Mol Lecture #25

Question 1

Thermodynamics and why the interest

Answer 1

The study of energy and its transformations
- the energy required to perform certain chemical reactions, the energy released by certain chemical reactions and linking these 2 processes.

Question 2

Energy is …

Answer 2

• the ability to do work (Life is an energy-driven process)

Question 3

Thinking about reactions going in the following way:

Answer 3

A+B → C+D
←

Question 4

Reactants Products (Thermodynamics tells us…)

Answer 4

• Thermodynamics can tell us whether a reaction requires or releases energy, but not its rate. (Important in thinking about how cells function→ living systems control the rates of reactions a lot of the time)

Question 5

Laws of thermodynamics (1st Law)

Answer 5

• Conservation of energy: Energy can be converted from one form to another but neither created nor destroyed

Question 6

Laws of thermodynamics (2nd Law)

Answer 6

• increasing entropy: Total disorder (entropy) of a system always increases or systems always progress to equilibrium. (ex. Going from one molecule towards a greater number of the molecules is entropy→ DNA wrapped around histones is an ordered state, when its is not wrapped around histones it’s going towards disorder)

Question 7

Forms of energy

Answer 7

Energy exists in a few forms
→ Chemical, heat, electrical (can be thought of as the ability to do work)

Question 8

Energy exists in 2 forms (Potential and Kinetic)

Answer 8

→ Potential Energy- Stored energy (ex. Rock sitting on top of the hill that could roll down– stored energy)
→ Kinetic Energy- Energy in motion (ex. Once the rock is rolling down the hill- in motion- it uses kinetic energy)
(ex. Energy is also stored in bonds- potential- and when the energy is used to break the bonds- kinetic energy)
- Energy can be converted between the states, but it is inefficient

Question 9

Free energy (Look at slides)

Answer 9

• energy available in a system to do work (ex. Bound (boundaries) what we’re talking about- system)
• Free energy (G) (J. Gibbs)
  Change in the whole free energy for a given reaction (delta G)

Question 10

What are the 2 terms that can change?

Answer 10

• Entropy & Enthalpy (combination of plus and minus that gives us the ultimate product of the reaction)
• Delta G tells us whether a reaction releases energy or requires it.

Question 11

Types of reactions

Answer 11

• Exergonic Reaction: releases energy
  → Delta G is negative
• Endergonic Reaction: requires energy
  → Delta G is positive
  Endothermic and Exothermic are in reference to the Delta H (Change in enthalpy)

Question 12

Types of Delta G: Negative Delta G

Answer 12

• exergonic reaction (spontaneous- could occur without energy being put in→ not in reference to rate*)
  → Reactions tend to be exergonic if:
  1) The products have less potential energy than the reactants
  2) If the products are less ordered than the reactants
  (They both have to add up to a negative delta G)

Question 13

Types of Delta G: Positive Delta G

Answer 13

• endergonic reaction (non-spontaneous)
  1) The products have more potential energy than the reactants
  2) If the products are more ordered than the reactants

Question 14

Equilibrium

Answer 14

• The condition of a system in which all competing forces are balanced

Question 15

Equilibrium Reaction Example: Glucose 1-phosphate → Glucose 6-phosphate *

Answer 15

• For it to go to 6-phosphate, it will achieve a negative delta G.
• At some point, we achieve a delta G that is equivalent (neither - or +); whatever parameters driving this reaction (ΔH and ΔS) that achieved the delta G are no longer pushing this reaction. (Equilibrium does not always mean that everything is balanced in terms of number)

Question 16

Metabolic Pathways: Metabolism

Answer 16

• the set of life-sustaining chemical transformations within cells of living organisms.
  –> Ex. Use exergonic and endergonic reactions to make and break molecules

Question 17

Catabolic Pathways:

Answer 17

Energy is released, and molecular building blocks are made available (ex. Breaking down into constituent nucleotides
→ - ΔG for whole pathway

Question 18

Anabolic Pathways:

Answer 18

Energy is required to build more complex molecules from simple ones. (ex. Dehydration synthesis, making peptides from amino acids, etc.)
→ + ΔG for whole pathway

Question 19

Coupling Reactions

Answer 19

• Use reactions/pathways that release energy to provide it for those that require energy
  → By using a high energy intermediate

Question 20

Hydrolysis of ATP

Answer 20

• GTP can also function to deliver energy as well, but its much more useful with ATP (due to evolution)
• Convenient intermediate for transferring energy between reactions
  -Releasing one phosphate or both to go to ADP

Question 21

Energy Coupling with ATP

Answer 21

• Hydrolize ATP in order to release energy

Question 22

Coupling ATP check slides

Answer 22

• Adding the phosphate onto glutamyl phosphate which is then converted to glutamine + phosphate
• Using ATP to do this reaction

Question 23

ATP/ADP cycle (Cellular Respiration)

Answer 23

• Taking energy from some source, and through chemical reactions we allow that energy to be harnessed so we can convert ADP +P to ATP
• Constantly making ATP in order to do these reactions happen