Search results
slideshare.net
- DNA replication occurs in preparation for mitosis, when a parent cell divides to produce two genetically identical daughter cells – as each daughter cell contains the same number of chromosomes as the parent cell, the number of DNA molecules in the parent cell must be doubled before mitosis takes place
www.savemyexams.com/a-level/biology/aqa/17/revision-notes/1-biological-molecules/1-5-nucleic-acids-structure--dna-replication/1-5-8-the-process-of-semi-conservative-replication/The Process of Semi-Conservative Replication | AQA A Level ...
People also ask
How does DNA replication occur in a cell?
Which phase of the cell cycle is responsible for initiation of DNA synthesis?
How initiation of DNA replication is coordinated with the eukaryotic cell cycle?
Why does DNA replication stall at the start of S phase?
How is DNA replication coordinated with macromolecular synthesis?
How does DNA replication occur in eucaryotic cells?
- Prophase. Figure 1: During prophase, the chromosomes in a cell's nucleus condense to the point that they can be viewed using a light microscope. Prophase is the first phase of mitosis.
- Prometaphase. After prophase is complete, the cell enters prometaphase. During prometaphase, the nuclear membrane disintegrates and the mitotic spindle gains access to the chromosomes.
- Metaphase. Figure 3: (a) Metaphase and (b) Anaphase. In metaphase (a), the microtubules of the spindle (white) have attached and the chromosomes have lined up on the metaphase plate.
- Anaphase. After metaphase is complete, the cell enters anaphase. During anaphase, the microtubules attached to the kinetochores contract, which pulls the sister chromatids apart and toward opposite poles of the cell (Figure 3c).
- Initiation
- Elongation
- Termination
DNA synthesis is initiated at particular points within the DNA strand known as ‘origins’, which have specific coding regions. These origins are targeted by initiator proteins, which go on to recruit more proteins that help aid the replication process, forming a replication complex around the DNA origin. Multiple origin sites exist within the DNA’s ...
Once DNA Polymerase has attached to the two unzipped strands of DNA (i.e. the template strands), it is able to start synthesising new strands of DNA to match the templates. DNA polymerase is only able to extend the primer by adding free nucleotides to the 3’ end. One of the template strands is read in a 3’ to 5’ direction, therefore the new strand ...
The process of expanding the new DNA strands continues until there is either no more DNA template strand left to replicate (i.e. at the end of the chromosome) or two replication forks meet and subsequently terminate.The meeting of two replication forks is not regulated and happens randomly along the course of the chromosome. Once DNA synthesis has ...
Mar 17, 2022 · The replication of DNA occurs during the synthesis phase, or S phase, of the cell cycle, before the cell enters mitosis or meiosis. The elucidation of the structure of the double helix provided a hint as to how DNA is copied.
In this section, we discuss how DNA replication is initiated and how cells carefully regulate this process to ensure that it takes place at the proper positions on the chromosome and also at the appropriate time in the life of the cell.
- Bruce Alberts, Alexander Johnson, Julian Lewis, Martin Raff, Keith Roberts, Peter Walter
- 2002
- 2002
The genetic program responsible for initiating DNA replication at the appropriate cell size, and for preventing re-initiation of DNA synthesis prior to mitosis, is not yet understood in detail, but recent work, particularly on yeast, has provided considerable insight into its general characteristics.
S (synthesis) phase: This phase is defined by the initiation and termination of DNA synthesis. G 2 (gap or growth 2) phase: This second “gap” phase lasts from the end of DNA synthesis to the onset of mitosis. The cell continues to grow but also prepares for what’s to come in the next phase.
