Lecture 26- ATP production & oxidative phosphorylation Flashcards

1
Q

What is metabolism?

A

Living systems acquire & use free energy in order to carry out their functions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

2 divides of metabolism

A

Catabolic
Anabolic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Catabolic metabolism

A

The degradation of nutrients to salvage components & gain energy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Anabolic metabolism

A

The synthesis of biomolecules for simpler components

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Autotrophs

A

Synthesis all cellular components from simple molecules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Photoautotrophs

A

Use light to produce carbohydrates which are oxidised giving free energy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Chemolithotrophs

A

Obtain free energy from compound oxidation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Heterotrophs

A

Oxidise carbohydrates, lipids and proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Classification of oxidising agents

A

Obligate aerobes- require O₂
Anaerobes- use sulphate or nitrate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Vitamins

A

Organic molecules obtained from diet
Water soluble (coenzyme precursors)
Fat soluble (required in diet eg. vitamin C)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Degradative pathways

A

Often converge on common intermediates
Further metabolised in central oxidadative pathway

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Biosynthetic pathways

A

Carry out the opposite
Few metabolites are the starting points

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Metabolic roles of liver (learn overview)

A

Metabolism of carbohydrate, lipid, amino acids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Metabolic roles of muscle (learn overview)

A

ATP production for muscle contraction
use glycogen, glucose, fatty acids an ketone bodies as fuel

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Metabolic roles of brain (learn overview)

A

Nerve transmission (high ATP requirement)
Use glucose and ketone bodies as fuels not fatty acids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Metabolic roles of adipose (learn overview)

A

Fat synthesis & storage

17
Q

-ve ΔG= ….
ΔG=0 = ….
+ve ΔG= …

A

-ve ΔG= favourable
ΔG=0 = equilibrium
+ve ΔG= unfavourable- usually require input of ATP

18
Q

Forms of cellular energy curency

A

Thioester bond-containing compounds
Reduced coenzymes
ATP

19
Q

NAD+ accepts … electron(s) and … proton(s)

A

2 (donated to ETC)
1

20
Q

FAD+ accepts … electron(s) and … proton(s)

A

2 (donated to ETC)
2

21
Q

ATP as an energy carrier

A

Biological importance depends on the free energy change that accompanies cleavage of phosphoanhydride bonds
Standard free energy of hydrolysis is -7.3 kcal/mol
Reactions with large +ve ΔG are possible by coupling with 2nd process with large -ve ΔG

22
Q

Substrate level phosphorylation

A

Direct addition of phosphate group to ADP to form ATP

23
Q

Oxidative phosphorylation

A

Energy-rich molecules are metabolised by oxidative reactions
Metabolic intermediates donate electrons to NAD+ & FAD to form NADH + H+ and FADH₂
As e- passes down ETC, they lose free energy- used to pump H+ across inner mitochondrial membrane -> H+ gradient which drives ATP synthesis from ADP + Pi

24
Q

ETC loaction

A

Inner mitochondrial membrane
impermeable so requires specialised transport systems
Highly convoluted crisae increase surface area
Mitochondrial matrix contains enzymes responsible for oxidation

25
Organisation of ETC
IMM contains 5 separate protein complexes and 2 mobile electron carriers Ultimately electrons combine with O₂ to form H₂O
26
Complex I
At least 34 polypeptides NADH binds to Complex I and electrons transferred to CoQ Electron's energy loss is used to pump 4H+ across the membrane
27
Complex II
Enzyme of TCA cycle-succinate dehydrogenase Accept electrons from FADH₂ Transfers electrons to CoQ vis Fe-S proteins No energy is lost so no protons are pumped at Complex II
28
Coenzyme Q
Small lipid molecule- hydrophobic quinone Diffuses rapidly with IMM Accept electrons from FE-S proteins from Complex I and Complex II
29
Complex III & Cyt c
Both cytochrome proteins Cut C is peripheral protein Electrons transferred from Complex III to Cut C to Complex IV At Complex III energy loss is used to pump 4 H+ across inner membrane
30
Complex IV
The only electron carrier in which the heme iron has co-ordination site for O₂ Transfers pair of electrons to 1/2 O₂ which is reduce to form H₂O 2 protons pumped across IMM
31
Why are electrons transferred?
The transfer of electrons does the ETC is energetically favourable NADH is a strong electron donor O₂ is a strong electron acceptor
32
Chemiosmotic hypothesis
Proton pumping across the IMM creates a H+ gradient Drives ATP synthesis via ATP synthase
33
ATP synthase
Protons pumped to the cytosolic side of mitochondrial membrane re-enter the matrix by passing through F₀ proton channel As protons pass down channel they drive the rotation of the C ring of F₀ which causes conformational change in beta subunit of F₁ domain
34
ATP yield of oxidative phosphorylation
Every pair of electrons from NADH- 2.5 ATP generated Every pair of electrons from FADH₂- 1.5 ATP generated So, from one glucose molecule 30 ATP generated by oxidative phosphorylation
35
P/O ratio
Number of ATP molecules formed per oxygen atom
36
Inhibitors of electron transport chain
Prevent the passage of electrons down ETC and so prevent H+ being pumped across IMM Inhibit ATP synthesis
37
Uncouplers of ETC & ATP synthesis
Chemicals- dinitrophenol Natural proteins- uncoupling protein (UCPs)
38
Other final electron acceptors
Allow organisms to live in anaerobic conditions eg. NO₃ which forms NO₂, N₂O or N₂ SO₄ which forms S or H₂S CO₂ which forms CH₄ (methanogenesis)