Enzyme practice test

ENZYME PRACTICE TESTPush F5 and use the arrow keys to quiz yourself and check the answers

1

Enzymes are what type of macromolecule?

Protein

Question… do you know all four types of macromolecules?

Protein, lipid, nucleic acid, and carbohydrate

2

Starch and sugar (monosaccharides) are both examples of what type of macromolecule?

Carbohydrate

3

How do we test for starch? What do the negative and positive results look like?

We use iodine to test for starch Negative = brown Positive = purple

4

How do we test for sugars? What do the negative and positive results look like?

We use Benedict’s Solution to test for starch Negative = clear blue Positive = cloudy and a color change

5

What monomers is a starch molecule made of?

Starch is made of many glucose molecules bonded together in a long chain

6

What does the enzyme amylase do?

Amylase breaks a starch molecule up into the individual glucose monomers

See the next slide for a visual representation of this process

7

If you were to leave starch in your mouth and mix with the amylase in your saliva, how would the food taste after 5 minutes? Why?

The food would taste sweet The amylase broke the bonds in the starch

molecules, so after a few minutes all you’d be left with is glucose, which is a sugar

If this is totally blowing your mind, go back to the previous slide and think about it. Or try doing it yourself and see how it goes

8

If you were to put catalase into a beaker of starch solution, what would happen? WHY?

Nothing would happen! Enzymes are specific. Like a lock and a key,

they only work on the reaction that includes substrates that fit their specific shape.

Catalase is only able to react with hydrogen peroxide- it has the wrong shape for starch

So, catalase is not able to break down starch molecuels

9

What is a catalyst?

A catalyst is anything that speeds up a reaction

Enzymes are a type of catalyst If something is said to be catalyzed, it means

the reaction was sped up by something For example, the hydrolysis of starch is

catalyzed by the enzyme called amylase

10

Write the chemical formula for the reaction catalyzed by the enzyme catalase. Do it in words AND in chemical formulas

Hydrogen Peroxide Water + Oxygen H2O2 H2O + O2

11

In a chemical reaction, what are the reactants?

Reactants are the things you start with in a chemical reaction

H2O2 H2O + O2

12

In a chemical reaction, what are the products?

Reactants are the things you end up with in a chemical reaction

H2O2 H2O + O2

13

In enzyme catalyzed reactions, reactants have a special name. What is the special name?

Substrates

In enzyme-catalyzed reactions, the word reactant and substrate means the same thing

H2O2 H2O + O2 In this case, the hydrogen peroxide can be called a substrate

14

When a potato is dropped into hydrogen peroxide, bubbles start to form. What are those bubbles?

O2 or oxygen gas

15

When a potato is dropped into hydrogen peroxide, bubbles start to form. What liquid would be leftover in the beaker if this reaction were to go to completion?

Water

16

What does excessive heat do to an enzyme?

Since enzymes are proteins, high temperatures cause the shape to change

When the shape changes, the enzyme doesn’t function correctly anymore

17

What is activation energy?

Activation energy is the amount of energy needed to get a reaction started

18

How are enzymes able to speed up reactions?

Enzymes lower the amount of activation energy needed to start a reaction

Don’t be fooled! Enzymes don’t provide energy or raw materials, they just provide a way for the reaction to take place that needs less activation energy.

19

After an enzyme releases the products of the reaction, what happens to the enzyme?

Nothing! Enzymes are like car keys- they can be used

over and over again (for the same car) as long as they aren’t damaged

The enzyme keeps it same shape and doesn’t get used up, so it’s able to keep catalyzing the reaction

20

How would the starch and water solution perform on these tests? Why?

It would test positive for starch and negative for sugars

Starch reacts with iodine so it tests positive for starch. But, the Benedict’s test doesn’t react to the glucose molecules because in starch, they’re all stuck together

Solution Positive (+) or Negative (-) for Starch

Positive (+) or Negative (-) for Simple Sugars

Starch and Water

21

How would a solution of starch, water, and amylase perform on these tests? Why?

It would test negative for starch and positive for sugars

The amylase breaks the bonds in the starch molecule, leaving only sugars. Therefore, it will no longer test positive for starch but the Benedict’s test will test positive for the sugars

Solution Positive (+) or Negative (-) for Starch

Positive (+) or Negative (-) for Simple Sugars

Starch Water and Amylase

22

What molecule is this?

This is a starch molecule It is made up of many glucose molecules

bonded together I know those are glucose molecules because

glucose has six carbons, and therefore it has six sides (hexagon)

23

When a student drops a piece of potato into a beaker of hydrogen peroxide, bubbles start to form. What was in the potato that made this happen?

The potato cells contain an enzyme called catalase.

23

Is this graph indicative of how enzymes react to different pH levels or concentration levels? How do you know?

This is what happens in different pH levels. Low and high pH levels cause the shape of the

enzyme to change, therefore it doesn’t work correctly anymore and the activity level goes down.

24 Is this graph indicative of how enzymes react to

different temperatures or concentration levels? How do you know?

Different concentration levels Increasing the concentration causes the activity

to go up at first. But once you reach a certain point, there are already enough helpers (enzyme molecules) to handle the substrates that are there

25 Is this graph indicative of how enzymes react to

different temperatures or concentration levels? How do you know?

This is what happens in at different temperatures High temperatures cause the shape of the

enzyme to change, therefore it doesn’t work correctly anymore and the activity level goes down.

Low temperatures cause reactions to take place more slowly, whether there is an enzyme present or not