chapter one

Question 1

True or false The value for equilibrium constants, Keq, depends on the temperature at which the reaction is taking place

Answer 1

False

Question 2

A Keq = 0.1 tell us what about where the equilibrium stands?

Answer 2

The reaction equilibrium lies to the left.

A larger Keq means the reaction is more likely to go to completion

Question 3

Consider the binding of oxygen to haemoglobin: Hb + O2—–> Hb-O2. If we decrease the pressure of the system, what is the effect on this equilibrium reaction?

Answer 3

The equilibrium shifts to the left

Question 4

Exothermic enthalpy changes are shown as

Answer 4

negative

exothermic=releasing heat

Question 5

Change in enthalpy of a system is due to heat supplied at

Answer 5

constant pressure

Question 6

what will happen when the mass-action ratio Q=0.8 and the Keq = 0.8

Answer 6

the reaction is at equilibrium

Question 7

For the reaction in which reactant A is converted to product B, tell whether this process is favorable or unfavorable at 4ºC and at 37ºC ?

H (kJ/mol)	            S (J/mol K) A	                 54	                   22 B	                 60	                   43

Answer 7

unfavorable, favorable

A is unfavorable because ΔG= ΔH-TΔ S. ΔG= 6-((277)(0.021))=0.183= positive=unfavorable

B is favorable because ΔG= 6-((310)(0.021))= -0.51

*check units, should be in kJ and Kelvin

Question 8

In glycolysis, glucose is broken down to yield energy. If the equilibrium constant of the isomerization of glucose-6-phosphate to fructose-6-phosphate is 0.5

would this reactions proceed in the forward or reverse direction when Q= 1.0?

What is the free energy of the reaction in kJ/mol at 37ºC?

In which direction will the reaction proceed if the concentration of glucose-6-phosphate=0.3M and fructose-6-phosphate= 0.15M as an initial state?

Answer 8

reaction will move backwards, 1.79, left

Question 9

volume of a sphere

Answer 9

4/3 Pi x r^3

Question 10

simplified surface to volume ratio formula

Answer 10

3/r

Question 11

what happens to the SA:V ratio as diameter of the cell increase

Answer 11

it decreases, smaller SA:V ratio is bad

Question 12

Calculate the surface-to-volume ratio for a spherical bacterium with a diameter of 0.6 micro m

Answer 12

diameter/2 = radius

r= 0.3

3/0.3=10

Question 13

describe rotation with single bonds as compared to double

Answer 13

single bonds allow free rotation unless there are very large or highly charged groups attached. double bonds restrict most rotation.

Question 14

first law of thermodynamics

Answer 14

the energy in the universe is constant but can shift in forms

Question 15

how do configurational and conformational isomers differ

Answer 15

configurational isomers have restricted rotation between covalent bonds. Cis/Trans isomers are configurational and when shifting to another structure must break the double bond.

conformational isomers can quickly convert between forms at room temperature. Exhibit free rotation between carbons at room temperature.

Question 16

Describe what a stereoisomer is and explain what is the difference between enantiomers and diastereomers

Answer 16

Stereoisomers are molecules with the same chemical bonds and formula but different configuration.

enantiomers are stereoisomers that are mirror images of each other. These are non-superimposable. Enantiomers also exhibit optical activity

diastereomers are stereoisomers that are not mirror images

Question 17

Describe optical activity of a racemic mixture

Answer 17

A racemic mixture shows no optical rotation. In a racemic mixture, there is equal concentration of both D and L enantiomers which essentially cancel each other’s rotation out

Question 18

configuration versus conformation

Answer 18

configuration is the fixed spatial arrangement while conformation is the spatial arrangement of substituent groups that are free to rotate to different positions without breaking bonds

Question 19

what does Keq measure

Answer 19

the tendency of a reaction to go to completion

Question 20

What does the value of Keq tell us

Answer 20

A larger Keq means the reaction tends to proceed until the reactants are almost completely converted to products

Question 21

stereoisomer formula

Answer 21

2^n where n is the number of chiral carbons

Question 22

R and S priority

Answer 22

—OCH3 > —OH > —NH2 > —COOH > —CHO > —CH2OH > —CH3 > —H

Question 23

compare an isolated system and a closed system

Answer 23

An isolated system does not exchange matter or energy with surroundings. A closed system exchanges energy only.

Question 24

If under a given set of conditions, the reaction A → B occurs with ∆G = –14 kJ/mol and the reaction C → B occurs when ∆G = +16 kJ/mol, then:

Answer 24

The conversion of A to C is exergonic

Question 25

mass-action ratio, Q

Answer 25

ratio of product concentrations to reactant concentrations at a given time – can be calculated to determine how far the reaction is from equilibrium

Question 26

compare ΔG and ΔGº

Answer 26

the Gibbs free energy depends on the experimental conditions whereas the standard free energy describes the Gibbs free energy for reactants and products that are in their standard state

Question 27

relationship between ΔGº and Keq

Answer 27

ΔGº= -RT ln Keq

Question 28

catabolism vs anabolism

Answer 28

catabolism = degradative, free-energy-yielding reactions – drives ATP synthesis – produces the reduced electron carriers NAD(P)H anabolism = synthetic pathways that require the input of energy

Question 29

If the equilibrium constant for an equation is 2.22x10^5M, calculate the standard free energy change at 25ºC.

Answer 29

-30.5kJ -(8.315x (25+273)) ln (2.22x10^5)

Question 30

compare transition state and activation energy

Answer 30

transition state = higher free energy than reactant or product activation energy, ∆G‡ = difference in energy between the reactant in its ground state and its transition state

Question 31

what sets limit of upper cell size

Answer 31

rate of transport and need to deliver O2 to all parts of the cell

Question 32

carbon arrangement and rotation

Answer 32

carbon atoms have a tetrahedral arrangement free rotation around each single bond limit rotation around double bond

Question 33

what 2 things make up most of the weight of a cell

Answer 33

water and proteins

Question 34

a molecule can have 2^n stereoisomers where n is the number of what

Answer 34

n is the number of chiral carbons

Question 35

what is the first law of thermodynamics

Answer 35

total amount of energy in the universe is constant, changes forms

Question 36

second law of thermodynamics

Answer 36

entropy of the universe is increasing