Table of Contents
What phase does DNA transcription occur?
Transcription is the first phase of the protein-making process, even though the actual protein synthesis doesn’t happen until the second phase. Essentially, what happens during transcription is that an mRNA “copies down” the instructions for making a protein from DNA.
What stage of the cell cycle is responsible for DNA replication?
S phase
S phase is the period during which DNA replication occurs.
What are the phases of DNA?
The synthesis of any macromolecule proceeds in three stages: initiation, elongation and termination. This is true for DNA replication as well. During initiation, DNA synthesis begins at a specific site, called an origin of replication.
What does S phase do?
S phase is the period of wholesale DNA synthesis during which the cell replicates its genetic content; a normal diploid somatic cell with a 2N complement of DNA at the beginning of S phase acquires a 4N complement of DNA at its end.
What is the cell doing during G1 and G2?
Initially in G1 phase, the cell grows physically and increases the volume of both protein and organelles. In S phase, the cell copies its DNA to produce two sister chromatids and replicates its nucleosomes. Finally, G2 phase involves further cell growth and organisation of cellular contents.
What happens before a cell enters the S phase?
Before the cell commits to the S phase it goes through the G1/S checkpoint, also called Enter S, where the nutritional status of the cell and the DNA integrity are checked. This is an especially important step for a cell about to enter the S phase.
What happens at the G1 checkpoint in the cell cycle?
The G1 checkpoint seems to be the determinant for the cell’s fate in the cell cycle. If a cell gets the green light at the G1 checkpoint, it usually makes the rounds (completing the cycle and dividing). Otherwise, it exits the cycle altogether, entering the G0 phase. Enter M and the Regulation of the G2 Phase
Where does DNA replication take place during interphase?
Throughout interphase, nuclear DNA remains in a semi-condensed chromatin configuration. In the S phase (synthesis phase), DNA replication results in the formation of two identical copies of each chromosome—sister chromatids—that are firmly attached at the centromere region.
What’s the chromosome number in the first growth phase?
In vertebrates and diploid yeasts the chromosome number is 2n at this phase, while in haploid yeasts the chromosome number is 1n. In short, the first growth phase is the time when just after birth ( in mitosis) the cell is preparing for DNA synthesis (in S phase).