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Standard Biology Chapter 22 Cellular Reproduction Section 22:1 Mitosis.

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Presentation on theme: "Standard Biology Chapter 22 Cellular Reproduction Section 22:1 Mitosis."— Presentation transcript:

1 Standard Biology Chapter 22 Cellular Reproduction Section 22:1 Mitosis

2 2 Mitosis One cell divides and divides to form 3 trillion cells (you) One cell divides and divides to form 3 trillion cells (you) Process of cell reproduction by which 2 new identical cells are formed from one parent cell Process of cell reproduction by which 2 new identical cells are formed from one parent cell

3 3 Mitosis Needed for growth, repair, and replacement of body parts Growth: new muscle Repair: broken bone need new bone cells Replacement: new blood cells when have loss of blood

4 4 Mitosis All body cells are formed by mitosis (body cells are all cells that are not sex cells)

5 5 Different Cells Have Different Life Span Cell Type Brain Cell Red Blood Cell Platelets Stomach Lining Liver Cells Intestine Lining Skin Life Span years 120 days 10 days 2 days 200 days 3 days 20 days

6 6 Mitosis Mitosis continues your entire life Cells go through mitosis at different rates, some are slow and some are fast

7 7 Cell Cycle Most of the time cells are not dividing, they are just growing and doing their job Most of the time cells are not dividing, they are just growing and doing their job Interphase: time between mitosis when cells grow, do their job and get ready for mitosis by: Interphase: time between mitosis when cells grow, do their job and get ready for mitosis by: Doubling chromosomes get sister chromatids Doubling chromosomes get sister chromatids Making more cell parts (mitochondria…) Making more cell parts (mitochondria…)

8 8 Steps of Mitosis Prophase Sister chromatids thicken so can be seen Sister chromatids thicken so can be seen Nuclear membrane disappears Nuclear membrane disappears Centrioles (animals only) move away from each other Centrioles (animals only) move away from each other Spindle fibers form between centrioles Spindle fibers form between centrioles

9 9 Prophase a.Chromosome (two sister chromatids) b.Centriole c.Spindle fiber d.Nuclear membrane (disintegrating)

10 10 Prophase

11 11 Steps of Mitosis Metaphase Sister chromatids are hooked to spindle fiber Sister chromatids are hooked to spindle fiber Sister chromatids are in center of cell Sister chromatids are in center of cell

12 12 Metaphase

13 13 Metaphase

14 14 Steps of Mitosis Anaphase Sister chromatids are pulled apart Sister chromatids are pulled apart

15 15 Anaphase

16 16 Anaphase PLANT ANIMAL

17 17 Steps of Mitosis Telophase Each chromatid forms a nucleus Each chromatid forms a nucleus Nuclear membrane forms around the 2 new nuclei Nuclear membrane forms around the 2 new nuclei Spindle fibers disappear Spindle fibers disappear Chromatids thin and can’t be seen Chromatids thin and can’t be seen Cell cytoplasm usually divides (cytokinesis) Cell cytoplasm usually divides (cytokinesis)

18 18 Telophase

19 19 Telophase After Telophase the 2 new cells are in interphase Cytokinesis is the division of the cell contents forming two new cells

20 20 Results of Mitosis Results of mitosis: get 2 new cells that are genetically identical (same chromosome) but smaller in size

21 21 Differences between mitosis in plants and animals 1. Plants don’t have centrioles, animals cells do; both have spindle fibers Centrioles

22 22 Differences between mitosis in plants and animals 2. Plants have cell wall so must add more cell wall between new cells not just pinch in cytoplasm to divide it

23 23

24 Standard Biology Chapter 22 Cellular Reproduction Section 22:2 Meiosis

25 25 Meiosis Sex cells (eggs and sperm) are produced by a process different from mitosis Meiosis: cell divides twice to form 4 new cells each with ½ the number of chromosomes Start with one body cell end with 4 sex cells

26 26 Meiosis Interphase happens just like mitosis, chromosomes are doubled Interphase happens just like mitosis, chromosomes are doubled

27 27 Steps of Meiosis: Meiosis I Prophase I Sister chromatids shorten and thicken Sister chromatids shorten and thicken Nuclear membrane disappears Nuclear membrane disappears Centrioles move to opposite ends of cell Centrioles move to opposite ends of cell Spindle fibers form Spindle fibers form Two pair of sister chromatids (matching chromosomes) come together; get tetrads; exchange genetic material Two pair of sister chromatids (matching chromosomes) come together; get tetrads; exchange genetic material

28 28 Steps of Meiosis: Meiosis I Prophase I Homologous Chromosomes (tetrads)

