It is highly important for DNA to be able to replicate itself so that chromosomes can be copied to give the exact same genetic code to every new cell that is made. It is the base pairing rules that allow DNA to replicate.
DNA replication takes part before cell division during mitosis and meiosis. It occurs in the Interphase stage of division. In this phase, the chromosomes become long, unravelled threads of chromatin making them visible under the microscope.
Replication happens in a series of different steps, each controlled by enzymes, with ATP supplying energy.
Two identical DNA molecules result from the replication process, with one original strand and one new strand. This process is called semi-conservative replication.
It is important to understand that semi-conservative replication is a complex, enzyme-controlled reaction. To understand just how complex DNA replication can be, it must be stated that deoxyribose is a five-carbon sugar. Chemists number the carbon atoms, 1 to 5. The phosphate group bonds C3 from one sugar to C5 of the net sugar, giving an antiparallel structure.
Because of this antiparellel structure, it influences DNA replication and becomes a complex process. The main steps in semi-conservative replication are outlined here:
1. The enzyme helicase unwinds the DNA helix and the base pairs are exposed.
2. The enzyme polymerase joins new bases, known as nucleotides, to the existing strand.
3. DNA polymerase, however, cannot begin adding bases directly to a new strand from scratch. A primer molecule containing an RNA of about 10 nucleotides is needed to start the replication. The RNA primer is removed later on when the process is finished.
4. The only way DNA polymerase can work is by bonding nucleotides directly down the entire length of the 3' - 5' strang. This is referred to as the leading strand in replication.
5. The other strand (running 5' - 3' ) must be copied in short segments of around 1000 bases, called Ohazaki fragments. This is known as the lagging strand in DNA replication.
6. The enzyme ligase bonds the Ohazaki fragments to form one continuous strand of DNA.
7. To ensure replication is as fast as possible, the DNA helix is opened at many sites along the entire molecule for simultaneous replication. Each opening becomes a replication fork allowing replication to proceed in both directions from the fork. This technique makes the DNA replication very fast and efficient.
The best objective to describe DNA replication is to understand the process by which a cell makes an identical copy of its DNA. This includes grasping the role of enzymes like DNA polymerase, the significance of semi-conservative replication, and the importance of fidelity to maintain genetic information.
Semiconservative replication ensures genetic stability by passing on only one parental DNA strand to each daughter cell, allowing for accurate transmission of genetic information. It also allows for genetic variation through the incorporation of new mutations during the replication process.
The template for semiconservative replication is the original DNA strand that serves as a guide for creating a new complementary strand. During DNA replication, each original parental strand acts as a template for the synthesis of a new daughter strand.
Semiconservative DNA replication occurs in the nucleus of eukaryotic cells and in the cytoplasm of prokaryotic cells. It involves separating the DNA strands and using each strand as a template to synthesize a new complementary strand.
Semiconservative DNA replication occurs during the S phase of the cell cycle. This is the phase where DNA is replicated before cell division. Each new DNA molecule contains one original strand and one newly synthesized strand.
The best objective to describe DNA replication is to understand the process by which a cell makes an identical copy of its DNA. This includes grasping the role of enzymes like DNA polymerase, the significance of semi-conservative replication, and the importance of fidelity to maintain genetic information.
Semiconservative replication ensures genetic stability by passing on only one parental DNA strand to each daughter cell, allowing for accurate transmission of genetic information. It also allows for genetic variation through the incorporation of new mutations during the replication process.
The template for semiconservative replication is the original DNA strand that serves as a guide for creating a new complementary strand. During DNA replication, each original parental strand acts as a template for the synthesis of a new daughter strand.
Semiconservative DNA replication occurs in the nucleus of eukaryotic cells and in the cytoplasm of prokaryotic cells. It involves separating the DNA strands and using each strand as a template to synthesize a new complementary strand.
Conservative replication and semiconservative replication are the ways DNA reproduces itself. The difference being whether the newly formed strands pair with each other or with an old one.
Semiconservative DNA replication occurs during the S phase of the cell cycle. This is the phase where DNA is replicated before cell division. Each new DNA molecule contains one original strand and one newly synthesized strand.
Semiconservative replication means that during DNA replication, each new DNA molecule contains one original ("old") strand and one newly synthesized ("new") strand. This process ensures that the genetic information from the original DNA molecule is conserved in the newly formed molecules.
The experiment that supported the hypothesis that DNA replication was semiconservative was known as the Meselson-Stahl Experiment.
Watson and Crick mentioned it slightly in their paper but didn't propose a full method of replication. a number of different people collaborated to work out the full model of replication which is still no totaly finished, (few proteins left to find)
Model A and Model B have similar results after replication cycle 1, showing consistent outcomes across multiple runs of the experiments. This suggests that the findings from both models are robust and reproducible.
Telomerase is the least related because it is not directly involved in the replication process of DNA like Okazaki fragments, the replication fork, DNA polymerase, or the semi-conservative model. Telomerase functions to maintain the length of telomeres in eukaryotic chromosomes, which is separate from the actual DNA replication machinery.
Semiconservative replication of DNA ensures that each newly synthesized DNA molecule contains one original parental strand and one newly synthesized daughter strand. This mechanism helps maintain genetic diversity and fidelity during cell division, allowing for accurate transmission of genetic information to the next generation. It also enables the repair of damaged DNA through mechanisms such as proofreading and mismatch repair.