The model explains how an enzyme can cause kinetic rate enhancement of a reaction and explains how reaction rates depends on the concentration of enzyme and substrate.

Michaelis-Menten Kinetics

Molecule which the enzyme will bond to catalyze a biological reaction.

Substrate

Not all living organisms have enzymes.

FALSE

Without enzymes, most chemicals reactions within cells would occur so slowly that cells would not be able to work properly.

TRUE

Catalysts accelerate the rate of a chemical reaction, sometimes changed but never destroyed.

FALSE

Enzymes are generally named after the substrate affected, and their names usually end in - ase.

TRUE

By temporarily binding to the substrate, an enzyme can lower the energy needed fora reaction to occur, thus making this reaction faster.

TRUE

Once the reaction between an enzyme and a substrate is complete, the substrate is changed to a product and the enzyme exhibit slight changes too.

FALSE

The following are some of the factors that can affect enzyme activity, EXCEPT..

enzyme specificity

Enzymes make anything happen that could not happen on its own, and makes it happen faster.

FALSE

Enzymes are not used up in reactions. They can be used repeatedly!

TRUE

Enzymes are needed in large amounts.

FALSE

Each enzyme can bind to any substrate.

FALSE

Enzymes chemically recognize, bind, and modify substrates.

TRUE

Why are enzymes are highly specific? Select the best answer.

because of their specific 3-dimensional shape

After the reaction is complete, the substrate has formed a new product or products and the enzyme is released to be reused.

TRUE

When the substrate and enzyme bind temporarily, an enzyme-substrate complex is formed.

TRUE

Enzyme specificity is often described using the“Induced-Fit Model” model of enzyme action

FALSE

Which of the following statements is correct?

The active site is the region on the enzyme where the substrate attaches; the shape of the active site determines which substrates the enzyme can bind.

The substrate molecule has a specific 3-dimensional shape that allows it to fit into the specific 3-dimensional shape of an enzyme’s active site.

Lock and Key Model

An interaction between the enzyme and substrate induces or changes the shape of the molecules to produce a suitable fit.

Induced-Fit Model

How do enzymes catalyze chemical reactions?

Enzymes speed up the rate of chemical reactions by lowering the activation energy

If it gets too hot, the enzyme becomes“denatured.”

TRUE

What is the “optimal temperature” for most of the enzymes in our body?

~98.6°F

Which of the following statements is incorrect?

As temperature decreases, kinetic energy increases and molecules are moving more.

Which of the following statements is incorrect?

when the chemical bonds within the enzyme are rearranged, the enzyme shape stays the same.

What is the “optimal pH” for most of the enzymes in our body?

~pH 8

The “optimal pH” for most of the enzymes in YOUR body is ~pH8. However, there are exceptions, such as the digestive enzymes of your stomach, which function in an environment of what pH

~pH3 - 4

How does the concentration of enzyme or substrate affects the enzyme reaction?

When enzyme concentration is low, the rate of reaction is slower.

The rate of reaction increases but by the time the rate of reaction decreases due to:

depletion of substrate

How does the concentration of coenzyme affects the enzyme reaction?

The increase in the coenzyme concentration causes an increase in the rate of enzyme action.

Many enzymes are activated by metal ions.

TRUE

Inhibitors decrease or even abolish enzyme activity.

TRUE

A coenzyme can function alone but can be reused several times when paired with an enzyme.

FALSE

It becomes active by binding of coenzyme or cofactor to enzyme.

aponenzyme

It is formed when associated cofactor or coenzyme binds to the enzyme's active site.

holoenzyme

Coenzymes that bind tightly to a protein yet will be released and bind again at some point.

co-substrate

Enzyme partner molecules that bind tightly or covalently to the enzyme.

co-enzyme

Michaelis-menten Enzyme is a general explanation of the velocity and gross mechanisms of enzyme-catalyzed reactions. It was first stated in what year?

1913

An enzyme that contains a region to which small, regulatory molecules may bind in addition to and separate from the substrate binding site and thereby affect the catalytic activity.

allosteric enzyme

The division of enzymes to six classes was "decided" by what organization?

