SACE Biology Topic 1

active site

The part of an enzyme or antibody where the chemical reaction occurs.

competitive inhibitor

A substance that reduces the activity of an enzyme by binding to the enzyme's active site in place of the substrate. A competitive inhibitor's structure is complementary to the active site.

non-competitive inhibitor

A substance that reduces the activity of an enzyme by binding to a location remote from the active site, changing its shape so that it no longer binds to the substrate.

enzyme-substrate complex

A temporary complex formed when an enzyme binds to its substrate molecule(s).

Substrate

reactant of an enzyme-catalyzed reaction

product

A substance produced by an enzyme-mediated reaction.

antibody

A protein that acts against a specific antigen. it has a shape complementary to part of the antigen and binds to it to inactivate the threat.

enzyme specificity

Enzyme specificity is the concept that each enzyme catalyzes only one kind of reaction.

induced fit

The change in shape of the active site of an enzyme so that it binds more snugly to the substrate, induced by entry of the substrate.

Effect of temperature on enzyme activity

As temperature increases, so does the rate of reaction up until the optimal temperature. After the optimal temperature, the rate of reaction decreases because the enzyme is denatured.

Effect of pH on enzyme activity

All enzymes work best at optimal pH. above and below the optimal pH the rate of reaction decreases. Extreme pH changes can denature the enzyme.

Effect of substrate concentration on enzyme activity

Increased substrate concentration increases the rate of reaction up until the point when the enzymes are saturated and are all in use.

Effect of enzyme concentration on enzyme activity

Increased enzyme concentration = increased rate of reaction (more active sites available):

Phenotypic expression

The observable physical or biochemical characteristics of an organism, as determined by both genetic makeup and environmental influences. The expression of a specific trait, such as stature or blood type, based on genetic and environmental influences.

Phenotype

the set of observable characteristics of an individual resulting from the interaction of its genotype with the environment.

cellular differentiation

the process by which a cell specializes to carry out a specific role

Epigenetics

the study of influences on gene expression that occur without a DNA change

Epigenome

The instructions that determine what and how genes are expressed in cells.

silenced genes

Genes that are not expressed due to epigenetic changes

Mutation

A change in a gene or chromosome.