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 Rod shaped structures inside the nucleus of Eukaryotic cells  Made of DNA and proteins  Contain the genes that make you, you!  Shape of the chromosome.

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Presentation on theme: " Rod shaped structures inside the nucleus of Eukaryotic cells  Made of DNA and proteins  Contain the genes that make you, you!  Shape of the chromosome."— Presentation transcript:

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2  Rod shaped structures inside the nucleus of Eukaryotic cells  Made of DNA and proteins  Contain the genes that make you, you!  Shape of the chromosome is maintained by histones

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4  3 forms of a chromosome › Chromatin – ball of yarn › Chromatid – half of an x, sometimes bent › Chromosome – X  Center of X is called a centromere

5  Sex Chromosomes › Determine the sex of the organism › Males XY › Females XX › 2 out of 46 in the human cell  Autosomes › All the other chromosomes › 44 out of 46 in the human cell

6 Chapter 8 Click below to watch the Visual Concept. Visual Concept Sex Chromosomes and Autosomes Section 1 Chromosomes

7  Also called homologues  2 copies of the chromosome › One from Mom; One from Dad  Have the same size  Have the same shape  Have the same information (genes)

8  Diploid › Cells that have chromosomes in pairs › Symbol 2n › Somatic cells or body cells are like this › Humans diploid number is 46.  Haploid › Cells that do not have chromosomes in pairs › Symbol 1n › Gametes are like this  Sex cells  Sperm and egg cells › Humans haploid number is 23.

9 Section 2 Cell Division Chapter 8 Cell Division in Prokaryotes, continued Binary fission is the process of cell division in prokaryotes.

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11  Asexual Reproduction › Production of offspring from one parent › Mitosis  Sexual Reproduction › Production of offspring from 2 parents › Meiosis

12 How do little elephants grow up to be BIG elephants?

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14 The process of asexual reproduction begins after a sperm fertilizes an egg.

15 Skin cancer - the abnormal growth of skin cells - most often develops on skin exposed to the sun. Cell that reproduce by asexual reproduction reproduce constantly.

16 Animated Mitosis Cycle Interphase Prophase Metaphase Anaphase Telophase & Cytokinesis

17 3 phases G1 – cell is growing S – DNA is being copied G2 – cell is preparing for mitosis CELL MEMBRANE Nucleus Cytoplasm Nuclear Membrane And nucleolus are visible CHROMATIN!

18 Animal Cell Plant Cell Photographs from:

19 Mitosis begins (cell begins to divide) Chromosomes are visible Centrioles (or poles) appear and begin to move to opposite end of the cell. Spindle fibers form between the poles. Centrioles Sister chromatids Spindle fibers Nuclear membrane & nucleolus disappear by end of prophase

20 Animal Cell Plant Cell Photographs from: Spindle fibers Centrioles

21 Chromosomes attach to the spindle fibers at the centromere Centrioles Spindle fibers CHROMOSOME

22 Animal Cell Plant Cell Photographs from:

23 Chromatids (or pairs of chromosomes) separate and begin to move to opposite ends of the cell. Centrioles Spindle fibers

24 Animal Cell Plant Cell Photographs from:

25 Two new nuclei form. Chromosomes appear as chromatin (threads rather than rods). Mitosis ends. Nuclei Chromatin Nuclear membrane & nucleolus are visible by end of telophase Overlaps with cytokinesis!

26 Animal Cell Plant Cell Photographs from:

27 Division of the cytoplasm Cell membrane moves inward to create two daughter cells – each with its own nucleus with identical chromosomes. Animal cells – form a cleavage furrow Plant cells – form a cell plate, which becomes the cell wall.

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29 Animal Mitosis -- Review Interphase Prophase Metaphase Anaphase Telophase Interphase

30 Plant Mitosis -- Review Interphase Prophase Metaphase Anaphase Telophase Interphase

31 I I nterphase P P rophase M M etaphase A A naphase T T elophase C C ytokinesis IPMATC I Pray M ore At T he Church

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35 Section 2 Cell Division Chapter 8 Control of Cell Division Cell division in eukaryotes is controlled by many proteins. Control occurs at three main checkpoints. 1.G1 checkpoint – check to see whether the cell is healthy and is large enough to divide 2.G2 checkpoint – check to make sure DNA is copied correctly 3.Mitosis checkpoint – if cell divided correctly, then signals are made to exit mitosis

36 Chapter 8 Click below to watch the Visual Concept. Visual Concept Control of the Cell Cycle Section 2 Cell Division

37 Chapter 8 Control of Cell Division, continued When Control is Lost: Cancer –Cancer is uncontrolled growth of cells –Cancer may result if cells do not respond to control mechanisms. –Can be caused by mutations in DNA

38 Section 3 Meiosis Chapter 8 Formation of Haploid Cells Meiosis is a process of nuclear division that reduces the number of chromosomes in new cells to half the number in the original cell. Start with 46 and end with 23 Meiosis leads to four haploid cells (gametes) rather than two diploid cells as in mitosis. Done by germ cells Meiosis produces haploid gametes. Is considered sexual reproduction Creates genetic diversity Two divisions

39 Section 3 Meiosis Chapter 8 Meiosis I Meiosis I includes prophase I, metaphase I, anaphase I, and telophase I. Crossing-over, which is when portions of homologous chromosomes exchange genetics material, occurs during prophase I and results in genetic recombination.

40  Homologous chromosomes (paired chromosomes) become visible  Nuclear membrane and nucleolus disappear  Spindle fiber starts to appear  Crossing over occurs – portions of the chromatid break off and attach to other homologous chromosome

41 Chapter 8 Click below to watch the Visual Concept. Visual Concept Tetrads and Crossing-over of Genetic Material Section 3 Meiosis

42  Homologous chromosomes (tetrads) line up at the equator and connect to spindle fibers at their centromeres

43  Homologous chromosomes split and individual chromosomes move to poles  They assort independently of one another- independent assortment

44  There are 2 new cells at this point  Each new cell has half the number of chromosomes as the parent germ cell  So they are now haploid

45  Has prophase II, metaphase II, anaphase II and telophase II  Exactly like mitosis  Four new haploid cells result › Four gametes › Depends on whether it is an animal or a plant cell

46 Chapter 8 Section 3 Meiosis

47  Spermatogenesis › Making of sperm cells › Meiosis will result in 4 mature sperm cells or spermatozoa  Oogenesis › Making of mature egg cells, or ova › Meiosis will result in 1 mature egg cell and 3 polar bodies that die

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