1. Cell Division Lesson 1 National 4 Cell Biology Unit

2. Everyone in this room started life as a single cell, a fusion of a sperm and egg cell. What processes must have happened to develop you from that single cell?

3. How many new cells do you think you will make in a day? Cell Division throughout Life

4. 330 000 000 in 20 minutes so… 23,760,000,000 new cells every day!

5. What do these pictures all have in common?

6. They are all examples of Cell Division in action for growth or repair!

7. Learning Intentions I will be able to explain the importance of cell division in allowing organisms to grow and repair. I will be able to describe the process of mitosis. I will be able to explain the importance of maintaining a chromosome complement.

8. Success Criteria I can explain how cell division allows growth and repair of organisms and give real life examples. I can label a diagram and show the stages of mitosis in order. I can define the term chromosome complement and explain why this is important to maintain when making new cells.

9. How do Cells Divide? MitosisMitosis – watch this clip on the process of mitosis and answer the following questions: 1.How are new cells produced? 2.What are chromosomes? Where are they found? 3.What kind of cells undergo mitosis? 4.What are the only kind of cells that do not undergo mitosis?

10. Put the following stages of mitosis in the correct order: New nuclear membranes form around the chromosomes, followed by new cell membranes, creating two new identical cells. Chromosomes replicate to form identical chromatids. Spindle fibres then pull the matching chromatids apart, to opposite poles of the cell. The membrane around the nucleus breaks down, and spindle fibres attach to the chromatids and line them up in the centre of the cell - equator.

11. Why do chromosomes need to be copied so carefully and put into each new cell? Chromosomes carry GENES, which are stretches of DNA. Each GENE codes for one protein e.g. one gene codes for haemoglobin, the substance in red blood cells that carries oxygen. One gene will code for collagen which makes a fibrous tissue that makes up parts of the body like tendons, ligaments and skin, and is also abundant in cornea, cartilage, bone, blood vessels, the gut, and intervertebral disc.

12. Chromosome Complement 1 The number of chromosomes that a species of animal or plant possesses. Why so you think it is important that each new cell has the same chromosome complement as the parent cell?

13. Chromosome Complement 2 Why so you think it is important that each new cell has the same chromosome complement as the parent cell? During growth and development of an organism will be able to provide the animal or plant with all the characteristics of its species. Losing any chromosome would mean a loss of genetic information – the information that forms the code allowing the cell to function correctly!

14. Success Criteria I can explain how cell division allows growth and repair of organisms and give real life examples. I can label a diagram and show the stages of mitosis in order. I can define the term chromosome complement and explain why this is important to maintain when making new cells.