section 5 proteins and enzymes
TRANSCRIPT
Section 5
Proteins and Enzymes
Starter Activity:
Write down as much as you can on a show me board about making proteins.
Proteins
Learning Intention:
• Identify the functions of a variety proteins.
Success Criteria:
• Research the functions of proteins and complete a scavenge hunt.
Watch and Listen
• Protein Video Clip
Types of proteins
Structural Enzyme Hormones Antibodies Receptors
Types of proteins
•There are five types of proteins to consider.
Scavenger Hunt In your teams:
• Answer the questions about proteins.
• You have 15minutes to answer as many as you can!
• The answers are hidden on fact cards placed around the room.
• You must not remove your question paper from the desk.
• You must not copy any other teams answers.
• You must not obstruct fact cards from other teams
• Prizes will be awarded for the winners!
• Proteins are large molecules made from smaller units called _____ _____ joined by peptide bonds.
• There are only _____ different types of _______ ________found in proteins.
• Cells make proteins. • There are many different proteins in a living
organism. • Each protein has a different _____and
_______It is the ________of amino acids in the protein that gives the protein a specific shape and so a specific job.
Copy and complete
Amino acids Amino acids
20
function
shape
sequence
The shape of the
protein is
SPECIFIC to the
job it has to do
What were the examples you came across?
Function of Proteins - Summary
Proteins can be
• Hormones - e.g. Insulin
• Enzymes - e.g. Amylase
• Antibodies - to help the body’s immune system
• Receptors – allows cells to recognise specific substances
• Structural - e.g. Keratin
Proteins
Learning Intention:
• Identify the functions of a variety proteins.
Success Criteria:
• Research the functions of proteins and complete a scavenge hunt.
Starter Activity:
On a show me board, using no notes, write down the four functions of proteins.
Enzymes
Learning Intention:
Learn how enzymes work.
Success Criteria:
State that enzymes speed up chemical reactions.
State why enzymes are reusable.
Catalyst
• Substances which speed up the rate of a chemical reaction.
• Take part but not changed by reaction.
• Can be used again and again.
• Lower the activation energy.
Catalyst
• Lower the energy input required for chemical reactions to take place.
What is an enzyme?
• Enzymes are biological catalysts that speed up a chemical reaction, while remaining unchanged.
• An enzyme is a chemical made of protein.
• We find them in every living cell.
What does an enzyme do?
• You will now carry out an experiment to investigate what an enzyme does.
• The enzyme you are using is called Amylase.
Test Tube A:
5ml of Starch
2ml of Amylase
Test Tube B:
5ml of Starch
2ml of Water
Food tests recap.
• You may remember food tests from S2.
• Iodine solution turns from brown to blue/black if starch is present.
• Benedicts Solution turns from blue to orange/red if sugar (maltose) is present when heated.
Method 1. Collect two test tubes. Label them A and B. 2. Add 5ml starch to both test tubes. 3. Add 2ml amylase to test tube A and 2ml water
to test tube B. 4. Take a few drops of sample A and place onto a
dimple tile, test this with iodine solution and record the results.
5. Repeat this for sample B. 6. Take a few drops of sample A and place this
into a test tube containing Benedicts solution, this will need to be heated to obtain your result.
7. Repeat this for Sample B.
Results
• Copy and complete the table.
Contents of test tube
Result of test with iodine solution
Result of test with Benedicts solution
Test Tube A: Starch and amylase
Test Tube B: Starch and water
Conclusion
• The enzyme _________ has catalysed the breakdown of _______ into sugar (Maltose).
amylase
starch
Enzymes Summary
• An enzyme is a biological catalyst made by all living cells.
• They speed up the rate of reaction.
• They are made of protein.
• Life could not exist without them.
• Amylase is an enzyme that breaks down starch to sugar.
Enzymes
Learning Intention:
• Learn how enzymes work.
Success Criteria:
• State that enzymes speed up chemical reactions.
• State why enzymes are reusable.
Starter Activity:
Tell your partner three things about an enzyme.
Your teacher will ask you to share.
Starter Activity:
Starter Activity:
Protein
How enzymes work
Learning Intention:
Learn what specific means.
Success Criteria:
State that enzymes are specific.
Enzymes
• Enzymes have an active site – this is where an enzyme reaction occurs.
• The shape of the active site of enzyme molecules is complementary to a specific substrate.
