1. Cell Division

2. Words to Know
Gamete – The male or female reproductive cell that contains half of the DNA – sex cell Egg Cell – The Ovum; the female reproductive cell (gamete); usually not mobile Sperm Cell– The male reproductive cell (gamete) ; usually mobile

3. Words to Know
Parent Cell – The old product being divided or used Daughter Cell – The new product(s) being formed or used Sisters – Identical products that are joined

4. Words to Know
Diploid – Meaning the cell has two sets of chromosomes = full set of chromosomes - In humans it would be 46 chromosomes Haploid – Meaning the cell has one set of chromosomes = half the chromosomes - Gamete cells -In humans it would be 23 chromosomes

5. Why do cells divide?
Grow
Reproduce
Repair

6. Cell Reproduction All organisms REPRODUCE. Why?
This allows for growth, development and the survival of the species

7. There are 2 types of reproduction
Asexual Reproduction
Requires A single parent!!!
Results in the offspring having the same hereditary material (DNA)

8. Asexual Reproduction (cont)…
In other words, the new cells are an exact copy of its parent (allow for little variation among species)

9. Types of Asexual Reproduction
Fission – cell splits in half (ex: Amoeba)

10. Types of Asexual Reproduction (cont)…
Budding – a new organism grows off from the side of an adult (ex: Hydra)

11. Types of Asexual Reproduction (cont)…
Regeneration – a new organism grows from a severed body part (ex: starfish)

12. MITOSIS

13. Mitosis
The process of cell division which results in the production of two daughter cells from a single parent cell.
The daughter cells are identical to one another and to the original parent cell.

14. Mitosis
Mitosis is the method used for cell division and reproduction in asexual organisms
Mitosis is associated with growth and repair in sexually reproducing organisms. .

15. Mitosis can be divided into stages
A preparation stage – Interphase
The four main MITOTIC STAGES
Prophase – Metaphase Anaphase – Telophase
The separation stage - Cytokinesis

16. Interphase – Preparation Step The cell prepares for the main four division phases
Plant Cell
DNA replicated
Organelles replicated
Cell increases in size
Animal Cell
DNA replicated
Organelles replicated
Cell increases in size

17. Interphase Plant Cell Animal Cell
Photographs from:

18. Prophase – 1st Mitotic Stage
Animal Cell
Chromatin condense to form chromosomes as chromatids joined by a centromere
Centrioles move to opposite ends of the cell
Nuclear membrane dissolves.
Plant cell
Chromatin condense to form chromosomes as chromatids joined by a centromere
Centrioles move to opposite ends of the cell
Nuclear membrane dissolves.

20. Prophase Plant Cell Animal Cell
Photographs from:

21. Metaphase – 2nd Mitotic Stage
Animal Cell
Spindle fibers align chromosomes at the center of the cell
Plant Cell
Spindle fibers align chromosomes at the center of the cell

23. Metaphase Plant Cell Animal Cell
Photographs from:

24. Anaphase – 3rd Mitotic Stage The paired chromosomes divide
Animal Cell
Spindle fibers pull chromosomes apart
½ of each chromosome (called chromotid) moves to opposite sides of the cell
Plant Cell
Spindle fibers pull chromosomes apart
½ of each chromosome (called chromotid) moves to opposite sides of the cell

26. Anaphase Plant Cell Animal Cell
Photographs from:

27. Telophase – 4th Mitotic Stage Partitioning of the cell begins
Plant Cell
2 nuclei form
Cell membrane starts to pinch in to form the 2 new daughter cells
Spindle fibers disappear
Animal Cell
2 nuclei form
Cell membrane starts to pinch in to form the 2 new daughter cells
Spindle fibers disappear

29. Telophase Plant Cell Animal Cell
Photographs from:

30. What happens to a cell after Mitosis is complete?
Cytokinesis
Cell splits into two identical daughter cells with complete set of organelles
Animal – nuclear membrane develops and cells pinch apart
Plants – Cell wall forms between two new cells and nuclear membrane develops.

31. Animal Mitosis -- Review
Interphase                                                             
Prophase                                                             
Metaphase                                                             
Anaphase                                                             
Telophase                                                             
Cytokinesis                                                             

32. Plant Mitosis -- Review
Interphase                                                             
Prophase                                                             
Metaphase                                                             
Anaphase                                                             
Telophase                                                             
Cytokinesis                                                             

33. How did you get here? Sexual Reproduction
Reproduction in which two (2) parents are involved
Sex cells are called gametes (egg and sperm cells are gametes)

34. What is sexual reproduction?
starts with the formation of gametes and ends when one gamete joins another gamete. The joining of egg and sperm is called fertilization, resulting in the production of a zygote
zygote

35. How are gametes produced?
Meiosis
A process whose purpose is to reduce the chromosome number in the cells
Produces 4 new cells with half the number of chromosomes as the parent - haploid

36. Meiosis – two divisions of the nucleus46
Parent Cell
1st Division 46 46
2nd Division –
4 new daughter cells with ½ the # of chromosomes 23 23 23 23

37. Meiosis continued
Diploid Cells: have two of every chromosome (body cells)
Haploid Cells: have just one chromosome from each pair (gametes)

38. MEIOSIS

39. One parent cell produces four daughter cells.
Meiosis
Meiosis is the type of cell division by which germ cells (eggs and sperm) are produced.
One parent cell produces four daughter cells.
Daughter cells have half the number of chromosomes found in the original parent cell

40. During meiosis, DNA replicates once, but the nucleus divides twice.

41. Four stages can be described for each division of the nucleus.
Meiosis
Four stages can be described for each division of the nucleus.

42. First division of meiosis
Meiosis I
First division of meiosis

43. First Division of Meiosis
Prophase 1: Each chromosome duplicates and remains closely associated. These are called sister chromatids.
Metaphase 1: Chromosomes align at the center of the cell.
Anaphase 1: Chromosome pairs separate with sister chromatids remaining together.
Telophase 1: Two daughter cells are formed with each daughter containing only one chromosome of the chromosome pair.

44. Prophase I

45. Prophase I

46. Metaphase I

47. Telophase I

48. Second Division of Meiosis

49. Second Division of Meiosis
Prophase 2: DNA does not replicate.
Metaphase 2: Chromosomes line up at the center of the cell
Anaphase 2: Centromeres divide and sister chromatids move separately to each pole.
Telophase 2: Cell division is complete.
Four haploid daughter cells are formed.

50. Prophase II

51. Metaphase II

52. Telophase II

53. Meiosis

54. Differences in Mitosis & Meiosis
Asexual
Cell divides once
Two diploid daughter cells
Genetic information is identical
Meiosis
Sexual
Cell divides twice
Four haploid daughter cells
Genetic information is different