International Union of Biochemists

These enzymes catalyze the transfer of electrons from one molecule, the reductant, also called the electron donor, to another, the oxidant, also called the electron acceptor.

oxidoreductases

The electron donor is..

reductant

The electron acceptor is..

oxidant

Which of the following is the function of enzymes classified under oxidoreductases?

remove 2H to form a double bond

Which of the following is the function of the enzymes classified under transferases?

transfer specific functional groups from one molecule to another

Which of the following is the function of the enzymes classified under hydrolases?

biochemical catalysts that use water to break a chemical bond

Transfer of functional groups

Transferases

Bonding of molecules using energy from hydrolysis of ATP

Ligases

Dehydrogenase

Oxidoreductases

Dehydrases

Lyases

Peptidases

Hydrolases

Kinase

Transferases

Epimerase

Isomerases

Amylases

Hydrolases

Synthetase

Ligases

Distinguishing feature:

Oxidoreductases

Distinguishing feature:

Tranferases

Distinguishing feature:

Hydrolases

Distinguishing feature:

Lyases

Distinguishing feature:

Isomerases

Distinguishing feature:

Ligases

The ability of an enzyme to choose exact substrate from a group of similar chemical molecules.

Specificity

It is also called relative or low specificity. Enzymes showing this type of specificity are specific to substrates having similar bonds and similar structure.

Bond Specificity

An enzyme reaction for the conversion of glucose to glucose-6-phosphate.

Hexokinase

It is also called moderate or structural specificity. The enzyme is specific to a bond and groups surrounding the bonds.

Group Specificity

Pepsin

endopeptidase that hydrolyzes central peptide bonds in which the amino group belongs to aromatic amino acids.

Carboxypeptidase

an exopeptidase that hydrolyzes peripheral peptide bond at the carboxyl terminal (end) of polypeptide chain.

It is also called absolute or high specificity, since here the specificity is high. Enzymes showing substrate specificity are specific only to one substrate and one reaction.

Substrate Specificity

It is also called stereo specificity. Here the enzyme is specific not only to substrate but also to its optical configuration. It is considered as the highest specificity shown by any class of enzyme in the living world.

Optical Specificity

A single enzyme can act on different substrates having similar molecular geometry and hence, here specificity is very less.

Geometrical Specificity

Enzyme which requires co-factors for their activity show what type of specificity?

Co-factor Specificity

Which of the following is true about Michaelis-Menten?

Used to predict the rate of product formation in enzymatic reactions

Allosteric enzymes typically have multiple active sites and often display _______.

cooperativity

Curve for the non-regulatory enzymes is hyperbolic, as also predicted by the Michaelis-Menten equation, whereas allosteric enzymes do not show Michaelis-Menten relationship because their kinetic behavior is greatly altered by variation in the concentration of modulators.

TRUE

Allosteric enzymes do not follow the Michaelis-Menten Kinetics. This is because allosteric enzymes have single active sites.

FALSE

Multiple active sites exhibit the property of cooperativity, where the binding of one active site affects the affinity of other active sites on the enzyme.

TRUE

Allosteric enzymes are influenced by substrate concentration.

TRUE

Allosteric Enzymes are regulated by other molecules.

TRUE

Enzymes interact with specific substrates

TRUE

Enzymes change shape after a reaction occurs

FALSE

Enzymes speed up reactions.

TRUE

One enzyme can be used for many different types of chemical reactions.

FALSE

Enzyme reactions can be slowed or halted using inhibitors.

TRUE

INCREASE or DECREASE the rate of an enzymatic reaction: Adding more enzyme

INCREASE

INCREASE or DECREASE the rate of an enzymatic reaction: Add more substrate

INCREASE

INCREASE or DECREASE the rate of an enzymatic reaction: Adjusting pH to optimal level

INCREASE

INCREASE or DECREASE the rate of an enzymatic reaction: Add a noncompetitive inhibitor

DECREASE

INCREASE or DECREASE the rate of an enzymatic reaction: Freezing

DECREASE