1 / 63

Cell Division

Explore the purposes and stages of cell division, understanding chromosomes and genes, and identifying mitosis through self-learning exercises.

lgaudreau
Download Presentation

Cell Division

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Cell Division

  2. Purposes of cell division • Increase the number of cells for growth and repair of worn out tissues • Transmit genetic information to later generations • Reproduction and heredity

  3. What's inside the nucleus? chromosome nucleus chromatins

  4. What is a chromosome? • Genetic materials found inside the nucleus of a cell • Made of protein and DNA • DNA controls protein synthesis  Control the appearance of characters and metabolic activities of an organism

  5. A gene is a short length of DNA on chromosome which controls an inherited character of the organism gene controlling skin colour gene controlling tongue rolling chromosome gene controlling eye colour • A chromosome carries a lot of genes gene controlling blood group

  6. Each species has a fixed number of chromosomes in the nucleus of each of its cells • Chromosomes always exist in pairs in the body (somatic) cells Homologous chromosomes • Each human somatic cell has 46 chromosomes • 23 pairs of homologous chromosomes

  7. Members of homologous chromosomes carry same genes • But the genes on the members of homologous chromosomes may be of different forms •  Alleles allele for white skin colour allele for white skin colour

  8. Alleles • Alternative forms of genes on the same position of the homologous chromosomes which control the same character but have different expressions

  9. 22 pairs are identical in both sexes • autosomes • The 23rd pair is different in male and female • sex chromosomes

  10. Steps of cell division • Nuclear division • Cytoplasmic cleavage

  11. CELL CYCLES

  12. Types of nuclear division • Mitosis • Meiosis

  13. Mitosis • Produces twoidentical daughter cells • Each daughter cell has the same kind and number of chromosomes as the original parent cell

  14. Interphase (Resting stage) • Chromosomes cannot be seen • Chromosomes duplicate and double in number

  15. Prophase nuclear membrane disappearing chromatids centromere • Chromosomes become visible • Each chromosome consists of two identical chromatids homologous chromosomes

  16. Metaphase • Chromosomes line up at the equator (centre of the cell) • Spindles are formed to attach to the centromere of each chromosome

  17. Anaphase chromosomes • Sister chromatids separate as individual chromosomes • They move apart towards the opposite poles

  18. Telophase nuclear membrane forming • Chromosomes gradually disappear • Nuclear membrane is form around each set of chromosomes

  19. Interphase Plant cell Animal cell

  20. Prophase Plant cell Animal cell

  21. Metaphase Plant cell Animal cell

  22. Anaphase Plant cell Animal cell

  23. Telophase Plant cell Animal cell

  24. Cytoplasmic division cleavage furrow cell plate • Division of cytoplasm • Animal cells : by formation of cleavage furrow • Plant cells : by formation of cell plate

  25. REVISION

  26. Can you identify the different stages of mitosis from the diagram below? anaphase interphase telophase metaphase prophase

  27. Self Learning Exercise Click the button for a photomicrograph showing the cells of a plant at different stages of mitosis Q: Arrange the above cells labelled 1 to 4 in the correct sequence of mitosis. A. 1 --> 2 --> 4 --> 3 B. 3 --> 2 --> 4 --> 1 C. 3 --> 4 --> 2 --> 1 D. 2 --> 3 --> 4 --> 1

  28. Here is a photomicrograph showing the cells of a plant at different stages of mitosis : Back

  29. Sorry, you’ve got the wrong answer!!! This is not a correct sequence of mitosis. Try again...

  30. Sorry, you’ve got the wrong answer!!! This is not a correct sequence of mitosis. Try again...

  31. Congratulation!!! You’ve got the correct answer!!! Click here

  32. Sorry, you’ve got the wrong answer!!! This is not a correct sequence of mitosis. Try again...

  33. Self Learning Exercise Click the button for a photomicrograph showing the cells of a plant at different stages of mitosis Q: What is the DNA content of cell 1 as compared with that of cell 3? A. DNA content of cell 1 and cell 3 are the same. B. DNA content of cell 1 is doubled that in cell 3. C. DNA content of cell 1 is only half of that in cell 3. D. DNA content of cell 1 is only quarter of that in cell 3.

  34. Here is a photomicrograph showing the cells of a plant at different stages of mitosis : Back

  35. Sorry, you’ve got the wrong answer!!! Remember that chromosomes are made of DNA, and the chromosomes in cell 3 are duplicated. Try again...

  36. Sorry, you’ve got the wrong answer!!! Remember that chromosomes are made of DNA, and the chromosomes in cell 3 are duplicated. Try again...

  37. Congratulation!!! You’ve got the correct answer!!! Go to next question...

  38. Sorry, you’ve got the wrong answer!!! Remember that chromosomes are made of DNA, and the chromosomes in cell 3 are duplicated. Try again...

  39. Self-Learning Exercise Q: Click this button to see the information for answering this question : Which cells contain the same amount of DNA? A. 1 and 2 only B. 1 and 3 only C. 2 and 3 only D. 1, 2 and 3

  40. Information : The photomicrograph below shows some plant cells at different stages of mitosis : Back to the question

  41. Sorry, you’re wrong!!! Remember that the different stages of cell division shown is mitosis! Try again!!!

  42. Sorry, you’re wrong!!! Remember that the different stages of cell division shown is mitosis! Try again!!!

  43. Sorry, you’re wrong!!! Remember that the different stages of cell division shown is mitosis! Try again!!!

  44. Congratulations!!! You’ve got the correct answer! Click here to end

  45. Significance of mitosis • To ensure that each daughter cell maintains exactly the same number and kind of chromosomes as the parent cell Mitosis is important in produce more cells for • growth • repair • replacing dead and damaged cells • asexual reproduction

  46. Meiosis • Producing cells with chromosome number half of the parent cell • Cells having pairs of homologous chromosomes - diploid (2n) • e.g. body (somatic) cells • Cells having one chromosome from each homologous pair - haploid (n) • e.g. gametes • Two nuclear divisions • Meiosis I and meiosis II • Four haploid cells are produced

  47. Prophase I • Chromosomes become visible • Nuclear membrane disappears

  48. Prophase I • Homologous chromosomes pair up • Crossing-over may occur between homologous chromosomes

  49. Metaphase I • Homologous chromosomes lie up at the middle of the cell randomly

More Related