DNA, genes and chromosomes

Biology, Genetics and evolution , Molecules and cells, Age 14-16

An introduction to this topic for KS4 pupils (14-16 yrs). Resource includes a Powerpoint for use with the whole class. This has diagrams, questions to check understanding and a class quiz with 10 questions to check how much pupils have learned (18 slides). There are also two different activity sheets (One to stretch higher ability pupils).


1DNA genes and chromosomesObjectives:
Structure of DNA
How the DNA code workshttp://teachable.net/res.asp?r=11652Genes and DNAThe information about the characteristics we inherit is carried by our GENES
The genes are located on CHROMOSOMES
These are long stringy molecules of a substance called deoxyribonucleic acid or DNA
A gene is simply a section of a DNA molecule3Human chromosomesHow many pairs of chromosomes are there in ordinary human cells?Where in the cell are the chromosomes found?4How does the DNA code work?The DNA molecule is made from two strands of bases joined together like a twisted ladder (the double helix)
There are four different bases called A C T and G
Three bases spell out the code for 1 amino acid5Diagram:ACCATGGTGTAA
TGGTACCACATTWhich type of molecules are made from amino acids?6The DNA codeSo a gene is a set of instructions for building a protein
Each gene contains the code for a different proteinHow many genes do you think humans have?
According to the human genome project

Human Chromosomes:
Human chromosomes seen under the electron microscope
Human chromosomes arranged in their pairs. This is called a karyotype
Where in the cell are chromosomes found?
Describe what a chromosome is made from as clearly as you can
Look at the photo of a set of human chromosomes. How many are there?
Look at the human karyotype. Is this a man or a woman? How can you tell?
Write definitions of the following following

Chromosomes
Read the information on the sheet and answer the numbered questions
How do we inherit things from our parents? The instructions for making a new baby are found in 2 places:
The egg cell of the mother
The sperm cell of the father
Which part of these cells do you think contains these instructions?
Most cells in your body contain a nucleus. Each nucleus contains chromosomes. It is the chromosomes that carry the instructions for making new people.
Look at the photo of human chromosomes:
What do the chromosomes look like?
Are they all the same size and shape?
How many can you see?
In most human cells there are 46 chromosomes. They can be put into 23 matching pairs.
Genes contain the instructions that we inherit. Genes control features such as eye colour. You get one copy of the gene from your mother and one from your father.
Genes are contained on the chromosomes.
How many genes are there for each feature