Anaphase

Anaphase is the separation of chromatids which gradually move in opposite directions.This phase comes between Metaphase and Telophase.

Anaphase deals with Cytology, which is the branch of biology that studies cell structure and division. 

The Process Of Cell Division Is An Organism Is of Two Types

Mitosis – Equational Division

• It is the type of division in which new cells formed have an identical number of chromosomes.
• It occurs in Haploid(n) as well as Diploid (2n).
• This division occurs at somatic Cells.
• The division of one cell produces two cells.
• This type of division helps in growth, regeneration of body parts of organisms. For example : hair growth and cell repair. 

The Two Phases Of Mitosis Are

Meiosis – Reductional Division

• It is the type of division in which new cells formed have half the number of chromosomes.
• It occurs in Diploid (2n) organisms only.
•  One cell forms four daughter cells.
• This type of division only helps gametes. 
• Example : Sperms and Ova/Egg.

Meiosis 

Mitosis- Anaphase is the same as Meiosis-i of Anaphase-i.

The following points cover the process of Anaphase-

• This phase comes after Metaphase.
• The chromosomes align at the equator of the metaphasic plate.
• Microtubules attached to the kinetochore region result in their shortening. (Microtubules are made up of Tubulin Protein).
• Spindle fibre is attached to the chromosomes.
• Chromosomes move towards the opposite poles.
• In late Anaphase a cleavage furrow starts forming after which the cell goes on cytokinesis 
• Cytokinesis refers to the kinetic division of the cytoplasm.
• Eventually the cell reaches the final stage called Telophase. 

Anaphase-I

• Occurs in Meiosis-I and Mitosis.
• Occurs after Metaphase-I.
• During Metaphase-I, the homologous chromosomes align at the metaphase plate. 
• Each chromosome is pulled towards opposite poles due to the tension developed by the microtubules.
• In late Anaphase-I, the chromosomes reach opposite poles.
• This further leads to the transition into Telophase-I.

Anaphase-II

• Occurs in meiosis-II.
• Occurs after Metaphase-II.
• During Metaphase-II, the kinetochore is attached to opposite poles of each chromosome.
• Each chromosome is attached to the centromere when pulled by microtubules.
• In Late Prophase, every chromosome moves upwards.
• This leads to the transition into Telophase-II.

Difference In Anaphase-I And Anaphase-II

Some Important Terms Related to Cytology

Cytokinesis- Cytokinesis refers to the process by which the cytoplasm is divided .

Karyokinesis- Karyokinesis refers to the process by which the nucleus is divided. 

( Cytokinesis + Karyokinesis = Cell Division )

Nucleus- It is the cell organelle which stores the genetic material like chromosomes, made up of DNA – Deoxyribonucleic acid.

Chromosome- These are long thread like structures, which contain DNA(Deoxyribonucleic acid) and proteins. 

Haploid(n)- It represents the single set of chromosomes present in a cell.

Diploid(2n)- It represents the double set of chromosomes present in a cell.

Microtubules- It is a cytoskeleton made up of tubulin proteins.

Spindle Fibre- It is a proteinaceous structure that helps chromosomes attach.

Kinetochore- It is a disc shaped structure, made up of protein which helps chromosomes attach with spindle fibre.

Centromere- It is the central region in chromosomes where the kinetochore is attached to X-shaped Chromosomes.

Conclusions

Anaphase is a phase in the process of cell division which falls under mitosis, in which every new cell produced has an equal number of chromosomes as the parent cell. 

Cell division is of two types- a)Mitosis-Equational division b)Meiosis-Reductional division. Anaphase occurs in both types of cell division. In Mitosis, there is only one Anaphase which comes after Metaphase, whereas in Meiosis it comes after Metaphase-I and Metaphase-II. Here Anaphase is divided into Anaphase-I and Anaphase-II respectively. 

Mitosis occurs in somatic cells (general body cell) and Meiosis occurs in Gametic cells.

In Anaphase, chromosomes are aligned at the equatorial plate and start moving towards opposite poles. At late Anaphase, furrows start forming, indicating that cells in the middle undergo cytokinesis, which further divides them. Furrow formation is of two types a) Centripetal in animals    b) Centrifugal in plants. 

Anaphase is a crucial stage in cell division because if the segregation of chromosomes does not occur it leads to a change in ploidy of cell or disjunction in chromosomes which further leads to non-functioning cells.