ATP

Question 7

What is OIL RIG?

Answer 7

oxidation is loss of electrons
reduction is gain of electrons

Question 8

What are the 3 Main Carriers?

Answer 8

ATP - Phosphate
NADH,NADPH,FADH2 - electrons and hydrogens
Acetly CoA - acetyl group

Question 9

How is Energy Created under Anaerobic Conditions?

Answer 9

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

Question 10

What Happens if an Aerobic Respiration turns Anaerobic?

Answer 10

• shortage of oxygen
• TCA stops when it runs out of NAD and FAD
• leads to lactic acid fermentation

Question 11

Can other Sugars other than Glucose be Used?

Answer 11

Yes - galactose and fructose from adipose or liver

but efficiency is poor

Question 12

What are the 4 Types of Regulation Mechanisms for Enzymes in Metabolism?

Answer 12

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

Question 13

How is Hexokinase Regulated?

Answer 13

allosteric regulation
- if there is too much glucose being converted to G-6P
- gets inhibits
- glucose stores as glycogen

Question 14

How is Phosphofructokinase Regulated? (3)

Answer 14

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

Question 15

How is Pyruvate Kinase Regulated?

Answer 15

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

Question 16

How is Pyruvate Dehydrogenase Regulated?

Answer 16

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

Question 17

How is Isocitrate Dehydrogenase from TCA Regulated?

Answer 17

• inhibited by ATP and NADH
• activated by ADP

Question 18

How is a-Ketoglutarate Dehydrogenase from TCA Regulated?

Answer 18

• inhibited by ATP, succinyl CoA and NADH

Question 19

What are the Main Enzymes in Glycolysis?

Answer 19

hexokinase
phosphofructokinase
pyruvate kinase
pyruvate dehydrogenase

Question 20

What are the Main Enzymes in TCA?

Answer 20

citrate synthase
isocitate dehydrogenase
a-ketoglutarate dehydrogenase

Question 21

what is isocitrate dehydrogenase, activated and inhibited by?

Answer 21

activated by ADP

inhibited by ATP and NADH

Question 22

what is a-ketoglutarate dehydrogenase inhibited by?

Answer 22

ATP, NADH, succinyl CoA

Question 23

What is the purpose of the ETC?

Answer 23

to reoxidise the co-enzymes used in glycolysis and TCA by transferring electrons

Question 24

Why cannot Electrons go Directly to the Electron Acceptors?

Answer 24

• too much energy is released at once

Question 25

What happens at each Electron Transport Chain complex?

Answer 25

energy is used to push H+ across the inter membrane space, creating a gradient to the mitochondrial matrix

Question 26

Define Redox Potential, What Happens if the Value is Higher?

Answer 26

the measure of the tendency of a redox pair to lose a pair of electrons.

• higher the positive value, higher the attraction to electron

Question 27

What is the Order of Electron Transporters and Why?

Answer 27

• NADH-Q Reductase Complex
• Succinate Dehydrogenase Complex
• Cytochrome C Reductase Complex
• Cytochrome C Oxidase Complex
• increasing standard redox potential

Question 28

describe what happens in ETC

Answer 28

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

Question 29

What is the Final Electron Acceptor?

Answer 29

oxygen