Chapter 8

Question 1

Metabolism

Answer 1

Totality of an organism’s chemical reactions. From the Greek metabole, change. _________ is an emergent property of life that arises from orderly interactions between molecules. The chemical reactions in the body’s cells that change food into energy.

Question 2

Metabolic pathway

Answer 2

Road map of many chemical reactions, arranged as intersecting ____________. In a _____________, a specific molecule is altered in a series of defined steps, resulting in a certain product.

Question 3

Catabolic pathways

Answer 3

Some metabolic pathways release energy by breaking down complex molecules to simpler compounds. These degradative processes are called __________________, or breakdown pathways. Opposite of Anabolic pathways.

Question 4

Anabolic pathways

Answer 4

Consume energy to build complicated molecules from simpler ones. Opposite of catabolic pathways.

Question 5

Bioenergetics

Answer 5

The study of how energy flows through living organisms.

Question 6

Types of energies

Answer 6

1. Kinetic energy: relative motion of objects
2. Heat/thermal energy: Kinetic energy associated with the random movement of atoms or molecules. Thermal energy in transfer from one object to another = heat
3. Potential energy: Energy possessed because of location/structure
4. Chemical energy: Potential energy available for release in a chemical reaction.

Question 7

Laws of Thermodynamics

Answer 7

First law: Energy of the universe is constant.
Second law: Every energy transfer/transformation increases the disorder (entropy) of the universe.

Question 8

Free energy

Answer 8

The portion of a system’s energy that can perform work when the temperature and pressure are uniform throughout the system.

Question 9

Change in Free Energy

Answer 9

Delta G (change of free energy), can be calculated for a chem. reactions: Delta G = Delta H- T Delta S.

Delta: The change in _____
H: enthalpy = total energy
S: Entropy = measure of disorder
T: Temp. in Kelvin.

Question 10

In a spontaneous reaction, Delta G must have a ___________ value (decrease in ____________)

Answer 10

negative; delta H

At equilibrium, Delta G = 0 (CELL IS DEAD)

Question 11

Exergonic vs Endergonic Reactions

Answer 11

Exergonic: Proceeds with a net release of free energy Delta G is negative.

Endergonic: Absorbs free energy from its surroundings. Delta G is positive

Question 12

ATP power

Answer 12

Adenosine triphosphate. Contains the sugar ribose, the nitrogenous base adenine and a chain of 3 phosphate groups. Loss of a phosphate group = energy.

Question 13

Three kinds of cellular work

Answer 13

1. Chemical: the physical work that is carried out within a cell, due to the energy derived from chemicals
2. Transport: the act or the means by which molecules, ions, or substrates are moved across a biological membrane, such as the plasma membrane
3. Mechanical: contraction of a muscle

Transport and mechanical work in the cell are nearly always powered by the hydrolysis of ATP.

Question 14

Energy Coupling

Answer 14

Use of an exergonic process to drive an endergonic one.

Question 15

How ATP performs work

Answer 15

When ATP is hydrolyzed in a test tube, the release of free energy merely heats the surrounding water. In an organism, this same generation of heat can sometimes be beneficial.

Question 16

Metabolic Disequilibrium

Answer 16

Cells die at equilibrium.

Question 17

Regeneration of ATP

Answer 17

The addition of phosphate to ADP. The free energy required to phosphorylate ADP comes from exergonic breakdown reactions (catabolism) in the cell.

Question 18

The Life of an Enzyme

Answer 18

1-2 days

Question 19

Catalyst

Answer 19

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

Question 20

Enzymes

Answer 20

A macromolecule that acts as a catalyst.

Question 21

Activation Energy (E_A)

Answer 21

Energy required to contort the reactant molecules so the bonds can break

Question 22

Substrate

Answer 22

The reactant an enzyme act on. Enzyme binds to its substrate.

Question 23

Active Site

Answer 23

Typically a pocket or groove on the surface of the enzyme where catalysis occurs. A restricted region of the enzyme molecule actually binds to the substrate.

Question 24

How Catalysis occurs in the enzyme’s active site

Answer 24

Products -> active site. Active site lowers E_A. Substrates are converted to products. Products released. Active site is available for new substrates.

Question 25

Effect of Environment on Enzyme Activity

Answer 25

Temperature and pH. Can also be affected by chemicals that specifically influence that enzyme.

Question 26

Regulation of Enzyme activity helps control metabolism

Answer 26

Enzymes help break down macromolecules like proteins, fats and carbohydrates.

Question 27

Allosteric Regulation of Enzymes

Answer 27

Term used to describe any case in which a protein’s function at one site is affected by the binding of a regulatory molecule to a separate site. May result in either inhibition or activation. Most enzymes known to be allosterically regulated are constructed from two or more subunits, each composed of a polypeptide chain with its own active site.

Question 28

Allosteric Activation

Answer 28

Allosteric activator stabilizes the active form of an enzyme. Good image in notes.

Question 29

Allosteric inhibition

Answer 29

Allosteric inhibitor stabilizes inactive form of an enzyme. Good image in notes.

Question 30

Allosteric: neither

Answer 30

Inactive form oscillates with the active form when the active form is not stabilized by substrate.

Question 31

Cooperativity

Answer 31

This mechanism amplifies the response of enzymes to substrates. Is considered allosteric regulation because even though substrate is binding to an active site, its binding affects catalysis in another active site.

Cooperativity is a phenomenon that occurs when a substrate acts as an allosteric activator. In cooperativity, the substrate binds to one active site, which increases the activity of the other active sites. This is considered allosteric regulation because the substrate affects active sites far from its binding site

Question 32

Feedback Inhibition

Answer 32

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

a form of negative feedback in which the final product of a series of reactions inhibits an enzyme from an earlier step in the metabolic pathway that produced it.

Question 33

Specific localization of enzymes within the cell

Answer 33

The cell is not just a bag of chemicals with thousands of different kinds of enzymes and substrates in a random mix. Compartmentalized and cellular structures help bring order to metabolic pathways.

Question 34

Anabolism

Answer 34

the synthesis of complex molecules in living organisms from simpler ones together with the storage of energy; constructive metabolism.

Question 35

Delta G of ATP

Answer 35

-7.3 kcal/mol

Question 36

ATP Energy

Answer 36

When an ATP is broken down via hydrolysis, it releases energy (heat).

Question 37

Sunlight Energy

Answer 37

Nuclear fusion in the sun. Photosynthesis.

Question 38

Gradient Energy

Answer 38

Allow cells to control the direction ions move across membranes. In mitochondria and chloroplasts, proton gradients generate a chemiosmotic potential used to synthesize ATP, and the sodium-potassium gradient helps neural synapses quickly transmit information.

When allowed to move with gradient, generate energy!

Question 39

Reduced molecule energy

Answer 39

When a molecule gains an electron, it gains energy.

Question 40

Highly ordered system

Answer 40

More unstable

Question 41

Add a -OH is called:

Answer 41

Hydroxylation

Question 42

Add a CH4 is called:

Answer 42

Methylation

Question 43

Sodium/Potassium pump

Answer 43

3 sodium per 2 potassium. Sodiums exit the cell, potassium enter.

Question 44

Cofactors.

Answer 44

An inorganic enzyme helper of enzymatic activity.

Question 45

Coenzyme

Answer 45

An organic enzyme helper of enzymatic activity.