These ends pose a problem for DNA replication. The DNA at the very end of the chromosome cannot be fully copied in each round of replication, resulting in a slow, gradual shortening of the chromosome.
Why is there a problem replicating the ends of linear DNA?
Why is there a problem replicating the ends of linear DNA? The primer used for lagging strand synthesis can’t be replaced because there is no available 3′ OH to add the replacement DNA on to. … The telomeres represent large buffer zones of DNA sequence that do not code for biomolecules.
Why can’t the ends of chromosomes be replicated?
The end-replication problem states that small stretches of DNA at the 3′ ends of chromosomes cannot be copied because these stretches are not covered by Okazaki fragments. Because of the end-replication problem, chromosome ends are slowly shortened over time.
What is the end of chromosome problem for linear replication quizlet?
with a linear chromosome, on the lagging strand (template 5′->3′) of DNA replication, when the last piece of RNA primer at the 3′ end is removed, the DNA cannot be extended and this creates the end replication problem.
What is the challenge of replicating chromosome telomere regions?
Telomeres, the chromosomal termini, pose quite a challenge to replication machinery due to the complexity in their structures and sequences. Efficient and complete replication of chromosomes is critical to prevent aberrant telomeres as well as to avoid unnecessary loss of telomere DNA.
What happens when DNA replication reaches the end of a linear chromosome?
When the replication fork reaches the end of the linear chromosome, there is no way to replace the primer on the 5′ end of the lagging strand. The DNA at the ends of the chromosome thus remains unpaired, and over time these ends, called telomeres, may get progressively shorter as cells continue to divide.
What is end replication problem and how is it solved?
This end-protection problem is solved by protein-DNA complexes called telomeres. Studies of mammalian cells have recently uncovered the mechanism by which telomeres disguise the chromosome ends.
How do the linear chromosomes in eukaryotes ensure that its ends are replicated completely?
How do the linear chromosomes in eukaryotes ensure that its ends are replicated completely? Telomerase has an inbuilt RNA template that extends the 3′ end, so primer is synthesized and extended. Thus, the ends are protected.
How does the enzyme telomerase meet the challenge of replicating the ends of linear chromosomes?
How does the enzyme telomerase meet the challenge of replicating the ends of linear chromosomes? It catalyzes the lengthening of telomeres, compensating for the shortening that occurs during replication. DNA is a self-replicating molecule.
Why do linear chromosomes present a problem during DNA replication quizlet?
Replication of the ends of linear chromosomes pose a challenge because once the last RNA primer is removed from the very end of lagging strand, there is no DNA polymerase that can replace it. Therefore, if no mechanism was available to deal with this problem, the result would be a gap at each end of the chromosome.
What is replication end problem?
Abstract. The end replication problem hypothesis proposes that the ends of linear DNA cannot be replicated completely during lagging strand DNA synthesis. Although the idea has been widely accepted for explaining telomere attrition during cell proliferation, it has never been directly demonstrated.
What is the cause of the end replication problem quizlet?
1) When replication gets to the end of the amplicon, the primer doesn’t have a place to lay it`s primers so there`s no where DNA polymerase can synthesize a new strand. … 2) This only happens in the lagging strand. You just studied 21 terms!
What is the end replication problem why in the absence of telomerase do the ends of the linear chromosomes get progressively shorter each time the DNA is replicated?
There are ends at the DNA in eukaryotes, unlike the prokaryotic DNA that become shorter after each replication cycle. This is known as the end replication problem. It occurs because the lagging strands of the DNA do not get synthesized for the end of the DNA after the removal of RNA primers.
What happens to the ends of linear chromosomes during each round of replication and how do cells address this problem?
The ends of the chromosomes pose a problem during DNA replication as polymerase is unable to extend them without a primer. Telomerase, an enzyme with a built-in RNA template, extends the ends by copying the RNA template and extending one end of the chromosome. DNA polymerase can then extend the DNA using the primer.
Which strand has end replication problem?
As we all know, with a linear chromosome, on the lagging strand (template 5′->3′) of DNA replication, when the last piece of RNA primer at the 3′ end is removed, the DNA cannot be extended and this creates the end replication problem.
How telomeres solve the end protection problem?
This end-protection problem is solved by protein-DNA complexes called telomeres. … The ends of linear eukaryotic chromosomes must not be perceived by the cell as broken DNA ends. Protein-DNA complexes called telomeres disguise the chromosome ends, thereby preventing the activation of DNA damage signaling pathways.