Cell Division: Phases of Eukaryotic Cell Division, Interphase, Prophase

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Interphase

  • The process through which a cell must go before mitosis, meiosis, and cytokinesis.

  • As per the new researches this phase has been found to be a very active phase.

G0 Phase (Resting Phase)

Here the cell neither divides nor prepares itself for the division.

G1 Phase (Gap 1)

The cell is metabolically active and shows continuous growth during the phase.

S Phase (Synthesis)

During this stage, the DNA replication or synthesis occurs.

G2 Phase (Gap 2)

Protein synthesis occurs in this phase.

Quiescent Stage (G0)

  • This stage is also known as the quiescent stage (G0) of the cell cycle.

  • Here the cells not undergoing further division exits the G1 phase and enters the inactive stage.

Prophase

  • This is the first stage of division.

  • In this stage, the nuclear envelope is broken down.

  • Here the long strands of chromatin condense to form shorter more visible strands called chromosomes.

  • The nucleolus disappears at this stage.

  • The spindle and spindle fibers refer microtubules associated with the alignment and separation of chromosomes.

Metaphase

  • The centromeres of the chromosomes convene themselves on the metaphase plate.

  • Cohesions are the complex complexes that are responsible for an imaginary line that is at equal distances from the two centrosome poles.

  • By microtubule organizing centers (MTOCs), chromosomes line up in the middle of the cell.

    • Pushing and pulling on centromeres of both chromatids.

    • The chromosome to move to the center.

  • All the microtubules, except for the kinetochores, are in a state of instability.

    • Promoting their progression towards anaphase.

  • The chromosomes are ready to split into opposite poles of the cell at this point towards the spindle to which they are connected.

Anaphase

  • It is a very short stage of the cell cycle and occurs after the chromosomes align at the mitotic plate.

  • Here the final signal dissipates and triggers the abrupt shift to anaphase.

    • Once the final chromosome is properly aligned and attached.

  • The activation of the anaphase-promoting complex causes abrupt shift.

  • The function of tagging degradation of proteins important towards the metaphase-anaphase transition.

  • The cell and plasma are elongated by non-kinetochore microtubules with the sister chromatids being pulled apart.

Telophase

  • This is the last stage of the cell cycle.

  • Here a cleavage furrow splits the cells cytoplasm (cytokinesis) and chromatin.

  • The division of the cellular contents is not always equal.

  • The division of the cellular contents vary by cell type as seen with oocyte formation.

    • One of the four daughter cells possess most of the cytoplasm.

Cytokinesis

  • Cytokinesis is the last stage of the cell division process.

  • There is a cytoplasmic division that occurs at the end of either mitosis or meiosis.

Cytokinesis Illustration

Cytokinesis Illustration

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FAQs

Q 1. What is cell division?

Answer:

  • Cell division is the process by which a parent cell divides into two or more daughter cells.

  • It occurs as a part of a larger cell cycle.

  • Each parental cell gives rise to the two daughter cells.

Q 2. What are the three types of cell division?

Answer:

The three types of cell division are:

i) Mitosis

ii) Meiosis

iii) Binary Fission

Q 3. Why is cell division necessary?

Answer:

The cell division is necessary for three important reasons:

i) It serves as a means of reproduction in unicellular organisms through binary fission.

ii) Cell division aids in the formation of gametes in multicellular organisms.

iii) The human body also repairs injuries by means of cell division.

Q 4. What are the forms of mitosis of karyokinesis step in eukaryotes?

Answer:

The forms of mitosis of karyokinesis step in eukaryotes are:

i) Closed intranuclear pleurotomies

ii) Closed extranuclear pleurotomies

iii) Closed Orth mitosis

iv) Semi open pleurotomies

v) Semi open Orth mitosis

vi) Open Orth mitosis