Name ________Fisher KEY_________

What Are Action Molecules? – 60 Informal PointsIntroduction

Chemical reactions are essential for life and occur in all living tissues. Regulating homeostasis depends upon properly maintaining these reactions. Enzymes are an important component for that maintenance. Enzymes are a type of protein called catalysts. A catalyst facilitates or helps a reaction to occur more readily by reducing the energy required for the reaction to occur. The catalyst is not part of the actual reaction, does not change the chemical reaction, and is not permanently altered by reaction. It does however facilitate the reaction and can be used over and over again.

Most chemical reactions in the body are dependent upon enzymes. Enzymes are highly specific and work on only one substance called its substrate. In this research activity, you will learn why enzymes are specific for a particular substrate.

ProcedurePart A: Enzymes

1. Use the Internet or other resources to research the following information about enzymes.

Vocabulary Term Definition/Description

Chemical Reaction Reactants Products

Reactants

The molecules that are used and changed in a reaction.

Products

Chemical substances formed as a result of a chemical reaction. They are always located on the right of the reaction.

Activation Energy

The minimum amount of energy needed to start a reaction.

Catalyst

A substance that speeds up the rate of a chemical reaction. Enzymes are catalysts.

Enzyme

A protein that acts as a biological catalyst to speed up reactions by lowering the activation energy.

Substrate

The reactant molecule that an enzyme binds to and changes.

Active Site

The part of the enzyme that binds to the substrate; it is where the “action” happens. For example, it may break the substrate into two or more pieces or it may take pieces of substrate and “glue” them into one bigger molecule.

A specific receptor site on an enzyme that is not the active site.

Allosteric Site

Enzyme-Substrate Complex

A large molecule formed by the bonding of an enzyme and its substrate.

Competitive Inhibitor

A molecule that reduces the activity of an enzyme by binding to the active site in place of the substrate because it mimics the structure.

Non-Competitive Inhibitor

A molecule that reduces the activity of an enzyme by binding to the enzyme at a location that is NOT the active site to change the shape of the enzyme so that the enzyme cannot bind to its substrate. (Also known as allosteric inhibitor.)

Allosteric Inhibitor

A molecule that reduces the activity of an enzyme by binding to the enzyme at a location that is NOT the active site to change the shape of the enzyme so that the enzyme cannot bind to its substrate. (Also known as non-competitive inhibitor.)

Reversible Inhibition

Enzyme inhibition that can be reversed since the inhibitor is attached to the enzyme by weak bonds that can be easily broken to remove the inhibitor and restore enzyme function.

Irreversible Inhibition

Enzyme inhibition that CANNOT be reversed since the inhibitor is attached to the enzyme by strong bonds that cannot be broken so enzyme function is never restored. The enzyme is permanently inactivated.

Feedback Inhibition

When the end product of a reaction acts as an enzyme inhibitor.

2. Answer the following questions in as much detail as possible:

a. Why are enzymes important?

Enzymes act as biological catalysts and speed up reactions by lowering the activation energy. They are NOT altered or changed by a reaction and are recyclable and can be reused over and over in a reaction.

b. Where are enzymes made?

Enzymes are proteins so they are made on the ribosomes, which are present in the cytoplasm of ALL cells, including prokaryotes. Prokaryotes are the simplest of cells, such as bacteria, and lack membrane-bound organelles. Ribosomes do not have membranes as many other organelles do. Ribosomes are free floating for bound to the rough endoplasmic reticulum (rER.) All living cells must be able to make ribosomes for life.

c. How are enzymes named? Give an example.

Enzymes end in “ase” and are commonly named after the substrates they have an effect on.

Ex. Sucrase breaks the sugar sucrose into glucose and fructose.

d. Describe the basics of the “Lock and Key” model of enzyme action.

e. Describe the basics of the “Induced Fit” model of enzyme action.

f. What factors can affect enzyme function?

Extreme heat can denature (change the shape of) the enzyme. pH, enzyme concentration, substrate concentration, and the presence of inhibitors also all affect enzyme function.

Ex. Pepsin works best in an acidic environment. It is produced in the stomach (pH = 2) and breaks down protein. When the environment becomes less acidic (or more basic) pepsin does not work as well.

3. Create a concept map or drawing/diagram showing how the “Lock and Key” model works. Be sure to label all pertinent vocabulary terms.

4. You must understand and know all forms of inhibition. Choose one form of inhibition and create a concept map or drawing/diagram showing how the model works. Be sure to label all pertinent vocabulary terms.

Inhibition Types: Competitive, Non-Competitive, Allosteric, Reversible, Irreversible, Feedback

Competitive:

Non-Competitive (Allosteric):

Feedback Inhibition:

Part B. Co-enzymes (a type of cofactor)5. Another aspect of enzyme function involves organic molecules called co-enzymes. These molecules are

an important part of your diet.

6. Use the Internet to research co-enzymes. Answer the following questions in as much detail as possible:

a. Describe the function of co-enzymes.

A non-protein molecule that is necessary for the functioning of an enzyme. Coenzymes are also known as cofactors.

b. Identify three different co-enzymes and identify foods that are good sources for these co-enzymes.

Vitamins are often precursors to coenzymes, which means they become coenzymes in the body.

Ex. Niacin (Vitamin B3) functions as two coenzymes, NAD and NADPH in the body which is required for cellular respiration. Niacin can be found in Turkey, chicken, peanuts, mushrooms, tuna, green peas, etc.

Remember, cell respiration occurs in the mitochondria of plant and animal cells. It takes glucose and turns it into ATP, which is the only usable form of energy.

Ex. Riboflavin (Vitamin B2) which aids in the breakdown of food. Found in beef, liver, mushrooms, spinach, almonds, etc..

Ex. Pantothenic acid (Vitamin B5) lowers stress, prevents hair loss, reduces anxiety. Found in fish, pork, chicken, milk, yogurt, mushroom, etc..

7. Return to the concept map or drawing you made in #3 about enzymes and expand it to include co-enzymes.

Conclusion Questions

1. Why do enzymes only work on their specific substrates?

Because it's either a lock and key, or an induced fit.

2. What would happen if there were no enzymes in the human body? Explain your answer.

If there were no enzymes in the human body, chemical reaction would not be able to take place, food would not be able to be digested, and the nutrients from the food would not be able to be transported and broken down. Enzymes are needed for most chemical reaction to take place at the right speed, and enzymes aid in breaking down food and transporting nutrients to the body.

3. Why is it important to eat a balanced diet containing essential vitamins?

It is important to eat a balanced diet containing nutrients to allow your body to receive the right amount of nutrients, including enzymes and co enzymes, so your body can function. It is also important to eat a balanced diet so your body has energy, and can function properly.