READING – from Biology in Context for Cambridge International A Level, Glenn and usan Toole, 2013, Nelson Thornes
READING – from Biology for the IB Diploma Second Edition, C.J. Clegg, 2014, Hodder Education
THE HUMAN GENOME PROJECT
The HGP was an international attempt to map the entire base sequence of the human genome, including the 1% which constitutes coding genes, the 8% regulatory sequences and the remainder, not all of which has clear functions . The project launched in 1990, funded by the US government and comprising an the international consortium of geneticists from the United Kingdom, France, Australia, China and several other collaborators. The HGP was officially completed in 2003 but not after some controversy caused by a privately funded attempt to unravel the genome, using different sequencing technology, with the intention of commercially capitalising on their results. This research was run by Craig Venter and his company Celera Genomics, but once President Clinton declared that the human genome and its information could not be patented, Venter collaborated with the HGP.
This powerpoint is some years old now and has a special focus upon ethical issues but the presentation is good; it is understandable; and it suffices! human-genome-project-ppt
The Nature of Science focus is upon gene sequencing and how the technology has so dramatically developed, and continues to develop, meaning that sequencing a genome can now be completed in as little as two days. In 1975 Sanger provided the first truly viable sequencing technique, from which were developed the automated techniques which assisted the HGP and Craig Venter. These techniques have now been well overtaken by the so-called ‘next-gen’ techniques which enable extremely rapid sequencing.
Genomes of a staggering number of species have now been sequenced and analysed. Some interesting comparisons and insights have emerged:
DNA MUTATIONS AND SICKLE CELLED ANAEMIA
COMPARISON OF NUMBER OF GENES IN HUMANS WITH OTHER SPECIES
(Note – this is not a comparison of the genome size but is a comparison of the total number of genes which code for proteins. Remember that this coding DNA constitutes just 1% of the genome.)
COMPARING BASE SEQUENCES IN DIFFERENT SPECIES USING A DATABASE – and much, much more!
I love the way the new syllabus can bring together different themes, concepts and understandings, through a focus upon one, seemingly small component. An understanding of cytochrome c might bring together and help a comprehension of this lot:
- protein structure structure (2.4 Proteins & HL 7.3 Translation)
- function in cell respiration as an electron carrier (8.2 Cell respiration HL)
- coding gene, CYCS, on chromosome 7 (3.1 Genes & 3.2 Chromosomes)
- mutations of DNA (1.6 Cell division, 3.1 Genes, 3.4 Inheritance)
- synthesis of a protein through transcription and translation (2.7 DNA replication, transcription and translation & HL 7.2 Transcription and gene expression & 7.3 Translation)
- comparing gene sequences in different species to provide support for cladistics and evolutionary arguments (5.1 Evidence for evolution & 5.3 Classification and biodiversity)
What is the specific context? Topic 3.1 – Genes. The IB syllabus suggests that students make a comparison between the amino acid sequences of cytochrome c in different species, using Genbank or some other database. Why cytochrome c? Because this electron carrier in mitochondrial membranes has been studied in depth as molecular evidence for the 3 Domain proposal for the classification of living organisms. Read on …. it is fascinating!
Now comparing amino acid sequences in different species. This is from Biology Second Edition, C.J. Clegg, 2014, Hodder Education and seems to work fine for cytochrome c oxidase, if you follow the instructions and use your head!