Enzymes
• Enzymes are specific
This means each enzyme only works on one substrate (e.g. Amylase can
only break down starch, nothing else)
Specificity
SUBSTRATE ENZYME PRODUCT(S)
Starch Amylase Maltose
Fats Lipase Fatty Acids &
Glycerol
Protein Pepsin Amino acids
Hydrogen peroxide Catalase Water + oxygen
Glucose-1-phosphate Phosphorylase Starch
Lock and Key Hypothesis
Each enzyme is specific and only works on one substrate- like a lock and key.
Enzyme Action
• Enzyme action results in product(s) being formed.
• This can be through a degradation reaction – when something is broken down into something smaller.
• This can be through a synthesis reaction – when things are built up together to make something bigger.
Enzymes
• You are going to carry out an investigation to find out if enzymes are specific.
• Think about how you might do this.
• Discuss your hypothesis with your lab partner
One Enzyme – One Reaction.
5ml Hydrogen peroxide + 5 drops of detergent +
2ml catalase
5ml Hydrogen peroxide + 5 drops of detergent +
2ml amylase
Method
• 1. Collect two test tubes. Label them A and B.
• 2. Add 2ml hydrogen peroxide to each.
• 3. Add 2ml catalase to test tube A and 2ml amylase to test tube B.
• 4. Record the height of foam in each test tube.
Results
Contents of test tube Height of foam (cm)
2ml hydrogen peroxide + 2ml catalase.
2ml hydrogen peroxide + 2ml amylase.
Conclusion
• In test tube A what happened?
• Why did this happen?
• In test tube B what happened?
• Why did this happen?
• What do both these results show us?
How enzymes work
Learning Intention:
• Learn what specific means.
Success Criteria:
• State that enzymes are specific.
Starter
Starter
A
Factors affecting enzyme activity
Learning Intention: Learn the effects that different conditions
have on enzymes Success Criteria: State two conditions that affect enzyme
activity. State what the term denatured means.
• Think about what might happen if the active site of an enzyme changed shape?
• What might make it change shape?
Factors that affect enzymes
• There are two factors that affect enzyme activity.
• These are pH and temperature.
• Each enzyme has its own set of optimum conditions. This means the conditions it works best at.
• If these are altered, it affects the rate at which an enzyme works
Factors affecting enzymes If the temperature and pH changes sufficiently beyond an enzyme’s optimum, the shape of the enzyme irreversibly changes.
normal denatured
heat
pH
This affects the shape of the active site and means that the enzyme will no longer work.
When this happens the enzyme is denatured.
Temperature
• All enzymes are made of protein, and proteins are denatured at high temperatures (above about 50°C).
• The rate of enzyme activity increases with temperature up to the optimum temperature.
• After that it decreases to zero as the enzyme is denatured.
Task
• Discuss as a class how you would carry out an investigation to see the affect of temperature on enzyme activity.
• You will then carry out this investigation.
pH
• pH also affects the rate of enzyme activity. Each enzyme has its own range of pH in which it will work.
Example Pepsin
(stomach)
Example Salivary Amylase
(mouth)
Example Catalase (liver)
Task
• Discuss as a class how you would carry out an investigation to see the affect of pH on enzyme activity
• You will then carry out this investigation
Quick Quiz
An enzyme that breaks down Hydrogen peroxide?
Catalase
The part of an enzyme where the chemical reaction occurs
Active site
What happens to an enzyme if it is placed in a temperature above it’s
optimum
It is destroyed/denatured
The temperature or pH that an enzyme works best at
Optimum
The type of biological molecule that an enzyme is
Protein
The small units that are the building blocks of all proteins
Amino acids
An enzyme that breaks down Starch
Amylase
What is the substrate in the following reaction:
Amylase
Starch Glucose
Starch
An enzyme that breaks down fats (lipids)
Lipase
The theory that explains how enzymes work
Lock and key theory
Task:
Using props or actions, explain the lock and key theory to your partner.
Your teacher may ask the person with the best explanation to share with the rest of the class.
Factors affecting enzyme activity
Learning Intention: • Learn the effects that
different conditions have on enzymes
Success Criteria: • State two conditions that
affect enzyme activity. • State what the term
denatured means.
Section 1- 4 revision.
• Your task – To produce a revision guide on your given section of topics 1-4.
• The challenge – You have one lesson to prepare your revision guide with your group which you will then use for revision with the rest of the class.
• The criteria - It can be in whatever form you choose – booklet, video, poster.
• It must cover all outcomes for that topic. • Every member of the group must have a copy of the
revision guide. • It must include ‘End of topic test questions’ at the
end based on the outcomes.