You and your Genes.

1. You and your Genes. By Helena Cowling

2. Genes, Chromosomes and DNA • Genes are parts of chromosomes and chromosomes are made up from DNA. • The chromosomes are found in the nuclei of cells. • Genes are there to make proteins. • DNA has a double helix shape.

3. Genes, chromosomes and DNA continued.. • Both of the strands of DNA are made up from smaller molecules. • four of these molecules are called bases. • Bases always pair up in the same way to connect the strands of DNA together. • the order of these bases gives instructions on how to make a particular protein.

4. Inheritance • The Egg and sperm cells are called sex cells. • The sex cells only have 1 copy of each chromosome. • When the sperm cell fertilises the egg, the nuclei from each connects so that the egg has two copies of every gene.

5. Inheritance continued… • Chromosome genes carry the same genes in the same place. • Different versions of genes are called alleles. • two alleles in a cell may be the same or different. • If a cell has one dominant allele and one recessive allele then the characteristics coded in the dominant allele will be inherited.

6. Babies and children • Babies may be similar to there parents in some way. • Brothers and sisters may be different to each other but they could also be very similar. • There are two chromosomes that determine a gender. A male has a X and Y chromosome and a female has two X chromosomes.

7. Genetic Diseases • Some diseases are caused by faulty genes. • These diseases are called genetic diseases. • Some examples of these are- cystic fibrosis, Huntington’s disease and Haemophilia • If a person has one recessive allele then they will not have the disease, but they will be a carrier. They could pass this allele onto there children. • People can check if they are a carrier of a genetic disease.

8. Family Trees • Using family trees can help people see if they are likely to get a genetic disease or if they will be a carrier or not. • You can also use Punnett squares or genetic cross diagrams to see what chance there is of someone having the disease. • What is the chance of a child having Huntington's disease? • There is a 50% chance of the child having Huntington’s disease. H= Dominant gene (Faulty gene) h= Recessive gene (Good gene) Mum Dad

9. Genetic testing. • Even though genetic testing can be helpful, it can also be wrong sometimes. • However it is controversial whether or not it should be allowed. • If someone is pregnant and they find out their child has a genetic disease they could decide not to have the child.

10. Genetic modification. • In the future, genetic modification could be used to treat or prevent genetic disease. • They could do this by putting normal alleles into the cells with the faulty alleles. • Genetic modification could also be used to make designer babies. • There are different ethical issues about this and many people are against it, but some people support the idea.

11. Natural Cloning • Some bacteria, simple animals and plants can reproduced on its own. • This is called asexual reproduction. • Animals and plants with lots of cells have specialised cells. These do certain jobs. • Some plant cells are unspecialised. These can then develop into any cell that the plant needs. • When gardeners take cuttings of plants it is the unspecialised cells that are used to grow new roots.

12. Cloning. • It is very difficult to clone animals or humans. • To do this you need to – Take an egg cell. Take out the nucleus. Take the nucleus from a normal cell. Put the new nucleus into the egg cell. • There are different ethical issues with this and lots of people are against it, especially religious groups.