Chapter 1 - Bioenergetics

Question 1

The conversion of mass into energy results in a large increase of what?

Answer 1

Disorder

Question 2

The energy needs of all organisms are provided either directly or indirectly by what?

Answer 2

The sun

Question 3

Any spontaneous chemical or physical change is always accompanied by an increase of what?

Answer 3

Disorder

Question 4

The second law of thermodynamics states that all natural processes result in an increase of

Answer 4

disorder or entropy

Question 5

The chemistry of life is done mostly by these 6 elements

Answer 5

Carbon
Hydrogen
Oxygen
Nitrogen
Sulfur
Phosphorus

Question 6

What is the most electronegative element in biological systems?

Answer 6

Oxygen

Question 7

What is free energy (G)?

Answer 7

The amount of energy capable of doing work in a reaction.

Question 8

What is an exergonic reaction?

Answer 8

An exergonic reaction is one that releases free energy. Delta G is negative.

Question 9

What is an endergonic reaction?

Answer 9

An endergonic reaction is one that absorbs free energy. Delta G is positive.

Question 10

What is Enthalpy (H)?

Answer 10

Enthalpy is the heat content of a reaction.

Question 11

What is an exothermic reaction?

Answer 11

A reaction that releases heat during it. Delta H is negative.

Question 12

What is an endothermic reaction?

Answer 12

A reaction that absorbs heat during it. Delta H is positive.

Question 13

What is Entropy (S)?

Answer 13

A quantitative expression for the randomness or disorder in a system. There is always an increase of entropy in any reaction.
Delta S is always positive.

Question 14

What is an isothermal system?

Answer 14

A system that works in constant temperature and pressure. Example: Cells.
They can only use free energy to do work.

Question 15

The process of turning free energy into ATP or other energy-rich compounds is known as…

Answer 15

Catabolism

Question 16

The process of breaking down energy-rich compounds to synthesize other various compounds is called…

Answer 16

Anabolism

Question 17

Are standard free energy changes additive?

Answer 17

Yes (see slide 26, Chp 1, for example)

Question 18

What are the 4 reasons for the basis of high energy of hydrolysis of ATP?

Or

Why is ATP so desperate to be Hydrolized

Answer 18

1. Resonance stabilization products
2. Electrostatic repulsion between negatively charged Oxygen atoms in ATP
3. High solvation energy of products
4. Protons produced by hydrolysis of ATP are diluted ten-thousand fold immediately after being produced

Question 19

Is the hydrolysis of ATP an exergonic or endergonic reaction?

Answer 19

Exergonic. It releases energy

Question 20

What is the oxidizing ability of atoms?

Answer 20

The capacity ot ability to accept electrons. (based on electronegativity - the more electronegative, the higher oxidizing ability)

Question 21

What are the 4 ways in which an electron can be transferred from one molecule to another?

Answer 21

1. Direct electron transfer (Ionic reaction)
2. As a hydrogen atom
3. As a hydride ion (in the case of NAD-linked Hydrogenases)
4. Through direct combination with oxygen: covalent incorporation of Oxygen into organic molecule.

Question 22

What is oxidation referred to as in biological systems?

Answer 22

Dehydrogenation

Question 23

What is Standard Reduction Potential (E^o)?

Answer 23

The electric potential generated by a redox reaction against a hydrogen electrode.
AKA the ability to get reduced (gain electrons)

Question 24

NADH and NADPH are what kind of electron carriers that act with dehydrogenases?

Answer 24

soluble

Question 25

What are the 4 truths of metabolic pathways?

Answer 25

1. Metabolic pathways are irreversible.
2. Every path has a committed step
3. Metabolic pathways are regulated
4. Some metabolic pathways are compartmentalized