Question

Eukaryotic replication forks: a. Move much more quickly than prokaryotic forks in order to copy the larger genome b. Do not move in pairs in opposite directions, forming 'bubbles' as prokaryotic replication c. Different groups (i.e. 'units) of forks become active at different times during 'S' -Phase d. Begin in heterochromatic regions earlier during S-Phase than euchromatic regions e. Move much more slowly through heterochromatin than euchromatin?

1) Move much more quickly than prokaryotic forks in order to copy the larger genome
2) Do not move in pairs in opposite directions, forming 'bubbles' as prokaryotic replication
3) Different groups (i.e. 'units) of forks become active at different times during 'S' -Phase
4) Begin in heterochromatic regions earlier during S-Phase than euchromatic regions
5) Move much more slowly through heterochromatin than euchromatin

Answer 1

Eukaryotic replication forks become active at different times during the S-Phase, and the replication rate is slower in eukaryotes than in prokaryotes, at about 100 nucleotides per second. Replication is also slower in heterochromatin compared to euchromatin.

Step-by-step explanation:

The correct answer to the student's question regarding eukaryotic replication forks is that 'Different groups (i.e., 'units') of forks become active at different times during 'S'-Phase'. This means that unlike prokaryotic replication, which typically occurs from a single origin, eukaryotic chromosomes, which are much larger and more complex, contain multiple origins of replication.

Furthermore, the rate of eukaryotic replication is significantly slower compared to prokaryotic replication, at about 100 nucleotides per second, which is 10 times slower than the rate in prokaryotes. Moreover, eukaryotic chromatin must undergo modifications to allow the DNA to be accessible to the replication machinery, influencing the timing and speed of replication forks.

Finally, it's also important to address that in eukaryotes, replication moves much more slowly through heterochromatin than euchromatin, due to the compact nature of heterochromatin which makes it more challenging for the replication machinery to access the DNA.