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Experts please answer !! Please answer my question!! Please explain the various stages of inter phase in simple terms with the diagram

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Answer

Cell cycle represents the coordinated steps of a cell division.

Every cell cycle is mainly divided into 2 phases:

1. Interphase

2. M phase

  • Interphase represents the events occurring before actual cell division starts. It is a kind of preparatory phase where cell grows in size, Duplicates its DNA to distribute to daughter cell and synthesizes proteins and other molecules for initiating mitosis.
  • M phase: It is the major dramatic phase of the cell cycle where actual cell division occurs.

 

Interphase is divided into 3 phases:

1. G1 phase or gap 1 phase

2. S or synthesis phase

3. G2 or gap 2 phase

​​​​Gap 1 phase: 

  • During this phase, the cell grows in size
  • synthesizes proteins required for DNA replication.
  • Checks that DNA replication occurs only once in one cell cycle.
  • DNA decondensed to form chromatin.​​​​​​

S phase

  • This is an important phase as DNA content of the cell doubles by replicating DNA. for example, If a cell has initially 2C DNA content, it will double to 4C. 
  • But an important point to be noted is that the ploidy of cells does not double. For example, If a cell is diploid (2n), it will remain diploid.
  • DNA replication is a crucial step as it should not produce an error in DNA because DNA is the genetic material
  • Therefore, the cell spends most of the time in the S phase. For example Mammalian cells spend 7 - 8 hrs in S phase.

Gap 2 phase:

  • S phase is followed by the G2 phase.
  • In this phase, the cell grows in size, synthesizes proteins required for the initiation of mitosis, which is the actual cell division.
  • It checks DNA replicated has no damage and error before it is separated into 2 daughter cells.

G0 phase

  • Also called as Quiescent phase.
  • When cell division is not required, cells arrest in this phase where they are metabolically active but not dividing any longer.
  • Also when nutrients and other growth factors are not sufficient for cell cycle, the cell gets arrested at this phase.
Below diagram represents interphase

 


​​​​​​​Regards,

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The?cell cycle?has three phases that must occur before?mitosis,?or cell division, happens. These three phases are collectively known as interphase. They are G1, S, and G2. The G stands for gap and the S stands for synthesis. The G1 and G2 phases are times of growth and preparation for major changes. The synthesis phase is when the cell duplicates the DNA in its entire genom

G1 Phase

G1 phase?is the time during which the cell makes more proteins so that it can grow to its proper size. The protein concentration within a cell is estimated to be 100 milligrams per milliliter. It is also the time when the cell makes more ribosomes, which are machines that make proteins. A cell will not exit the G1 phase and enter the S phase until it has enough ribosomes. The late end of the G1 phase is also when the mitochondria of the cell fuse together into a network of mitochondria, which helps these organelles become more efficient at producing energy molecules.

Synthesis (S) Phase

S phase, or synthesis phase, is the time during which the cell copies its DNA in preparation for mitosis. Since DNA does not exist by itself in the nucleus but is packaged by proteins, new packaging proteins must also be made to wrap the copied DNA. These package proteins are called histones. The production of histone proteins and the copying of DNA are closely linked. Stopping one process will stop the other. S phase is also the time when the cell produces a lot more phospholipids. Phospholipids are the molecules that make up the cell membrane and the membrane of the cell?s organelles. The amount of phospholipid doubles during S phase.

G2 Phase

The?G2 phase?is the time during which a cell replicates its organelles in preparation for mitosis. Not only does the DNA need to be divided, but so do the organelles. G2 is the last chance for the cell to make more protein in preparation for division. The cell has twice the amount of DNA during G2 than it did during G1. G2 is necessary for the cell to make sure that all of the DNA is in intact; no breaks and no nicks. The G2 to mitosis transition is the last checkpoint before the cell commits to entering mitosis.

G0 Phase

G0 phase can occur right after mitosis and right before G1 phase, or a cell in G1 phase can enter G0 phase. Entry into G0 is known as leaving the cell cycle. Cells that mature to become highly specialized cells are said to differentiate. Cells exit the cell cycle and enter G0 in order to differentiate. Terminally differentiated cells are those that never enter the cell cycle again, meaning they stay in G0 and never divide. However, some cells can be triggered to leave G0 and re-enter G1, which allows them to divide again.

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