Bioenergetics

Question 1

Catabolism in the body breaks down energy containing nutrients such as carbohydrates, fats, and proteins into energy depleted end products. What are these end products?

Answer 1

CO2, H2O and NH3

Question 2

During catabolism, what energy-rich products are captured?

Answer 2

ATP, NADH, NADPH, FADH2

Question 3

Precursor molecules amino acids, sugars, fatty acids and nitrogenous bases create which cell macromolecules?

Answer 3

Proteins, polysaccharides, lipids, nucleic acids

Question 4

Radiant energy

Answer 4

A form of kinetic energy which is carried in photons from the sun, and is the ultimate source of all forms on energy in living systems.

Question 5

Thermal energy

Answer 5

A form a kinetic energy. Protein molecules function optimally at a particular temperature or need certain thermal energy to function.

Question 6

Mechanical energy

Answer 6

A form of kinetic energy. Movement of cells and cell componenets.

Question 7

Electric energy

Answer 7

A form of kinetic energy. Movement of charged particles down gradients of electric potential.

Question 8

Where are the four places where we see potential energy stored?

Answer 8

1. Stored in chemical bonds
2. Stored in concentration gradients
3. Stored in electric fields from charge separation
4. Stored in redox pairs

Question 9

First Law of Thermodynamics

Answer 9

Energy is neither created, nor destroyed. Energy can be converted into different from but it always conserved.

Question 10

Second Law of Thermodynamics

Answer 10

The entropy of the universe is always increasing. Energy is always flowing towards a more stable state, and this energy transfer can be used to carry out work. An example of this is heat transferring to a colder location.

Question 11

Negative ΔG indicates…

Answer 11

Negative ΔG indicates that a reaction is thermodynamically favorable and will occur spontaneously at a constant temperature.

Question 12

Positive ΔG indicates….

Answer 12

Positive ΔG indicates that a reaction is thermodynamically unfavorable and will not occur spontaneously as constant temperature.

Question 13

ΔH

Answer 13

H (products)-H (reactants); change in enthalpy or bond energy within a reaction

Question 14

In an exothermic reaction, ΔH is….

Answer 14

In an exothermic reaction, ΔH is negative and the favorable.

Question 15

In an endothermic reaction, ΔH is….

Answer 15

In an endothermic reaction, ΔH is positive and unfavorable.

Question 16

When disorder increases in a system, ΔS is….

Answer 16

When disorder increases in a system, ΔS is positive and favorable.

Question 17

When disorder decreases in a system, ΔS is….

Answer 17

When disorder decreases in a system, ΔS is negative and unfavorable.

Question 18

Enthalpy

Answer 18

Function of type of bonds, which we start with and which we end with. It is the amount of heat used or released in a system as constant pressure.

Question 19

If ΔG is negative, what direction does a reaction run?

Answer 19

From left to right, the more negative Gibbs free energy is, dictates how much of A+B=C+D

Question 20

Gibbs Free energy equation under standard conditions (also, what are they?).

Answer 20

ΔG = H - TΔS; 298K, 1 atm pressure, pH=7, 1M reactants

Question 21

What is the rate of the forward reaction proportional to?

Answer 21

The product of the concentration [A] and [B]; v(forward)=k(forward)[A][B]

Question 22

What is the rate of the backward reaction proportional to?

Answer 22

The product of the concentration of [C] and [D]; v(backward)=k(backward)[C][D]

Question 23

What is the equilibrium constant?

Answer 23

Keq=k(backward)/k(forward)= [C][D]/[A][B]

Question 24

If k>1 at equilibrium?

Answer 24

If K is greater than 1 at equilibrium, the reaction is favored.

Question 25

If k<1 t equilibrium?

Answer 25

If K is less than 1 at equilibrium, there is no free energy.

Question 26

Why might a thermodynamically favorable reaction not occur?

Answer 26

A thermodynamically favorable reaction may not occur because the rate of reaction is limited by high activation energy. For example, the combustion of glucose.

Question 27

What are the two classes of high energy bonds we need to know?

Answer 27

1. Thioester bonds (C-S)

2. Phosphate bonds

Question 28

Thioester bonds and how energy is released.

Answer 28

Thioester bonds in acetyl coA, are used as an energy source within cells. When fuel is broken down within our bodies, it is converted into a simple two carbon unit with the thioester bond, acetyl coA. The bond is broken through hydrolysis and the reaction is spontaneous.

Question 29

Phosphate bonds/ ATP and how energy is released.

Answer 29

ATP is the universal energy currency; Energy is released by hydrolysis of the two high energy phosphoanhydride bonds in ATP. Nucelophilic attack can occur at 3 positions on ATP.

Question 30

Reduction Potential (E)

Answer 30

Reduction potential (E) is a measure of the readiness with which an atom or molecule accepts an electron relative to H+

Question 31

Positive E means….

Answer 31

The more positive the value of E, the more a molecule like to accept electrons.

Question 32

Negative E means…

Answer 32

The more negative the value of E, the more a molecules like the donate electrons

Question 33

What is the major source of electrons in cells?

Answer 33

Glucose

Question 34

What is the final electron acceptors in cells?

Answer 34

O2

Question 35

How is ATP made within the cell?

Answer 35

ATP is made by harnessing the energy in gradients of H+ concentration and electrical potential across the inner membrane of the mitochondrion.

Question 36

What is mitochondrial ATPase?

Answer 36

A mechanical device that converts the energy of the proton gradient to high energy phosphate bonds by rotational catalysis.

Question 37

What is a redox reaction?

Answer 37

All chemical reactions in which atoms have their oxidation state changed.Redox reactions involve the transfer of electrons.