Webcast from 23andme on human evolution. Continued: What are genes?, What are SNPs? (Single Nucleotide Polymorphisms), Where do your genes come from? and What is phenotype?. These webcasts provide an easy to understand overview. Sergey Brin, Google co-founder and husband of 23andme co-founder Anne Wojcicki. People have 23 pairs of chromosomes.
For a variation to be considered a SNP, it must occur in at least 1% of the population. SNPs, which make up about 90% of all human genetic variation, occur every 100 to 300 bases along the 3-billion-base human genome.
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SNPs do not cause disease, but they can help determine the likelihood that someone will develop a particular illness. One of the genes associated with Alzheimer’s disease, apolipoprotein E or ApoE, is a good example of how SNPs affect disease development. ApoE contains two SNPs that result in three possible alleles for this gene: E2, E3, and E4. Each allele differs by one DNA base, and the protein product of each gene differs by one amino acid.
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SNPs do not cause disease, but they can help determine the likelihood that someone will develop a particular illness. One of the genes associated with Alzheimer’s disease, apolipoprotein E or ApoE, is a good example of how SNPs affect disease development. ApoE contains two SNPs that result in three possible alleles for this gene: E2, E3, and E4. Each allele differs by one DNA base, and the protein product of each gene differs by one amino acid.
Related: Understanding the Evolution of Human Beings by Country – Evolution is Fundamental to Science – 8 Percent of the Human Genome is Old Virus Genes – science webcasts