Chapter 6: Energy and Metabolism

Question 1

____________ are proteins or RNA molecules that act as catalysts to speed up reactions in living organisms.

Answer 1

Enzymes

Question 2

What is a substrate?

Answer 2

A reactant molecule that binds to the active site of an enzyme

Question 3

What are enzymes?

Answer 3

Proteins or RNA molecules that act as catalysts.

Question 4

Where does a substrate bind on an enzyme in order for a chemical reaction to take place?

Answer 4

Active site

Question 5

______________, or reactants, are molecules that bind to an enzyme at the active site and are converted to products in chemical reactions.

Answer 5

substrates

Question 6

What is produced by the binding of enzyme and substrate?

Answer 6

Enzyme-substrate complex

Question 7

Which of the following describes the active site of an enzyme?

Answer 7

It is the part of the enzyme where the substrate fits.

Question 8

When several enzymes that catalyze different steps of a sequence of reactions are associated with one another in a noncovalently bonded assembly, they form a(n)
complex.

Answer 8

multienzyme

Question 9

What is the optimal pH range for most human enzymes?

Answer 9

6 to 8

Question 10

Changes in pH affect an enzyme because the interaction of charged amino acid residues in the enzyme are affected by

Answer 10

hydrogen ion concentrations.

Question 11

What are competitive inhibitors?

Answer 11

competitive inhibitors?

Competitive inhibitors bind to the active site of an enzyme and prevent substrates from binding.

Question 12

The ____________ site is a specific region of an enzyme to which non-competitive inhibitors bind in order to regulate enzyme activity.

Answer 12

Allosteric

Question 13

___________ inhibitors bind to the active site of an enzyme and prevent the substrate from binding.

Answer 13

Competitive

Question 14

Temperature affects chemical reactions in the following way: increasing the temperature of an uncatalyzed reaction __________ the rate of that reaction.

Answer 14

increases

Question 15

__________ enzymes are enzymes that can exist in either an active or inactive conformation.

Answer 15

Allosteric

Question 16

How can the functioning of an enzyme be affected by the external environment?

Answer 16

Temperature and pH can greatly affect the function of some enzymes by causing denaturation.

Question 17

The optimum pH of most enzymes is 6 to ___.

Answer 17

8

Question 18

How can some enzymes function well at a very low pH?

Answer 18

They maintain their three dimensional shape even at a very low pH.

Question 19

__________ are small chemical components, usually inorganic ions, such as Zn2+, Cu2+, and Mn2+, that are often found in the active site participating directly in catalysis.

Answer 19

Cofactors

Question 20

What type of reactions are involved in the synthesis of larger molecules from smaller precursor molecules?

Answer 20

Anabolic

Question 21

Metabolic reactions are broken down into two main categories. Of those two main categories, what type of reactions are involved in the harvest of energy by breaking down larger molecules into smaller molecules?

Answer 21

Catabolic

Question 22

Heat is a measure of the random motion of molecules, a form of ___ energy.

Answer 22

Kinetic

Question 23

Work in the cell or in the physical world can only be done with expenditure of ___; it is defined as the capacity to do work.

Answer 23

Energy

Question 24

Cells use ____ hydrolysis to drive endergonic reactions

Answer 24

ATP

Question 25

A reaction that requires an input of energy is said to be a(n) ____ reaction

Answer 25

endergonic

Question 26

What occurs during a redox reaction?

Answer 26

When an atom or molecule is oxidized, the electron that is removed is transferred to another atom or molecule, which is thereby reduced.

Question 27

During a chemical reaction, which molecules become oxidized?

Answer 27

Molecules that have an electron removed.

Question 28

Chemical reactions are ___, which means that they can proceed in either direction (reactants to products to reactants)

Answer 28

Reversible

Question 29

ATP hydrolysis has a ______ ΔG

Answer 29

negative

Question 30

Which of the ATP’s phosphate bonds is hydrolyzed in most cellular reactions?

Answer 30

The outermost

Question 31

Select the three components of ATP

Answer 31

Adenine
Ribose
A chain of 3 phosphates

Question 32

Phosphate bonds in ATP are high energy bonds, because they are

Answer 32

unstable

Question 33

What cause the rate of some chemical reactions to be very slow?

Answer 33

Large activation energy

Question 34

______ energy is the energy required to destabilize existing chemical bonds and initiate a chemical reaction

Answer 34

activation

Question 35

Which characteristic of ATP is responsible for its high energy?

Answer 35

the repulsion of the negative phosphate groups

Question 36

What is the 1st law of thermodynomics?

Answer 36

Energy cannot be created or destroyed it can only change from one form to another

Question 37

What is the 2nd law of thermodynomics?

Answer 37

Energy cannot be transformed from one form to another with 100 % efficiency some energy is always unavailable

Question 38

Entropy

Answer 38

A measure of randomness or disorder of a system; measure of how much energy in a system has become so dispersed it is no longer available to do work