Bio - unit 2a: enzymes/proteins

Energy

The ability to do work, or cause change. The ability to move matter. The ability to rearrange matter.

kinetic energy

Energy of motion. (Heat -Thermal Energy-random movement of atoms or molecules.)

chemical energy

Potential energy released during chemical reactions (Think: organic molecules-biomass)

first law of thermodynamics

Law of energy conservation. Energy (or matter) cannot be created nor destroyed, but can be transferred or transformed.

second law of thermodynamics

In every energy transfer or transformation, some of the energy becomes unusable (unable to be used for work). Some of the energy is converted to heat (disordered-random molecular motion)

metabolism

All of the chemical activities of a cell (anabolic or catabolic)

Enzyme

Biological Catalysts

Globular proteins that act as catalysts. 3-D shape (conformation) and active site.

Most enzyme names end in ASE

Catalyst

Molecules that change the rate of a reaction without being consumed by the reaction.

Speeds up the rate of a reaction that is necessary to sustain life.

(causes reactions to start sooner than they would have without a catalyst/enzyme).

Active site

Catalytic Center.

Pocket or groove on the surface of an enzyme that binds to a substrate. Specific

region in enzyme which interacts with its substrate. (both binding and catalytic

reactions occur here)

Substrate

Reactant(s) that an enzyme binds with and acts upon.

Activation Energy

Initial investment (input) of energy to start a chemical reaction. Enough of an input of energy to cause existing bonds in a substrate to weaken, become unstable, and thus break.

enzyme-substrate complex

Combination of the enzyme and substrate. Substrate bound to the active site of the enzyme—this is where the reaction takes place.

lock and key hypothesis

Lock=enzyme, Key=substrate.

Each substrate in a given reaction can only be acted upon by a specific enzyme. Each enzyme is specific -catalyzes the reaction of particular substrate(s).

Induced Fit hypothesis

As the substrate enters the active site of the enzyme, it induces the enzyme to change its shape (now the active site fits even more snuggly around the substrate). This squeezing of the enzyme on the substrate puts stress on the substrate's chemical bonds and weakens them.

Free Energy

Energy available to do biological work.

Exergonic reaction

Chemical reactions that involve a net release of free energy.

Endergonic reaction

Chemical reactions that involve a net absorption of free energy.

Exothermic reaction

Chemical reactions that release heat.

endothermic reaction

A reaction that ABSORBS energy in the form of heat

Cofactor/Coenzyme

Non-protein helper. Molecule or ion that temporarily joins the enzyme to aid in its function.

Cofactor=Inorganic minerals (zinc, copper, iron)

Coenzyme=Organic vitamins

Denature

Loss of an enzyme's 3-D shape (unfolds) Enzyme loses its conformation and hence its active site. Enzyme is no longer functional(becomes inactive). Conditions such as extremes in pH, temp, salinity, etc. cause enzymes to denature.

Competitive Inhibitor

A chemical that interferes with an enzymes activity competing for the active site of the enzyme (thus blocking the substrate from entering the active site.

noncompetitive inhibitor

A chemical that binds to another site on an enzyme, thus changing the enzymes shape (and its active site) The substrate no longer fits the active site.

Catabolic reaction

Reactions that break down complex molecules into simpler compounds; degradation reactions; releases energy; hydrolysis reaction; exergonic reaction

Anabolic reaction

Reactions that build complex molecules from simpler ones. Requires an input of energy

Endergonic reactions(energy "in")

Condensation reaction (dehydration synthesis)

How an Enzyme lowers activation energy

Microenvironment

Orientation

Direct participation

Straining of bonds