29 29 Steps of Meiosis: Meiosis I Metaphase I Tetrads in center of cell Tetrads in center of cell Spindle fibers attached to chromosomes Spindle fibers attached to chromosomes

30 30 Steps of Meiosis: Meiosis I Metaphase I Tetrads

31 31 Steps of Meiosis: Meiosis I Anaphase I A pair of sister chromatids gets pulled away from the other pair of sister chromatids A pair of sister chromatids gets pulled away from the other pair of sister chromatids

32 32 Steps of Meiosis: Meiosis I Telophase I Cell divides Cell divides Nuclear membrane DOES NOT REFORM Nuclear membrane DOES NOT REFORM

33 33 Steps of Meiosis: Meiosis II Prophase II and Metaphase II Spindle fibers attach to sister chromatids Spindle fibers attach to sister chromatids Sister chromatids are in middle of cell Sister chromatids are in middle of cell Prophase II Metaphase II

34 34 Steps of Meiosis: Meiosis II Anaphase II and Telophase II Sister chromatids are pulled apart Sister chromatids are pulled apart Nuclear membrane reforms Nuclear membrane reforms Anaphase IITelophase II

35 35 Result of Meiosis Results of Meiosis: end with 4 sex cells that have ½ of the chromosomes as parent cell

36 36 Sperm, Egg, and Fertilization Comparison of Sperm and Egg How Alike 1. sex cells 2. formed by meiosis 3. ½ number of chromosomes 4. humans develop at puberty How Different 1. egg larger than sperm 2. sperm has tail, can move 3. sperm form in male testes 4. eggs form in female ovary 5. only get 1 egg in meiosis 6. get 4 sperm in meiosis

37 37 Sperm, Egg, and Fertilization Formation of Polar Bodies Happens in meiosis to produce eggs Happens in meiosis to produce eggs Cell division is not equal, most of cytoplasm goes to one cell Cell division is not equal, most of cytoplasm goes to one cell Polar body is the cell formed with little cytoplasm Polar body is the cell formed with little cytoplasm Polar bodies do not form eggs, they die Polar bodies do not form eggs, they die

38 38 Sperm, Egg, and Fertilization Formation of Polar Bodies

39 39 Sperm, Egg, and Fertilization Fertilization Joining of sperm and egg Joining of sperm and egg Chromosomes come together and pair up forming a new organism with the correct number of chromosomes Chromosomes come together and pair up forming a new organism with the correct number of chromosomes New organism has ½ chromosomes form mother and ½ chromosomes from father New organism has ½ chromosomes form mother and ½ chromosomes from father

40 40 Sperm, Egg, and Fertilization

41 Standard Biology Chapter 22 Cellular Reproduction Section 22:3 Changes in the Rate of Mitosis

42 42 Changes that Occur in the Human Body with Age Body System Trait 20 Year Old 70 Year Old Skin/Nails Rate of fingernail growth 1mm/week 0.6mm/ week Nervous Reaction Time 0.8 sec 0.95 sec Circulatory Pumping action of heart 3.7 L/ min 2.9 L/ min NervousMemory 14 of 24 words recalled 7 of 24 words recalled

43 43 Changes that Occur in the Human Body with Age Body System Trait 20 Year Old 70 Year Old Respiratory Lung volume per breath 5.5 L/ inhalation 3.0 L/ inhalation Muscular % body fat (male) 15%30%

44 44 Aging Becoming older Becoming older All living things age All living things age Loss of hair Loss of hair Wrinkled skin Wrinkled skin Bone calcium loss Bone calcium loss Cells wear out faster than they are replaced or are not replaced (mitosis slows down) Cells wear out faster than they are replaced or are not replaced (mitosis slows down) Muscle cells (including heart) are not replaced, each cell can get bigger but no new cells Muscle cells (including heart) are not replaced, each cell can get bigger but no new cells

45 45 Aging

46 46 Cancer Healthy cells: regular rate of mitosis Healthy cells: regular rate of mitosis Cancer: too fast rate of mitosis Cancer: too fast rate of mitosis Shape of cell and nuclei change Shape of cell and nuclei change Abnormal cells crowd out normal cells Abnormal cells crowd out normal cells Fig p. 478 Fig p. 478

47 47

48 48

49 49 Causes of Cancer Environmental factors Chemicals: chewing tobacco (mouth) Smoking tobacco (lung)

50 50 Causes of Cancer Environmental factors Radiation: UV light (skin) Viruses: (warts and cervical cancer) Diet

51 51 Causes of Cancer Genetic Factors Runs in a family Runs in a family Locate the gene may be able to prevent the cancer Locate the gene may be able to prevent the cancer Many cancers thought to be a combination of environmental and genetic factors Many cancers thought to be a combination of environmental and genetic factors


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