Tag Archives: biology

Rna Telomerase

[mage lang=”en|es|fr|en” source=”flickr”]rna telomerase[/mage]
How is telomerase RNA synthesized?

telomerase RNA component (TERC) is transcribed from the TERC gene.

the TERC gene is located –

Cytogenetic Location: 3q26

Molecular Location on chromosome 3: base pairs 169,482,397 to 169,482,847

Tom Cech Part 1

Telomerase Polymerase

[mage lang=”en|es|fr|en” source=”flickr”]telomerase polymerase[/mage]
differences and similarities in dna polymerase, primase, and telomerase?

name three differences and three similarities between those three

1. DNA Polymerase III Responsible for DNA Replication
Polymerase III is really an aggregate of ten different polypeptides and is referred to as a holoenzyme. The assembled aggregate has a total molecular weight of 760 kDa. The subunits are present in the holoenzyme in equal ratios. There are only 10-15 holoenzyme molecules per cell, and when the holoenzyme binds to the DNA, it remains firmly attached and proceeds along the growing chain until the strand is complete. The holoenzyme is a dimmer with two active sites, one for synthesizing the leading strand and one for extending the lagging strand. How the holoenzyme by passes the previously synthesized strand to get the next primer on the lagging strand is not exactly understood, but it likely involves folding the DNA at the site of synthesis.
2. The Primosome is Responsible for DNA strand initiation.
The primosome is a huge protein composed of 15 subunits responsible for the initiation of each new Okazaki fragment. As mentioned earlier, DNA polymerase can not initiate new strand synthesis, but RNA polymerases can initiate strand synthesis de novo. The primosome accomplishes initiation of strand synthesis by synthesizing a short segment of RNA for the DNA polymerase to use as a primer. The primase component of the primosome is responsible for synthesis of the short RNA fragment. However, it can not act alone; it must be present in the primosome complex.
3. Telomerase
It adds specific DNA sequence repeats (“TTAGGG” in all vertebrates) to the 3′ end of DNA strands in the telomere regions, which are found at the ends of eukaryotic chromosomes. This enzyme is active only in germ cells and cancer cells.Embryonic stem cells express telomerase, which allows them to divide repeatedly and form the individual. In adults, telomerase is highly expressed in cells that need to divide regularly (e.g., in the immune system), whereas most somatic cells express it only at very low levels in a cell-cycle dependent manner.
Good day Guy. Hope you are enjoying answers.

Telomerase Dna Replication

[mage lang=”en|es|fr|en” source=”flickr”]telomerase dna replication[/mage]
DNA replication question?

how does shortening of the telomeres(leading to unstable chromosomes which will result in the cell line dying) occurs if the telomeric loss can be compensated by the enzyme telomerase?

That’s a good question.

In yeast, protozoa and other single-celled organisms, telomerase is active. These cells can divide forever. However, in most cells of higher organisms, telomerase is inactive and the ends of the chromosomes get shorter with each cell division. At a certain telomeric length, the cells no longer divide.

However, if telomerase becomes active, and the ends of the chromosomes lengthen, a signal is conveyed for cells to keep dividing, which can lead to cancerous growth.

Hope that helps.