Bio 004, College of the Desert

  1. Cell Division
    • CellDivision: replacement of damaged or lost cells; growth

    • At least 60,000,000,000 cells in the human body: Cell division starts with a single fertilized egg.

  2. Chromosomes
    • Chromosomes:DNA-containing structures that carry the organism’s genetic legacy

    • Prior to cell division, chromosomes are duplicated so that each daughter cell receives equal proportions of DNA from the mother cell.

  3. Asexual Reproduction
    • Asexual Reproduction: production of off-spring by a single parent that does not

    • involve fertilization of an egg by a sperm.
    • 1. Parent and offspring share identical genes.

    • 2. Maintains cells in multicellular organisms.

    • 3. Maintains certain species (kinds) of organisms.

  4. Sexual Reproduction
    • Sexual Reproduction: production of off-spring by two parents that involves fertilization of an egg by a sperm.

    • 1. Maintains a constant chromosome number.

    • 2. Creates genetic diversity

  5. Chromatin
    • Chromatin: combination of DNA and protein. Protein helps to organize DNA and control gene activity. DNA’s total length in one cell’s 46 chromosomes = 2 m: Chromosomes are most easily seen during mitosis DNA is coiled, then supercoiled as it is packed in nucleus

    • Histones (small proteins) are critical in DNA packing

    • Nucleosome is DNA wound around histone molecules.

    • 2. Prior to cell division, chromosomes are duplicated.

    • 3. Results are genetically identical sister chromatids.

    • 4. Sister chromatids are joined together in the center at the centromere.

  6. Cell Cycle
    • Cell Cycle:
    • 1. 90% of the cell cycle is dedicated to interphase.
    • 2. During interphase, the cell is replicating DNA, cytoplasm, and organelles.
  7. Mitosis

    Mitosis: nucleus and DNA divide and are evenly distributed between two cells.

  8. Cytokinesis

    Cytokinesis: cytoplasm divides in two. End result is two genetically identical daughter cells.

  9. Mitotic Spindle
    Mitotic Spindle: structure of microtubules that guides the separation of the daughter chromosomes : Stage upon which mitosis occurs.
  10. Centrioles

    Centrioles: structures of microtubules that build the spindle in animal cells. Centrioles are not found in plant cells even though plant cells have spindles.

  11. Cleavage Furrow
    Cleavage Furrow: indentation at the equator in animal cells :A ring of microfilaments just under the plasma membrane pinches the parent cell into two daughter cells
  12. Cell Plate

    Cell Plate: membranous disk that forms at the equator in plant cells: Vesicles containing cell wall material collect at the equator of the parent cell fusing together until the division into two daughter cells.

  13. Cancer

    Cancer: disease of the cell cycle; excessive cell division that invades other tissues of the body, sometimes resulting in death In tissue culture, cancer cells are “immortal”; most cell lines die out after 20 – 50 cell divisions.

  14. Tumor
    Tumor: abnormally growing mass of cells.
  15. Benign
    Benign: lump of abnormal body cells that remain at the site of origin.
  16. Malignant

    Malignant: lump of abnormal body cells that spreads from the site of origin by way of the circulatory system (metastasis).

  17. Cancer Treatment
    • Cancer Treatment

    • 1. Radiation therapy: Expose tumors to high-energy radiation - damages DNA, disrupts cell division

    • 2. Chemotherapy: Expose tumors to high-dose drugs - alters spindle function, disrupts cell division.

    • 3. Surgical removal: duh

  18. Apoptosis

    Apoptosis: genetically programmed cell death (cell suicide) : Controlled by a single gene (p53) in which 1,000+ mutations have been observed (mutations = cancer).

  19. Somatic Cell
    Somatic Cell: typical human body cell that contains 46 chromosomes.
  20. Homologous Chromosomes
    Homologous Chromosomes: matched pair of chromosomes in a somatic cell; one inherited from mom, the other from dad.
  21. Karyotype
    Karyotype: micrograph of a cell’s chromosomes arranged by size and pattern.
  22. Sex Cells
    Sex Cells: egg in female, sperm in male. Gametes contain only half the chromosome # (23).
  23. Sex Chromosomes
    Sex Chromosomes: chromosome pair that determines gender and characteristics that accompany gender: Female (♀) = XX (homologous) Male (♂) = XY (not homologous)
  24. Autosomes

    Autosomes: chromosomes NOT directly involved in determining gender. Any of the 22 pairs of chromosomes in humans that are NOT sex chromosomes.

  25. Diploid

    Diploid: homologous pairs of chromosomes found in somatic cells (46 in humans); 2n.

  26. Haploid

    Haploid: single set of chromosomes found in sex cells (23 in humans); n

  27. Fertilization
    Fertilization: union of the nucleus of a sperm with the nucleus of an egg, forming a zygote.
  28. Zygote
    Zygote: A fertilized egg.
  29. Meiosis
    • Meiosis: process that produces haploid daughter cells in diploid organisms.

    • 1. Cuts the chromosome number in half.

    • 2. Increase genetic diversity.

  30. Synapsis

    Synapsis: homologous chromosomes align themselves next to one another.

  31. Crossing-Over
    Crossing-Over: m- exchange of corresponding segments between homologous chromosomes.
  32. Segregation
    Segregation: homologous chromosomes separate and move along spindle fibers towards opposite poles.
  33. Independent Assortment
    Independent Assortment: each pair of homologous chromosomes segregates independently of the other chromosome.
  34. Nondisjunction

    Nondisjunction: situation in which members of a chromosome pair fail to separate during division I or II. Results in abnormal numbers of chromosomes in gametes. Causes unknown.

  35. Down’s Syndrome
    • Down’s Syndrome: results from trisomy 21 – in which the 21st pair of chromosomes

    • have an extra chromosome. Characteristics include: fold of skin at inner corner of eye, round face, flattened nose bridge, small irregular teeth, short stature, heart de-fects, and susceptibility to respiratory infection, leukemia, and Alzheimer’s.
    • 1. Incidence increases with a mother’s age.

  36. Klinefelter’s Syndrome

    Klinefelter’s Syndrome (XXY): Testes are small; male is sterile often with breast enlargement, other feminine body contours.

  37. Turner’s Syndrome

    Turner’s Syndrome (XO): Short stature, web of skin extending between neck and shoulders; female is sterile due to underdeveloped sex organs along with secondary sexual characteristics.

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Bio 004, College of the Desert
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