Telomeres and Telomerase || End Replication Problem in Eukaryotes

Telomeres and Telomerase - This video is on end replication problem which occurs in eukaryotes along with NEET PG MCQs. End Replication Problem in Eukaryotes - 00:47 minutes Telomeres - 01:42 minutes Telomerase - 05:23 minutes Clinical significance of Telomerase - 07:39 minutes NEET PG MCQs on Telomere and Telomerase - 08:26 minutes The DNA Molecules in eukaryotes chromosomes are Linear i.e. Have two ends. This is in contrast to bacterial chromosome that is circular (Have no ends.). Free ends of linear chromosome are not readily replicated by cellular DNA polymerases. 5’End of each new strand will be generally short as compared to that of 5’ end of template strand. So each time cell replicates its genome in order to divide; its chromosomes becomes shorter. This problem is resolved by the synthesis of special structures called telomeres (Greek word: Telo= ends) at the ends of each chromosome by telomerase, a specialized polymerase that carries its own RNA template. Telomeres The ends of chromosome contain structures called telomeres Telomeres consist of hundreds of tandem repeats of 6 nucleotide G rich sequence. Human telomeres G rich sequence is 5’ TTAGGG-3’. They have two functions: 1.To protect chromosome from fusing with each other 2.And to solve end replication problem. They are essential for proper maintance of chromosome and play a major role in ageing and cancer. Telomerase (Telomere Terminal Transferase) Enzyme which prevents shortening of DNA Has an intrinsic RNA primer Has Reverse Transcriptase (RNA Dependent DNA Polymerase) activity Present in Germ line, stem cells, most cancer cells. Absent from most somatic cells. #endreplication #Telomeres #telomerase #reversetranscriptase #NEETPG #NEETPGbiochemistry #USMLE #biochemistrybasicsbyDrAmit #aging