Lecture 13

Question 1

Gibbs energy variable

Answer 1

Thermodynamic potential of the system

Maximal work a system can perform

Question 2

Enthalpy

Answer 2

H

Total heat content of the system

Question 3

Temperature

Answer 3

T

Measurement of the avg kinetic energy of a system

Question 4

Entropy

Answer 4

S

Tendency of energy to become dispersed or

Measure of order of randomness in a system

Question 5

Gibbs free energy formula

Answer 5

Delta G= delta H - T deltaS

Question 6

Endothermic rxn

Answer 6

Absorb energy in the form of heat

Question 7

Exothermic rxn

Answer 7

Release energy in form of heat

Question 8

Spontaneous rxn

Answer 8

Process that can occur without a constant input of energy

Question 9

Rxn will tend to be spontaneous if what

Answer 9

They are exothermic

Products have less energy than reactants

Or

If entropy of products is greater than entropy of reactants

Question 10

Combustion of glucose formula

Answer 10

Rxn of glucose with oxygen to form CO2 and water

C6H12O6 + 6O2 -> 6CO2 + 6H2O

Rxn releases a significant amount of heat (delta H is less than zero) and is spontaneous (negative delta G)

Question 11

Exothermic Exergonic rxn

Answer 11

Condition of glucose

Question 12

Exothermic and Endergonic rxn

Answer 12

Freezing of water

Question 13

EndothermicEndergonic rxn

Answer 13

Photosynthesis

6 CO2 + 6H2O + light energy -> C6H12O6 + 6O2

Question 14

Since second law of thermodynamics is that entropy must increase do cells violate this law?

Answer 14

No

Living systems are open (therefore they can maintain highly organized state)

Living systems being in both energy and matter from surroundings and use them to maintain an organized state

They real ease energy and disordered molecules into the environment

Question 15

One way to identify life

Answer 15

Life consumes energy and converts it to work that decreases local entropy

Question 16

Metabolic pathways

Answer 16

Metabolism
Catabolic pathway
Anabolic pathway

Question 17

Metabolism

Answer 17

Collection of all chemical rxns present within a cell or organism

Question 18

Catabolic pathway

Answer 18

Energy released by the breakdown of complex molecules to simpler compounds

Question 19

Anabolic pathway

Answer 19

Energy consumed to build complicated molecules from simpler ones

Question 20

Metabolic pathways AKA

Answer 20

Biosynthetic pathways

Question 21

Energy coupling

Answer 21

Coupling of an Endergonic reaction to an Exergonic reaction

Question 22

Hydrolysis of ATP

Answer 22

Exergonic rxn that can be coupled to make otherwise Endergonic reactions proceed spontaneously

Question 23

Coupling reactions require what

Answer 23

Enzymes

Question 24

How do enzymes facilitate reactions

Answer 24

They are catalysts that lower activation energy

Question 25

How do enzymes work

Answer 25

Bring molecule’s together Expose reactant molecules to altered charge environments that promote catalysis Enzymes change the shape of substrate molecules

Question 26

Active site enzymes

Answer 26

In a biochemical reaction the active site of an enzyme combines briefly with reactants (substrates) and is released unchanged

Question 27

Temperature and pH effect on enzymes

Answer 27

Most enzymes have an optimal temperature and pH where it operates at peak efficiency At temp and ph levels above or below these optimal level the rxn rates drop off Ph about 7 usually

Question 28

Enzymes secreted from cells may have pH where

Answer 28

Further away from neutrality

Question 29

Changes is pH in terms of enzyme How does it work

Answer 29

Affect the charged groups in the amino acids of the enzyme

Question 30

How does temp affect an enzyme

Answer 30

As temp rises rate of reactions increase High temperatures denature proteins including enzymes and reduce the rate of reactions

Question 31

Enzyme cofactors

Answer 31

Non protein groups that bind precisely to an enzyme Necessary for catalysis to occur

Question 32

Cofactors

Answer 32

Often metallic ions (iron. Copper. Zinc. Manganese) Mg essential for ATP dependent rxns Fe present in hemoglobin and cytochromes. Involved in electron transport

Question 33

Coenzymes

Answer 33

Organic molecules. Such as vitamins NAD+ (nicotinamide adenine dinucleotide) Involved in redox rxns. Carrying electrons from one rxn to another FAD (flaxen adenine dinucleotide). Another electron carrier used in redox rxns

Question 34

Concentration dependence of enzymatic rxns

Answer 34

In the presence of excess substrate. The rate of catalysis is proportional to the amount of enzyme

Question 35

When substrate concentration is low Vs high

Answer 35

Rxn rate slows Enzymes and substrates collide infrequently Vs Enzymes become saturated with reactants Rate of rxn levels off

Question 36

Enzyme inhibitors

Answer 36

Non substrate molecules that can bind to an enzyme and decrease its activity

Question 37

Competitive inhibition

Answer 37

Inhibitor competes with normal substrate for active site

Question 38

No competitive inhibition

Answer 38

Inhibitor doesn’t compete with normal substrate for active site. Instead combines with sites elsewhere on the enzyme

Question 39

Feedback inhibition

Answer 39

A type of metabolic regulation Product of a rxn inhibits its own synthesis Helps conserve cellular resources

Question 40

Redox rxns

Answer 40

Cells transfer energy by redox rxns. Usually energy can be transferred through the transfer of electrons Usually involves the transfer of a hydrogen atom (containing an electron and a proton) rather than just an electron

Question 41

Oxidation

Answer 41

Loses electrons Gives up energy as it releases electrons

Question 42

Reduction

Answer 42

Gain electron Receives energy with the electron

Question 43

Most common encountered acceptor molecules in a living cell include

Answer 43

NAD+ -NADH Nicotinamide adenine dinucleotide NADP+ -NADPH nicotinamide adenine dinucleotide phosphate FAD+ -FADH2 Flavin adenine dinucleotide Each of these electron transfer agents can exist in a reduced state. In which it has more free energy, or in oxidized state which it has less energy

Question 44

Which has less energy potential Oxidized or reduced

Answer 44

Oxidized

Question 45

Which has more energy potential Oxidized or reduced

Answer 45

Reduced