A DNA molecule is made up of two strands of polynucleotides which can be described as anti-parallel meaning one strand is moving from a 3’ to 5’ direction …show more content…
He subsequently named these ends telomeres and deduced that they not only protected the ends of the chromosomes but prevented them from fusing with other chromosomes. Scientist Elizabeth Blackburn further studies these telomeres on the single celled organism Tetrahymena thermophila and found that they contain a series of G repeats and which code for no particular gene. It was found that in humans this repeat sequence is TTAGGG and can be repeated anywhere between 100 and 1000 times. After each cycle of DNA replication , some of the telomere repeat sequence is lost at the 5’ end of the newly synthesized daughter strand however as these are non-coding sequences, their loss has no great effect on the cell.. however these sequences are not unlimited meaning after a certain number of DNA replication cycles all the repeat sequences of telomeres would be lost and the DNA would thus begin to lose coding sections of DNA. However this didn’t appear to occur and the discovery of the enzyme telomerase helped shine a light as to why this was not the …show more content…
Together they decided to couple DNA from Tetrahymena thermophila with linear chromosomes and this was then introduced into yeast cells. They found that the telomere DNA from Tetrahymena thermophile was able to protect chromosomes in the yeast cell showing clear evidence towards telomeres acting as mechanisms to protect the end of linear chromosomes. In 1984 further research on telomeres and their production was conducted by Carol Greider and Elizabeth Blackburn a cell extract from Tetrahymena thermophile was analysed for enzymic activity. This extract was then mixed with synthetic DNA primers and free nucleotides. They found that the DNA primer had been extended by a number of telomere sequence demonstrating enzymatic activity. This gave evidence towards telomeres being synthesised by an enzyme and they named this subsequent enzyme