How Many DNA Molecules Make Up an Unreplicated Chromosome? – Get Yourself Informed!
DNA or Deoxyribonucleic is really unique. It is actually a molecule that series of instructions needed by an organism to live, develop, and produce and found inside every cell. The DNA is then passed down to children from their parents. DNA also replicates through mitosis and meiosis process. But, how many DNA molecules make up an replicated chromosome? Get to know more about the information in the following article.
Why DNA Replicates?
It has been stated before that DNA is a genetic material. It functions to define every cell in the human body. Organelles and biomolecules should be copied before they are distributed to all the cells. Each of the cells will also duplicate and they will be divided through the process of meiosis and mitosis. But, why the DNA should be replicated? Well, the replication process is important to make sure that the new cell will receive chromosomes with the right number each. The process by which the DNA is replicating is called DNA replication. The replication process of the DNA is very important for the organism reproduction, cell growth, and cell repair. There are several steps that make use of multiple proteins, they are RNA and replication enzymes. But, do all of the molecules in DNA replicate? If they don’t, how many DNA molecules make up an unreplicated chromosome? And why don’t they replicate? Before finding the answer, it will be better if we talk about the DNA structures and the steps involved in the replication process first.
DNA is constructed of molecules which are called nucleotides and each of them consists of a nitrogen base, a sugar group, and a phosphate group. The nitrogen base has four types, they are adenine (A), cytosine (C), thymine (T), and guanine (G). The bases’ order serves to determine the genetic code that provides instructions for DNA. For a human, the DNA comes with more than 5 billion bases, in which 99% of them are similar in all people. There are a couple of spiral nucleic acid chains that are twisting to create a double helix shape in the double-stranded DNA. In this way, the DNA can come with more compact form. DNA molecules come with a quite long size that makes them hard to fit into the cells if they do not have the right packaging. The genetic material will then coil tightly to form structure so they can fit into the cells. The structures form chromatin which will condense to shape chromosomes when the cells are divided. But, before the replication process, the chromatin formes will loosen to give access to cell replication machinery to enter the DNA strands. It also plays important role in determining the amount of replicated DNA and how many DNA molecules make up an unreplicated chromosome will be. There are 23 pairs of chromosomes in the human which are placed inside the nucleus’ cells.
Why Don’t Chromosomes Replicate?
Once DNA is condensed, it will create some recognizable different shapes which can be aggregated and counted during Karyotyping. However, the DNA can’t undergo replication since the enzymes needed during the replication process can’t enter the double-stranded DNA. The DNA needs to unwound to make it possible for the genetic material to give access to the essential enzymes to replicate. Thus, the number of DNA will be doubled once it replicates. Not only that, the chromosomes should also be doubled. They will then get segregated into daughter cells equally in order to maintain the number of chromosomes. So, how many DNA molecules make up an unreplicated chromosome is two.
There are some enzymes that play important role in the DNA replication process to catalyze various stages during the process.
1. DNA helicase
This enzyme functions to separate and unwind double-stranded DNA since this can move easily along the DNA. The DNA helicase will then form the fork of replication by breaking the bonds of hydrogen found in the genetic material’s nucleotide pairs.
2. DNA primase
This enzyme is included in the RNA polymerase type that functions to boost the primers of RNA. They are kinds of short RNA molecules that serve as templates of the starting point in the replication process of DNA.
3. DNA polymerases
The DNA polymerases function to synthesize the new molecules of DNA. This is done by adding nucleotides to the DNA in order to lead and lag the strands.
4. DNA gyrase or topoisomerase
This kind of DNA replication enzyme functions to rewind and unwind the DNA strand to avoid the genetic material to get supercoiled or tangled.
Exonucleases are actually a group of enzymes that work to remove the bases of nucleotides from the DNA chain’s end.
In the DNA replication process, there are 4 stages involved, they are:
1. Replication Fork Formation
The double-stranded molecule should be unwound first into two single strands. In addition, the interactions between base pairs should be separated too with the help of DNA helicase enzyme. The base pairs will be broken into Y shape which is also called as replication fork. This will be the place where replication template will be started.
The primer, a short piece of RNA binds to the strand’s 3’ once they have been broken. The primer will always bind in order to serve as the DNA replication’s starting point.
By using the elongation process, the DNA polymerases will create a new strand. The newly formed strands will keep continuous since the replication proceeds on the leading strand of 5’ to 3’ direction. Meanwhile, the lagging strand replication process will start by binding with various primers at once. The replication process will be discontinued once the new fragments formed have been disjointed.
This is the last process of the DNA replication and the enzyme involved in the stage is exonuclease which will remove the primers from the strands. They will be replaced appropriately with the appropriate nitrogen bases. At the end of the process, two DNA molecules will be produced. So, get informed with how many DNA molecules make up an unreplicated chromosome now?