BIOL 101 Homework Learn It Enzymes solutions complete answers

BIOL 101 Homework Learn It Enzymes solutions complete answers 

 

Learn It: Explain how enzymes speed up chemical reactions.
At any given moment, there is a seemingly endless number of reactions taking place within organisms. Constant reactions are either breaking down molecules or building molecules. Although the types of reactions occurring may vary, in all cases the molecules involved are moving about randomly. When two molecules collide, there is the potential for a reaction. When explaining this concept in class, instructors will often have students close their eyes and begin walking around. Without seeing where you are going, you are moving about randomly, mimicking molecular movement. As a result, there is a high probability that you will collide with a desk, a chair, or another student. As you might imagine, you will probably collide with many things while carrying out this exercise in class. So, it's obvious that the probability of colliding with something random is high and will happen rather quickly, but what about colliding with something very specific? Now, that might take a while!

The same thing applies to molecules. There is a high probability that molecules will collide with one another as they move about randomly. But colliding with just the right molecule needed for a reaction? That has a much lower probability of occurring.

As mentioned previously, the types of reactions taking place vary, but they all have one thing in common; they require specific amounts of energy to begin. The amount of energy required for a chemical reaction to begin is called the activation energy, and that's where enzymes come in; they lower the activation energy needed for a reaction to begin.

Enzymes can speed up the rate at which chemical reactions occur by interacting with the specific molecules needed for the reaction. Another way of saying that is that enzymes catalyze reactions. For example, in the figure you will notice two molecules or reactants, reactant A and reactant B-C. These reactants, like other molecules, move about randomly. While the probability of these two specific reactants colliding may be low, an enzyme can speed up or catalyze the reaction by binding to the reactants and bringing them into close proximity so the reaction may occur, thus increasing the probability of obtaining the products of the reaction (A - B + C).

 

Enzymes are molecules with binding pockets, or active sites, where specific reactants, or substrates, can bind. Each particular enzyme has just the right shape, size, polarity, and charge to favor its interaction with its specific substrates. With the action of enzymes, organisms can carry out the seemingly endless number of reactions occurring within them in a much shorter time frame.

 

Enzymes catalyze chemical reactions by doing which of the following?

     Decreasing the activation energy of the reaction

   Decreasing the number of products formed

   Increasing the amount of time needed to complete a reaction

   Increasing the number of reactants

 

Which of the following best describes the activation energy of a reaction?

The amount of energy required for a reaction to start

     The amount of energy released from a chemical bond

   The amount of energy stored in the substrates

   The amount of energy stored in the enzyme

 

How can an active site best be described?

     The area within an organism where the most reactions take place

   A pocket on an enzyme where substrate binds

   The region of a substrate that binds to an enzyme

   The region of a substrate that forms chemical bonds

 

How do enzymes lower the activation energy of chemical reactions? Select all that apply.

     Bringing products closer together

   Increasing the number of reactants available

   Bringing reactants closer to one another

Orienting reactants correctly in space for chemical reactions to occur

 

Which of the following reaction elements can be changed by an enzyme? Select all that apply.

     The initial concentration of reactants

   Activation energy

   The energy of the products of a reaction

Time required for many reactions to occur

 

Enzymes decrease the activation energy of a reaction by  the reactants and  the reaction. After the reaction has finished, the enzyme