End of Marking Period is November 7th - Parent Teacher Conference is November 20th and 21st

Lesson 4

Effect of PH on Enzyme Activity

Learning Intention

Students will be able to determine whether mixing vinegar with an enzymatic solution would make it more or less effective and why.

Success Criteria

Reminders:

We are now in Marking Period 2.
Biochemistry quiz this tuesday

Agenda

Activity 1: Student Choice Warm-Up

Activity 2: Turn n' Talk #1

Activity 3: Student Discovery

Activity 4: Turn n' Talk #2

Activity 5: Stop n'Jot

Activity 6: Create a Graph

NGSS Standard

HS-LS1-6.

Construct and revise an explanation based on evidence for how carbon, hydrogen, and oxygen from sugar molecules may combine with other elements to form amino acids and/or other large carbon-based molecules.

Activity 1

Student Choice

Warm-Up

sc1 (8 min)

Part 2

Turn n' Talk

UNO

sc 2 - (2 min)

Mr. Pinho didn't believe that the enzymatic cleaner alone would clean his t-shirt. So he also applied white vinegar to the shirt along with the enzymatic cleaner. Turn and talk, will mixing the chemicals do a better job of cleaning his shirt stains?

Part 3

Student

Discovery

sc4 - (10 min)

Directions:

Try to figure out on your own what PH is and why it would affect enzyme activity.

When you are done with your resource, answer the three questions below in your notebook:

How pH Affects Enzyme Activity

Paragraph 1:
Inside every living thing, special proteins called enzymes help chemical reactions happen faster. Enzymes work like tiny tools inside our cells—they help break down food, build important molecules, and keep the body running smoothly. But enzymes can only work well under certain conditions. One of the most important conditions is pH, which is a measure of how acidic or basic something is.

Paragraph 2:
The pH scale goes from 0 to 14. A pH of 7 is neutral, like pure water. Numbers below 7 are acidic, like lemon juice or stomach acid, and numbers above 7 are basic, like baking soda. Every enzyme has a best pH, called its optimal pH, where it works the fastest. If the pH changes too much, the enzyme slows down and may not work well.

Paragraph 3:
Why does this happen? Enzymes have a specific shape that allows them to fit with the molecules they work on. If the pH is too high or too low, it can change the enzyme’s shape. When the shape changes, the enzyme may no longer fit with its molecule, so the reaction slows down or stops. This process is called denaturation, which means the enzyme’s structure has been damaged.

Paragraph 4 (Revised):
Different enzymes in the body work best at different pH levels. For example, the enzyme pepsin in your stomach works best in very acidic conditions because stomach acid has a pH around 2. In contrast, the enzyme in your saliva—amylase, which begins breaking down starches in your mouth—works best in a more neutral environment. Saliva usually has a pH close to 7, which helps amylase start digestion before the food even reaches your stomach.

Paragraph 5:
If the pH in an environment changes suddenly, enzymes can stop working as well. This can happen in lakes and rivers when pollution changes the pH, affecting the enzymes inside plants and animals. It can also happen in the human body if illness changes the pH in certain areas. When enzymes do not work properly, important life processes slow down, showing how vital pH is for life on Earth.

Questions:

1) What does the pH scale measure, and what pH value is considered neutral?

2) How can a change in pH affect the shape and function of an enzyme?

3) Why does the enzyme amylase in saliva work best around a pH of 7 instead of a very acidic or very basic pH?

Part 4

Turn n'Talk

TWO

sc3- (5 min)

Turn and talk to your table. Discuss whether Mr. Pinho would get better results mixing the enzyme cleaner with vinegar.

Use the below vocabulary in your discussion:

Enzyme

Substrate

Macromolecule

Amino Acids

Simple Sugar

Fatty Acids

Activity 5

Stop n' Jot

(5 min)

Key Concept:

Enzymes are some picky proteins!!!

They do not work well outside of their OPTIMAL pH.

Each type of enzyme has an optimal pH where they work best. Outside of this pH range, the enzyme does not work.

Optimal:

The best or most favorable.

Activity 7

Turn n'Talk #3

sc5 - (5 min)

Use because, but and so in a paragraph to describe whether mixing vinegar and enzyme cleaner would be MORE likely or LESS likely to clean Mr. Pinho's shirt

Enzyme

Substrate

Macromolecule

Amino Acids

Simple Sugar

Fatty Acids

Activity 8

Graph

sc5 - (5 min)

Directions:

Draw the relationship between pH and enzyme activity on the graph below for an enzyme that has an optimal pH of 7 and a pH range of 3 to 5. Hit the envelope button in the top right corner to send your answers to us.

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