Variations on a Theme

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Variations on a Theme
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Species Characteristics
What characteristics are Shared by each of these
Species?
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Individual characteristics- make a person unique
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Although your genes carry your master plan
there are other factors that make you YOU!
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Like What?

• Environment

• Spiritual life

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Genetics- The Study of Heredity
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Genes

• A section of DNA that codes for
• a particular trait
• (the recipe for
• a protein)

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Chromosomes

• Threadlike structures composed of DNA
• and proteins found in the nucleus of the
• cell.

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• Chromatid- one of the identical halves of the
  chromosome
• Centromere- constricted area where chromatids are
  joined

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Homologous Pairs and Homologues
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MITOSIS MEIOSIS

• Diploid- has two of each chromosome- 2n- product
  of mitosis
• Haploid- 1 of each chromosome- 1n- product of
  meiosis

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Humans have 46 chromosomes or 23 pairs of
chromosomes
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Fruit Flies

• 8 chromosomes or 4 pairs

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Goldfish

• 100 chromosomes or 50 pair

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Crayfish

• 200 chromosomes or 100 pair

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Lilies, Tomatoes, White Pines

• All have 24 chromosomes or 12 pair
• Its not the chromosome number that determines
  the species but the genes on the chromosomes

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What is a Karyotype?

• A photograph or stained, separated and sorted
  chromosomes

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How many chromosomes would there be in a human
diploid cell? A haploid cell?
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Haploid cells are for reproduction
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What is the difference between a gene and a
chromosome?
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Cell Division

• And the Cell Cycle

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What is the cell cycle?
The life cycle of a cell
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Interphase Mitosis Cytokinesis
Metaphase
Prophase
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Mitosis

• The division of a cell to produce two identical
  daughter cells

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• Interphase
• Chromosomes are copied
• Appear as threadlikecoils
• (chromatin)at the start, but
• each chromosome and its
• copy (sister chromosome)
• change to sister
• chromatids at end of
• this phase.
• Chromatid

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• Prophase
• Mitosis begins
• Centrioles appear
• Spindle fibers
• form between
• the poles

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• Metaphase
• Chromatids attach to spindle fibers in center

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• Anaphase
• Chromatids separate and begin to move to opposite
  sides of the cell

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• Telophase
• Two nuclei form
• Chromosomes appear as
• chromatin (threads rather
• than rods
• Mitosis ends

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• Cytokinesis
• Membrane moves inward to create two daughter
  cells with identical chromosomes

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Prophase

• Whitefish

• Onion

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Metaphase

• Whitefish

• Onion

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Anaphase

• Whitefish

• Onion

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Telophase

• Whitefish

• Onion

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All Together Now
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Uses of Mitosis

• Growth
• Repair and replace old or damaged cells
• Asexual reproduction

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Meiosis

• Forming Gametes for Sexual Reproduction

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Who discovered meiosis?

• Van Beneden

• Studying Ascaris

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Meiosis Vocabulary

• Zygote- a diploid cell formed by the union of a
  haploid sperm and egg
• Meiosis- the forming of sexual gametes by
  reducing the number of chromosomes from diploid
  to haploid through two divisions.

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Meiosis- two divisions

• 1st division reduces the of chromosomes from
  diploid to haploid
• 2nd division doubles the number of cells

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Meiosis
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Comparison of Mitosis and Meiosis
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Compare Metaphase

• Mitosis Metaphase

• Meiosis Metaphase I

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Compare Anaphase

• Mitosis Anaphase

• Meiosis Anaphase I

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Compare Daughter Cells Produced

• Mitosis

• Meiosis

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Purpose of Meiosis

• To form gametes for sexual reproduction
• Four viable sperm are produced from
  spermatogenesis
• One viable egg produced from oogenesis

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Meiosis Vocabulary

• Gametes- haploid cells that, when united, form a
  diploid zygote- ex. sperm, eg

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Meiosis Vocabulary

• Fertilization- the process of forming a zygote

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Meiosis Vocabulary

• Sperm- male gamete
• Egg- female gamete

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Meiosis Vocabulary

• Forming of Sperm

• Forming of Eggs

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Meiosis Vocabulary

• Sexual Reproduction-The fertilization (union) of
  haploid gametes to produce offspring that are not
  genetically identical to either parent