Ch. 8 An Introduction To Metabolism

Question 1

What is Metabolism?

Answer 1

The totality of an organism’s chemical reactions

Question 2

What is energy?

Answer 2

The capacity to cause change

Question 3

Free energy

Answer 3

Energy available to do work in a living system when temperature and pressure are uniform

Free energy change = 🔼 G (this is how it’s abbreviated)

Question 4

What is kinetic energy

Answer 4

Energy associated w/ motion

Question 5

Heat (aka thermal energy)

Answer 5

Is kinetic energy associated w/ random movement of atoms or molecules

Question 6

Potential energy

Answer 6

Energy that matter possesses b/c of it’s location or structure

Question 7

What is this an example of?

The contraction of leg muscles pushes bicycle pedals

Answer 7

Kinetic energy

Question 8

What is this an example of?

Water behind a dam, for instance possesses energy b/c of the altitude above sea level

Answer 8

Potential energy

Question 9

What type of energy is contained in chemical bonds in a molecule?

Answer 9

Chemical energy

Question 10

What are the characteristics of an endergonic reaction?

Answer 10

Absorbs free energy from it’s surroundings; essentially stores free energy in molecules so
🔼G is positive

Question 11

What are the characteristics is exergonic reaction

Answer 11

Proceeds w/ a net release of free energy; b/c the chemical mixture loses free energy 🔼 G is negative

Question 12

What are the characteristics of an anabolic reaction?

Answer 12

It links simple molecules to form complex ones (endergonic)

Question 13

What are the characteristics of catabolic reaction?

Answer 13

Breaks down complex molecules into simpler ones ( exergonic)

Question 14

What is energy coupling

Answer 14

The use of an exergonic process to drive an endergonic one; most energy coupling in cells is mediated by ATP

Question 15

What is the general structure of ATP?

Answer 15

3 phosphate groups, sugar ribose, and the nitrogenous base adenine

Question 16

What type of charge do the phosphate groups possess?

Answer 16

Negative charge

Question 17

ATP has 3 phosphate groups. Which phosphate group is broken off to release energy?

Answer 17

Terminal phosphate bond / Triphosphate group

Question 18

Which phosphate groups is added to re-build ATP?

Answer 18

Inorganic phosphate + ADP + energy = ATP

Question 19

Why does it take so much energy to build ATP/ Why does it release so much energy? (hint: electrical charges of the phosphate groups)

Answer 19

The phosphate groups have a strong negatively charged

Question 20

Hydrolysis breaks down ATP: Is the breakdown of ATP endergonic or exergonic?

Answer 20

Exergonic

Question 21

Hydrolysis breaks down ATP: Is the synthesis (re-building) of ATP endergonic or exergonic?

Answer 21

Endergonic

Question 22

What is the energy given off by the ATP used for?

Answer 22

To perform three types of cellular work: chemical, transport, and mechanical

Question 23

Where does the energy to rebuild ATP come from? (Be specific!)

Answer 23

The energy released by breakdown reactions (catabolism) in the cell is used to phosphorylate (add inorganic phosphate to) ADP, regenerating ATP

Question 24

What is a catalyst?

Answer 24

A chemical agent that speeds up a reaction without being consumed by the reaction

Question 25

What type of molecule are most enzymes?

Answer 25

Protein molecules (macromolecule)

Question 26

How do enzymes work?

Answer 26

They speed up reactions without adding heat

Question 27

How do enzymes affect the energy of activation?

Answer 27

They reduce the activation energy

Question 28

Do enzymes affect the change in free energy (ΔG) of a reaction?

Answer 28

No, ΔG is unaffected by the enzyme

Question 29

What is the same and what is the difference btw the progress of reactions with or without an enzyme?

Answer 29

Same: Free energy Different: course of reaction and activation energy

Question 30

How does the active site of an enzyme lower an EA barrier? Explain.

Answer 30

Enzyme can converts one or two reactant molecules to one or more product molecules

Question 31

Substrate

Answer 31

The reactant on which an enzyme works

Question 32

Active site

Answer 32

The specific region of an enzyme that binds the substrate and that forms the pocket in which catalysis occurs (the puzzle piece slot that substrate goes inside of)

Question 33

Transition state

Answer 33

When the molecules have absorbed enough energy for the bonds to break and the reactants are in this unstable condition

Question 34

Enzyme-substrate complex

Answer 34

A temporary complex formed when an enzyme binds to it’s substrate molecule(s)

Question 35

Induced fit

Answer 35

Caused by the entry of the substrate, the change in shape of the active site of an enzyme so that it binds more snugly to the substrate

Question 36

What is the function of cofactors and coenzymes?

Answer 36

A coenzyme is just an organic molecule serving as a cofactor which is any nonprotein molecule or ion that is required for the proper functioning of an enzyme Can be permanently bound to active site or bind loosely and reversible, along with substrate, during catalysis

Question 37

What environmental conditions affect enzyme activity?

Answer 37

Temperature and pH

Question 38

Why do enzymes susceptible (harmed) to denaturation? (what kind of molecules are they?)

Answer 38

Each enzyme has an optimal temperature and pH that favor the most active shape of the protein molecule

Question 39

What is a metabolic pathway?

Answer 39

Each step is catalyzed by a specific enzyme, it begins with a specific molecule and ends with a product

Question 40

Why is the role of enzymes important in a metabolic pathway?

Answer 40

A cell can regulate metabolic pathways by controlling the enzyme concentration in the cell

Question 41

What are enzyme inhibitors?

Answer 41

Certain chemicals selectively inhibit the action of specific enzymes

Question 42

Competitive inhibitors

Answer 42

Bind to the active site of an enzyme, competing with the substrate

Question 43

Noncompetitive inhibitors

Answer 43

Bind to a different part of an enzyme, causing the enzyme to change shape and making the active site less effective (aka allosteric control)

Question 44

What examples of enzyme inhibitors?

Answer 44

Toxins, poisons, pesticides, and antibiotics

Question 45

How does feedback inhibition work? Explain.

Answer 45

A metabolic pathway is halted by the inhibitory binding of it’s end product to an enzyme that acts early in the pathway.