Grade 10 Science – The Cell Cycle

Mitosis is cell division that produces two identical daughter cells.

Why is cell division important? There are three reasons:

(1)Reproduction – To produce new cells

(2)Growth – As multicellular organisms grow, the number of cells increases

(3)Repair – Cells need to heal to stay alive

Grade 10 Science – The Cell Cycle

Mitosis consists of four distinct phases:

(1)Prophase

(2)Metaphase

(3)Anaphase

(4)Telophase.

The cell cycle has two other stages:

(1)Interphase – A long resting, growth and preparation stage. In this stage, the DNA strands duplicate.

(2)Cytokinesis – The final stage of cell division. The CYTOPLASM divides to produce the two daughter cells.

Grade 10 Science – The Cell Cycle

Interphase

In the interphase stage, the cell is growing in size and replicating its DNA in preparation for division. As well, the nucleus can be easily viewed.

Interphase is the longest stage of the cell cycle. It is also considered the “living phase” of the cell, in which the cell obtains nutrients, grows, reads its DNA, and conducts other "normal" cell functions.

Grade 10 Science – The Cell Cycle

Prophase (Phase 1)

This is the first phase of mitosis.

During prophase, the nuclear envelope around the nucleus starts to break down and all the chromosomes start to coil up in the centre of the cell.

Since the DNA strands duplicated during interphase, each chromosome consists of two identical strands called “sister chromatids” held together by a centromere. An individual strand is a chromatid.

Grade 10 Science – The Cell Cycle

Metaphase (Phase 2)

During metaphase, the chromosomes pairs line up in the middle of the cell.

A spindle fibre is attached to each chromosome. The fibre will pull a chromosome to either side of the cell.

Grade 10 Science – The Cell Cycle

Anaphase (Phase 3)

During anaphase, the centromere splits, and the spindle fibres become shorter pulling each chromosome pair apart and to the opposite ends of the cell.

From this separation, each chromosome pair splits into two identical single-strand parts

Grade 10 Science – The Cell Cycle

Telophase (Phase 4)

The final stage of cell replication. The chromosomes become longer and a nuclear envelope begins to reform around the chromosomes.

This phase is followed by Cytokinesis. A new cell wall is created down the centre and two daughter cells are formed.

Grade 10 Science – The Cell Cycle

The cell cycle is very complicated. It is an ordered set of events culminating in cell growth and division of the parent cell into two daughter cells.

This link will help illustrate the beauty of the cells and various features of Cell Division and the Cell Cycle