life @ cellular level - thermodynamics of life

Question 1

What is the 1st law of thermodynamics?

Answer 1

Energy can be converted from one form to another but the total energy of the universe remains constant.

Question 2

What is the 2nd law of thermodynamics?

Answer 2

All energy transformations ultimately lead to more disorder in the universe, i.e. increase the entropy

Question 3

Gibbs Free Energy is a useful, energy of a closed system, what 3 quantities can it be defined by?

Answer 3

Enthalpy (H) - heat/energy released to surroundings

-Entropy (S) - randomness/disorder

Absolute temperature (T)

G=H-TS

Question 4

Gibbs free energy can be used to define the spontaneity of a reaction, when do they occur?

Answer 4

if a system:

Gives up energy e.g. water runs downhill

Becomes more random and increases in entropy

Question 5

why does spontaneous energy changes have a negative value for their change in free energy?

Answer 5

A spontaneous process must decrease enthalpy (H) and/or increase entropy (S)

Question 6

what is reaction coupling?

Answer 6

it’s a strategy used by cells, in which an energetically favourable reaction is linked with an energetically unfavourable reaction

Question 7

what does ΔG = 0 mean?

Answer 7

the reaction is at an equilibrium which is incompatible with life.

Reactions usually do not reach equilibrium in our bodies as they are open systems i.e. energy passes from the environment to the organism and back to the environment.

Question 8

what is the dynamic steady state?

Answer 8

Where the rate of input/supply equals the rate of output/removal

Question 9

when does a system reach a Dynamic Steady State?

Answer 9

When a = b (equal reaction rates) the system is in a dynamic state because the intermediate molecule does not change concentration

Question 10

what is metabolism?

Answer 10

The chemical process in a living organism by which food is used for tissue growth

Question 11

what is catabolism and anabolism?

Answer 11

Catabolism is the breaking-down aspect of metabolism.

Anabolism is the building-up aspect of metabolism

Question 12

what is the form of energy harvested from catabolic pathways?

Answer 12

ATP

Question 13

what is the ATP energy harvested from catabolic pathways used in?

Answer 13

anabolic pathways to form complex molecules (proteins, DNA, Fatty acids.. etc.)

Question 14

what is metabolism catalysed by?

Answer 14

enzymes

Question 15

why do spontaneous reactions move toward equilibrium but do not reach it?

Answer 15

because the body is an open system where the products are used in subsequent reactions

Question 16

since spontaneous reactions aren’t instantaneous, what do they depend on?

Answer 16

the enzymes function by selectively altering the rate of metabolic reactions.

Question 17

what are intermediary metabolites?

Answer 17

The molecules that are used in link between catabolic and anabolic reaction pathways e.g. ATP, ADP, NADH, NAD+

Question 18

what is ATP hydrolysis?

Answer 18

a catabolic reaction used to release free energy

collected to do energetically unfavourable reactions (+ΔG)

Question 19

what is an exergonic process?

Answer 19

one in which there is a positive flow of energy from the system to the surroundings

Question 20

how does the exergonic, catabolic (break-down) pathway ‘save’ free energy?

Answer 20

within a system by forming ATP.

Question 21

what is an endergonic process?

Answer 21

is a reaction that requires energy to be driven e.g. photosynthesis

Question 22

how is the endergonic, anabolic (build-up) pathway ‘supplied’ with free energy?

Answer 22

within a system from converting ATP to ADP

Question 23

what reactions do ATP - ADP interconversions involve? and why?

Answer 23

ATP hydrolysis and ADP condensation

to ensure the flow of free energy between pathways

Question 24

What’s the difference between ADP Condensation and ATP Hydrolysis thermodynamically?

Answer 24

ATP has a higher potential energy than ADP/Pi

ATP Hydrolysis occurs with a decrease in Free Energy, it is catabolic/exergonic.

Question 25

describe an intermediate process in glucose metabolism (phosphoenolpyruvate):

Answer 25

Phosphoenolpyruvate (PEP) is converted to pyruvate

releases potential energy which is stored in the form of ATP by an ADP-ATP interconversion through phosphoryl transfers.

Question 26

what driving force is the ATP - ADP interconversions behind?

Answer 26

muscle contractions and membrane potentials which can store or release energy in the form of phosphoryl group transfer between molecules

Question 26

what do cellular redox reactions use?

Answer 26

Metabolic intermediaries as electron carrier molecules such as NAD+ and FAD+, act as coenzymes in metabolic pathways to facilitate fuel oxidation and biosynthesis reactions.