Notes
I recently had the opportunity to go to a lecture by Sam Rhine on genetics, and I have to say, it was really interesting. It was definitely the most interesting tour or lecture I have been on so far. I would definitely go to another lecture of his if given the opportunity or even to a lecture on genetics by a different speaker. After settling down in the auditorium, Mr. Rhine began his lecture by starting to speak about genomes and genes. The definition of genome is the sum total of all the genetic information for any biologic organism. There are two types of genes; coding DNA genes which are sequences of DNA responsible for production of a specific Protein molecule, and non-coding DNA genes which are sequences of DNA responsible for production of a specific RNA molecule. In September 2013 it was found that 1.5% of the genome is coding DNA, while 98.5% is non-coding DNA. He then moved on to gene control/gene regulation. Transcription Factors turn transcription on and off. They attach to the promoter, which acts as “docking site”. TF Activators bind to the promoter and turns genes on. TF Repressors bind to the promoter and turns gene off. Enhancers can also bind to DNA and enhance protein output. On January 1, 1900 the human life expectancy was 47 years, but 100 years later on Jan 1, 2000, the human life expectancy was 77 years. Telomeres are the protective cap on the end of all of our chromosomes, and they prevent the unraveling of the coding DNA, which lies below the Telomere. There are about 15,000 non-coding DNA nucleotides on the tips of each chromosome. When coding DNA unravels, there is a greatly increased chance for cancer. DNA polymerase always makes a mistake at the end of the DNA molecule, and that means that we lose about 300 nucleotides with every mitotic division from end of chromosome. 15,000 total nucleotides divided by about 300 nucleotides lost every mitotic division equals about 50 times cells can divide before the telomeres erode away.