Energy Reactions In Cells

Question 1

Metabolism

Answer 1

The set of processes which derive energy and raw materials from food stuffs and use them to support repair, growth and activity of tissues of the body to sustain life.

Question 2

Catabolic pathways

Answer 2

Break down larger molecules into smaller ones.

Release large amounts of energy.
Oxidative - release H atoms.

Question 3

Anabolic pathways

Answer 3

Synthesise larger important cellular components.

Use energy released from catabolism (ATP).
Reductive - uses H atoms

Question 4

Energy in metabolism?

Answer 4

Chemical bond energy

Question 5

Exergonic

Answer 5

Releases energy

Question 6

Endergonic

Answer 6

Requires energy

Question 7

Gibbs free energy of exergonic reactions

Answer 7

Gibbs free energy < 0

Energy of reactants > energy of products

Question 8

Gibbs free energy of endergonic reactions

Answer 8

Gibbs free energy > 0

Energy of reactants < energy of products

Question 9

H-carrier molecules

Answer 9

Coenzymes that act as carriers of reducing power (H atoms).

Question 10

Adenylate kinase

Answer 10

Switched on when ATP levels are dropping; catalyses 2ADP -> ATP + AMP.

Question 11

High energy signals

Answer 11

ATP
NADH
NADPH
FAD2H

• these activate anabolic pathways

Question 12

Low energy signals

Answer 12

ADP
AMP
NAD+
NADP+
FAD

• these activate catabolic pathways

Question 13

What regulates gene expression, changing anabolic processes to catabolic pathways?

Answer 13

AMP dependent kinase

Activated by AMP (and ADP).

Question 14

Creatine phosphate

Answer 14

Used as a reserve of high energy stores.

It is formed when ATP concentrations are high, and the reaction is reversed when ATP levels fall, providing a short term boost to ATP conc.

Question 15

Creatine phosphate reaction

Answer 15

Creatine + ATP <—> Creatine phosphate + ADP

Catalysed by creatine kinase

Question 16

Creatine kinase

Answer 16

Enzyme that catalyses formation of creatine phosphate.

Used as a marker for muscle damage eg cardiac muscle damage in MI. However it is not very specific, so cardiac specific trope in tests are preferred.

Can still be used for suspected muscle injury or unexplained muscle weakness (myopathy).

Question 17

Isoforms on CK

Answer 17

3 combos possible, as CK is made of two subunits, M and B.

• MM, BB and MB

CK-MB is used as a marker for muscle damage.

Question 18

Creatinine

Answer 18

Breakdown product of creatine and creatine phosphate.

Usually produced at a constant rate, unless the muscle is wasting.

It is excreted via kidneys, so can be used to assess kidney function.

Conc. in urine is marker of urine dilution.