'Entropy' and 'Free Energy' in Metabolism

Question 1

What is the relation between cellular respiration and photosynthesis reactions?

Answer 1

• They are coexistent and are ultimately dependent on each other

Question 2

What are most metabolic reactions?

Answer 2

• Exothermic and exergonic
• They rely on enzyme action

Question 3

What are less common metabolic reactions?

Answer 3

• Endothermic and endergonic
• They require energy to be driven forward

Question 4

Free Energy Exchanges

Answer 4

• Cells constantly carry out thousands of exergonic and endergonic reactions
• Sometimes the free energy produced by an exergonic reaction can help drive an endergonic reaction forward

Question 5

Energy Coupling

Answer 5

Process when exergonic reactions are used to drive endergonic reactions

Question 6

Coupled Reactions

Answer 6

• Reactions where an energetically favourable (spontaneous) reaction is able to drive an energetically unfavourable reaction forward
• Reactions involved in energy coupling

Question 7

Coupled Reaction Formulas

Answer 7

1. A –> B + C
2. D + E –> F

Question 8

In biological reactions what molecule helps in the process of coupling?

Answer 8

ATP!!

Question 9

What is ATP?

Answer 9

• Stands for: Adenosine triphosphate
• Primary source of energy for endothermic reactions to occur in cells

Question 10

What is ATP made up of?

Answer 10

• Adenine
• Ribose sugar
• 3 phosphates

Question 11

What is inorganic phosphate?

Answer 11

• Phosphate group that has no attached carbons

Question 12

Formula of the hydrolysis of ATP

Answer 12

ATP + H2O –> ADP + Inorganic Phosphate

Question 13

In order for cells to function…

Answer 13

• They must regenerate ATP molecules
• This is done by coupling ATP and ADP molecules

Question 14

What does Pi represent?

Answer 14

Inorganic phosphate

Question 15

ATPase

Answer 15

• An enzyme that hydrolyzes the last phosphate and removes it from ATP when the cells require Gibbs free energy to work

Question 16

Phosphorylation

Answer 16

• The addition of inorganic phosphate to a molecule
• Phosphorylated molecules are more reactive

Question 17

What cells possess more ATP molecules?

Answer 17

• Muscle cells
• Sperm cells
• Nerve cells

Question 18

Reduction-Oxidation

Answer 18

• When biochemical reactions involve the transferring of electrons from one molecule to another

Question 19

Reduction

Answer 19

• Process of gaining electrons
• Often in the form of hydrogen atoms

Question 20

Oxidation

Answer 20

• Process of losing electrons
• Hydrogen atoms in biological systems

Question 21

Memory Tool

Answer 21

LEO THE LION SAYS GER
Lose Electrons = Oxidation
Gain Electrons = Reduction

Question 22

Reducing Agent

Answer 22

• The substance that loses electrons
• ie. becomes oxidized

Question 23

Oxidizing Agent

Answer 23

• The substance that gains electrons
• ie. becomes reduced

Question 24

Example of a Reduction-Oxidation (REDOX) Reaction

Answer 24

• Burning or combustion reactions
• Cellular respiration is a slow, controlled redox reaction

Question 25

H+ implies...

Answer 25

- A proton - Is an ion

Question 26

H implies...

Answer 26

- An electron

Question 27

Coupled Redox Processes

Answer 27

- In some biochemical reactions a series of redox reactions occur where electrons are gained, lost, gained, lost etc...until the final product is reduced - Each successive oxidation agent possess a stronger pull for the electron than the previous one