0
DNA contains the map of how the cell runs and survives. Replication is needed when a cell has to replace itself or another cell. This provides a way for cells to renew itself. Each strand of DNA needs to be copied and added to the new cell that is being created.
During replication, the nitrogenous bases separate and allow replication to happen. This the process.
1. Helicase is added to the DNA strand to separate the strands. It causes the nitrogenous bases to break apart and create a replication bubble. At the end of the bubble, there are replication forks that cause elongation of the DNA strands. Proteins prevent the strands from re-sticking.
2. DNA polymerase is used for process of adding new new nitrogenous bases to the separated strands. It starts at an origin of replication and moves in a direction from the 3' side of the strand to the 5' side. It can only add nucleotides in this direction. The strand that is synthesized continuously in this direction is known as the leading strand.
3. Replication moves in the same direction on both strands. It does not encounter much resistance on the leading strand which has the direction of 3' to 5'. The other strand has an anti-parallel direction to the leading strand it is complementary and runs in 5' to 3'. This is known as the lagging strand. This strand needs RNA primer to start the replication process. After the RNA primer starts the process, DNA polymerase starts adding the DNA nucleotides. This can only happen in small segments and is known as Okazaki segments. RNA primer is used for each segment to continue the replication process. After each segment is done, DNA polymerase removes the RNA primer segments and replaces them with DNA nucleotides. Ligase glues the different DNA segments together to create a continuous strand.
4. The end of the strands cannot be replicated and are left out of the replication. This area is referred to as telomeres and do not contain genetic material. The loss of this information does not change the expression of the genes.
5. During the synthesis, DNA polymerases scan the strands and makes sure that nucleotides are correctly matched. If there is an incorrectly matched nucleotide, enzymes fix the problem by replacing the nucleotide. Mutations within the DNA sequence are rare because of this proofreading. 6. After this process there are 2 complete strands of the same DNA.
7. If there is damage to DNA sequence it can be repaired through a process called nucleotide excision repair. Nuclease cuts out the incorrect matching and then replaces it with the correct DNA. Ligase then glues the strand back together. Damage can come from chemical or motor damage.
What else can I help you with?
True or false replication start at one end of DNA molecule and proceeds to the other end?
False: DNA replication starts at origins of replication which can be anywhere on the DNA molecule. Replication is taking place at multiple origins at the same time.
In prokaryotes where does DNA replication occur in the cell?
In prokaryotes, DNA replication occurs in the cytoplasm. The replication process begins at the origin of replication on the DNA molecule and proceeds bidirectionally. Multiple replication fork structures are formed to speed up the replication process.
Why does DNA replication proceed in the 5' to 3' direction?
DNA replication proceeds in the 5' to 3' direction because the enzyme responsible for building new DNA strands, DNA polymerase, can only add nucleotides to the 3' end of the growing strand. This results in the new strand being synthesized in the opposite direction, from 5' to 3'.
Where does DNA replication begin-?
The DNA replication machinery initially assembles and begins replication at the origin of replication. It contains high levels of AT base pairs for easier unzipping and there's usually one per bacteria chromosome, several for archaea chromosome, and many many more for eukaryotic linear chromosomes.
How does DNA replication differ in prokaryotes and eukaryotes?
1. In eukaryotic cells replication forks make several start sites along the DNA strand which forms replication "bubbles" which get larger the more DNA is copied, and stop when DNA replication is complete. In prokaryotic cell's DNA is formed in a loop, two replication forks start along one part of the loop (origin replication) and the replication forks copy DNA in opposite directions until they meet at the other side of the loop, making an exact copy of DNA.
True or false replication start at one end of DNA molecule and proceeds to the other end?
False: DNA replication starts at origins of replication which can be anywhere on the DNA molecule. Replication is taking place at multiple origins at the same time.
In prokaryotes where does DNA replication occur in the cell?
In prokaryotes, DNA replication occurs in the cytoplasm. The replication process begins at the origin of replication on the DNA molecule and proceeds bidirectionally. Multiple replication fork structures are formed to speed up the replication process.
