Download VGEC: Student Handout Wear a Chimp on Your Wrist 1

VGEC: Teacher Notes
Wear a Chimp on Your Wrist 1 & 2
A linked pair of activities that explore the base pairing rules in DNA and the way in which the codons along a
section of DNA specify the amino acid sequence of a protein.
In Wear a Chimp on Your Wrist 1 students work out the matching sequence to a given 21 base-pair DNA
sequence using the base-pairing rules. They then use coloured beads to produce a two-stranded bracelet
that matches their DNA sequence.
In Wear a Chimp on Your Wrist 2 students use a codon table to identify the amino acid sequence specified
by their sequence from Wear a Chimp on Your Wrist 1. They then use larger beads to make a singlestranded ‘protein’ bracelet.
Learning objectives
Wear a Chimp on Your Wrist 1: base pairing
To understand the base pairing rules of DNA, and the way in which the sequence of one DNA strand
specifies the sequence of a matching strand.
To understand the way in which some DNA sequences are shared by different organisms, but differ
from species to species.
Wear a Chimp on Your Wrist 2: codons and amino acids
To understand the way in which sets of three bases – codons – specify amino acids and the amino acid
sequences of proteins.
Possible curriculum links
Key Stage 4: 5c Organisms and health
Files and folders provided
1 Chimp1&2.docx/rtf/pdf
This document – includes Teacher Notes and Student Handouts.
2 SpeciesAlignment.docx/rtf/pdf
(optional).
A handout that compares the DNA sequences of the organisms
3 BeadColours.pdf
A handout showing the bead colours for the bases (optional)
4 DNASequences21BP.docx/rtf/pdf
Folder: Contains the 21 base-pair DNA sequence sheets
Key vocabulary
DNA (short for deoxyribonucleic acid): the material from which genes are made.
Base pair: a pair of complementary nitrogenous bases that form the structure of DNA by holding the
two strands of the double helix together. The bases pair in a specific way: adenine (A) always pairs with
thymine (T) and guanine (G) always pairs with cytosine (C).
Virtual Genetics Education Centre: http://www.le.ac.uk/genetics/genie/vgec/
1
Genetic code: the order of the bases along a single strand of DNA.
Codon: a sequence of three bases that codes for a specific amino acid (or a ‘stop’ signal).
Procedure
Wear a Chimp on Your Wrist 1
Students pick a sheet for the animal they want. They can choose DNA from the following living things:
human, chimp, elephant, grizzly bear, wallaroo (a relative of the kangaroo), owl, python, salmon, fruit fly
and maize.
Students complete the bottom half of the sequence on the sheet using the DNA base pairing rules.
A pairs with T
G pairs with C
Students make a bracelet to match their sequence using double-stranded thread and coloured beads.
The colour code for the beads is:
A is BLUE
T is ORANGE
G is GREEN
C is YELLOW
Wear a Chimp on Your Wrist 2
Students use the DNA code from Wear a Chimp on Your Wrist 1 to produce a protein bracelet that
matches their DNA bracelet.
Students use the top line of their DNA sequence (not the one they worked out). They work out the
sequence of amino acids using a codon table.
They then make a single-stranded ‘protein’ bracelet to match their amino acid sequence using the
single-stranded thread and the larger coloured beads.
Materials
Wear a Chimp on Your Wrist 1
Print-outs of the DNA sequences. If these are laminated, they can be used over and over again.
Beads – blue, orange, green and yellow. (We use opaque plastic 9 × 6 mm beads from toy and hobby
shops.)
Thread for DNA bracelets. To form a double-stranded thread, fold a 550 mm length of thread back on
itself and tie a loop at one end. (We use clear 1 mm stretch plastic thread.)
Scissors (to trim the bracelets) and pens.
Wear a Chimp on Your Wrist 2
Beads – a different colour for each amino acid. (We use opaque plastic 18 × 8 mm beads from toy /
hobby shops.)
Thread for protein bracelets. A single-stranded thread approximately 300 mm long. (We use clear 1 mm
stretch plastic thread.)
Scissors (to trim the bracelets) and pens.
Virtual Genetics Education Centre: http://www.le.ac.uk/genetics/genie/vgec/
2
Background notes
The gene sequence that was used for all the different organisms is the first 21 bases of the cytochrome
b gene.
The gene is involved in helping to release energy from food.
Almost all life on earth gets energy from food in the same way, which is why this gene is found in
everything from plants to humans.
As you can see, the DNA sequence of the gene doesn’t need to be the same for the protein produced
from it to do the same job. However, more closely related animals do tend to have a more similar DNA
sequence for the same gene. (You can see that there are very few differences between the chimp and
the human DNA sequence.)
DNA is a double-stranded chemical made up of pairs of building blocks called nucleotides. There are
four different types of building blocks, called A, G, C and T. A DNA sequence is made up of a
sequence of A, G, T and C in a specific order, as read along one of the two strands of DNA.
As the students make their DNA bracelet they will need to follow the pairing rules so that they are
making both of the matching strands that make up the structure of DNA:
A always pairs with T
G always pairs with C
Because of these pairing rules, you just need to know the sequence of one strand of DNA to work out
the sequence of the other stand of DNA which produces to complete DNA structure.
For example, if you have a DNA sequence:
AGGTACCTAGT
You can use the pairing rules to work out the sequence on the other side of the DNA structure:
TCCATGGATCA
So the double-stranded sequence of DNA would look like this:
AGGTACCTAGT
TCCATGGATCA
Virtual Genetics Education Centre: http://www.le.ac.uk/genetics/genie/vgec/
3
VGEC: Student Handout
Wear a Chimp on Your Wrist 1
1
Pick a sheet for the animal you want. You’re going to make a bracelet to represent part of their DNA
You can choose DNA from the following living things:
Human
Chimp
Elephant
Grizzly bear
Wallaroo (a relative of the kangaroo)
Owl
Python
Salmon
Fruit fly
Maize
2
Complete the bottom half of the sequence on the sheet using the DNA base pairing rules.
A pairs with T
3
G pairs with C
Make a bracelet to match your sequence using the double-stranded thread and the coloured beads.
The colour code for the beads is:
A is BLUE
T is ORANGE
G is GREEN
C is YELLOW
4
Congratulations! Now you can wear your DNA bracelet.
Virtual Genetics Education Centre: http://www.le.ac.uk/ge/genie/vgec/
VGEC: Student Handout
Wear a Chimp on Your Wrist 2
1
In this activity you will use the DNA code from Wear a Chimp on Your Wrist 1 to produce a protein
bracelet that matches your DNA bracelet.
2
Each group of three letters – or bases – is called a codon, and each codon specifies an amino acid.
(A protein is a series of linked amino acids.)
3
Use the top line of your DNA sequence (not the one you worked out). Work out the sequence of amino
acids. The codon table below will help you to decide which amino acid is represented by each codon.
4
Make a bracelet to match your amino acid sequence using the single-stranded thread and the larger
coloured beads.
Virtual Genetics Education Centre: http://www.le.ac.uk/ge/genie/vgec/