S1, End replication problem telomerase

identify telomeres

repetitive dna nserunce at the end of all human chromosomes

what does telo and meres mean in greek

end and part : end part

what is the reppititve sequence

TTAGGG

function of telomeres

protect end of chromosomes (caping)

prevent chromosomes fusion

allow complete DNA replication

they shorten each time after each replication

what is molecular clock

mechanism that count how many times cell has divided

what is the end replication problem

dna replicative enzymes can’t replicate the last DNA sequence at th end of the chromosomes thus there information get lost with them

which Okazaki fragment primer can’t be placed with DNA segment

the last one

identify telomerase

ribonucleoprotein enzyme (revise transcriptase

how does solve the end replication problem

is has its own RNA temple which is complementary to telmric sequence by that it make up for the lost telomeres part

explain step of telmerase

recognition of telomeric sequence

binding and elongation

translocation by primate and telomerase

which cels has active telomeres

germ stem blood and cancer cells

which cells has shorter telomeres 1infant 2elder

2

how many time cell can divide before senescence

40-60 times

in cancer cells how does telomerase act

1 very active switched on

2 cells become immortal