Bio 8.txt

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  1. Cell division
    • Reproduction of individual cells
    • Parent cell splits into 2 daughter cells
  2. Chromosomes
    The structures that contain most of a cell's DNA
  3. Asexual reproduction
    • The creation of genetically identical offspring by a single parent
    • Done without sperm/eggs
  4. Sexual reproduction
    • Requires fertilization of an egg by a sperm
    • 2 parents
  5. Binary fission
    • Type of cell division
    • "dividing in half"
  6. Chromatin
    • Fibers composed of half DNA and half protein molecules
    • Too thin to be seen under a light microscope
  7. Sister chromatids
    • 2 copies of each chromosome attached together
    • Identical copies of DNA
  8. Centromere
    • Tightest spot sister chromatids are attached
    • Like the waist
  9. Cell cycle
    • Sequence of events from
    • When a cell forms until it divides itself into 2
  10. Interphase
    • 90% of cell division
    • 3 stages- g1 (first gap), s (synthesis) and g2 (second gap)
    • Duplicates chromosomes; cell doubles in size in preparation for division
    • Centrioles prepared
  11. Mitotic phase (M phase)
    • Part of the cell cycle when the cell actually divides
    • About 10% of the time
    • 2 identical daughter cells produced
  12. Mitosis
    • Part 1 of mitotic phase
    • Nucleus and contents, like DNA, duplicate
  13. Cytokinesis
    • Cytoplasm divides in 2
    • Usually overlaps with mitosis
  14. Prophase
    • The chromatin becomes chromosomes visible with a light microscope
    • Sister chromatids join together at centromere
    • Mitotic spindle starts to form- microtubules grow
  15. Prometaphase
    • Nuclear envelope fragments and disappears
    • Microtubules reach defined chromosomes- attach to kinetochore
    • Chromosomes move to center of nucleus
  16. Metaphase
    • Mitotic spindle fully formed
    • Chromosomes on metaphase plate in between two polls of spindle
    • Microtubules attach specific chromosomes
  17. Anaphase
    • Centromeres come apart
    • Sister chromatids separated- moved to opposite ends of the cell
    • Cell elongates
  18. Telophase
    • Cell elongation continues
    • Nuclear envelopes begin to form
    • Chromosomes uncoil into chromatin
    • Cytokinesis stars
    • Cleavage furrow forms
  19. Mitotic spindle
    Football shaped structure of microtubules that guide the separation of the sets of sister chromatids
  20. Centrosomes
    • Microtubules for mitotic spindle emerge from 2 centrosomes
    • Cytoplasmic material that contains pairs of centrioles
    • Microtubules organizing centers
  21. Cleavage furrow
    • A shallow indentation in the cell surface
    • Start of cytokinesis
    • Eventually pinches parent cell in half
  22. Cell plate
    • Fused vesicles that form a membranous disk
    • Grows outward and eventually fuses with the plasma membrane to create to daughter cells
  23. Growth factor
    • A protein secreted by body cells that stimulates other cells to divide
    • ie. Injury causes new skin to grow
  24. Density-dependent inhibition
    • Cells only divide until a surface is covered
    • Crowded cells don't continue dividing
    • Not present in cancer cells
  25. Anchorage dependence
    Cells won't divide when not in contact with a aloud surface
  26. Cell cycle control system
    • Set of molecules that trigger and coordinate key events in the cell cycle
    • Cells must get the signal at certain stages to begin or continue dividing. It doesn't happen automatically
    • Without approval to move to S stage, cell enter G0 and never divides-muscle cells
  27. Tumor
    An abnormal cell thy escapes detection
  28. Benign tumor
    • Cells that remain at the original site of creation
    • Usually easily removed in surgery
    • Only a real problem if they grow in a spot that disrupts organs like the brain
  29. Malignant tumor
    • Can spread into neighboring tissues and other parts of the body
    • Displaces tissue and interrupts organs as it grows
  30. Cancer
    A person with cancer has a malignant tumor
  31. Metastasis
    • When cancer cells spread beyond their original location
    • Spread when cancer cells get in blood stream
  32. Carcinomas
    Cancers that start in the skin or internal body coverings like the lining of the intestine
  33. Sarcomas
    Cancers that start in tissues that support the body like bone or muscle
  34. Leukemias
    Cancers of blood-forming tissues like bone marrow
  35. Lymphomas
    Cancers in blood-forming tissues like lymph nodes
  36. Somatic cell
    • A typical human body cell
    • Contains 46 chromosomes
  37. Homologous chromosomes
    • Two chromosomes of a matching pair
    • Similar in size, shape, banding pattern and loci location
  38. Locus
    A particular spot on a chromosome that holds the gene for a specific trait
  39. Sex chromosomes
    • X and Y chromosomes
    • In males, the only non-homologous chromosome pair
    • Females have 2 Xs and males have an X and a Y
  40. Autosomes
    • All chromosome pairs except sex chromosomes
    • 22 pairs in humans
  41. Life cycle
    • Development of a fertilized egg into a new adult organism
    • The sequence of stages leading from one generation to the next
  42. Diploid
    • All body cells contain pairs of homologous chromosome
    • Abbreviated 2n
  43. Gametes
    • Egg and sperm cells
    • Single set of chromosomes
    • Haploid cell
    • Abbreviated n
  44. Haploid
    • A cell with a single chromosome set
    • Humans have 23 chromosomes per haploid cell
  45. Fertilization
    When a sperm cell fuses with an egg cell
  46. Zygote
    • Product of fertilization
    • 2 sets of homologous chromosomes- one set from each parent
    • Diploid
  47. Meiosis
    • Cell division that produces haploid gametes in diploid organisms
    • Similar to mitosis except 2 stages- meiosis I and meiosis II (closer to mitosis)
  48. Tetrad
    Set of four chromatids
  49. Crossing over
    An exchange of corresponding segments between non-sister chromatids of homologous chromosomes
  50. Chiasma
    • Sites of crossing over
    • Appear as an X shaped
    • region
    • A place where two nonsister chromatids are attached
  51. Genetic recombination
    Production of gene combinations different from those carried by the parent chromosomes
  52. Karyotype
    An ordered display of a person's chromosomes condensed and doubled like in mitosis
  53. Trisomy 21
    • An extra chromosome 21
    • A total of 47 instead of 46 chromosomes
    • Causes down syndrome
  54. Down syndrome
    • Affects 1/700 children
    • Most common birth defect in the US
    • Frequently causes a round face, a skin fold in the inner corner of the eye, a flatter nose, small teeth, and short stature
    • Also causes heart defects, and mental retardation
  55. Nondisjunction
    • Occasional mishap where chromosomes fail to separate
    • Occurs during either meiosis I or II
  56. Deletion
    • Caused when a chromosome fragment is lost
    • Cause serious physical and mental problems
  57. Duplication
    When a fragment joins with a sister chromatid or a homologous chromsome
  58. Inversion
    • Less likely to cause serious problems
    • Fragment reattaches to chromosome but flipped
    • Chromosome still there so less dangerous
  59. Translocation
    • When a fragment attaches to a non homologous chromosome
    • Exchange segments
    • May or may not be harmful
    • Often cancerous
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Bio 8.txt
2012-01-08 07:05:26
bio chapter

bio chapter 8
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