Energy & Molecular Interactions

Question 1

What is Energy?

Answer 1

ability to do work or cause change

Question 2

What is Bioenergetics?

Answer 2

the study of energy in living organisms

Question 3

What is Kinetic Energy?

Answer 3

energy of motion

Question 4

What is Potential Energy?

Answer 4

stored energy

Question 5

The First and Second Law of Thermodynamics

Answer 5

1st Law: Energy is neither created or destroyed. It is only transferrable or convertible.
2nd Law: The entropy of a system is increased. (hotter object to a cold object) –> to increase randomness and disorder

Question 6

What is Gibbs Free Energy?

Answer 6

It’s “available” energy which is used to do work or capture chemical bonds

Question 7

What variables affect Gibbs Free Energy?

Answer 7

Enthalpy (total energy of a closed system)
Entropy (order of system)
Temperature

Question 8

Endergonic Reaction

Answer 8

it is a required investment of energy –> a non spontaneous reaction or anabolic –> Positive G

Question 9

Exergonic Reaction

Answer 9

a release of energy –> a spontaneous reaction or catabolic –> Negative G

Question 10

How does a catalyst increase the rate of a chemical reaction?

Answer 10

by lowering the activation energy

Question 11

Ligand

Answer 11

A substrate (or small molecules that bind)

Question 12

Substrate

Answer 12

a reactant

Question 13

Define Induced Fit

Answer 13

When the active sites changes its shape for the substrates to fit/bind

Question 14

What is Specificity?

Answer 14

when substrate(s) bind to a specific target
High Specificity: One other molecule
Low: Many other molecules

Question 15

What is Affinity?

Answer 15

the tightness/measure of strength in which a substrate binds to an enzyme or other types of proteins
- the binding is reversible

Question 16

What is Potency?

Answer 16

the amount of substrate needed to produce a certain effect.
- for example, EC50, can be used to compare the POTENCY of substrates that reach 50% of the maximum response better.

Question 17

What is Efficacy?

Answer 17

the capacity in which the response from a substrate can produce. (Maximum effect)

Question 18

What is Kd?

Answer 18

it is used to compare affinities

Question 19

What is Vmax?

Answer 19

The rate of product when enzyme become saturated by substrate

Question 20

What is EC50?

Answer 20

a concentration of substrate where enzyme reaches 50% Vmax.
- compares potency of substrate

Question 21

What is Saturation?

Answer 21

It is the point of no change in chemical reaction even after adding additional substrates.

Question 22

Define Competitive Antagonist

Answer 22

prevent AGONISTS from binding –> physically blocking the binding site

Question 23

Define Cofactor

Answer 23

metal ions –> help form the active site through a conformational change of the enzyme or help in enzyme-substrate binding.

Question 24

Define Coenzyme

Answer 24

organic molecules derived from water-soluble vitamins –> transport hydrogen atoms and other small molecules between enzymes

Question 25

Define Allosteric Antagonist

Answer 25

“inhibitors” that attach to the allosteric site of the enzyme/protein, and alter the shape of the binding site to NOT allow a substrate to bind to the enzyme.

Question 26

Define Allosteric Agonist

Answer 26

“activators” that attach to the allosteric site of the enzyme, and alter the active site for the substrate to fit and bind –> enhance function.

Question 27

How do cells regulate protein activity?

Answer 27

• Temp. and pH
• Concentration of cofactors, coenzymes, and enzymes
• Covalent modification of the protein
• Location of the enzyme
• Allosteric Antagonists and allosteric agonists

Question 28

Define Phosphorylation

Question 29

Define Kinase

Answer 29

attach a phosphate to a protein

Question 30

Define dephosphorylation

Question 31

Define Phosphatase

Answer 31

remove a phosphate from a protein

Question 32

Define Proteolysis

Question 33

Explain how and why temperature and pH can affect protein function.

Answer 33

The optimal temperature is 37 degrees celcius
The optimal pH is 7.4
- Ex. immune system works better at a slightly higher temperature, if too much, protein denatures.
- ex. Digestive enzymes work best at differing pH, it can be reversible, but if it’s obscure, then it becomes irreversible

Prevents protein from denaturing