1. Genomes & their evolution Ch 21.4,5

2. About 1.2% of the human genome is protein coding exons. In 9/2012, in papers in Nature, the ENCODE group has produced a stunning inventory of previously hidden switches, signals and sign posts embedded like runes throughout the entire length of human DNA. 21.4 – Multicellular eukaryotes have much noncoding DNA & many multigene families

3. DNA sequences – non coding Regulatory sequences Repetitive DNA sequences – Tandem repeats – Interspersed repeats

4. Transposable elements Segments of DNA that can move from one place to another within an organism’s genome Movement is by a form of recombination

5. Transposons & Retrotransposons

6. Retrotransposons – 40% of human genome DNA Transposons – 3% of human genome Both require transcription to work - can interrupt gene function - can introduce genetic variation, through rearrangment

7. Alu elements Transposable elements – family of related sequences About 10% of human genome 300 nt long, do not code for any proteins

8. Other repetitive DNA Simple sequence DNA – many copies of short tandem repeated sequences STR – short tandem repeat – 3% of human genome

9. Multigene families Many genes occur in multigene families- collections of identical or very similar genes Allow for many copies of the mRNA and protein i.e. family for rRNA molecules – identical genes - rRNA is final product i.e. globin families – non identical genes – produce proteins found in polypeptide subunits in hemoglobin.

10. 21.5 Duplication, rearrangement & mutation contribute to genome evolution Errors in Meiosis and duplication of genes Nondisjunction can result in polyploidy

11. Human & mouse chromosomes

12. Unequal crossing over can lead to duplication of genes Transposons are homologous in chromosomes, can get duplicated

13. Transposons and evolution 3 ways Transposons may have contributed to the evolution of the genome Promote recombination between different chromosomes Disrupt genes or control elements Carry genes or individual exons to new locations http://www.youtube.com/watch?v=9MPiRx3S PMM http://www.youtube.com/watch?v=9MPiRx3S PMM