Chapter 3: Energy, Catalysis, and Biosynthesis

Question 1

Describe the 2nd Law of Thermodynamics

Answer 1

• entropy ( amount of disorder) must increase
• occurs in any naturally occuring process

Question 2

Describe the 2nd Law of Thermodynamics in cells

Answer 2

order increases inside the cell, but the heat released causes a decrease in order in the surroundings

Question 3

Catabolism

Answer 3

• releases energy
• increases entropy(S), creates disorder

Question 4

Give an example of Catabolism

Answer 4

Food molecule energy can be converted, either into useful forms of energy(biosynthesis building blocks) to drive new molecule creation in anabolic pathways, or be lost as heat

Question 5

Anabolism

Answer 5

• requires energy
• decreases entropy(S), creating order

Question 6

Example of anabolism

Answer 6

the process puts together the many molecules needed to form the cell

Question 7

What is free energy?

Answer 7

• energy used to do work
• different molecules have different levels/abilities of free energy
• the change in free energy (Delta G) determines whether reactions occure in cells and how they occur (spontaneous or not)

Question 8

Describe the direction of chemical reactions

Answer 8

the chemical reaction proceeds in a direction that causes a loss of free energy

Question 9

-Delta G

Answer 9

• change in gibbs energy that is a favorable reaction
• when delta G is negative, the disorder of the universe increases when the reaction occurs (Y to X)
• occurs spontaneously

Example: ATP converted to ADP and Phosphate

Question 10

+Delta G

Answer 10

-change in Gibbs energy that is an unfavorable reaction

• when delta G is positive, the universe becomes more ordered
• occurs only if coupled to energetically driven favorable reaction

Example: ADP + Phosphate = ATP

Question 11

How are anabolic reactions related to free energy?

Answer 11

anabolic has a postivie delta G change, this decreases entropy (amount of disorder)

these reactions are unfavorable

Question 12

How are catabolic reactions related to free energy?

Answer 12

catabolic reactions have a negative delta G change, this increases entropy (amount of disorder)

these are favorable reactions

Question 13

What is a common activated carrier?

Answer 13

ATP!!

Question 14

Describe the principle of coupled chemical reactions

Answer 14

• energy can be collected by an enzyme to drive unfavorable reactions, while some of the energy is still lost as heat

Example: the oxidation of glucose to CO2+H2O produces only heat, but when coupled to 2nd reaction, it can have synthesis of activated carriers (ATP)

Question 15

What are two major ways of producing an unfavorable reaction?

Answer 15

An energetically unfavorable reaction (Delta G > 0) cannot occur unless coupled to an energetically favorable reaction, such that net free energy change for the pair of reactions s negative (less than 0)

changing the concentration of reactnts or product can also drive energetically unfavorable reactions by decreasing Delta G

Question 16

Name the formula: For a reaction from Y -> X

Answer 16

DG = DG0 +RT ln [X]/[Y]

DG-delta G

DG0-standard Gibbs free energy
RT-gas constant
Y-product
X-reactant

concentration of reactants and products determine the D for a reaction; higher concentration of one pushes energy in one direction

Question 17

How do you make Delta G smaller?

Answer 17

• this means more negative
• change the value of reactants, more reactants pushes the reaction forward

Question 18

How do you make Delta G bigger?

Answer 18

• increase the value of products

Question 19

What do enzymes do?

Answer 19

• enzymes convert substrate to products while remaining unchanged themselves

Question 20

Describe Catalysis

Answer 20

• a substrate molecule binds to an enzyme and undergoes reaction to form a product
• the product then gets released
• although the enzyme participates, it remains unchanged; it will continue this cycled structure

Question 21

How do enzymes affect energetic reactions?

Answer 21

• enzymes are required even in energetically favorable reactions to overcome activation energy
  -enzymes lower activation energy barrier (lowers the work the of the reactant of stabilizing many conditions to reach the product goal)

-reverse reactions requires lots more of activation energy, so rarely occurs

Question 22

Describe the conversions between ATP and ADP in its cycle

Answer 22

• ATP and water can form ADP and phosphate (hydrolysis, favorable reaction, -Delta G)
• ADP and phosphate reverses reactions to form ATP (condensation, unfavorable, must be coupled to energetically favorable reaction, +Delta G)