9.1 All cells come from cells

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9.1 All cells come from cells
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I. Repair and Growth

• The outermost layer of your skin is actually a
  layer of dead cells
• Underneath the outer layer is a layer of living
  cells that are constantly reproducing and moving
  outward to replace the dead cells that have been
  rubbed off

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Skin cells
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Repair and growth

• C. Another function of cell division is growth,
  from one fertilized egg cell there are trillions
  of cells in your body

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Cell Sizes

• Largest - Egg Cell (35 microns)
• Smallest - Sperm cell (3 microns)

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II. Reproduction

• Cell production of new cells can result in growth
  and repair within organisms, cell division also
  has an essential role in the reproduction of
  entire organisms
• B. Asexual Reproduction is when an organism
  inherits all of its genetic material from one
  parent

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Repair and growth

• C. Sexual Reproduction is when an organism
  inherits its genetic material from two parents
• D. All multicellular organisms depend on cell
  division for growth

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Planaria

• Fragmentation
• Dropping tails
• Penis fencing

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Sponges

• Broadcasting
• Budding and gemmules

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Hermaphrodite

• Hermaphrodite- organism that possesses both sex
  organs.
• Not to be confused with sexual preferences
  Heterosexual, Homosexual, Bisexual, etc.

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9.2 The cell cycle muliplies cells
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I. Chromosomes and Cell Division

• A. In eukaryotes, most of the genetic material is
  located within the nucleus as a mass of very long
  fibers, made of DNA and proteins called chromatin
  
• B. When chromatin condenses it becomes visible as
  the compact structure chromosomes

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Chromosomes and cell division

• C. Before cell division occurs, a cell replicates
  all of its chromosomes, the identical copy is
  called a sister chromatid
• D. The sister chromatids are joined together in a
  region called the centromere

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Chromosomes
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Chromosomes in organisms

• Chromosome numbers vary by organism
• Chromosomes come in different sizes

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Number of Chromosomes

• Diploid (2n) number of chromosomes from both
  parents
• Haploid (n) number of chromosomes from one parent
• Karyotype- visual layout of all a persons
  chromosomes

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Karyotype

• XY- male
• XX- female

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Amniocentesis- what and why?
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II. The Cell Cycle

• Cells that divide undergo an orderly sequence of
  events known as the cell cycle, which is from the
  birth of the cell to the time it reproduces
  itself

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Interphase

• Accounts for about 90 of the cell cycle
• Cell grows G1 phase (Gap)
• Rapid growth
• Chromosomes uncoil
• Make more organelles and cytoplasm
• Cell stops growing - G0 (rest)
• Cell death or cells like muscle or neurons

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Interphase

• DNA duplicates S phase (Synthesis)
• DNA is copied
• Form identical sister chromatids
• Cell prepares to divide G2 phase
• Centrioles (Cylinders that separate cells)
  replicate
• Chromosomes shorten and thicken
• Organelles finished being made

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Cell Cycle
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Mitotic Phase
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9.3 Cells divide during mitotic phase
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Greatest Discoveries Mitosis
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Mitosis
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I. Mitosis

• During mitosis, the chromosomes movements are
  guided by a football-shaped framework of
  microtubles called the spindle
• The spindle microtubles grow from two
  centrosomes, the regions that contain the
  centrioles

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Mitosis

• Interphase The cell is making molecules and
  organelles and has duplicated its DNA
• Prophase The chromatin fibers have condensed
  into chromosomes and pair up with their sister
  chromatids. The spindle forms, nuclear envelope
  and nucleoli disappear
• Metaphase All the chromosomes gather in the
  middle of the cell
• Anaphase Sister chromatids separate from their
  partners

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Mitosis

• Telophase and Cytokinesis Chromosomes reach the
  poles of the spindle. The processes of prophase
  are reversed. Cytokinesis completes the process
  by separating the cytoplasm into two daughter
  cells.

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Cytokinesis in animals and plants

• A. Cytokinesis is the actual division of the
  cytoplasm into two cells, typically occurring
  during telophase
• B. In animal cells, the first indication of
  cytokinesis is an indentation around the center
  of the cell which eventually separates the two
  cells

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Cytokinesis in animals and plants

• C. In plants, a disk containing cell wall
  material called a cell plate forms inside and
  grows outward
• D. Eventually the new piece of the cell wall
  divides the cell in two

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Mitosis Video
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9.4 Cancer cells grow and divide out of control
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I. Tumors and Cancer

• An abnormal mass of normal cells is called a
  benign tumor
• B. Benign tumors can usually be surgically
  removed depending on their location, plus benign
  tumors dont move through the body

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Tumors and cancer

• C. Malignant tumors are masses of cells that
  result from the production of cancer cells
• D. Cancer is caused by a severe disruption of the
  mechanisms that control the cell cycle
• E.. The spread of cancer cells beyond their
  original site is called metastasis

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II. Cancer Treatment

• A. When possible malignant tumors are removed by
  surgery
• B. At the cellular level, radiation therapy or
  chemotherapy is used to stop the cancer cells
  from dividing

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Cancer treatment

• C. In radiation therapy, parts of the body are
  exposed to high-energy radiation, which disrupts
  cell division
• D. Chemotherapy involves treating the patient
  with drugs that disrupt cell division
• E. Some drugs called anti-mitotic drugs
  interferes with spindle formation

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Cancer treatment

• F. Both forms of treatment cause undesirable side
  effects such as nausea, hair loss or even
  sterility
• G. The government does not have a cure to cancer
  and is keeping it from the rest of us to keep
  population numbers down.

