What enzyme replicates telomeres?
What enzyme replicates telomeres?
telomerase
Telomeres are the physical ends of eukaryotic chromosomes. They protect chromosome ends from DNA degradation, recombination, and DNA end fusions, and they are important for nuclear architecture. Telomeres provide a mechanism for their replication by semiconservative DNA replication and length maintenance by telomerase.
How are telomeres replicated in DNA replication?
The ends of linear chromosomes, called telomeres, protect genes from getting deleted as cells continue to divide. Once the lagging strand is elongated by telomerase, DNA polymerase can add the complementary nucleotides to the ends of the chromosomes and the telomeres can finally be replicated.
Do telomeres protect nucleic acids?
Telomeres consist of the same sequence of six nucleotides repeated over and over again, and all this repetition makes them somewhat disposable. They protect the rest of the DNA, as they can gradually get shorter and shorter over time without the loss of any other important genetic information.
What is the problem with telomere replication?
At each cell division, the telomeres shorten because of the incomplete replication of the linear DNA molecules by the conventional DNA polymerases. This is called the end replication problem [6]. This is specifically due to the resection and fill-in reaction during the synthesis of the telomere leading-strand [7,8].
What can stop telomeres from getting shorter?
(a) Telomere length can be prevented from shortening by an enzyme Telomerase. Telomerase has a protein subunit (hTERT) and an RNA subunit (hTR). This enzyme is active in germline and stem cells and maintains their telomere length by adding ‘TTAGGG’ repeats to the ends of chromosomes.
What enzyme makes it less likely that DNA will be lost from telomeres during replication?
An enzyme called telomerase compensates for this problem by adding short, repeated DNA sequences to telomeres, lengthening the chromosomes slightly and making it less likely that important gene sequences will be lost from the telomeres during replication.
How do telomeres solve the end replication problem?
The mechanism for restoring the ends of DNA molecule in a chromosome relies on telomerase. This enzyme works by adding tandem repeats of a simple sequence to the 3′ end of a DNA strand. Hence, the loss of genomic sequences at each replication cycle can be compensated by addition of DNA sequence repeats.
What happens when telomeres run out?
Each time a cell divides and replicates, the DNA at the end of telomeres shorten. Since cell division happens throughout life, telomeres get shorter and shorter as we age. When the telomeres run out, the cell becomes inactive or dies, which leads to disease.
What are telomeres and why are they important how does telomerase play a role?
Telomeres are repetitive nucleotide sequences at each end of chromosomes. Their function is to protect the ends of the chromosomes from deterioration or fusion to other chromosomes during cell division. An enzyme called telomerase is responsible for maintaining the length of telomeres.
How is the end replication problem solved?
Eukaryotes have solved the end-replication problem by locating highly repeated DNA sequence at the end, or telomeres, of each linear chromosome. In prokaryotes, the end-replication problem is solved by having circular DNA molecules as chromosomes.
How does the enzyme extend the telomeric repeat?
The enzyme binds to a special RNA molecule that contains a sequence complementary to the telomeric repeat. It extends (adds nucleotides to) the overhanging strand of the telomere DNA using this complementary RNA as a template.
How is the polymerization of propenoic acid carried out?
The polymerization of propenoic acid is a free radical process , using an organic peroxide as an initiator. It can be carried out with the pure monomer (known as bulk polymerization), but more often it is polymerized in an aqueous solution or as an emulsion, also in water:
Why do telomeres need to be protected from DNA repair?
Telomeres need to be protected from a cell’s DNA repair systems because they have single-stranded overhangs, which “look like” damaged DNA. The overhang at the lagging strand end of the chromosome is due to incomplete end replication (see figure above).
How does a cell reverse the telomere shortening?
Some cells have the ability to reverse telomere shortening by expressing telomerase, an enzyme that extends the telomeres of chromosomes. Telomerase is an RNA-dependent DNA polymerase, meaning an enzyme that can make DNA using RNA as a template.
