Does DNA polymerase bind to telomeres?
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.
How are telomeres shortened with each DNA replication?
Telomeres are subjected to shortening at each cycle of cell division due to incomplete synthesis of the lagging strand during DNA replication owing to the inability of DNA polymerase to completely replicate the ends of chromosome DNA (“end-replication problem”) (Muraki et al., 2012).
What enzyme prevents telomere shortening?
(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 is the difference between DNA polymerase and telomerase?
Telomerase adds complementary RNA bases to the 3′ end of the DNA strand. Once the 3′ end of the lagging strand template is sufficiently elongated, DNA polymerase adds the complementary nucleotides to the ends of the chromosomes; thus, the ends of the chromosomes are replicated.
What feature of DNA polymerase causes the end replication problem solved by telomerase?
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 . This is specifically due to the resection and fill-in reaction during the synthesis of the telomere leading-strand [7,8].
What enzyme extends telomeres?
Telomerase is a ribonucleoprotein that extends the telomeric ends of the chromosomes to counterbalance the natural shortening due to incomplete DNA replication in eukaryotic cells.
What is the role of DNA polymerase during DNA synthesis?
What is the role of DNA polymerase during DNA synthesis? DNA polymerase is the enzyme that catalyzes the addition of a nucleotide onto the 3′ end of a growing DNA strand. DNA polymerase is the enzyme complex responsible for synthesizing a new strand of DNA, using an existing strand as a template.
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.
What is the role of telomeres in DNA replication?
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.
Why do telomeres become shorter during DNA replication in eukaryotes?
How does telomerase prevent linear chromosomes from shortening during replication?
Explain how telomerase prevents linear chromosomes from shortening during replication. Telomerase binds to the overhang at the end of a chromosome. Once bound, it begins catalyzing the addition of deoxyribonucleotides to the overhang in the 5′ -> 3′ direction, lengthening the overhang.