Bell Work: 1/30/12 Draw the three pictures and explain why the third picture is correct.

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Bell Work 1/30/12Draw the three pictures and
explain why the third picture is correct.
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Objectives

• Describe the relationship among genes,
  chromosomes, and inherited traits. (SPI
  0707.4.3)
• Sequence a series of diagrams that depict
  chromosome movement during plant cell division.
  (SPI 0707.1.4)
• Classify methods of reproduction as sexual or
  asexual. (SPI 0707.4.1)

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Mitosis Review

1. Interphase- DNA is copied
2. Prophase- Chromatin (DNA wrapped around protein)
   forms into chromatids (rods)
3. Metaphase- Chromatids line up in the middle of
   the cell
4. Anaphase- Chromatids separate
5. Telophase- two new nuclei form around the
   chromatin (separated chromatids)
6. Cytokinesis- two new cells form

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Mitosis Hand Motions
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Mitosis process of a somatic (body) cell
dividing to produce an exact copy of itself
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Mitosis

• Interphase
• DNA copies itself (chromosomes are copied)
• Centrioles copy

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Mitosis

• Prophase
• DNA condenses into chromatids (rod-like
  structures), held together by centromeres
• Spindle fibers begin to form
• Centrioles move to opposite sides
• Nuclear membrane breaks apart

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Mitosis

• Metaphase
• Chromatids (chromosomes) line up across the
  center of the cell
• Spindle fibers attach to the centromere

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Mitosis

• Anaphase
• Spindle fibers pull the chromatids to opposite
  ends of the cell

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Mitosis

• Telophase
• Nucleus forms around the chromatids
• Chromosomes unwind

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Mitosis

• Cytokinesis
• Division of the cytoplasm and the rest of the cell

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FYI Chromosomes

• Human body cells have 46 chromosomes, or 23 pairs
  of chromosomes.
• Each chromosome contains certain types of genes.
• For example, chromosome 21 codes for Down
  Syndrome, or Trisomy 21.
• A sex cell is produced with an extra copy of
  chromosome 21 the gamete thus has 24
  chromosomes. When combined with a normal gamete
  from the other parent, the embryo now has 47
  chromosomes, with three copies of chromosome 21.

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MeiosisIn sexual reproduction, two parent cells
join together to form offspring that are
different from both parents.These parent cells
are called sex cells (sperm egg).Sex cells are
made during meiosis.
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Meiosisprocess of a cell dividing to produce 4
cells with half the genetic materialWhy do the
cells produced in meiosis only need half of the
genetic material?
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Meiosis

• Interphase I
• DNA copies itself (chromosomes are copied)
• Centrioles copy

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Meiosis

• Prophase I
• DNA condenses into chromatids, held together by
  centromeres and attach to the membrane
• Spindle fibers begin to form
• Centrioles move to opposite sides
• Nuclear membrane breaks apart

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Meiosis

• Metaphase I
• Chromatids line up on each side of the center of
  the cell
• Spindle fibers attach to the centromere

Meiosis is a bit different because there
something called crossing-over happens with the
DNA. This crossing over is an exchange of
genes. The genes are mixed up, not resulting in a
perfect duplicate like mitosis.
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Meiosis

• Anaphase I
• Spindle fibers pull the chromosome pairs apart to
  opposite ends of the cell

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Meiosis

• Telophase I
• Nucleus forms around the chromosomes

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Meiosis

• Cytokinesis
• Division of the cytoplasm and the rest of the
  cell

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Meiosis

• Interphase II
• Cell rests
• DNA DOES NOT duplicate
• Centrioles duplicate

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Meiosis

• Prophase II
• DNA condenses into chromatids, held together by
  centromeres
• Spindle fibers begin to form
• Centrioles move to opposite sides
• Nuclear membrane breaks apart

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Meiosis

• Metaphase II
• Chromosomes line up across the center of the cell
• Spindle fibers attach to the centromere

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Meiosis

• Anaphase II
• Spindle fibers pull the chromatids to opposite
  ends of the cell

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Meiosis

• Telophase II
• Nucleus forms around the chromatids
• Chromosomes unwind

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Meiosis

• Cytokinesis
• Division of the cytoplasm and the rest of the
  cell

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Mitosis vs. Meiosis
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Mitosis
Meiosis

• Both are processes of cell division
• Both reproduce new cells
• Both go through Interphase, Prophase, Metaphase,
  Anaphase, Telophase, Cytokinesis

• Asexual cell reproduction (only one parent cell
  is needed)
• Produces an exact copy of itself with 46
  chromosomes
• Reproduces two new cells
• Somatic cells body cells (skin cells, blood
  cells, bone cells, muscle cells)

• Sexual cell reproduction (two parent cells are
  needed)
• Produces cells with half as many chromosomes (23)
• Reproduces four new cells
• Sex cells (sperm egg)

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Sex ChromosomeChromosome 23 (XX or XY)
xx
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Determining the Sex or Gender of Offspring

• Sex chromosomes carry genes that determine the
  sex or gender of offspring.
• In humans, females have two X chromosomes and
  males have one X and one Y chromosome.
• During meiosis, one of each of the chromosome
  pairs ends up in a sex cell.

• Baby boy XY
• Baby girl XX
• Example

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Living Things Reproduce

• 2 Types of Reproduction
• Asexual- a single parent produces an offspring
  identical to the parent
• Sexual- two parents produce an offspring with
  traits of both parents

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Challenge Questions

• When animals go through sexual reproduction, what
  type of cell division are they going through?
• meiosis
• When animals go through asexual reproduction,
  what type of cell division are they going
  through?
• mitosis

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Types of Asexual Reproduction In Animals

• Budding happens when a part of the parent
  organism pinches off and forms a new organism.
• The new organism separates from the parent and
  lives independently.
• Jellyfish hydra

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Types of Asexual Reproduction In Animals

• Fragmentation parts of the organism break off
  and a new organism grows identical to the parent.
  
• Worms starfish

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Types of Asexual Reproduction In Animals

• Regeneration organism loses a body part and that
  part may develop into a new organism.
• Sea star

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Asexual Reproduction in Other Organisms

• Binary fission is a method of asexual
  reproduction in which an organism splits into
  two.
• This occurs in bacteria and other single-celled
  organisms

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Asexual Reproduction in Plants

• Some plants can reproduce asexually when they are
  cut or damaged. These plants can sprout new
  growth from their roots, stems, and leaves.
• In wild strawberry plants, stems are capable of
  arching downward and taking root in the ground,
  resulting in the formation of a new plant. This
  is an example of asexual reproduction.

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3-2-1 Reflection

• 3 differences between mitosis and meiosis
• 2 different types of asexual reproduction
• 1 way this relates to your life (real world)