Question

4. Why do eukaryotic chromosomes shorten with each round of DNA replication?

A) The end of the chromosome has a 5’ overhang

B) A free 3’ hydroxyl is required for DNA polymerase to initiate replication

C) DNA ligase links the 5’ hydroxyl of one fragment to the 3’ phosphate of an adjacent fragment

D) Because the shelterin complex recognizes and binds telomeric DNA

E) To prevent chromosomes from undergoing non-homologous end joining

Answer 1

The answer is: A)The end of the chromosome has a 5’ overhang because during chromosomal replication the enzymes that duplicate DNA cannot continue their duplication all the way to the end of a chromosome. So in each duplication the end of the chromosome will be shortened and this is because of the synthesis of Okazaki fragments needs to RNA primers be attaching onto the lagging strand. This overhanging at the lagging strand end of the chromosome is due to incomplete end replication.