Topic 5

Question 1

Thermodynamics

Answer 1

is a special branch of chemistry that is concerned with the study of energy transformations that occur in a certain collection of matter

Question 2

kinetic energy

Answer 2

is energy that can be associated with the relative motion of objects, movement, thermal, light, Sound or electrical.

Question 3

potential energy

Answer 3

energy that is not kinetic but energy that matter possesses because of its location or chemical structure. Chemical energy is associated with potential energy being available in a chemical reaction

is stored energy that has the ability to do work (available energy). Chemical, Gravity, Elastic, Nuclear (energy in atoms nucleus)

STORED IN CHEMICAL BONDS

Question 4

redox reactions

Answer 4

occur during certain chemical reactions, electron can be transferred from one atom to another

Reduction has a higher level of energy than oxidized form, and Reactions are always paired.

DURING A REDOX REACTION THE MOLECULE THAT GAINS AN ELECTRON HAS BEEN REDUCED AND NOW HAS A HIGHER ENERGY LEVEL

Question 5

oxidation

Answer 5

involves losing electrons & increasing oxidation number

involves losing a hydrogen for a given compound

releases energy

Question 6

reduction

Answer 6

involves gaining electrons and decreasing oxidation number

involves gaining a hydrogen for a given compound

stores energy

Question 7

First Law of Thermodynamics

Answer 7

the energy of the universe is constant: and energy can be transferred and transformed, but it cannot be created or destroyed, only converted to other forms (Principle of Conservation of energy)

Question 8

Second Law of Thermodynamics

Answer 8

Every energy transfer or transformation increase the entropy of the universe

All energy transformation are inefficient (Energy losses: Friction, Heat, Light, Sound, Eddy Currents)

Question 9

Heat

Answer 9

thermal energy - associated with kinetic energy, as it involves random movement of atoms or molecules

Heat is an example of radiant or electromagnetic energy

Heat is the most convenient way of measuring energy: 1 calorie = heat required to raise 1 gram of water 1ºC

Question 10

entropy

Answer 10

a measure of molecules disorder, or randomness

Question 11

enthalpy

Answer 11

is the energy in a molecule’s chemical bonds (H)

Question 12

free energy

Answer 12

the amount of energy available to break and form other chemical bonds in a particular defined system
(G)

Question 13

endergonic

Answer 13

absorb energy from their surroundings

Energy is absorbed, (not Spontaneous)

Transforming kinetic to potential energy. (Ex: Photons of light converted to ATP in photosynthesis)

If ΔG is positive, the products have more free energy than the reactants, and requires an input of energy

Question 14

exergonic

Answer 14

release energy to the surroundings

Energy is released, (Spontaneous)

Transforming Potential to Kinetic Energy. (Ex: Breakdown of Glucose via Glycolysis to produce ATP)

If ΔG is negative, the reactants have more free energy than the products, thus reaction will proceed spontaneously, and release excess free energy as heat

Exergonic reaction fuels an Endergonic reaction

Question 15

activation energy

Answer 15

the energy required to initiate a chemical reaction

The Enzyme applies stress to distort particular bond to lower activation energy

Question 16

catalysis

Answer 16

the increase in the rate of a chemical reaction by a catalyst

Question 17

adenosine triphosphate (ATP)

Answer 17

the main energy currency for all cells and used for almost every energy-requiring process in the cell.

Composed of a …
Ribose – 5 carbon sugar
Adenine – purine nitrogen base
Chain of 3 phosphate bonded – Energy is stored in the bonds, as it takes an input of energy to create the bonds, the energy is then released when the bond is broken (ENERGY IN AN ATP MOLECULE IS STORED IN THE BONDS CONNECTING THE 2ND & 3RD PHOSPHATE GROUPS)

Question 18

enzyme

Answer 18

globular proteins that act as biological catalysts (Some enzymes are RNA based)

Enzyme function can be affected by any chemical of physical conditions that can have an effect on the shape of the enzyme and thus affecting the rate of reactions

Rate of enzyme-catalyzed reaction depends on the concentrations of substrate and enzyme available.

can be either suspended in the cytoplasm or attached to cell membranes and organelles

Multienzyme complexes – subunits work together to form molecular machine, products can be delivered easily to next enzymes

Allosteric Enzymes – enzymes that can be either activate or become inactivated.

Question 19

active site

Answer 19

are pockets or clefts for substrate binding, and the site where the enzyme-substrate complex forms

Question 20

enzyme-substrate complex

Answer 20

forms a precise fit

Question 21

effects of free energy on reactions

Answer 21

• If free energy decreases, the reaction can proceed. If free energy increases, the reaction can’t proceed.
• If Gibbs free energy is negative, the reaction is spontaneous. If Gibbs free energy is positive (exergonic), the reaction is not spontaneous (endergonic). If Gibbs free energy is zero, the reaction is in equilibrium.
• The rate of a chemical reaction depends on the free energy, entropy, and concentration of the reactants and products.

Question 22

What is the importance of ATP in cellular processes?

Answer 22

• transports the energy necessary for all cellular metabolic activities
• serves as a shuttle, delivering energy to places within the cell where energy-consuming activities are taking place

Question 23

How do enzymes work?

Answer 23

• Enzymes recognize and bind to their substrates through hydrogen bonds, ionic bonds, and hydrophobic interactions
• The formation of these temporary bonds creates tension on certain bonds, and can force a redistribution of electrons within the substrate molecules
• The strain imposed by physical forces/electron re-distribution, creates a strain on a covalent bond within the substrate molecule, resulting in bond breakage
• Substrate activation is the process of straining substrate bonds

Question 24

A reaction will proceed spontaneously in which of the following conditions?

Answer 24

The reactants have a higher free energy than the products

Question 25

What is the principal source of energy coming from in a biological world?

Answer 25

the sun’s release of protons

Question 26

Enzymes require an optimal temp. & pH, otherwise what effect does changes in temp. & pH cause for enzymes?

Answer 26

the three-dimensional shape of the enzyme