Intro To Metabolism

Question 1

How much oxygen is consumed per minute in a resting human?

Answer 1

350 ml

Question 2

How much can a human’s consumption of oxygen be increased per minute during exercise?

Answer 2

X5

Question 3

Why is oxygen required in humans?

Answer 3

To oxidise substrates - produces energy for body’s needs

Question 4

Definition of oxidation:

Answer 4

Addition of oxygen

Removal of electrons (and H+ ions)

Question 5

Definition of reduction:

Answer 5

Removal of oxygen

Addition of electrons (and H+ ions)

Question 6

What two limbs are involved in metabolism?

Answer 6

Catabolism and anabolism

Question 7

What is anabolism?

Answer 7

Large molecules built from smaller molecules

Requires energy

Question 8

What is catabolism?

Answer 8

Larger molecules broken down into smaller molecules

Releases energy

Question 9

What is energy released by catabolism used for?

Answer 9

To drive anabolism and other energy-requiring processes

Question 10

What is change in free energy?

Answer 10

When chemical reactions either absorb or release energy

Question 11

Change in free energy: symbol

Answer 11

ΔG

Question 12

When is there a change in free energy?

Answer 12

When a metabolite is converted into another

Question 13

Reaction to find ΔG:

Answer 13

[C][D]
ΔG = ΔG˚ + RT loge ———-
[A][B]

Question 14

What does ΔG stand for?

Answer 14

Free energy change

Reactants at concentration given

Question 15

What does ΔG˚ stand for?

Answer 15

Standard free energy change

All reactants at conc. 1 mol

Question 16

What does R stand for?

Answer 16

Gas constant

Question 17

What does T stand for?

Answer 17

Absolute temperature

298K

Question 18

What is ΔG at equilibrium?

Answer 18

0 as gross amount of A,B,C,D unchanged

Question 19

When is ΔG˚ measured?

Answer 19

When 1 mol of A,B,C,D are added together in standard conditions until equilibrium reached

Question 20

What happens if A,B,C,D concentrations are different to how they are in equilibrium?

Answer 20

ΔG changes inside cell

Question 21

What happens if ΔG is negative?

Answer 21

Spontaneous reaction

Reaction moves left -> right

Question 22

What happens if there is more product in reaction?

Answer 22

ΔG˚ is negative as reaction lies to right - more energy released

Question 23

When can a reaction only occur spontaneously?

Answer 23

If ΔG is negative

Question 24

What is meant by a spontaneous reaction?

Answer 24

No energy input

Question 25

Magnitude of ΔG?

Answer 25

Does NOT indicate rate of reaction

Question 26

Why doesn’t magnitude of ΔG indicate RofR?

Answer 26

As RofR depends on energy requires for reaction to occur Free energy of activation

Question 27

What does ΔG* stand for?

Answer 27

Free energy of activation Unrelated to ΔG

Question 28

Difference between ΔG and ΔG*:

Answer 28

ΔG = amount of energy in system that can do work ΔG* = energy needed for system to move from A+B to C+D

Question 29

What will a reaction normally involve the formation of?

Answer 29

Intermediate (transitional) state

Question 30

What’s required for formation of intermediate state?

Answer 30

Energy Slow RofR as need to get all reactant molecules up to transition state before products are formed

Question 31

What happens if catalyst is added to reaction?

Answer 31

Fast reaction Reduces transition state of energy ΔG* much lower

Question 32

Why does a catalyst lower transition state of energy?

Answer 32

Provides substrate to allow reactants to come together at lower energy states

Question 33

When can a sequence of coupled reactions take place without energy input?

Answer 33

When there is an overall negative change in ΔG between starting materials and final products

Question 34

Coupled sequences: individual reactions with positive free energy change:

Answer 34

Can be driven by those with negative free energy change

Question 35

Why is ATP formed?

Answer 35

To allow energy-requiring processes to occur

Question 36

How is ATP formed?

Answer 36

Energy released during catabolism is stored in a usable form

Question 37

Inorganic phosphate:

Answer 37

PO4(3-) Or Pi

Question 38

What can Phosphate groups sometimes shown as?

Answer 38

-P to make structures look simpler

Question 39

What’s phosphorylation?

Answer 39

Adding phosphate group to molecules (converts ADP to ATP)

Question 40

Hydrolysis of ATP:

Answer 40

Broken down into ADP and Pi Releases energy

Question 41

Approx. Amount of energy released in hydrolysis of ATP?

Answer 41

-7 to -12 kcal/mol (reaction lies to right)

Question 42

What are ATP, ADP and AMP like under appropriate conditions?

Answer 42

Interconvertible

Question 43

What is hydrolysis of ATP used to drive?

Answer 43

Energy-requiring processes

Question 44

What else can ATP be formed from?

Answer 44

When fuel molecules are oxidised

Question 45

What nucleotides can serve a similar role to ADP and ATP?

Answer 45

Guanosine diphosphate (GDP) and guanosine triphosphate (GTP)

Question 46

How much ATP does a resting human consume in 24hrs?

Answer 46

Approx 50kg

Question 47

What is ATP needed for?

Answer 47

Body movement Neuronal activity Cellular movements Active transport Synthesis of large molecules

Question 48

How many stages in ATP generation?

Answer 48

3

Question 49

Stage 1 of ATP generation?

Answer 49

Fats, polysaccharides and proteins broken down into monomers and absorbed into gut

Question 50

Stage 2 of ATP generation:

Answer 50

Monomers processed into AcetylCoA - used in citric-acid cycle

Question 51

Stage 3 of ATP generation:

Answer 51

AcetylCoA broken down in stages Movement of electrons to oxygen - produces ATP

Question 52

What can effect activity of key enzymes?

Answer 52

Allosteric changes Effects of substrate and downstream products Covalent modification of enzymes (e.g. phosphorylation)