SPM Biology 5 Cell Division (Part 1)

Nuclear Division: Introduction to Mitosis and Meiosis

Nuclear division can be divided into two types, Mitosis and Meiosis. Before the students go through the processes of both nuclear divisions, I will normally explain the concept of Mitosis and Meiosis.
So, what is Mitosis? what is Meiosis? They are both division of cell, but what are the differences between them? Please take a look the table below;

Comparison between mitosis and meiosis

Chromosomes

• Chromosomes are thread-like structures located inside the nucleus of animal and plant cells. 
• Each chromosome is made of protein and a single molecule of deoxyribonucleic acid, or "DNA". 
• Passed from parents to offspring, DNA contains the specific instructions that make each type of living creature unique. 
• The term chromosome comes from the Greek words for color (chroma) and body (soma). 
• Scientists gave this name to chromosomes because they are cell structures, or bodies, that are strongly stained by some colorful dyes used in research.

Chromosome

Basic structure of chromosome

So what do chromosomes actually do?

• The unique structure of chromosomes keeps DNA tightly wrapped around spool-like proteins, called histones. 
• Without such packaging, DNA molecules would be too long to fit inside cells.
•  For an organism to grow and function properly, cells must constantly divide to produce new cells to replace old, worn-out cells. 
• During cell division, it is essential that DNA remains intact and evenly distributed among cells.
• Chromosomes are a key part of the process that ensures DNA is accurately copied and distributed in the vast majority of cell divisions.