Question

Replication orgins (OR): Which of the following statements is true?

1) Located in many places within eucaryotic chromosomes
2) Point on chromsome where duplicated chromosomes (i.e. sister chromatids) are attached
3) Point on a chromosome where kinetochores attach during mitosis
4) Located at each end of eucaryotic chromosomes
5) Exist as repeating sequences synthesized by the enzyme telomerase

Answer 1

The true statement about replication origins is that they are located in many places within eukaryotic chromosomes. Eukaryotic cells can have multiple origins of replication, and these are essential for initiating DNA replication efficiently across the chromosomes.

Step-by-step explanation:

Out of the statements provided regarding replication origins (OR), the true statement is:

1) Located in many places within eukaryotic chromosomes

Eukaryotic chromosomes have multiple origins of replication, allowing DNA replication to occur at several points simultaneously. In contrast to prokaryotic cells, where the origin of replication is typically a singular point, eukaryotic cells like humans can have up to 100,000 origins. These origins are not just multiple in number but also strategically located to initiate replication efficiently.

Each origin of replication in eukaryotic cells is where the replication process begins. Enzymes recognize specific sequences in the DNA, which allows the replication machinery to bind and start unwinding the DNA, forming replication forks that proceed bidirectionally. Eukaryotic replication is similar to prokaryotic replication but occurs at a slower rate of approximately 100 nucleotides per second.

Autonomously Replicating Sequences (ARS), found in yeast which is a eukaryote, serve a similar function as the origin of replication in prokaryotes like E. coli. These origins are essential for the accurate and efficient duplication of chromosomes during cell division.