True or false In eukaryotic chromosomes DNA replication begins at a single point in the chromosome and proceeds in two direction?
It's true, it's in the book
Why does DNA replication proceed in the 5' to 3' direction?
DNA replication proceeds in the 5' to 3' direction because the enzyme responsible for building new DNA strands, DNA polymerase, can only add nucleotides to the 3' end of the growing strand. This results in the new strand being synthesized in the opposite direction, from 5' to 3'.
Where does DNA replication begin-?
The DNA replication machinery initially assembles and begins replication at the origin of replication. It contains high levels of AT base pairs for easier unzipping and there's usually one per bacteria chromosome, several for archaea chromosome, and many many more for eukaryotic linear chromosomes.
How does DNA replication differ in prokaryotes and eukaryotes?
1. In eukaryotic cells replication forks make several start sites along the DNA strand which forms replication "bubbles" which get larger the more DNA is copied, and stop when DNA replication is complete. In prokaryotic cell's DNA is formed in a loop, two replication forks start along one part of the loop (origin replication) and the replication forks copy DNA in opposite directions until they meet at the other side of the loop, making an exact copy of DNA.
How do eukaryotes speed the process of replication-since they have multiple long chromosomes?
The eukaryotic genome is so much larger than the prokaryotic genome that it would not be practical to rely on a single origin of replication site when copying it for cell division. By incorporating several, the eukaryotic cell can divide without unnecessarily long delay in chromosomal replication.
Does DNA replication start at only one place in the DNA?
What do you mean by one area? If by one area you mean does it start at one area then stop and continue on another area then no, DNA replication is continuous and when it takes place it is the most important thing going on in the cell. The cells resources are directed at this process * DNA replication means copying the entire DNA molecule, so it involves the entire molecule, but not all at the same time. In bacteria (prokaryotic cells) replication begins at one point in the molecule and continues all the way round the circular molecule.Beginning at just one place would take too long in eukaryotic cells; someone has calculated that our longest chromosomes would take about a fortnight to replicate, and we cannot wait that long! So replication begins at a number of sites along the length of the DNA molecule. At each replication site, as the DNA strands are separated there is a bulge in the molecule called a replication bubble. As replication proceeds these bubbles become longer, and eventually they merge into one another and the job is done.
What are the key differences between topoisomerase and helicase in terms of their roles in DNA replication and how do they contribute to the overall process?
Topoisomerase and helicase are both enzymes involved in DNA replication, but they have different roles. Topoisomerase helps to relieve the tension in the DNA molecule by cutting and rejoining the DNA strands, allowing them to unwind and prevent tangling during replication. This helps to prevent supercoiling and maintain the integrity of the DNA molecule. Helicase, on the other hand, is responsible for unwinding the double-stranded DNA molecule by breaking the hydrogen bonds between the base pairs. This allows the DNA strands to separate and serve as templates for the synthesis of new DNA strands. Overall, topoisomerase and helicase work together to ensure that DNA replication proceeds smoothly by unwinding and untangling the DNA molecule, allowing for accurate and efficient replication to occur.
Differentiate the number of replication forks in prokaryotic and eukaryotic DNA?
Prokaryotic DNA replication typically proceeds bidirectionally from a single origin of replication, resulting in two replication forks. Eukaryotic DNA replication is more complex due to multiple origins of replication, leading to many replication forks scattered throughout the DNA. The exact number of replication forks in eukaryotic cells can vary depending on the species and cell type.
What is centrifugal replication?
Centrifugal replication is a process in which DNA replication is initiated at a specific point and proceeds in two directions away from that point. This method uses a centrifuge to separate the newly synthesized DNA strands by their density. It is often used to study the replication of circular DNA molecules, such as plasmids.
What does the replication fork do in DNA replication?
The replication fork is a structure formed during DNA replication where the parental DNA strands are separated and new complementary strands are synthesized. It allows for the simultaneous synthesis of two new DNA strands in opposite directions. The replication fork moves along the DNA strand as replication proceeds.
