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DNA jigsaw
TEACHER NOTES
Can you crack the code?


KS3+ desk activity
DNA base pairing
Prior knowledge:
o DNA as the code of life
o DNA physical structure as two parallel strands
Introduces:
o Base pairing
o DNA variation between species
Materials:
o DNA jigsaw pieces: colour print the templates onto card and cut tight to the line. It’s best to
laminate the pieces, in which case leave as narrow a margin as possible. If the margins are too
wide, it will be difficult to assemble the pieces.
o Student worksheets (either colour or black and white – two versions provided)
Activity:
1. Check jigsaws have all ten pieces.
2. Build the jigsaw (matching A/T and G/C to form two long strands). Make sure they understand that the
sequences on the worksheet do not give any clues, and that their completed jigsaw will have blunt ends.
3. Work out what the mystery coloured bases must be and write these on the worksheet, using them to
identify which animal the DNA comes from. If they want to check their results later, they will need to also
record which jigsaw set they used (what colour edges does it have).
The jigsaws are tricky to get started but then easy to finish. It’s good to let them repeat the exercise with
another set as there is great satisfaction in using their new skills to complete the second one more quickly.
Plenary:
Answers:
Red = Hamster, Blue = Guinea Pig, Pink = Cat, Green = Dog, Orange = Rhinoceros, Yellow = Human.

The average (human) gene contains 3000 bases, this is a simplified version.

Effect of mutations, the fact that they do not necessarily change the meaning of the code.

Differences between species vs differences between individuals.
Linked activity:

“Cheeky cells” activity introduces the nucleus as a cell component
Linked topics (not provided):


DNA technologies using sticky ends
‘Sticky ends’ use in DNA technologies
DNA jigsaw
WORKSHEET
Can you crack the code?
Which animal is this DNA from?
You have some chopped-up DNA. Work out what the coloured bases are to identify the animal.
Instructions:
1. Complete the jigsaw, matching the bases to make two parallel strands. Adenosine (A) goes with
Thymine (T) and Cytosine (C) goes with Guanine (G). Coloured bases can match with anything.
Example:
A
C
T
G
G
G
T
A
T
G
A
C
C
C
A
T
C T G
The two strands must start and finish in the same place
2. Work out what the coloured bases must be (A, T, C or G) and write them on the coloured
squares below (there are two rows so you can do two different jigsaws if you have time).
3. Compare these to the answers in the other rows to find out what animal your DNA is from.
First jigsaw:

Second jigsaw:

Hamster
C
G
C
G
A
Guinea pig
C
C
G
T
A
Cat
C
G
C
T
T
Dog
A
C
C
G
A
Rhinoceros
A
G
G
T
T
Human
A
C
G
G
T
Which animal is your jigsaw sequence from?
DNA jigsaw
WORKSHEET
Can you crack the code?
Which animal is this DNA from?
You have some chopped-up DNA. Work out what the coloured bases are to identify the animal.
Instructions:
1. Complete the jigsaw, matching the bases to make two parallel strands. Adenosine (A) goes with
Thymine (T) and Cytosine (C) goes with Guanine (G). Coloured bases can match with anything.
Example:
A
C
T
G
G
G
T
A
T
G
A
C
C
C
A
T
C T G
The two strands must start and finish in the same place
2. Work out what the coloured bases must be (A, T, C or G) and write them on the coloured
squares below (there are two rows so you can do two different jigsaws if you have time).
3. Compare these to the answers in the other rows to find out what animal your DNA is from.
orange
blue
pink
green
red
orange
blue
pink
green
red
Hamster
C
G
C
G
A
Guinea pig
C
C
G
T
A
Cat
C
G
C
T
T
Dog
A
C
C
G
A
Rhinoceros
A
G
G
T
T
Human
A
C
G
G
T
Jigsaw:
Jigsaw:
Which animal is your jigsaw sequence from?
DNA jigsaw
A
A
T
G
T
A
A
TEMPLATE SET 1/6
C
T
A
A
C G
T
C
C
T
T
C
G
G
A
T
T
T
G
A
G
T
C
C
T
T
A
C
G
A
G
T
A
A
C
A
A
A
C G
T
G
C
C
G
A
A
G A
T
T
T
T
T
DNA jigsaw
A
A
T
G
T
A
A
TEMPLATE SET 2/6
C
T
A
A
A G
T
C
C
T
T
C
G
G
A
T
T
T
G
A
G
T
C
C
T
T
A
C
C
A
G
T
A
A
G
A
A
A
C G
T
G
C
C
G
A
A
G A
T
T
T
T
T
DNA jigsaw
A
A
T
G
T
A
A
TEMPLATE SET 3/6
C
T
A
A
A G
T
C
C
T
T
C
G
G
A
T
T
T
G
A
G
A
C
C
T
T
A
C
G
A
G
T
A
A
C
A
A
A
C G
T
G
C
C
G
A
A
G A
T
T
T
T
T
DNA jigsaw
A
A
T
G
T
A
A
TEMPLATE SET 4/6
C
T
A
A
C G
T
C
C
T
T
C
G
G
A
T
T
T
G
A
G
T
C
C
T
T
A
C
G
A
G
T
A
A
G
A
A
A
C G
T
G
C
C
T
A
A
G A
T
T
T
T
T
DNA jigsaw
A
A
T
G
T
A
A
TEMPLATE SET 5/6
C
T
A
A
A G
T
C
C
T
T
C
G
G
A
T
T
T
G
A
G
A
C
C
T
T
A
C
C
A
G
T
A
A
C
A
A
A
C G
T
G
C
C
T
A
A
G A
T
T
T
T
T
DNA jigsaw
A
A
T
G
T
A
A
TEMPLATE SET 6/6
C
T
A
A
C G
T
C
C
T
T
C
G
G
A
T
T
T
G
A
G
A
C
C
T
T
A
C
C
A
G
T
A
A
G
A
A
A
C G
T
G
C
C
T
A
A
G A
T
T
T
T
T