2.4 dividing to multiply
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This document summarizes the key differences between mitosis and meiosis: - Mitosis is used for asexual reproduction and somatic cell production in the body. It creates identical daughter cells from a parent cell. - Meiosis is used for sexual reproduction to create the gametes (sperm and egg cells) that have half the number of chromosomes. When gametes fuse during fertilization, the full number is restored. - There are two rounds of meiotic cell division. This leads to genetic variation between daughter cells as they are not identical, with different combinations of maternal and paternal chromosomes. This variation provides a survival advantage to offspring.
2.4 dividing to multiply
- 1. 2.4 Dividing to Multiply
- 2. Two types of Reproduction Use Mitosis Use Meiosis
- 5. Variation Variation with in a species can provide some individuals with an increase chance of surviving over others. Asexual reproduction no variation as daughter cells identical to parent (mitosis) Sexual reproduction great variation as daughter cells are not identical. With 23 pairs of chromosomes in each sperm and eggs there is 8 388 608 different possible ways to divide to make the daughter cells ( Gametes) (meiosis)
- 6. Humans
- 7. Two main types of Cells and their production in our body 1. Gametes (sex cells egg and sperm) = 23 chromosomes Produced by Meiosis 2. Somatic Cells (normal body cells) = 46 chromosomes Produced by Mitosis
- 9. Mitosis Somatic Cell Production Body constantly making new cells. Process of making new cells
- 10. Normal Cell division: Mitosis Mitosis - When a normal body cells (autosomal) undergoes cell division. Mitosis is how cells grow.
- 11. Mitosis
- 13. Meiosis Gametes (Sex Cells) Production Sex cells: 1. Sperm 2. Eggs Nuclei of sex cells contain have the number of chromosomes then normal cells = 23 individual chromosomes Fertilization = 23 + 23 = 46 SPERM EGG Sex cells made when a normal body cell in the sex organs divides into and the Pairs separate (no replication occurs)
- 14. Chromosomes carried in the sperm are called maternal chromosomes Chromosomes carried in the sperm are called paternal chromosomes MUM DAD
- 15. Remember your Human Karyotype Below is from one cells nucleus and all 23 pairs of chromosomes have been colour coded to make it easier to see partner chromosomes. We are going to use two chromosomes as an example in the next few slides. Chromosome number 1 From Mum From Dad Chromosome number 4 From Mum From Dad
- 16. Teacher Discussion and Demo with Play-Doh
- 17. Student Activity Play-Doh chromosomes Your will need per pair: Two coloured play-Doh pieces 1 m string that should be cut up into 4 pieces. Instructions: In pairs collect your two coloured play-Doh (one colour for mum and one for dad) as per teacher demo and make the chromosomes below. Use one piece of string to make the nucleus envelope. Chromosome number 1 Chromosome number 4
- 18. Activity Continued . Mitosis vs Meiosis Worksheet Read through Mitosis vs Meiosis worksheet. Colour code your chromosomes as per your play-Doh. Practically do the mitosis and then the meiosis division using your play-Doh and string following the diagrams on the worksheet. Answer the questions on the bottom of the sheet.
- 20. So what have you learnt? Complete a postie on LIFE to compare Meiosis and Mitosis and show your understanding by answer the questions below. Use your textbook page 66 to 67. Why use it? Where does it occur? Features of cells produced.
- 21. Girl or Boy Read page. 69 Complete Investigation 2.2 Whats the chance? 1. Read instructions 2. Predict number of times your get tails and heads. Give a reason for your prediction. 3. Complete the practical. Record class results in the table on board. 4. Answers questions 2 to 6.
- 22. Exercises Workbook pg. 13 to 15 Textbook Pg. 70 Remember 2 to 4, 6, 7 (b, c, d, f, h, I, j)