Energy and Metabolism

Energy

The capacity to do work, which is any change in the state or motion of matter.

Radiant (sun) energy

The ultimate source of energy for life on earth, primarily from the sun.

Photosynthesis

The most common way organisms capture sun's energy (0.02), converting it to chemical energy in bonds of organic molecules.

Cellular respiration

The process that makes energy available to plants and animals by breaking organic molecules to release usable energy.

Matter

Anything that has mass and takes up space.

Energy

Any change in the state or motion of matter, expressed in units of work (kilojoules, kJ) or units of heat (kilocalories, kcal).

Energy transformation

The process where energy is converted from one form to another, such as kinetic energy to potential (chemical) energy.

Exergonic reaction

A chemical reaction that releases energy to the surroundings, where the bonds being formed are stronger than the bonds being broken.

Exergonic BREAK bonds

Endergonic reaction

A chemical reaction that absorbs energy from the surroundings, where the bonds being formed are weaker than the bonds being broken.

Need/use ATP - Make bonds

Dehydration synthesis

A type of endergonic reaction where energy is absorbed to form bonds.

Thermodynamics

The study of energy transfer, where energy is never completely transferred, and some is converted into heat that disperses into the surroundings (entropy).

Entropy

The collection of all the wasted energy (heat) that decreases the amount of usable energy available to do work.

Kinetic energy

The energy of motion that can be transformed into potential energy.

Potential energy

Stored energy that can be converted into kinetic energy.

Anabolism

Making larger molecules from smaller molecules; are endergonic. e.g.: linking of amino acids to form proteins.

Catabolism

Larger molecules broken into many smaller molecules; releases energy (ATP). e.g.: degradation of starch to form monosaccharides.

What are the 2 metabolic pathways?

Anabolic and Catabolic

What is ATP?

Energy currency of the cell. Consists of adenine, ribose, and three phosphate groups.

Cells maintain high levels of ATP and constantly use its ATP stores.

Hydrolysis of ATP

Yielding ADP and inorganic phosphate is an exergonic reaction.

Activation Energy

The energy required to break the existing bonds and begin a reaction.

If none of the particles has enough energy to react, energy must be added from outside to activate the reaction.

Energy of Activation (EA)

Also referred to as Activation Energy; affects the rate of chemical reaction.

Enzymes

Biological catalysts that increase the speed of a chemical reaction without being consumed by the reaction.

REDUCE activation enerygy. (aka, catalyst)

All enzymes tend to have what shape?

All enzymes tend to be tertiary and have a very specific temperature and pH.

Denaturation of Enzymes

Enzymes denature if they are exposed to an unusual temperature, pH, etc.

Each enzyme has ___ and binds to ____ ?

Each enzyme has an active site that binds to reactants (substrates).

Enzyme-Substrate Complex

Enzyme has a lot of affinity (ability to bind to) for the substrate, but not with the product.

Apoenzyme

Protein component that is the inactive form of the enzyme.

Cofactor

A molecule that binds to apoenzyme and activates it.

All enzymes generally need a cofactor.

Holoenzyme

Apoenzyme + Cofactor. (becomes whole)

Coenzyme

An organic, nonpolypeptide compound that binds to the apoenzyme and serves as a cofactor.

Non-protein

Enzymes do NOT need

How do cells control the activity of some enzymes?

By altering the enzyme's shape.

Regulatory molecules bind to an allosteric site on the enzyme.

Inhibitors

Molecules that may bind to the enzyme and slow down its activity.

Activators

Molecules that may bind to the enzyme and increase its activity.

Cyclic AMP

Removes the allosteric inhibitor and activates the enzyme.

Competitive Inhibition

Occurs when an inhibitor binds to the enzyme's active site, blocking the substrate from binding.

Non-competitive Inhibition

Occurs when an inhibitor binds to an enzyme's allosteric site, causing the enzyme to change shape.

Feedback Inhibition

The final product is an inhibitor for the first enzyme in a metabolic pathway. (say's that's enough!)

Flow of Energy

Plants photosynthesize and then are eaten by organisms and the energy is transferred.

When a plant is eaten by an animal, the animal does not receive all of the energy from the plant.

What Links Exergonic and Endergonic Reactions?

ATP