Biology Exam 2

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Biology Exam 2
2014-10-19 17:51:22
Biology Notes.
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  1. Know the difference in genome, chromosomes and chromatids.
    Genome- complete collection of an organisms genetic info. (DNA) Half of the DNA comes from the father and the other half from the mother.

    Chromosomes- humans have 46 chromosomes. 23 homologous pairs.

    Chromatid- A chromatid is one copy of a duplicated chromosome, which is generally joined to the other copy by a single centromere.
  2. Know the phases of a cell cycle.
    Phase 1: Interphase- Cell is growing.

    Phase 2: Mitotic Phase- division phase.
  3. Phases of Mitosis.
    • Prophase- duplicated chromosomes condense, nuclear envelope breaks down, spindle fibers form.
    • Prophase

    Metaphase- spindle fibers attach to chromosomes, chromosomes line up along cell 'equator'.

    Anaphase- spindle fibers shorten and pull sister chromatids apart and toward opposite ends of cell.

    Telophase- chromosomes begin to unwind from condensed shape, nuclear envelopes form., spindle fibers break down, cleavage furrow forms.

  4. Phases of Meiosis.
    In meiosis, chromosomes are duplicated once, but the cell is divided twice.

    Meiosis I=prophase I, metaphase I, anaphase I, telephase I.

    Meiosis II=prophase II, metaphase II, anaphase II, telephase II.
  5. Meiosis I.
    • Prophase I- Chromosomes condense, nuclear envelope breaks down, spindle fibers form. Homologous chromosomes link-form tetrads. In mitosis homologous chromosomes don't link. Crossing over occurs in Prophase I. Homogolous chromosomes exchange reciprocal portions of selves. Between non-sister chromatids. Increases genetic diversity of gametes, therefore increasing genetic diversity of eventual offspring.
    • Prophase
    • Metaphase I- Spindle fibers move homologous pairs of chromosomes to equator. Maternal chromosomes on one side/paternal on the other. Independent assortment occurs. Different homologous pairs align randomly at equator, each side with a combination of maternal and paternal chromosomes, also increases genetic diversity and therefore eventual offspring.

    • Anaphase I- Spindle fibers pull homogolous pairs apart, sister chromatids are still together.
    • Telophase I- Nuclear envelopes form, spindle fibers break down. Cytokinesis results in two daughter cells with one set of chromosomes=two haploid cells.

  6. Meiosis II.
    Prophase II- Nuclear envelopes break down, spindle fibers form. The process is occuring in the two new cells now.

    Metaphase II-spindle fibers move chromosomes to equator.

    Anaphase II-spindle fibers pull sister chromatids apart.

    Telophase II- nuclear envelopes form, spindle fibers break down. Cytokinesis results in four daughter cells with one set of chromatids=four haploid cells (haploid gametes) these would be sperm or eggs in humans.

  7. Be able to compare/contrast Mitosis & Meiosis outcomes-parent/daughter types, chromosomes #, etc.
    • Mitosis
    • Mitosis happens in all cells in your body.
    • 1 parent cell=two genetically identical daughter cells.
    • # chromosomes is the same in parent and daughter cells.
    • Diploid to diploid (2n=2n)
    • Occurs in somatic cells.
    • Meiosis
    • Meiosis happens only in sex cells.
    • 1 parent cell=four genetically different daughter cells.
    • # chromosomes in daughter cells= half # chromosomes in parent cell.
    • Diploid to haploid (2n-1n).
    • Occurs in sex cells to produce gametes (sperm, egg)
  8. Know the difference in haploid and diploid cells and types of each.
    Haploid cells- describes cells having one set of chromosomes (1n). Gametes are haploid-eggs and sperm.

    Diploid cells- describes cells having two sets of chromosomes (2n). Somatic cells are diploid-red blood cells, bone cells, muscle cells, liver cells, etc.
  9. Understand how crossing over and independent assortment cause genetic diversity.
    • The crossing over is the process of exchange of DNA between homologous
    • chromosomes whereas the independent assortment is the process in which
    • the chromosome pairs align themeselves at the equator of the cell .
    • Crossing over takes place in Prophase I of meiosis I whereas the
    • independent assortment takes place in metaphase I of meiosis I.
  10. Be familiar with the characteristics/causes of cancerous cells.
    • Cancer is unrestrained cell division, results in tumor.
    • Due to mutations in DNA. Specifically, geneds that control cell division.
    • Cancer cells are non-specialized, don't contribute to body function.

    • Causes:
    • Environmental factors; chemical, radiation.
    • Viruses bring mutated genes into cells.
    • Random errors during DNA synthesis.
  11. Know who is considered to be the father of genetics and why.
    • Austrian monk Gregor Mendel is considered the father of genetics. He studied pea plants to determine the principles that govern inheritance. He considered how certain characters (seed color, height, etc) of the plants showed up in successive generations.
    • Based on his studies, Medel came up with three principles that seemed to govern inheritance:
    • -Basic units of inheritance are material elements that come in pairs.
    • -Elements do not change, even over many generations.
    • -Pairs separate during gamete formation.