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Understand DNA Extraction

In this worksheet, students will understand the molecular components that make up the DNA our cells use to sustain life and reproduce, looking at key definitions and explaining the structure of DNA.

'Understand DNA Extraction' worksheet

Key stage:  KS 4

GCSE Subjects:   Biology: Single Subject, Biology: Combined Science

GCSE Boards:   Pearson Edexcel

Curriculum topic:   Natural Selection and Genetic Modification

Curriculum subtopic:   Natural Selection and Genetic Modification

Difficulty level:  

Worksheet Overview

QUESTION 1 of 10

DNA is what all genetic information is made up of.

 

It's a long chain of tightly wound-up coded instructions which cells follow to make proteins.

 

When cells want to make a specific protein, they read DNA in small chunks at a time, called a gene.

 

All this genetic information in us is called our GENOME!

 

 

When we zoom into DNA, it's actually a bunch of small units called nucleotides- a group made of a phosphate group, a sugar, and a base.

 

But in the bigger picture, these nucleotides make DNA look like 2 linked swirly strands, which we call the double helix.

 

Being made of lots of small units makes DNA a polymer.

 

 

Nucleotides like to join up, and they do this through their BASES!

 

They can have any 1 of the bases Adenine, Thymine, Cytosine, Guanine, but these bases are very fussy about who they pair with:

 

A goes with T and C goes with G!!!

 

 These groups are COMPLEMENTARY base pairs, and what joins the double helix strands together is the weak hydrogen bonds between the bases in the middle.

 

 

 

EXPERIMENT TIME

 

 Knowing about DNA means scientists can play around with it too, like taking a piece of DNA out of fruit cells!

Let’s use a banana:

 

1. Peel it and mush it up

2. Add a little salt and a bit of washing up liquid

3. Heat at 60°c GENTLY for 5 minutes

4. Filter the mix and only keep THE LIQUID

5. Cool in an ice bath and then carefully pour cold ethanol on top of it

 

And voilà! You should see bits of DNA with bubbles in them where the banana and ethanol meet!

 

 

But, you got me, it’s not bananas scientists really care about: it’s Genetic Profiling!

 

In our genomes, there are combinations of DNA that are very specific to us that can be used as a passport.

 

If we use what we know to extract small, unique bits of DNA from humans, we can make a unique profile of DNA bands for every person.

 

This method is a lifesaver because it has helped us determine paternity, by comparing DNA between parents and the baby, and even to solve crime!

A nucleotide is made up of what three things?

 

A Base

A Gene

Proteins

A Phosphate Group

A Sugar

DNA

If you were to extract DNA from a kiwi, how would you go about it?

 

 

Column A

Column B

1.
Peel and mash up the kiwi
2.
Filter the concoction and KEEP THE LIQUID only
3.
Cool the solution a water bath
4.
Add cold ethanol on top of the mix
5.
Add a little salt and some washing up liquid to th...
6.
Heat the mixture gently for 5 mins

There are 4 bases, 3 of which are Adenine, Thymine and Cytosine. The fourth is called...?

Which of these possible combinations of DNA bases (Adenine, Guanine, Cytosine and Thymine) are correct?

Label the picture of the nucleotides below: 

 

Match the term with its definition:

 

Column A

Column B

Genome
A small piece of the double helix of DNA
Gene
All of a human's DNA
Double Helix
The Structure of DNA

As DNA is made of lots of small nucleotide subunits, this makes DNA a what?

Fill in each blank with ONE word below:

What is one of the key ways DNA extraction is used in science?

What joins complementary base pairs together?

  • Question 1

A nucleotide is made up of what three things?

 

CORRECT ANSWER
A Base
A Phosphate Group
A Sugar
EDDIE SAYS
I know there's a lot of new information in this topic so it's very easy to get the terms confused, but practising with questions like this one will make you remember them all better! A nucleotide is a unit of DNA made up of three pieces: a phosphate group, a sugar and a base.
  • Question 2

If you were to extract DNA from a kiwi, how would you go about it?

 

 

CORRECT ANSWER

Column A

Column B

1.
Peel and mash up the kiwi
2.
Add a little salt and some washin...
3.
Heat the mixture gently for 5 min...
4.
Filter the concoction and KEEP TH...
5.
Cool the solution a water bath
6.
Add cold ethanol on top of the mi...
EDDIE SAYS
DNA extraction is a very helpful concept and maybe an experiment you've already tried at school! You could be asked to design an experiment like this so it's important to know the key steps. If you do all the steps above correctly, you should be able to see fragments of DNA where the ethanol and mixture meets.
  • Question 3

There are 4 bases, 3 of which are Adenine, Thymine and Cytosine. The fourth is called...?

CORRECT ANSWER
GUANINE
G
EDDIE SAYS
The four bases are Guanine, Adenine, Thymine and Cytosine, or G, A, T and C
  • Question 4

Which of these possible combinations of DNA bases (Adenine, Guanine, Cytosine and Thymine) are correct?

CORRECT ANSWER
EDDIE SAYS
How did you get on? When the bases bond in the centre of the double helix, Adenine can only join to Thymine and Cytosine can only join to Guanine. However, the initials can be switched around, for example, both CG and GC are acceptable, as are TA and AT.
  • Question 5

Label the picture of the nucleotides below: 

 

CORRECT ANSWER
EDDIE SAYS
The arrangement of a nucleotide is important because how it bonds gives DNA it's double helix shape. On the outside, it is a phosphate group, which is linked to a corner of a 5 sided sugar called a pentose sugar. The sugar then bonds to a base- depending on the nucleotide, this could be A, T, C or G, which then sticks out into the middle of the double helix, waiting to hydrogen bond to a base from a nucleotide from the opposite strand!
  • Question 6

Match the term with its definition:

 

CORRECT ANSWER

Column A

Column B

Genome
All of a human's DNA
Gene
A small piece of the double helix...
Double Helix
The Structure of DNA
EDDIE SAYS
So, do you think you have a good grasp of all the definitions in this topic? Zooming in on the DNA more and more closely, the entire bunch of genetic information is our genome. When it's unravelled, a piece of its double helix is a gene, but in the most basic form, DNA is made of blocks of nucleotides that make up the double helix.
  • Question 7

As DNA is made of lots of small nucleotide subunits, this makes DNA a what?

CORRECT ANSWER
POLYMER
EDDIE SAYS
You might have already heard this term used before in chemistry, so that tells you it's a useful term to know! A polymer is a large molecule made of many small units, in this case, many nucleotides make the chemical DNA.
  • Question 8

Fill in each blank with ONE word below:

CORRECT ANSWER
EDDIE SAYS
Were you confident in answering this question? Drill it into your mind that bases fit together in COMPLEMENTARY BASE PAIRS- A with T and C with G!
  • Question 9

What is one of the key ways DNA extraction is used in science?

CORRECT ANSWER
GENETIC PROFILING
EDDIE SAYS
Learning how to extract DNA is not propelled by a fruit obsession! Removing small fragments of personally unique DNA from humans has allowed us to create genetic profiles for people, letting us identify people in situations like paternity testing or crimes!
  • Question 10

What joins complementary base pairs together?

CORRECT ANSWER
WEAK HYDROGEN BONDS
HYDROGEN BONDS
EDDIE SAYS
Did you get this one right? Weak hydrogen bonds link together two bases from two nucleotides lined up horizontally, joining up the two sides of the double helix.
---- OR ----

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