Intro to thermodynamics

Question 1

What is metabolism?

Answer 1

The net coordinated enzyme catalysed chemical reactions within an organism.

Question 2

What do energetics dictate?

Answer 2

Dictates the rates and equilibrium positions of reaction.

Dictates how bonds are made and broken.

Question 3

What is chemical energy?

Answer 3

The energy ‘locked up’ in molecules
Forming bonds releases energy
Breaking bonds uses energy

Question 4

Three system types

Answer 4

Isolated system - no exchange or matter or energy
Closed system - Exchange of energy but not matter
Open System - Energy and matter is exchanged

Question 5

1st Law of Thermodynamics

Answer 5

The law of conservation of energy.
Energy can’t be created or destroyed, just transformed.
In an isolated system the energy will remain constant.

Question 6

Entropy

Answer 6

(S)
Measure of disorder in a system.
Energy is required to put order in place.

Question 7

Enthalpy

Answer 7

(H)
Heat content of a system
Energy can be added to a closed system by heat or work.

Question 8

Exothermic Reaction

Answer 8

Reactants start higher than products -ve delta G

Question 9

Endothermic Reaction

Answer 9

Reactants start lower than products +ve delta G

Question 10

Hess’s Law

Answer 10

The total change in enthalpy to go from initial to the final state is independent of the path taken.

Question 11

2nd Law of thermodynamics

Answer 11

When energy is converted from one form to another, some of the energy becomes unavailable to do work.

Question 12

Gibbs Free energy

Answer 12

(G)
The net available energy of a reaction
delta G = delta H - T x delta S

Question 13

Exergonic Reaction

Answer 13

Delta G is negative
Reaction releases energy into the environment
Can occur spontaneously
Reactants start higher than products

Question 14

Endergonic Reaction

Answer 14

Delta G is positive
Reaction requires free energy to proceed
If energy not provided then the reaction will not occur.

Question 15

Delta G0’

Answer 15

Free energy under ‘standard biological conditions’

Question 16

Standard biological conditions

Answer 16

All reactants and products are at an initial concentration of 1 mol.
Pressure of 1.0 atm
Temperature at 25 degrees
pH 7

Question 17

Equation for delta G

Answer 17

Delta G = Delta G0’ - RT ln (B)/(A)

Question 18

How to ensure the reaction goes the way we want - -ve delta G

Answer 18

Alter concentrations so delta G becomes negative

Couple the reaction with a positive delta G value to one with a negative delta G, so the overall is negative delta G.

Question 19

Example of a coupled reaction to make delta G negative

Answer 19

1st reaction in glycolysis:
Glucose + phosphate –> glucose 6 phosphate
the delta G is positive

Coupled reaction:
Glucose + ATP –> Glucose 6 phosphate + ADP
the delta G is negative

Question 20

What is ATP made up of

Answer 20

Nucleotide, sugar and phospate

Question 21

4 examples of nucleosides

Answer 21

Cytodine - used for lipid biosynthesis
Uridine - used for glycogen biosynthesis
Adenosine - used as energy carrier
Guanosine - used for transmembrane signalling

Question 22

How much ATP does the body require per day and how many times is it recycled in a day?

Answer 22

Requires 100-150 moles of ATP daily

Recycled 500-750 times in a single day

Question 23

Cellular functions of ATP

Answer 23

Ion Pumping
Protein Synthesis
Cell Replication
Muscle Contraction

Question 24

What happens with ATP in sugar metabolism

Answer 24

Energy is used to make ATP which releases energy for endergonic processes.

Question 25

Free energy varies:

Answer 25

from one cell to another
within the cell when conditions vary
from compartment to compartment within the cell

Question 26

Why is ATP such a universal currency of free energy?

Answer 26

Delta G of ATP to ADP is large enough to drive many reactions but small enough that ATP can be synthesised by nutrients.
ATP is relitively stable in aqueous solution.