BIO 120 FINAL Bioenergetics

What is Metabolism?

Energy generation and usage

What is Metabolism carried out largely by?

Enzymes

Anabolism

Build Something Up (examples: photosynthesis, lipid synthesis)

Catabolism

Breaking something down (ex, cellular respiration, glycolysis)

Two major types of energy?

Potential Energy : Ball has potential energy

Kinetic Energy: The potential energy is transformed into kinetic energy

Thermodynamics

-Describes energy and its transformation

-Looks at things as a SYSTEM and its SURROUNDINGS

Thermodynamic Systems

Biological Systems are OPEN SYSTEMS!!

Biological systems are _____ systems. What does this mean?

Open systems. They exchange matter and energy with their surroundings.

Examples : a nucleus, a cell, a goat, an ecosystem

Example of Thermodynamic Systems

A cell

Are matter and energy interchangeable?

E=mc²

Yes they are!

They are just different forms of the same thing

The First Law of Thermodynamics

-Energy can’t be created or destroyed

-However, energy CAN BE transformed and transferred

Second Law of Thermodynamics

-energy and matter MOVE FROM ORDERED TO DISORDED (they will naturally spread out over time )

ex. diffusion

What is the amount of disorder called?

Entropy (S)

Entropy of universe is constantly …

increasing

Biological systems are very ordered, but overall the entropy ______ in surroundings

increases

Gibbs Free Energy (G)

Amount of energy of a system available to do work

What is change in free energy called?

Delta G

Exergonic

System loses free energy

Endergonic

System gains free energy

2 Exergonic examples

-Diffusion across a membrane

-Active Transport

(ENERGY RELEASED from one ion flowing down concentration gradient)

(Use that energy to drive a solute against its concentration gradient)

Enzymes (2 points)

-Biological catalysts that create, destroy, or modify things.

-Catalyze reactions that otherwise happen slowly or not at all

Lock and Key

1)The enzyme's active site has a rigid, pre-formed shape that is perfectly

complementary to the substrate

2)The substrate fits into the active site like a key into a lock, with no conformational

changes

Induced Fit

1)The enzyme's active site is flexible and can change shape upon substrate binding

2)Both the enzyme and substrate undergo conformational changes to achieve optimal

binding

3 Common Ways Enzymes Act

A. Create - Bind two (or more) substrate molecules and

bond them together into one molecule.

B. Modify - Modify substrate

C. Destroy - Break a substrate molecule apart

What analogy to use for activation energy?

It takes a spark to start a fire

What do enzymes do to activation energy?

Enzymes LOWER the activation energy for a chemical reaction

How do enzymes lower activation energy for a reaction?

Enzymes stabilize their substrates in the TRANSITION STATE, which speeds up the reaction.

3 Transition State Examples

A. Enzymes bring substrates close together in specific

orientations that favor reaction, reducing the energy

needed for proper molecular alignment

B. Enzymes can create a charge distribution in the active

site that matches the transition state.

C. By binding substrates, enzymes can induce strain in

specific bonds, making them easier to break.

The ATP Cycle (2 points)

• ATP is regenerated from ADP + Pi

• Most ATP is generated this way (as

opposed to de novo).

When is energy released in the ATP cycle?

Energy is released during hydrolysis of ATP to ADP + P

The reaction in the previous card releases ___ energy so it is _____.

free, exergonic

Use free energy released from ATP hydrolysis (an exergonic reaction) to drive an

_______ reaction.

endergonic reaction.

Factors influencing enzyme activity

-Temperature

-pH

-Concentration of enzyme and substrate(s)

-Other molecules (inhibitors, activators)

Enzymes have consistent with their environment

Example: pepsin is a protease

(breaks up proteins) in the

stomach, where it is acidic.

Example: Trypsin is another

protease that resides in the small

intesting, where the pH is alkaline.

pH optima

Example: pepsin is a protease

(breaks up proteins) in the

stomach, where it is acidic.

Example: Trypsin is another

protease that resides in the small

intesting, where the pH is alkaline.

Enzymatic activity with temperature

increases

At high temps, proteins and enzymes

denature

Example: The enzyme that makes the brown pigment melanin is denatured in

warmer regions of the body

Competitive inhibitors

compete with substrate for binding site

Non-competitive inhibitors

binding somewhere else on the enzyme inactivates

the active site

Non-competitive activators

binding somewhere else activates enzyme