Chris Willocks Year 10 Genetics Chemical code for life

2 History In 1953 Watson and Crick unravelled the structure of DNA Deoxyribonucleic acid Double helix Controversy of how results were obtained

3 DNA Deoxyribonucleic acid Double helix Rails are alternating phosphates and sugars Rungs are 4 bases DNA is universal -all living things from bacteria to humans have the same 4 bases

4 Bases 4 bases are: Adenine Thymine Cytosine Guanine Base pairs: A - T G - C

5 DNA Replication DNA is copied before a cell divides DNA unzips New nucleotides are added Each new strand is identical to original

6 DNA and chromosomes DNA coils tightly around proteins Like twisting a piece of string See sample DNA

7 Genetic code Sections of DNA (up to 1000 bases) form a single gene Each gene codes for a protein Proteins determine characteristics such as eye colour

8 Gene expression Genes code for polypeptides Polypeptides are made from amino acids Polypeptides combine to form proteins

9 Mutations A mutation is any change in DNA or chromosome that produces an alteration in the characteristic it codes for Occur naturally

10 Mutagens Mutagens increase the rate of mutations X-rays, UV light, pesticides, benzene, Agent Orange

11 DNA mutations Some DNA mutations do not cause changes to the proteins = silent mutation Other mutations make major changes to proteins

12 Cystic fibrosis Most common inherited disease Sufferers have a missing protein in cell membranes Mucous secretions are very thick Sufferers need considerable medical intervention to survive

13 Cystic fibrous mutation Caused by a single base deletion in the DNA Causes a frameshift mutation

14 Down’s syndrome Mistake in chromosome number Mistake during meiosis

15 Down’s syndrome and maternal age Risk of Down’s syndrome increases with maternal age

16 Human Genome Project (HGP) Collaborative work from laboratories around the world The purpose is to map every gene on the human genome Finished sequencing the bases in 2000

17 Human genome project Future progress: 1.to identify all the genes 2.Identify mutations and the corresponding diseases 3.dangerous variations among newly conceived babies in utero will be predetermined. 4.Will be able to change the harmful traits that the baby might have so that it will not encounter any kind of genetic disease