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Explain The Role of Enzymes

In this activity, students will explain the function and production of enzymes, as well as the different conditions necessary for optimal enzyme action.

'Explain The Role of Enzymes' worksheet

Key stage:  KS 4

Curriculum topic:  

Curriculum subtopic:  

Difficulty level:  

Worksheet Overview

QUESTION 1 of 10

Without enzymes, we would never function!

 

Every chemical reaction our bodies need to survive- respiration, digestion, even thinking- all depend on fast reactions maintained by enzymes.

 

Both chemistry and biology are mad about enzymes, so let’s get going!

 

1. Question: Who are they?

Answer: Well, enzymes are a type of protein made by cells.


Reminder: A protein (or polypeptide) is a polymer of a chain of specifically ordered amino acids which is then folded.


The amino acid chain is folded and held in place by chemical bonds, giving a unique 3D shape.

 

For enzymes, the final structure always includes an area called an active site, and the shape always only matches one molecule!

 

So NO FIT = NO REACTION!

 

 

2. Question: What do they do?

Answer: They are biological catalysts!


A catalyst speeds up reactions WITHOUT BEING USED UP

 

3. Question: How do they work?

Answer: THE LOCK AND KEY HYPOTHESIS:

a. The right specific enzyme is present, with its active site being the right fit for the starting ingredient or substrate.


b. The substrate attaches to the active site, and this match is described as the enzyme-substrate complex


c. The speed of the reaction increases, a product is made and the enzyme is reused

 

 

Factors of Reaction

 

Every enzyme has its own ideal temperature and pH!

 

Let's start with TEMPERATURE:

 

There are 3 key points:

 

- Every enzyme has its favourite temperature

 

-Changing the temperature will change the number of successful collisions

 

-Too much heat can denature the active site

 

So let's break it down:

 

The chemical bonds holding the amino acids in their 3D shape are sensitive to levels outside the enzyme’s ideal range, and most boiling temperatures damage an active site beyond repair.

 

So this is where we discuss denaturation!

 

 Being denatured means the active site starts to breakdown because too high a temperature is breaking the chemical bonds.

 

 Denaturation can lead to the whole reaction slowing down and no product being made.

Also, enzyme-substrate complexes are dependent on collisions between the enzyme and the substrate.

 

The enzyme and the substrate need energy to move around so they have a better chance of hitting each other and reacting.

 

But if the temperature dips too low, there is less movement and so less chance of successful collisions being made, slowing down the reaction.

 

And let's not forget pH!

 

This can also have a big impact on the active site shape, again because of the sensitivity of the chemical bonds between the amino acids in the folded 3D structure.

 

If the pH makes a huge change outside the enzyme’s comfort zone, the active site will be denatured, the substrate won’t be able to fit, which, you guessed it, slows the reaction right down!

As a protein, an enzyme is made of what subunit?

Match these terms to their definition

Column A

Column B

Enzyme-Substrate Complex
When a substance fits exactly into the active site...
Denaturation
A reactant or starting ingredient
Substrate
When so many chemical bonds are broken between the...

The 3D shape of an active site is held in place by what?

Strong forces

Chemical bonds

A tightly packed structure

Why is it important that an active site is unique?

So the body has a better control over the number of reactions being catalysed

The body doesn't have the ability to make one catalyst that can cover all chemical reactions

So other cells can't steal each other's enzymes and one is left deficent

True or False: 

 

'All molecular collisions between the enzyme and the substrate successfully lead to an enzyme-substrate complex'

So the body has a better control over the number of reactions being catalysed

The body doesn't have the ability to make one catalyst that can cover all chemical reactions

So other cells can't steal each other's enzymes and one is left deficent

Here is a scenario:

 

'In the stomach, Lipase works best as a catalyst in 37 degrees at pH 2 to break down fats.'

 

Indicate whether the rate of reaction would increase or decrease if the following changes were made:

What two things have to be taken into account when selecting an enzyme?

 

[Select 2 options below]

Its preferred temperature

Its preferred speed

Its preferred time of day

Its preferred pH

An enzyme has the role of a catalyst, but it's actually a what?

 

[Choose all the correct options below]

Protein

Polypeptide

A Large Molecule

A catalyst speeds up a reaction. 

What else is an important factor of a catalyst?

Label this diagram about the 'Lock and Key Hypothesis:

 

  • Question 1

As a protein, an enzyme is made of what subunit?

