Enzymes

What is the definition of the substrate active site of an enzyme?

a pocket on the enzyme where a substrate binds

Enzymes influence chemical reactions in living systems by?

affecting the rate at which reactions occur

These do not compete with an enzyme's substrate for the active site. Instead, they attach to another site on the enzyme, causing a change in the enzyme's shape. This is the definition of what term?

allosteric inhibitor

The activity of enzymes may be affected by?

allosteric inhibitors

At high temperatures, the rate of enzyme action decreases because the increased heat?

alters the active site of the enzyme

noncompetitive inhibitor

binds at a site distinct from the active site, causing change in enzyme shape and function

competitive inhibitor

binds at the active site but no reaction occurs

How do enzymes catalyze reactions?

by lowering the activation energy required for the reaction to occur

Denature (verb)

destroy the characteristic properties of (a protein or other biological macromolecule) by heat, acidity, or other effects that disrupt its molecular conformation.

The "lock and key hypothesis" attempts to explain the mechanism of?

enzyme specificity

Cofactor

enzymes that require ions or other molecules to function

feedback inhibition

the final product acts as an inhibitor of the first enzyme, which shuts down the pathway.

Noncompetivie inhibitors have the ability to change the shape of the active site in such a way that it loses affinity for its substrate.

true

metabolic pathways

Enzyme-catalyzed reactions operate here

The enzyme binds to its substrate, forming what?

Enzyme-substrate complex

Lock and Key Model

Enzymes are specific. The only wok on the substrate that they "fit." Just like a lock has a specific key to open it.

True or false: Enzymes fit with any shape of molecules.

FALSE. Each substrate/reactant has a unique shape. The have a specific substrate the work on

True or False: Enzymes start chemical reactions.

FALSE. Enzymes don't start reactions- they SPEED UP reactions that would occur eventually.

Irreversible inhibition

Inhibitor covalently binds to a side chain in the active site. The enzyme is permanently inactivated. Some insecticides act in this way

V-max

Maximum velocity. Enzyme is completely saturated with substrate.

Allosteric sites can be modified by

Noncovalent binding; Covalent binding of a molecule or chemical group

Each enzyme has an optimal _________ and _________ in which it can function.

Temperature; pH

An enzyme's activity can be affected by what three factors?

Temperature; pH; Concentration of the Substrate

What is the active site?

The active site is the region on the enzyme where the substrate binds.

Activation Energy

The energy required to initiate a reaction.

Enzyme substrate

The reactant that an enzyme acts on

A competitive inhibitor of an enzyme-catalyzed reaction?

is usually structurally similar to the substrate

Allosteric

non-substrate molecule binds a site other than the active site

Inhibitors can be produced by the cell to?

regulate metabolism

Any substance that is acted upon by an enzyme is called a?

substrate