Telomerase

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Telomerase
In the linear DNA of eukaryotic cells, RNA primers cannot be added to the 3' end of the DNA (lagging strand) in order to allow DNA polymerase to replicate the very end of the strand.
The enzyme telomerase extends the 3' end of the lagging strand by adding a DNA sequence to which a primer can attach. DNA polymerase III can now replicate the 3' end of the lagging strand.
Prokaryotic cells don't have this problem and therefore don't have telomerase because they have circular chromosomes and during replication both replication forks meet in the middle.

Photo by Fatma Uzbas / CC BY

Practice: Prokaryote Telomerase?
Why don't prokaryotic chromosomes require a telomerase during replication?

A) Because their DNA is double stranded

B) Because they have circular chromosomes

C) Because their mechanism of replication uses completely different enzymes than eukaryotes

D) Because they do not require an RNA primer for replication

I don't know

Practice: Absence of Telomerase
What would happen to a eukaryotic chromosome after repeated rounds of replication if the telomerase was not functioning properly?

A) The ends of the chromosomes would become longer and longer

B) Nothing would happen since telomerases help with DNA unwinding

C) The telomeres would become shorter each time the cell divides

D) The lifespan of a cell would be longer

I don't know

Wize AP Biology Textbook > DNA Replication & Repair

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Telomerase

Practice: Prokaryote Telomerase?

Practice: Absence of Telomerase