1. Unit 1 – Living Cells

2.  The study of the human genome  - involves sequencing DNA nucleotides  - and relating this to gene functions  In 2003, the human genome project (HGP) was completed  The entire DNA sequence of the human genome was completed  - aided by techniques like DNA sequencing, and cataloguing single nucleotide polymorphisms (SNP’s)

3.  The analysis of data produced by DNA technology  - using statistical analysis and computer technology  Allows the identification of:  - Protein-coding sequences  - Start sequences  - Stop codons  - specific base sequences  Can be used for  - evolutionary biology  - inheritance  - personalised medicine

4.  The study of diversity, relatedness and classification in living things  Can be used to study origins of humans  - and their evolutionary relationships  Human DNA only varies by 0.3%  - most variation in within Africa  Out of Africa theory:  Humans originated in Africa  Evolved within Africa over millions of years  - lots of genetic variation  Small groups migrated out of Africa recently  - 100,000 years ago

5.  Now possible to determine a DNA sequence for every individual:  Personal genomics  - becoming cheaper and faster  - allows for analysis of mutations  - if they are harmful or neutral  - links specific genetic sequences to genetic diseases  - however, environmental factors still play a role

6.  Studies the effects of drugs on the human population  In the future, could be used to customise medical treatment  - suitable drugs and dosage could be prescribed for each individual  - reduced risk of “side effects”

7.  Possibility to scan individual DNA for predisposition to, and predict risk to, disease  - risk could be reduced by specific drug treatment & lifestyle choices  Ethical issues:  - Who should have access to this info?  - Could it affect employability/insurance/fa mily?  - Potential for genetic discrimination

8.  Polymerase Chain Reaction (PCR):  Creates many copies of a piece of DNA - amplification  - outside the body (in vitro)  Primers are used  - single stranded DNA  - complimentary to a specific target sequence of DNA (at the 3’ end)  - DNA separated – by heat treatment  - primer binds to target sequence  - DNA cooled  - DNA polymerase then adds nucleotides to the primers  Allows many copies of DNA to be extracted from a tiny sample

9.  DNA probes  Detect a specific sequence of nucleotide bases in a DNA sample  - the target DNA  Probes are fluorescent labelled  Probes are part of a DNA microarray  - arrangement of thousands of different probes  Useful for:  - identifying genes that are active/inactive (cancers)  - genetic identification

10.  PCR allows many copies of DNA to be produced  - copies can then be screened for sequences linked to genetic disease  - estimate risk of disease onset  - confirm diagnosis  e.g. cystic fibrosis testing  - blood testing can identify a mutant allele for cystic fibrosis

11.  DNA profile:  - human genome contains many, repetitive non-coding sequences  - differ in number and length between individuals  - can therefore construct an individual DNA profile  PCR can amplify a small DNA sample from a crime scene  - samples from victims and suspects can then be separated by gel electrophoresis, and compared  - also used to resolve paternity disputes  - child will share 50% of bands in common with each parent