Biology ch 13

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Author:
cswett
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28589
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Biology ch 13
Updated:
2010-07-31 22:33:16
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Biology asexual reproduction mitosis meiosis
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Lecture and Book covering asexual reproduction, mitosis and meiosis
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  1. asexual reproduction
    • without sex
    • single organism productes genetically identical offspring
    • two sexes not necessary for reproduction
    • ONLY MITOSIS IS EXHIBITED
    • THERE IS NO SPERM
    • TO FERTILIZE AN OVUM
    • DAUGHTER CELL IS IDENTICAL TO PARENT CELL IN GENETICS
  2. Types of asexual reproduction
    • 1. Binary Fission
    • 2. Budding
    • 3. Fragmentation
    • 4. Parthenogenesis
  3. Binary Fission
    • Bacteria (prokariotic cell)
    • cell splits into two identical cells
    • Genetically Identical
    • Takes 20 minutes for bacteria to reproduce
  4. Budding
    • EUKARYOTE (Aquatic organisms - Hydra, sponges)
    • GENETICALLY IDENTICAL
    • Sessile - fixed - used by organisma that are fixed to one spot and cant move
    • Buds a new organism off the side and pinches it off
  5. Fragmemtation
    • Worms
    • Genetically Identical
    • Worm splits into 7 to 9 pieces
  6. Parthenogenesis
    • "VIRGIN BIRTH"
    • Females give birth to females
    • Whip tailed lizard - no males in species- lay eggs - only daughters
    • Honey Bee - Queen mates one time in life - sperm receptical to make drones
    • Drones - males - sit around
    • Worker bees - female - no sperm used - genetically identical
  7. Regeneration
    • sometimes considered asexual
    • Planaria - starfish
    • *when injured* body splits and forms two identical organisms
  8. Hermaphrodism
    • organism contains both male and female sexual organs
    • can produce both eggs and sperm
  9. Mitosis
    • The divistion of the nucleus of a cell
    • Only occurs in somatic cells
    • Results in two Genetically Identical cells
    • Causes of mitosis:
    • Death
    • Damage
    • Disease
    • Growth
    • Results In:
    • 1 Replication
    • 1 Division
  10. somatic cells
    all body cells except the reproductive cells
  11. chromatin
    • chromosomes when they are unpacked in the nucleus of the cell.
    • cannot see individual chromosomes in this state
    • when DNA is getting ready to replicate it packs up its chromosons and condendes into recognizable strands
  12. sister chromatids
    • DNA duplicates itself - results in two identical chromotids attached as the centromere
    • centromere - "waist" where two chromotids are attached
    • arm - part of the chromotid on either side of the centromere
  13. miotic phase (M)
    • includes mitosis and cytokinesis
    • shortest part of cell cycle
    • alternates with interphase
  14. interphase
    • 90% of cell cycle
    • cell grows and copies its chromosomes in prep for cell division
    • G1 Phase - first gap - cell grows
    • S Phase - synthesis - copies its chromosomes
    • G2 Phase - second gap - grows more - produces more cytoplasm and organelles
  15. Cell Cycle
  16. Stages of Mitosis
    • 1. Prophase
    • Prometaphase (lab)
    • 2. Metaphase
    • 3. Anaphase
    • 4. Telophase
    • 5. Cytokinesis
  17. kinetochore
    • each of the sister chromatids has a kinetochore - a protein
    • the two kinetochores face in opposide directions
    • during metaphase - microtubules attached to the centromere at the kinetochore and pull the sister chromatids apart
  18. prophase
    • the nuclear membrane breaks down
    • each duplicates chromosome appears as two sister chromatids, bound at a point called the centromere, making an "X" shape
    • centrioles duplicate form and move toward the poles (in an animal cell)
    • mitotic spindle begins to form
  19. metaphase
    • Nuclear membrane is gone
    • Cenrtosomes are at the poles producing microtubules (Mitotic spindle) which attached to the kinetochore of each chromotid
    • The chromosomes are lined up along the cell's equator, (the equatorial plate)
    • When the individual chromatids (½ of the"X") are separated from the chromosome (the "X"), they are now each referred to as a chromosome (i.e. In metaphase, the chromosome, composed of two chromatids, separates into the individual chromatids, which are then renamed chromosomes, even though they were only one half of a chromosome only moments before!)
  20. anaphase
    • Microtubules pull sister chromotids apart - now called Daughter Chromosomes
    • This stage is almost egg-shaped because of the pulling of the microtubules attached to the kinetochore (a protein) of the centromere.
  21. telophase
    • mitosis (spliting of one nucleus into two) is now complete
    • nuclear envelope reforms
    • cleavage furrow
  22. cytokinesis
    • cytoplasm divides and in animal cells the cleavage furrow pinches the cell in two
    • you now have two diploid cells
  23. diploid

