L9- Kreb and ETC

Question 1

excess G-6-P can..

Answer 1

feed into the pentose phosphate pathway to produce NADPH for biosynthesis and 5C sugars
- stored as glycogen

Question 2

both fructose and galactose can enter glycolysis via

Answer 2

some extra steps

Question 3

which stage does kreb cycle begin

Answer 3

stage 3

Question 4

at the end of glycolysis what are we left with

Answer 4

pyruvate (3C x 2)

Question 5

what happens to pyruvate once it has been formed during glycolysis

Answer 5

is transported from cytoplasm across mitochondrial membrane into the matrix

Question 6

which enzyme catalysis the combining of pyruvate + CoA +NAD+ to form Acetyl CoA

Answer 6

Pyruvate dehydrogenase (PDH)

Question 7

pyruvate –> acetylCoA

Answer 7

3C to 2C

Question 8

which cofactors does PDH require

Answer 8

FAD, thiamine pyrophosphate and lipoid acid- B-vitamins provide these factors

Question 9

PDH catalysing pyruvate –> acetyl CoA is a ………. reaction

Answer 9

irreversible- releases CO2

–> key regulatory step

Question 10

PDH is activated by

Answer 10

• Pyruvate
• NAD+
• ADP
• Insulin
• CoASH (coenzyme A- free SH group)
• Dephosphorylation

Question 11

PDH is inhibited by

Answer 11

• Acetyl-CoA
• NADH
• ATP
• Citrate
• Phosphorylation

Question 12

the TCA cycle is also known as

Answer 12

the kreb cycle

Question 13

kreb cycle is considered the

Answer 13

hub of metabolism

• sugars
• fatty acids
• ketone bodies
• amino acids
• alcohol

Question 14

where does the kreb cycle occur

Answer 14

in the mitochondrial matrix

Question 15

acetyl converted to

Answer 15

2CO2–> by breaking C-C bonds in acetyl CoA

Question 16

products of the kreb cycle

Glucose (6C) + 2 pyruvate (3C) + 2 acteyl CoA (2C) + TCA =

Answer 16

Products:

• 6NADH
• 2FAD2H
• 2GTP (ATP equivalent)

Question 17

kreb cycle is

Answer 17

oxidative and releases some energy (GTP)

Question 18

kreb cycle is regulate by

Answer 18

high and and low energy compounds (ATP/ADP and NADPH/NAD+ ratio)

Question 19

4 main step of kreb cycle

Answer 19

1. broken all C-C bonds
2. oxidised all the C-atoms to CO2
3. broken all the C-H bonds
4. Transferred all the H atoms (H+ and e-) to NADH + H and FADH2

Question 20

NADH and FADH produced in the kreb cycle are used to power

Answer 20

ATP synthesis in the ETC

Question 21

what sort of reaction is the kreb cycle

Answer 21

substrate level phosphorylation

Question 22

what is stage 4 of catabolism

Answer 22

the electron transport chain

Question 23

what sort of reaction is the electron transport chain

Answer 23

oxidative phosphorylation

Question 24

where does ETC occur

Answer 24

inner membrane of the mitochondria- cristae

Question 25

during the ETC what happens to NADH and FADH2

Answer 25

re-oxidised--> to form more NAD+ and FAD+ which can be re-used

Question 26

what is required during ETC

Answer 26

oxygen | - - Electrons transferred from NADH and FADH2 to molecular oxygen

Question 27

two processes occur in ETC

Answer 27

1. Electrons on NADH and FADH2 transferred through a series of carrier molecules to oxygens (Electron transport) 2. Free energy released used to drive ATP synthesis (Oxidative phosphorylation)

Question 28

describe how the ETC works

Answer 28

Electrons from NADH are passed onto an electron carrier PTC1, this drives Hydrogen atom from the matrix into the inner membrane. • Electrons are transferred through a series of carrier molecules (mostly within proteins) to oxygen with release of energy

Question 29

energy released during electrons transfer

Answer 29

1) 30% energy used to form proton gradient | 2) the rest used to release heat

Question 30

[H+] gradient across inner mitochondrial membraner

Answer 30

proton motive force

Question 31

return of protons is

Answer 31

faired energetically by electrochemical potential

Question 32

how do protons return from the inner membrane space to the mitochondrial matric

Answer 32

via ATP synthase

Question 33

when H+ flows through ATP synthase down proton gradient

Answer 33

ATP synthesis

Question 34

which reducing powerful has more energy : NADH or FAD2H

Answer 34

NADH - NADH use 3 PTCs - FADH2 uses 2 PTCs - Greater PMF more ATP synthesised

Question 35

when ATP is high and ADP what occurs to ATP synthase

Answer 35

no substrate to synthesise ATP --> inward flow of H_ stops | --> conc of H+ in intramitochondrial space increases preventing further H+ primping- stop ETC

Question 36

example of ETC inhibitors

Answer 36

Cyanide and carbon monoxide uncouplers

Question 37

ETC and Cyanide and carbon monoxide

Answer 37

- Blocks electron transport e.g. prevents acceptance of electrons by oxygen - No oxidative phos- no ATP

Question 38

ETC and uncouplers

Answer 38

- Increase permeability of the mitochondrial inner membrane to protons - Decreases proton gradient and therefore reducing proton motive force - No phosphorylation of ADP by ATP synthase

Question 39

Ox/Phos diseases

Answer 39

Genetic defects in proteins encoded by mtDNA (some subunits of the PTCs and ATP synthase)  decrease in ETC and ATP synthesis .

Question 40

brown adipose tissues contains a high conc of

Answer 40

thermogenin

Question 41

thermogenin

Answer 41

a UCP1 (uncoupling protein) --> naturally occurring uncoupling protein

Question 42

brown adipose tissue and its response to the cold

Answer 42

noradrenaline (norepinephrine) activates : 1. Lipase which releases fatty acids from Triacylglycerol 2. Fatty acid oxidation  NADH/FADH2  electron transport 3. Fatty acids activate UCP1 4. UCP1 transports H+ back into mitochondria 5. So, Electron Transport uncoupled from ATP Synthesis. 6. Energy of p.m.f. is then released as extra heat.

Question 43

family of UCPs

Answer 43

role in heat generation by uncoupling- may have other functions

Question 44

who has more brown adipose tissue

Answer 44

newborn infants and hibernating animals

Question 45

newborn infants

Answer 45

have lots of brown adipose around vital organs to maintain heat

Question 46

oxidative phosphorylation

Answer 46

- requires membrane associated complexes e.,g. inner mito membrane - cannot occur in absence of oxygen - major process for ATP synthesis in cells requiring large amount of energy

Question 47

substrate level phosphorylation

Answer 47

- requires soluble enzymes - can occur in absence of O2 - minor process for ATP synthesis inc ells requiring large amounts of energy

Question 48

summary of ATP synthesis from glucose

Answer 48

glucose --> pyruvate --> 6CO2 and 6H20 + 32 ATP