Grade 5/6 DNA lesson

1. How is a human
made?

2. A human is made from:
1 egg (from Mum) and 1 sperm (from Dad)
The information stored to grow a person is in 46
chromosomes.
23 chromosomes come from the egg and 23 come from
the sperm.

3. What is a
chromosome?

4. A chromosome is made up of tightly coiled DNA.
Every cell in the human body contains 23 pairs of
chromosomes. 22 of the pairs look the same in males
and females. The 23 rd is different: females have two X
chromosomes and males have one X and one Y.

5. This means that each cell, with its 23 pairs of
chromosomes has the information to make anything
required in the whole human body.
It is like a pantry with all of the ingredients you need.
Sometimes a cell just needs to make another skin cell,
sometimes it needs to make a liver cell. Just like the
pantry ingredients could make a cake, or they could
make a pasta bake.

6. Each chromosome
can contain around
1000 genes.

7. What is a
gene?

8. Genes, which are made up of DNA, act as instructions to
make molecules called proteins.
The Human Genome Project has estimated that humans
have between 20,000 and 25,000 genes.
Each gene has one set of instructions or ‘recipe’ to
perform one function in our body.
Most genes are the same in all people, but a small
number of genes (less than 1 percent of the total) are
slightly different between people. These small
differences contribute to each person’s unique physical
features.

10. What is
DNA?

11. DNA is deoxyribonucleic acid.
It is a double sided helix.
The information in DNA is stored as a code made up of
four chemical bases: adenine (A), guanine (G), cytosine
(C), and thymine (T)

12. The order, or sequence, of these bases determines the
information available to carry out a certain function,
similar to the way in which letters of the alphabet
appear in a certain order to form words and sentences.
DNA bases pair up with each other, A with T and C with
G, to form units called base pair.

13. An important property of
DNA is that it can replicate,
or make copies of itself.
When it ‘unzips’ one side
provides the pattern for
the creation of the other
side.
Duplication is critical when
cells divide because each
new cell needs to have an
exact copy of the DNA
present in the old cell.

14. How much DNA
do we have?

15. Genes are all different sizes from a few hundred DNA
bases to two million bases.
Humans have 25,000 genes, so that’s a lot of DNA!
The smallest gene is 500 base pairs long and makes the
histone protein.

16. So what do
genes really do?

17. The DNA in genes create proteins.
Proteins are everything to do with our bodies:
• Structure : making skin, organs, nerves etc etc
• Function : antibodies for immunity, blood cells,
enzymes etc etc

18. The End Now, do this tour:
http://learn.genetics.utah.edu/content/begin/tour/
and play some games here:
http://www.routesgame.com/games/?challengeId=7
and make some origami DNA here:
http://www.wellcome.ac.uk/Education-resources/Teaching-and-education/Big-
Picture/All-issues/Genes-Genomes-and-Health/WTDV027165.htm