Question

The diagram below represents a stage during cell division. Study the same and then answer the questions that follow :
(a) Name the parts labelled 1, 2 and 3.
(b) Identify the above stage and give a reason to support your answer.
(c) Mention where in the body this type of cell division occurs.
(d) Name the stage prior to this stage and draw a diagram to represent the same.

Answer 1

(a): Anaphase stage:

1. Anaphase is considered a short phase.
2. This phase involves the separation of sister chromatids and their separation.
3. The spindle fibers contract causing the centromere to split.
4. After this, the sister chromatids are pulled apart to opposite ends of the cell.

Parts in the given diagram:

1. Centriole:

• All animal cells have two centrioles.
• They help the cell during cell division.
• They help in cell division by forming microtubule organising centres.
• They are found in animal cells. Spindle fibres made up of microtubules arise from each centriole.
• There are two centrioles at each pole of the dividing cell.

2. Spindle fibres:

• The spindle fibre arise from the centrioles from one end.
• They get attached to the chromosomes aligned at the metaphase plate at centromeres.
• The shortening of the spindle fibres caused the splitting of the centromere, separation of the chromatids of the chromosomes and their movement towards the opposite poles.

3. Chromatids:

• A chromosome is made up two Identical Sister Chromatids.
• And each sister chromatids are joined at the centromere.
• They are the most condensed form of the DNA.
• Each chromatid carry identical DNA copy.

(b): Anaphase:

1. The stage described in the diagram is the late anaphase of mitosis in an animal cell.
   
2. The stage can be identified by the presence of separated chromatids which are moving towards the opposite poles.
   
3. Also, there is shortening of the spindle fibres.
4. The appearance of the furrow in the cell membrane classifies the stage as the late anaphase.​
   

(c): Location:

1. The anaphase shown is the stage of mitotic cell division.
2. The mitosis occurs in the somatic cells of the body.
3. Somatic cells are responsible for the growth and development of an organism.
4. They are required for repair and regeneration.

(d): Metaphase:

1. The stage before anaphase is called the metaphase stage.
2. During the metaphase stage, the chromosomes are aligned at the equatorial region of the cell.
   
3. The spindle arising from the centrioles get attached to the chromosomes at centromeres.
4. The chromosomes are at the most condensed state at this phase.
5. The below diagram shows the metaphase stage of mitosis: