Enzymes Flashcards

Flashcards for reviewing key concepts about enzymes.

What are enzymes?

Biological catalysts that speed up chemical reactions by lowering activation energy.

What role do enzymes play in biological processes?

Enzymes break down the primary structure of molecules and are highly specific.

What are enzymes made of?

Enzymes are typically proteins, except for ribozymes which are RNA molecules with enzymatic activity.

What is an example of a protease enzyme and its function?

Trypsin catalyzes the hydrolysis of peptide bonds formed by the carboxyl group of lysine and arginine.

What peptide bonds does Trypsin catalyze?

Trypsin catalyzes the hydrolysis of peptide bonds formed by the carboxyl groups of lysine and arginine.

Name three classes of Enzymes.

Oxidoreductases, Transferases, and Hydrolases.

What is the function of oxidoreductases?

These enzymes catalyze oxidation-reduction reactions, like lactate dehydrogenase.

What is the function of transferases?

These enzymes transfer functional groups, such as the aspartate amino transferase in the Krebs cycle.

What is the function of hydrolases?

These enzymes catalyze hydrolysis reactions, like acetylcholinesterase in the muscular system.

Splitting agent

Breaking down molecule by adding water.

Where are enzymes synthesized?

Ribosomes attached to the Rough Endoplasmic Reticulum (RER).

How are enzymes classified?

All classes; determined by the reaction they catalyze.

What is the composition of a holoenzyme?

Apoenzyme (inactive protein portion) + Cofactor (non-protein activator) = Holoenzyme (active whole enzyme).

What happens if the enzyme concentration doubles

Rate increases linearly.

How does substrate concentration affect the rate of an enzyme-catalyzed reaction?

The rate increases with increasing substrate concentration until the enzyme is saturated.

What effect does temperature have on enzyme Activity?

Enzyme activity decreases and enzymes can become denatured.

What conditions do enzymes function best in?

Enzymes have optimal activity at a certain temperature and pH.

Are enzymes affected by pH?

Enzymes are active at a certain pH and are used to digest food.

How does the enzyme function according to Lock-and-Key model?

The substrate binds to the portion of the enzyme with a complementary shape.

What does lock and key model fail to explain?

Lock and key model fails to explain complimentary.

The induced fit model

Complimentary fit.

How does the enzyme function according to Induced-fit model?

Binding of the substrate induces a change in the conformation of the enzyme that results in a complementary fit.

What is the function of an Inhibitor?

Inhibitors interfere with the substrate-active site binding and slow down the catalytic rate.

Competitive Inhibition definition

Substance binds to it before the substrate.

What is the mechanism of action for noncompetitive inhibition?

The inhibitor binds itself to a site other than the active site (allosterism), thereby changing the conformation of the active site.

Competitive inhibition

Interferes with the active site of enzyme.

Non competitive inhibition

Changes the shape enzyme so it cannot bind to the substrate.

What are antiviral drugs?

They attack the immune system.

How do protease inhibitors work against HIV?

Protease inhibitors prevent HIV from replicating by blocking protease.

What roles can Enzymes provide?

Can provide alternative pathway to broken bonds and new ones are formed.

How do enzymes affect activation energy?

Lowers the activation energy for a reaction, making the transition state more favorable.

What enzyme is a hormone produced by P1?

CRH.

How do inactive molecules reach their active form?

Inactive. Zymogen prothrombin to thrombin.

Allosterism

Enzyme regulation based on an event occurring at a place other than the active site but that creates a change in the active site.

Allosterism definition

regulator binds (activating chemical reaction)

Negative modulation

Inhibition of an allosteric enzyme

Positive modulation

Stimulation of an allosteric enzyme.

Kinase Enzymes

Add phosphate to proteins wherefore Tephosphorylation; Enzymes active or inactive.

Isozymes

Multiple enzymes catalyzing the same reaction.

Inhibitor

Interferes with the substrate-active site binding and slows down the catalytic rate.