    haploid
    diploid - notated as 2n - contains two sets of chromosomes - one inherited from each parent (for humans 2n = 46 (has 22 homologs and 1 set of sex chromosomes)

    haploid - notated as n - contains one set of chromosomes - for humans n = 23 - 22 autosomes and 1 sex chromosome
  24. homologous chromosomes
    homologs
    homologous pairs
    • two chromosomes composting a pair have the same length, centermere position, and pattern
    • both chromosomes of each pair contain genes controlling the same inherited trais (on trait from mom and one from dad)
    • Humans have 22 pair of homologs (44 chromosomes) and one set of sex chromosomes (female XX is a homolgous pair but make XY do not match)
  25. gametes
    zygote
    • sex cells - eggs and sperm (haploid cells)
    • zygote is a fertilized egg (becomes diploid because it contains two sets of chromosomes)
  26. Meiosis
    • One cell results in 4 that are not genetically identical
    • Process:
    • 1 Replication
    • 2 Divisions
  27. Stages of Meiosis
    • Prophase I
    • Metaphase I
    • Anaphase I
    • Telophase I
    • Cytokinesis I
    • Prophase II
    • Metaphase II
    • Anaphase II
    • Telophase II
    • Cytokinesis II
  28. Prophase I
    • In interphase the chromosomes replicated forming sister chromotids
    • Homologues pair up - (sister chromotids that control same traits pair up - one set for maternal genetic materical and one for paternal
    • Form a Tetrad (4 chromosomes)
    • Crossing Over - exchange corresponing segments of DNA by nonsister chromotids
    • 1st step in genetic variation - crossing over
    • Chiasmata - points where crossing over occured
    • Centrisomes move to poles, spindle forms, nuclear envelope breaks down
  29. Metaphase I
    • 2nd step in genetic variation - homologs can line up along the metaphase plate in any order
    • both chromotis of one homologue are attached to the kinetochore mcrotubules from one pole
  30. Anaphase I
    • Each pair of homologous chromosomes separates and are pulled toward the poles
    • Sister chromotids stay together as they are pulled to the pole
    • Starts to get egg shaped
  31. Telophase I
    • Two haploid cells form (each cell has a single set of replacated chromosomes)
    • each chromosome consisted of two sister chromotids that have exchanged DNA with their non sister homologue
    • animal = cleavage furrow forms
    • plant = cell plate forms
  32. Cytokinesis I
    • cells pinch off
    • results in two haploid cells ( one set of chromosomes) with a set of sister chromotids in each cell
  33. Prophase II
    • starts with two haploid cell with sister chromotids in each cell that are not genetically identical
    • No crossing over
    • Spindle forms, centrisomes move to poles
  34. Metaphase II
    • chromosomes line up along the metaphase plate (equator)
    • kinetochore of sister chromotids are attached to poles
  35. Anaphase II
    • two haploid cells with non-identical sister chromotids
    • sister chromotids (which are not genetically identical due to crossing over) are pulled apart and pulled toward the poles
  36. Telophase II
    • Nucleus forms
    • Animal - cleavage furrow
  37. Cytokinesis II
    • cytoplasm separates
    • resuls in :
    • 4 haploid daughter cells (one set of chromosomes)
    • Each of the daughter cells is genetically different form the other sister cells and from the parent cells

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