Chapter 6

Question 1

Bioenergetics

Answer 1

The study of how energy flows through living organisms

Question 2

Energy

Answer 2

The capacity to do work and cause change

Question 3

Three kinds of energy

Answer 3

1. Kinetic energy
2. Potential energy
3. Chemical energy

Question 4

Kinetic energy

Answer 4

The energy of motion

Performs work by transferring motion to other matter

Question 5

Thermal energy

Answer 5

Heat, or thermal energy, is kinetic energy associated with the random movement of atoms

Question 6

Potential energy

Answer 6

Stored energy

The ability to change into another kind of energy to do work or cause a change

Question 7

Chemical energy

Answer 7

The energy in molecular bonds

A form of potential energy

Question 8

Thermodynamics

Answer 8

Study of energy transformations

Question 9

First law of thermodynamics

Answer 9

The energy of the universe is constant. Energy/matter can be transferred and transformed, but it cannot be created or destroyed.

Question 10

Second law of thermodynamics

Answer 10

Every energy transfer or transformation increases the entropy (disorder/randomness) of the universe. Ordered forms of energy are at least partly converted to heat.

Question 11

Breakdown of glucose results in loss of ___________ and an increase in _________

Answer 11

potential energy, entropy

Question 12

Exergonic reaction

Answer 12

A chemical reaction that releases energy

Question 13

Endergonic reaction

Answer 13

Requires an input of energy and yields products rich in potential energy

Question 14

Metabolism

Answer 14

The thousands of endergonic and exergonic chemical reactions produced in an organism.

Question 15

Metabolic pathway

Answer 15

A series of chemical reactions that either break down a complex molecule or build up a complex molecule.

Question 16

A cell does 3 main types of cellular work

Answer 16

1. Chemical work
2. Transport work
3. Mechanical work

Question 17

Energy coupling

Answer 17

To accomplish work, a cell must manage its energy resources, and it does so by energy coupling—the use of exergonic processes to drive an endergonic one.

Question 18

ATP (adenosine triphosphate)

Answer 18

ATP is the energy currency of cells

ATP is the immediate source of energy that powers most forms of cellular work.

It is composed of adenine (a nitrogenous base), ribose (a five-carbon sugar), and three phosphate groups.

Question 19

Phosphorylation

Answer 19

The transfer of an ATP molecule’s third phosphate from ATP to some other molecule.

In this process, ATP energizes molecules.

Question 20

Energy of activation

Answer 20

Although there is a lot of potential energy in biological molecules, such as carbohydrates and others, it is not released spontaneously.

Energy must be available to break bonds and form new ones. This energy is called energy of activation.

Enzymes speed up the rate of the reaction by lowering energy of activation, and they are not used up in the process.

Question 21

Enzymes

Answer 21

Enzymes are proteins that speed up the cell’s chemical reactions by lowering energy barriers. They function as biological catalysts.

Question 22

Catalysis

Answer 22

A cell uses catalysis to drive (speed up) biological reactions.

Question 23

Substrate

Answer 23

An enzyme’s specific target molecule.

Question 24

Active site

Answer 24

An enzyme has an active site where the enzyme interacts with the enzyme’s substrate. Their shape is critical to their role as biological catalysts.

Question 25

For optimum activity, enzymes require certain environmental conditions, including:

Answer 25

Temperature: human enzymes function best at 37° C, or body temperature; high temperatures will denature human enzymes pH: enzymes require a pH around neutrality for best results

Question 26

Cofactors

Answer 26

Nonprotein enzyme helpers that are inorganic, such as zinc, iron, and copper.

Question 27

Coenzymes

Answer 27

Nonprotein enzyme helpers that are organic molecules and are often vitamins.

Question 28

Competitive inhibitors

Answer 28

Enzyme inhibitor that inhibits because they compete for the enzyme’s active site and thus block substrates from entering the active site.

Question 29

Noncompetitive inhibitors

Answer 29

Enzyme inhibitors that bind somewhere on the enzyme other than the active site, changing the shape of the enzyme and making it so that the substrate will no longer fit into the active site.