Human Molecular Genetics - Lecture Twenty Three : What does the Genome tell us about being human ?
4 important questions on Human Molecular Genetics - Lecture Twenty Three : What does the Genome tell us about being human ?
What are Aligning Genes ?
- We can observe common points and points of differences
- Usually coding regions (exons) are aligned (and not non-coding regions introns), as these are the sequence of bases that actually translate to proteins
- Genes that are common between two species
- Due to identical/closely similar gene sequences
How to compare genes between species ?
- Comparing the conserved genes can identify evolutionary relationships between species that have diverged
- Comparing the differences can identify DNA encoding differences in our biologies.
- DIVERGENCE : When two or more populations of the same ancestral species accumulate independent genetic changes over time, eventually becoming genetically distinct species
- CHALLENGES :
- Many genes are shared with other animals
- Function of most genes is unknown
What is a Hominid Phylogenetic Tree ?
- Neanderthals and Homo sapiens are different species from the hominid family
- They had a common ancestor at one point, before two populations (from this common ancestor) separated and diverged from one another
- Different selection pressures experienced by each group resulted in different genes being selected for by nature
- Over time, this results in the accumulation of enough genetic difference that the two groups are now distinct species
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Comparing Genes between Hominids
- Homo Sapiens and Neanderthals : Europeans/Asians carry some Neanderthal alleles
- 2-4% of the genome of non-Africans consists of Neanderthal allele variants
- Whereas some Africans have none of these Neanderthal alleles
- Denisovans were a group of primitive hominid species or homo sapien subspecies (debate over whether they were an entirely different species)
- Melanesians (indigenous people of New Guinea, Fiji, Vanuatu) share 4-6% of Denisovan alleles
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