Enzymes

At what temperature is enzyme activity the greatest

At about 37 degrees Celsius

How do enzymes do this

By lowering the activation energy (the energy needed to start a reaction)

Why do cells use different enzymes to catalyze different reactions

Cells must use different enzymes to catalyze different reactions due to the specifications of the enzymes. Each enzyme has a shape specific to the shape of its substrate.

How are enzymes needed

Enzymes are needed in small quantities and can be reused

Is an enzyme "used up" by the reaction it catalyzes? Explain.

Enzymes are not used up by the reactions they catalyze. During a reaction, the enzyme combines loosely with its substrate. When the reaction is finished, the two separate, leaving the enzyme unchanged.

How do enzymes help accelerate reactions

Enzymes lower activation energy needed for chemical reaction

Increasing the temp. or pH will

Increase a reaction to a point at which it will then decrease (the enzyme will start to denature or break down)

Increasing the amount of substrate or enzyme will

Increase the reaction to a point at which it will remain constant

Could life exist without enzymes? Explain

It could not exist, because biochemical reactions of the life processes do not occur rapidly enough without enzymes to sustain life.

What are the 2 theoretical models for enzyme-substrate complexes

Lock and key and induced fit

Enzymes have_________

Optimum pH and temperatures (at which they work best)

Enzyme actions are ____

Reversible (a+b-> c and c->a+b)

The substance with which an enzyme reacts

Substrate

What is meant by enzyme specificity

The active site on an enzyme has a complex configuration with which only one substrate molecule fits. Thus, the enzyme forms a complex with only one type of molecule. Lock and key concept

What is the induced fit?

The enzyme adjusts to fit the substrate when it binds to it

What is the lock and key

The enzyme and the substrate match up and fit together like puzzle pieces

What is the x

The point of saturation

What do enzymes enter a reaction with?

They enter into the reaction with the substrate at the active site such as hydrogen bonds (a substrate which is H2O2)

What is the optimum ph for pepsin? As ph increases above that point, what happens to enzyme activity?

4.4; above that point, it's activity decreases

In what way does an enzyme affect the reaction it catalyzes? How does the enzyme produce this effect?

An enzyme increases the rate of reaction it catalyzes. It does this by combining with the substrate to form a highly reactive enzyme-substrate complex. When the reaction is completed, the enzyme and newly formed reaction product separate.

What do enzymes permit

Permit reactions to proceed under milder conditions of temperature and pH (human temp. of 98.6, blood pH near 7)

What are enzymes

Proteins

Enzymes are ____

Specific (fit together like a lock and key, 1000-4000 per cell with many ending in -ase)

What is a catalyst

Substrates that cause a reaction to occur at a faster rate without being affected.

What is the active site of an enzyme

The active site is the part of the enzyme into which the substrate fits.

How does increasing substrate concentration affect the rate of enzyme action when enzyme concentration remains constant

The rate if substrate action increases to a certain point, but above that point it remains constant

How does increasing enzyme concentration affect the rate of enzyme action when the substrate concentration remains constant

The rate of enzyme action increases at a certain point, but above that point it remains constant

How is the rate of enzyme reaction regulated?

By the relative amounts of enzyme and substrate

What are all enzymes

Catalysts but not all catalysts are enzymes

What is the relationship among enzymes, energy, and reaction rates

Chemical reactions cannot proceed without a certain level of energy, the activation energy. Typically, temperatures in a cell are not high enough to provide the activation energy. Enzymes speed the rates of reaction by lowering their activation energies

Enzymes many be assisted by what

Coenzymes (such as vitamins)

What are the characteristics of enzymes? Why are enzymes essential to life

Enzymes are usually proteins that speed up the rate of chemical reactions. Typically, an enzyme is specific for a chemical reaction. Without enzymes, chemical reactions would proceed too slowly for life to exist.

Describe and enzyme

Globular, usually quaternary structure