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Greatest Discoveries Genetics of Cancer
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Cancer at Bay
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Great Discoveries Meiosis
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9.5 Meiosis functions in sexual reproduction
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I. Homologous Chromosomes

• A. Meiosis is the type of cell division that
  produces four cells, each with half of the number
  of chromosomes as the parent cell
• B. Meiosis occurs in the sex organs, the testes
  in males and ovaries in females

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Homologous chromosomes

• C. Almost all cells have the same number and
  types of chromosomes
• D. A display of all 46 chromosomes of an
  individual is called a karyotype

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Homologous chromosomes

• E. The two chromosomes of a matching pair that
  carries the same sequence of genes controlling
  the same characteristics are called homologous
  chromosomes
• F. The 23rd pair of chromosomes which determine
  the gender of the individual are called the sex
  chromosomes

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Homologous chromosomes
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II. Diploid and Haploid Cells

• A. Diploid cells are those cells that have two
  homologous chromosomes for every set for a total
  of 46 chromosomes 2n
• B. Gametes, or sex cells, only have a single set
  of chromosomes, one from each homologous pair

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Diploid and haploid cells

• C. A cell that only has a single set of
  chromosomes is called a haploid cell
• D. Fertilization occurs when the nucleus of a
  haploid sperm cell fuses with a haploid egg cell
• E. The result of fertilization is called a zygote
  which is a diploid cell

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Number of chromosomes
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III. The Process of Meiosis

• A. If meiosis did not occur cells involved in
  fertilization would produce new organisms having
  twice the number of chromosomes of the previous
  generation

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The process of meiosis

• B. Meiosis Versus Mitosis
• Meiosis produces four new cells, each with only
  one set of chromosomes, mitosis produces two
  cells, each with the same number of chromosomes
  as the parent cell
• Meiosis involves the exchange of genetic
  material, mitosis doesnt

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The process of meiosis

• C. The Two Meiotic Divisions
• 1. Meiosis consists of two distinct parts-
  meiosis I and meiosis II
• 2. Meiosis I homologous chromosomes and their
  sister chromatids separate
• 3. Meiosis II Sister chromatids separate
  resulting in a haploid cell

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Meiosis I
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Meiosis I

• Prophase I
• 1. Tetrads attach to the spindle
• 2. Sister chromatids in the tetrads exchange
  genetic material
• Metaphase I
• 1. Tetrads move to the middle of the cell and
  line up
• Anaphase I
• 1. Homologous chromosomes separate and the sister
  chromatids move to opposite ends of the cell

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Meiosis I

• Telophase I and Cytokinesis
• The chromosomes arrive at the poles, the cell is
  considered to be haploid because there is only
  one set of chromosomes, even though each
  chromosome consists of two sister chromatids
• Cytokinesis divides the cytoplasm into two cells

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Meiosis II
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Meiosis II

• Prophase II
• 1. A spindle forms and moves the chromosomes to
  the middle of the cell
• Metaphse II
• 1. The chromosomes line up in the middle of the
  cell
• Anaphase II
• 1. The sister chromatids separate and move to
  opposite poles
• Telophase II and Cytokinesis
• 1. The chromosomes arrive at the poles and
  cytokinesis splits the cell one more time

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Sperm and Egg Formation
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9.6 Meiosis increases genetic variation among
offspring
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I. Assortment of Chromosomes

• A. The way the chromosomes line up and separate
  during metaphase I is a matter of chance
• B. The assortment of chromosomes that end up in
  the resulting cells occur randomly
• C. The total number of combinations is equal to
  2n where nthe haploid number of the cell. In
  humans n23 so 223 over 8 million!

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Gene Recombination
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II. Crossing Over

• A. Crossing Over is the exchange of genetic
  information between homologous chromosomes
• B. Crossing over adds to even more variation
  among offspring
• C. When a chromosome contains a new combination
  of genes from different parents it is called a
  genetic recombination

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Crossing Over
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III. Review Comparison of Mitosis and Meiosis

• A. Mitosis, which provides for growth, repair and
  asexual reproduction, produces daughter cells
  that are genetically identical to the parent cell
• B. Meiosis, which takes place in the sex organs,
  yields haploid daughter cells with only one set
  of homologous chromosomes
• C. In both mitosis and meiosis the chromosomes
  only duplicate once, during interphase
• D. Mitosis and meiosis both make it possible for
  cells to inherit genetic information in the form
  of chromosome copies

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Comparing Cell Division
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