<em>A reason for disruption of the cell cycle is;</em>
A. Mutation
<u>A mutation in a protein that is meant to either slow or stop the cell cycle can cause a cell to lose control and possibly form cancer.</u>
The DNA polymerases are enzymes that create DNA molecules by assembling nucleotides, the building blocks of DNA. These enzymes are essential to DNA replication and usually work in pairs to create two identical DNA strands from one original DNA molecule. During this process, DNA polymerase “reads” the existing DNA strands to create two new strands that match the existing ones.
Every time a cell divides, DNA polymerase is required to help duplicate the cell’s DNA, so that a copy of the original DNA molecule can be passed to each of the daughter cells. In this way, genetic information is transmitted from generation to generation.
Before replication can take place, an enzyme called helicase unwinds the DNA molecule from its tightly woven form. This opens up or “unzips” the double stranded DNA to give two single strands of DNA that can be used as templates for replication.
DNA polymerase adds new free nucleotides to the 3’ end of the newly-forming strand, elongating it in a 5’ to 3’ direction. However, DNA polymerase cannot begin the formation of this new chain on its own and can only add nucleotides to a pre-existing 3'-OH group. A primer is therefore needed, at which nucleotides can be added. Primers are usually composed of RNA and DNA bases and the first two bases are always RNA. These primers are made by another enzyme called primase.
Although the function of DNA polymerase is highly accurate, a mistake is made for about one in every billion base pairs copied. The DNA is therefore “proofread” by DNA polymerase after it has been copied so that misplaced base pairs can be corrected. This preserves the integrity of the original DNA strand that is passed onto the daughter cells.

A surface representation of human DNA polymerase β (Pol β), a central enzyme in the base excision repair (BER) pathway. Image Credit: niehs.nih.gov
Structure of DNA polymerase
The structure of DNA polymerase is highly conserved, meaning their catalytic subunits vary very little from one species to another, irrespective of how their domains are structured. This highly conserved structure usually indicates that the cellular functions they perform are crucial and irreplaceable and therefore require rigid maintenance to ensure their evolutionary advantage.
If you're referring to what a group of zebras is called. Its very interesting, a group of zebras is called a Dazzle or a Zeal!
Mangroves swamps or forests are productive wetlands and grow in saline and humid climates. They play an important role in fisheries, coastal protection and wildlife habitat.
<h3>What is the importance of mangrove forests?</h3>
The mangroves are located in the subtropical and the tropical region where the climate is high in humidity and have saline and waterlogged forests.
The mangroves interact with the ecosystem through various means and help other aquatic organism for shelter and reproductive sites.
They help the ecosystem in maintaining water quality and help in coastal protection along with aiding the wildlife habitat. The fishes reside in the roots and the forests structures and lay their eggs.
Therefore, option d. all of the above is correct.
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