CHAPTER 6

Is an exergonic reaction spontaneous or non-spontaneous?

Spontaneous

In an exergonic reaction, are the reactants favored or are the products favored to form?

Products

In an exergonic reaction, will heat energy be absorbed or released into the environment?

release heat

In an exergonic reaction, will the ΔG be positive or negative?

negative

How would an enzyme affect the rate of an exergonic reaction; (increase or decrease) the rate?

increase

A reaction has a ΔG = +3.3 kcal/mol; what can you predict about this reaction?

Endergonic

non-spontaneous

reactants favored

all energy absorbed

When chemical bonds between atoms are formed, will energy need to be added or released?

released

How are chemical bonds between atoms broken; will energy need to be added or released to break a bond?

added

The strength at which a chemical bond holds two atoms together is referred to as

bond strength

The energy required to break a bond is referred to as

bond energy

What type of energy is stored between the atoms of covalent bonds?

chemical potential energy

Name two forms of energy that are important to Biology?

light and heat energy

What does it mean when a reaction has met chemical equilibrium?

when the rate of the formation of the products is the same as the rate of the formation of the reactants

What is an oxidation reaction between atoms?

redox reaction:

when one atom loses an electron

What is a reduction reaction between atoms?

redox reaction:

when one atom gains an electron

In the following reaction, has Sodium been oxidized or reduced? Has Chlorine been oxidized or reduced?

NA: oxidizes

CL: reduced

Organic molecules are broken down when they are no longer needed, what is this process called?

Catabolism

Organic molecules are only synthesized from smaller precursor molecule when they are needed, what is this process called?

Anabolism

Competitive Enzyme Inhibitor

will mimic a substrate and will “race” for the active site of an enzyme.  If the competitive inhibitor gets to the active site of the enzyme first, then the substrate cannot bind.  The competitive inhibitor will “fit” into the active site of the enzyme, but no product will be produced.

Non-Competitive Enzyme Inhibitor

will bind to an allosteric site on the enzyme, and once it binds, the active site of the enzyme will be changed, and the substrate will not fit into the active site.

What are the characteristics of an enzyme?

Catalyst Protein that speeds up chemical reactions

What are the steps of the catalytic cycle of an enzyme?

1. Active Site Empty
2. Active Site
3. Induce Fit
4. Reaction with product formation
5. Release of products
6. Active site empty again

In a catalytic reaction: Is the enzyme used up in the reaction?

NO

In a catalytic reaction: Does the enzyme become part of the reaction?

NO

In a catalytic reaction: Does the enzyme become part of the products?

NO

In a catalytic reaction: Does the enzyme add energy to the reaction?

NO

In a catalytic reaction: Can an enzyme react with many different substrates?

??????yes

In a catalytic reaction: Can an enzyme be denatured? If so, what type of factors will denature them?

Yes! Temperature and pH

Some enzymes work optimally with a cofactor; give an example of a cofactor.

Zinc, Iron, Vitamin B12, Vitamin B6

In a catalytic reaction: Some enzymes work better if they have a “side kick” such as B12 or Zinc; what are these called?

??????Cofactors

What does the First Law of Thermodynamics state about energy?

energy cannot be created or destroyed it can only be converted from one form to another

What does the Second Law of Thermodynamics state about the entropy (disorder) of a system as a result of an energy conversion; is entropy increased or decreased?

in an energy conversion entropy will always be increased

What is a coupled reaction?

when an endergonic reaction combines with an exergonic reaction (or uses the energy from an exergonic reaction) to drive both reactions forward to spontaneously produce product