Human Genomics. Higher Human Biology

Transcription

1 Human Genomics Higher Human Biology

2 Learning Intentions Explain what is meant by human genomics State that bioinformatics can be used to identify DNA sequences

3 Human Genomics The genome is the whole hereditary information of an organism that is encoded in the DNA. Human genomics is the study of the human genome It involves determining the sequence of the nucleotide base molecules along the DNA.

4 Human Genomics The sequence of bases can be determined for individual genes and entire genomes This genetic information can be used to find the function of different genes. Entire genomes can be compared using single nucleotide polymorphisms (SNPs). (These are differences between individuals due to base substitutions. ) SNPs

5 The Human Genome Project The human genome project began in 1990 and was completed on 14 th April The main aims of the project were: To identify the approximate 100,000 genes in the human DNA. Determine the sequences of the 3 billion bases that make up human DNA. genome sequencing animation

6 Bioinformatics Is the use of computer technology to identify DNA sequences The enormous amount of data produced by DNA and protein sequencing can be managed and analysed using computer technology and shared over the internet

7 Bioinformatics Computer programs can be used to identify Gene sequences by looking for coding sequences similar to know genes Start sequences (there is a good chance that each of these will be followed by a coding sequence Sequences lacking stop codons (a protein coding sequence is normally a very long chain of base triplets containing no stop codon except the one at its end

8 Bioinformatics Computer programmes can also be used to search for base sequences that code for specific amino acid sequences of known proteins. This can be useful in medicine, for example in genetic screening for diseases.

9 Videos BBC documentary (1 hour) XoyorWY Ethics of genome project (5 mins) cs-of-the-human-genome-project/8732.html

10 Learning Intentions Describe what is meant by systematics Explain the role of genomics in personalised medicine Explain what pharmacogenetics is and how it is used

11 Systematics Systematics is the study of a group of living things with respect to their diversity, relatedness and classification. It compares human genome sequence data and genomes of other species to provide information on evolutionary relationships and origins Video

12 Systematics Systematics has been used to examine genetic differences between populations of humans. It shows that the biggest genetic variation occurs in populations in Africa. This has led scientists to put forward the out of Africa theory, which suggests that modern humans originated in Africa.

13 Personalised Medicine Personalised medicine is based on an individuals genome. It would allow scientists to predict an individuals susceptibility to disease, select treatment that is more likely to be successful, and avoid adverse reactions to medication. Video

14 Personalised Medicine To make use of this technique, scientists need to: Locate mutant variants in the genome Distinguish between harmful and neutral variants Establish a link between the mutation and a disease The nature of the disease might depend on genetic and environmental factors.

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16 Pharmacogenetics Pharmacogenetics is the study of how people's genetic makeup affects their responses to drugs. If a drug is known to produce side effects in some people, pharmacogenetic testing may help identify at-risk patients.

17 Rational drug design Drugs work by interacting with target molecules (receptors) in our bodies and altering their activities in a way that is beneficial to our health.

18 Once DNA sequencing has identified the genes involved in a specific disease and established the structure of the protein expressed, the Pharmacogenetisists try to synthesise a specific drug. Pharmacogenetics

19 Pharmacogenetics The drug produced will bind to proteins involved or prevent their synthesis by binding to a specific region of the DNA preventing transcription of abnormal mrna or by binding to the abnormal mrna preventing translation

20 The Future In the future, genomics could be used to predict risk of disease. What are some ethical issues of sequencing individuals genomes? Would you have your genome sequenced?

21 On each card is a statement covering an issue related to personal genomics. Each of these ethical issues need to be considered when discussing whether or not personal genomics is a good thing and should be an area of scientific development. Arrange the cards into a diamond with the statement they agree with most at the top and least at the bottom. Strongly agree Strongly disagree

22 Learning Intention Describe the steps involved in PCR

23 PCR PCR (polymerase chain reaction) is a technique that replicates short sections of DNA quickly. This amplification of DNA is an in vitro (outside the body) process.

24 Primers Amplification of DNA using PCR involves the use of primers. The primer is a piece of single stranded DNA complementary to a specific target sequence at the 3 end of the strand to be replicated.

25 PCR Steps 1. DNA is heated to separate the DNA strands (by breaking the hydrogen bonds). 2. DNA is cooled to allow the primers to bind to target sequences of DNA. 3. Heat tolerant DNA polymerase adds nucleotides to the primers at the 3 ends of original DNA strands.

26 PCR Steps 4. Repeated cycles of heating and cooling amplify the region DNA. 5. In one hour, a short length of DNA can become a million. pcr animation pcr glow

27 PCR game pcr song

28 DNA Microarray This is an arrangement of thousands of different DNA probes as tiny spots attached to a glass slide. It is used to detect a specific sequence of nucleotide bases in a sample of DNA. This is how the DNA to be amplified can be identified.

29 DNA Probe A DNA probe is a short single stranded piece of DNA that is complementary to a specific sequence. A fluorescent label is attached to the probe to allow detection.

30 SQA Notes Polymerase Chain Reaction (PCR) : amplification of DNA using complementary primers for specific target sequences. DNA heated to separate strands then cooled for primer binding. Heat-tolerant DNA polymerase then replicates the region of DNA. Repeated cycles of heating and cooling amplify this region of DNA. Primers are complementary to specific target sequences at the two ends of the region to be amplified.

31 Learning Intention Give some applications of DNA profiling.

32 DNA Profiling DNA profiling allows the identification of individuals by comparing regions of the genome with highly variable number of repetitive sequences of DNA. This can be used forensically, for example to identify criminals and in paternity testing, or medically, for example to analyse disease risk. Glow

33 DNA Profiling Which child is the mother s from a previous marriage? Which child is adopted?

34 DNA Profiling Which suspect committed the crime?