CORRECT ANSWER
EDDIE SAYS
So like we've said, an enzyme is a protein, which is a chain of amino acids that has been folded into a 3D shape. This gives then a 3D area called an active site, allowing the enzyme to perform its function as a catalyst.
  • Question 2

Match these terms to their definition

CORRECT ANSWER

Column A

Column B

Enzyme-Substrate Complex
When a substance fits exactly int...
Denaturation
When so many chemical bonds are b...
Substrate
A reactant or starting ingredient
EDDIE SAYS
These are important new terms to understand so I hope the matches seemed straight forward. An enzyme-substrate complex is a fancy phrase for when the active site gets filled with the substance that matches its unique space- this if often the reactant in a reaction, but as it depends on the reaction, we called this varying molecule a substrate. Denaturation is the break down of the active site's specific shape as the chemical bonds holding the 3D shape break down- please note that enzymes can't die, only stop working, as they are not living things! Keep working through the questions to find out more about what we have to control in reactions to prevent an enzyme from becoming denatured!
  • Question 3

The 3D shape of an active site is held in place by what?

CORRECT ANSWER
Chemical bonds
EDDIE SAYS
Every protein is a unique sequence of many possible amino acids. Once the protein has folded into the shape it needs for its function, something has to hold everything together, and the amino acids create more links called chemical bonds so the protein can remain 3D rather than a simple one-tier chain.
  • Question 4

Why is it important that an active site is unique?

CORRECT ANSWER
So the body has a better control over the number of reactions being catalysed
EDDIE SAYS
Every protein is a unique sequence of many possible amino acids. This specific selection means the folding the chain does is one of a kind, meaning the active site is a space for only one substance that also ha the same shape so an enzyme-substrate complex can be made with that perfect fit. This type of control means every reaction needs one enzyme and the body gets to decide if it will make this enzyme and so if the reaction will take place. If there was one enzyme that worked for all reactions, the body would start working in too many individual directions, with no organisation or synchronisation- just imagine what your heartbeat or breathing would be like!
  • Question 5

True or False: 

 

'All molecular collisions between the enzyme and the substrate successfully lead to an enzyme-substrate complex'

CORRECT ANSWER
EDDIE SAYS
Did you feel confident answering this question? So to speed up a reaction, the goal is to make as many enzyme-substrate complexes as possible. However, as all the ingredients and the enzyme and the increasing product are all whizzing around in the mixture, sometimes when the active site and the substrate meet, the fit isn;t quite right- imagine it like having the right lock and key but putting the key in upside down or sideways because you're in a rush! As you can imagine, this means that not every bump in between leads to a complex, but the more collisions that happen, the higher the number of successful collisions there'll be over time.
  • Question 6

Here is a scenario:

 

'In the stomach, Lipase works best as a catalyst in 37 degrees at pH 2 to break down fats.'

 

Indicate whether the rate of reaction would increase or decrease if the following changes were made:

CORRECT ANSWER
EDDIE SAYS
Like we've said, enzymes are picky when it comes to their preferred temperature and pH, and this is because they need certain conditions so their chemical bonds aren't disrupted too much and the active site stays functional. Increasing the temperature to increased the rate of reaction is understandable, as you're trying to give all the particles more energy to collide, but go too far and the enzyme denatures, slowing down the reaction instead. The same goes for pH changes, as too acidic or alkalotic and the chemical bonds start breaking and we lose the active site. If the temperature dips too low, there will be less successful collision making enzyme-substrate complexes as the reactants will have too little energy to move, which slows down the reaction, so don't be too cautious! However, a good way to increase the rate of reaction is to of course add more ingredients, and adding more enzymes and substrates will make the reaction continue for longer and so make more product. You add more substrate because it's being converted into a product, but you also need more enzyme because otherwise all the active sites will be full and won't be able to interact with the extra substrate!
  • Question 7

What two things have to be taken into account when selecting an enzyme?

 

[Select 2 options below]

CORRECT ANSWER
Its preferred temperature
Its preferred pH
EDDIE SAYS
The 2 major factors involving optimal enzyme function is TEMPERATURE and pH!!! Every enzyme has an ideal temperature range and pH to work in, and if these stray too far outside the enzyme's comfort zone, we get denaturation!
  • Question 8

An enzyme has the role of a catalyst, but it's actually a what?

 

[Choose all the correct options below]

CORRECT ANSWER
Protein
Polypeptide
A Large Molecule
EDDIE SAYS
How did you get on with this definition? An enzyme is a protein, which can also be called a polypeptide. It has a large molecule structure because it's made of many small units put together.
  • Question 9

A catalyst speeds up a reaction. 

What else is an important factor of a catalyst?

CORRECT ANSWER
IT'S NOT USED UP
IT'S REUSED
IT'S RECYCLED
EDDIE SAYS
How was it answering this question? A true catalyst doesn't need to be replaced frequently and should be considered recyclable, so once one reaction is finished, while the ingredients get topped up, the catalyst can be left alone.
  • Question 10

Label this diagram about the 'Lock and Key Hypothesis:

 

CORRECT ANSWER
EDDIE SAYS
So the Lock and Key Hypothesis is quite simple: Unique active site, or LOCK, is chosen for the reaction, this connects to a specific KEY making a complex, and the desired product or effect takes place, the reaction happening at a good pace and the catalyst goes on the be reused. If this concept is still a little confusing, refer back to the diagram and notes in the introduction for some help!
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