Energy and Metabolism

Some chemical reactions ____ energy and some ____ energy

require, release

Cells must continually ___ more energy to replenish what

they lose from energy-requiring reactions

obtain

Metabolism

all the chemical reactions that happen

inside cells

Breakdown of glucose, a simple sugar

C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + energy

Synthesis of glucose (opposite reaction)

6CO₂ + 6H₂O + energy → C₆H₁₂O₆ + 6O₂

What is the “energy” in the breakdown and synthesis of glucose?

ATP

What is ATP (Adenosine triphosphate)?

primary energy currency of all cells

Metabolic Pathway

A series of biochemical reactions that convert a substrate

molecule into a final product

What are the two metabolic pathways?

1.) Anabolic

2.) Catabolic

Anabolic pathway

Requires an input of energy to synthesize

complex molecules from simpler ones

Example of an anabolic pathway

Nucleic acids to DNA

Catabolic pathway

the breaking down of complex molecules

into simpler ones

What is an example of a catabolic pathway?

complex proteins to amino acids

Which pathway requires energy (ATP)

Anabolic pathway

Which pathway releases/makes energy (ATP)?

Catabolic pathways

Bioenergetics

the study of energy flow through living

systems (including cells!)

Energy

the ability to do work

Three types of energy

1.) Kinetic

2.) Potential

3.) Chemical

Kinetic energy

energy resulting from objects being in

motion

Potential energy

the potential of an object to do work

Chemical Energy

Potential

energy that exists within chemical

bonds that is released when the

bonds break

In the breakdown and formation of glucose, what type of energy is involved?

Chemical energy in the form of ATP

Thermodynamics

The study of energy and energy

transfer involving physical matter

First law of thermodynamics

“Law of Conservation of Energy”; energy cannot be

created or destroyed

What does the law of conservation of energy detail?

1.) The total amount of energy in the universe remains constant

2.) But energy can be redistributed from place to place or

changed into different forms

What is the second law of thermodynamics?

Every energy transfer involves some loss of

energy in an unusable form (mostly as heat), resulting in a

more disordered system

Can energy transfer be completely efficient? (2nd Law)

No energy transfer is completely efficient. All transfers

trend toward disorder unless energy is constantly used to

maintain order

What happens when more energy in the system is lost to the surroundings?

The system becomes less ordered and more random (increased entropy)

Entropy

the measure of randomness or disorder within a

system

Free energy (Gibb’s, G)

A measure of how much energy is available to do work

(usable energy). Specifically, the energy that is available after we account for entropy

The amount of free energy available ___ as chemical

reactions happen (use and create energy)

changes

What is Gibb’s free energy measured as?

delta G (ΔG; change in free energy following a

chemical reaction):

What is the Gibb’s free energy equation?

ΔG = ΔH – TΔS

What is ΔG in ΔG = ΔH – TΔS?

The amount of usable energy

What is ΔH in ΔG = ΔH – TΔS?

Enthalpy

What is enthalpy?

The total amount of energy

What is T in ΔG = ΔH – TΔS?

The absolute temperature

What is ΔS in ΔG = ΔH – TΔS?

The amount of energy lost to entropy

So, ΔG = ΔH – TΔS is basically

Usable energy = Total energy - Unusable energy

ΔG is negative:

energy was RELEASED during the chemical reaction

Exergonic reaction:

a reaction that has a negative ΔG,

decreases free energy, and increases entropy; spontaneous

reactions

ΔG is positive:

energy was required for the chemical

reaction to occur

Endergonic reaction

a reaction that has a positive ΔG,

increases free energy, and decreases entropy; non-

spontaneous reactions

Release of energy = ?

less available usable energy (free energy)

What type of reaction is this?

Exergonic reaction

What type of reaction is this?

Endergonic

Which reaction type is spontaneous?

Exergonic