Edited Invalid date
9.2 DNA Replication
When a cell divides, it is important that each daughter cell has the same copy of the DNA.
The process of DNA replication is used to accomplish this.
The S phase of the cell cycle is where the replication of DNA occurs.
The structure of the double helix gave a clue as to how it is copied.
The adenine nucleotides pair with the other two.
The two strands are related.
A strand of DNA with a sequence of AGTCATGA will have a strand with the same sequence.
The sequence of bases in one strand can be used to create the correct sequence of bases in the other strand.
It is possible to recreate the other strand if you have one strand.
The model suggests that the two strands of the double helix separate during replication, and each strand serves as a template from which the new strand is copied.
The model of DNA replication is semiconservative.
The original strands of DNA are shown in gray and the newly synthesized strands are shown in blue.
Each of the two strands that make up the double helix serves as a template from which new strands are copied.
The new strand will complement the old strand.
There are two strands of new double strand, one parental and one daughter strand.
Two DNA copies have the same sequence of bases and are divided into two daughter cells.
The process of DNA replication is very complex because of the complexity of the genomes.
It occurs in three stages.
To form structures called nucleosomes, histones are bound to eukaryotic DNA.
The replication process involves the accessibility of the DNA to the relevant genes.
The origin of replication is a specific sequence of nucleotides.
Two replication forks are formed at the beginning of replication, and they are extended in both directions as replication proceeds.
Multiple origins of replication can be found on the chromosomes, and can occur at the same time.
The primer is removed and replaced with a new one.
One strand, which is similar to the parental strand, is synthesised continuously toward the fork so the polymerase can add more nucleotides.
Each fragment requires a primer made ofRNA to start the synthesis.
There are new bases added to the parental strands.
One strand is made continuously, while the other strand is made in pieces.
Primers are removed, new DNA nucleotides are put in place, and the backbone is sealed.
The opening of the origin of replication leads to the formation of a replication fork.
A primer is formed by the synthesis of an RNA molecule.
The leading strand and lagging strand have different ways of making DNA.
The fragments are joined by ligase.
You have isolated a cell strain in which the joining together of the fragments is impaired and you suspect that there is a change in the activity of the replication fork.
The end of a line in eukaryotic chromosomes is the reason for the linearity of the chromosomes.
You have learned that the polymerase can add only one direction.
The lagging strand has no place for a primer to be made for the DNA fragment to be copied at the end of the chromosomes.
The ends of the cell are unpaired and get shorter as the cells divide.
Each round of DNA replication shortens the telomeres, which are the ends of the chromosomes.
A six base-pair sequence is repeated 100 to 1000 times in humans.
The telomerase is attached to the end of the chromosomes and the bases of the RNA template are added on the end of the DNA strand.
Once the lagging strand template is sufficiently long, DNA polymerase can add nucleotides to the ends of the chromosomes.
The ends of the chromosomes are duplicated.
The ends of linear chromosomes are maintained by telomerase.
Germ cells, adult stem cells, and some cancer cells are some of the cells that telomerase is found to be active in.
The discovery of telomerase and its action was made by Elizabeth Blackburn.
The scientist who discovered how telomerase works is Elizabeth Blackburn.
Adult cells that go through cell division have their telomeres shortened.
These studies used mice that were deficient in telomerase.
The function of the testes, spleen, and intestines were improved by the telomerase reactivation in these mice.
Treatment of age-related diseases in humans may be possible with the reactivation of the telomeres.
The prokaryotic chromosome has a less extensive coiling structure than the eukaryotic chromosomes.
The chromosomes are coiled around the proteins.
Structural differences necessitate some differences in the DNA replication process in two life forms.
The small size of the genome and large number of variant available make DNA replication very well-studied in prokaryotes.
1000 nucleotides are added per second.
The process is much quicker than in otheryotes.
There are differences between prokaryotic and eukaryotic replications.
Mistakes can be made while adding nucleotides.
Every newly added base is edited by it.
Incorrect bases are removed and replaced with the correct ones.
The wrongly incorporated base is excised from the DNA and replaced with the correct base.
It's important to correct thymine dimers, which are caused by ultraviolet light.
The two thymine nucleotides on one strand are covalently bonding to each other.
If the dimer is not removed and repaired, it will lead to a change.
Individuals with flaws in their nucleotide excision repair genes are more likely to develop skin cancer early in life.
Proofreading corrects errors during replication.
The incorrect base is detected after replication.
This base is detected by the mismatch repair proteins and removed by nuclease action.
The correct base has filled the gap.
The repair of thymine dimers is done by the nucleotide excision.
When exposed to the sun's UV rays, thyemine can form thyemine dimers.
They are excised and replaced in normal cells.
A permanent change in the DNA sequence is what it is.
Cancer can be caused by defects in repair genes.
Review flashcards and saved quizzes
Getting your flashcards
Privacy & Terms