1. Meiosis Year 10 Li To understand the process of Meiosis. I can
- Accurately define what meiosis is
-Accurately list the phases of meiosis and what occurs in each stage
-Create an accurate poster that outlines all the phases of meiosis as well as provide a description of each stage with a picture.

2. Revision

3. What is a chromosome?
Chromosomes are made up of long coiled molecules of DNA. This chemical is divided into regions called genes. The DNA molecule contains four different molecules called bases. There are four different bases. Each gene is made up of a pattern of these four bases.

4. Check your understanding
Complete the complementary base pairs AAATCCTGGTTCAA TTTAGGACCAAGTT What are the four bases? Cytosine Adenine Thymine Guanine

5. Parts of the chromosome
There are four parts to a chromosome
Telomere
Centromere - the central region of the chromosomal structure. It's where the two sister chromatids are joined to each other.
Short Arm - all human chromosomes possess two arms - a short arm and a long arm. It is termed the 'p' arm.
Long Arm - is termed the 'q' arm.
Telomere - The ends of the chromosome
Short arm or ‘p’ arm
Long arm or ‘q’ arm

6. Introduction video Meiosis square dance Meiosis rap video
Video of meiosis
Introduction video Meiosis square dance Meiosis rap video

7. Terms you need to know
Haploid cell = for example egg or sperm cell they have one of each chromosomes. Diploid cell = all other cells in the body they contain two of each chromosome. Gametes = another name for haploid cells (e.g. sperm and egg cells) when these two cells fuse together they form a zygote cell Parent/mother cell = cell that is replicated Daughter cell = cells that are made from the parent/mother cell Tetrads = A four-part structure that forms during the prophase of meiosis and consists of two homologous chromosomes, each composed of two sister chromatids.

8. What is meiosis
Meiosis is a two-part cell division process in organisms that sexually reproduce that results in new cells. Each new cell contains half the number of chromosomes of the original cell.
The new cells produced in meiosis are referred to as gametes as they only have half the number of chromosomes that the parent cell (the original cell that was divided) There are two stages of meiosis: meiosis I and meiosis II. At the end of the process, four daughter cells are produced.

9. The different stages
Phase 1 Interphase Prophase I Metaphase I Anaphase I Telophase I/Cytokinesis Interkinesis - break period Phase 2 Prophase II Metaphase II Anaphase II Telophase II Cytokinesis- End result of meiosis is 4 haploid daughter cells

10. Phase 1

11. Interphase
-the cell replicates its chromosomes -each chromosome has two sister chromatids held together by a centromere

12. Prophase 1
-chromosomes coil up and a spindle forms -homologous chromosomes come together. -Crossing Over may occur when chromatids exchange genetic material -Crossing Over results in new combinations on a chromosomes

13. Metaphase 1
-the centromere of each chromosome becomes attached to a spindle fibre -the spindle fibres pull the tetrads to the equator of the spindle -homologous chromosomes are lined up side by side as tetrads

14. Anaphase 1
-homologous chromosomes separate and move to opposite ends of the cell -centromeres do not split -this ensures that each new cell will receive only one chromosome from each homologous pair

15. Telophase 1
-the spindle breaks down and the chromosomes uncoil -the cytoplasm divides to yield two new cells -each cell has half the genetic information of the original cell because it has only one homologous chromosome from each pair

16. Phase 2

17. Prophase II
-a spindle forms in each of the two new cells and the fibres attach to the chromosomes

18. Metaphase II
-the chromosomes are pulled to the centre of the cell and line up randomly at the equator

19. Anaphase II
-the centromere of each chromosome splits -the sister chromatids separate and move to opposite poles

20. Telophase II
-nuclei re-form -the spindles break down -the cytoplasm divides

21. What Meiosis produces (cytokinesis)
-four haploid sex cells from one original diploid cell -each haploid cell contains one chromosome from each homologous pair -haploid cells will become gametes transmitting genes to offspring

22. What are the stages of meiosis What does meiosis produce
Key concepts
What is meiosis
What are the stages of meiosis
What does meiosis produce