Chapter 7 Biology

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Chapter 7 Biology
2012-03-06 01:10:34

Chapter 7 Biology
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  1. Genes
    instruction sets for biochemical, physical, behavioral traits
  2. Heredity
    the passing of characteristics from parent to offspring through their genes
  3. Gregor Mendel
    • learned about heredity by conducting experiments
    • studied pea plants
    • crossed true breeding purple flower plants with true breeding white flower plants
  4. True-Breeding
    always produced offspring with the same variant of the trait as the parents
  5. Mendels Law of Segregation
    • youve got two copies of each gene but only one copy in each sperm or egg
    • a dominant trait masks the effect of a recessive trait
  6. Pattern of Inheritance
    • Each parent puts into every sperm or egg it makes a single set of instructions (gene) for building the trait
    • Offspring thus find themselves with two copies of the instructions for any trait (called alleles)
    • The actual trait produced by an individual depends on the two copies of the gene that they inherit from their parents (homozygous and heterozygous)
  7. Phenotype and Genotype
    • Phenotype: outward appearance of an individual
    • Genotype: organisms genetic composition
    • Not always possible to determine an indiviuals genotype from its phenotype
  8. Pedigree
    • type of family tree
    • help scientists, doctors, animal and plant breeders, and prospective parents determine: the genes that individuals carry, the genes that their offspring will likely carry
  9. incomplete dominance
    a heterozygote displays a characteristic somewhere between the characteristics of the two homozygotes
  10. codominance
    a heterzygote displays characteristics of both homozygotes
  11. Multiple Allelism
    • occurs when there are three or more alleles for a gene within a population . An individual still inherits only two alleles - one from each parent
    • Red blood cells: AA, AO, BB, BO, AB, OO (genotype) A, B, AB, O (phenotypes)
  12. Antigens
    • chemicals on the surface of some cells
    • they act as signposts that tell the immune system whether the cell belongs in the body
    • antibodies are immune system molecules that attack cells with foreign antigens
  13. Polygenic Trait
    trait that is influenced by many different genes
  14. Pleiotropyd
    occurs when one gene influences multiple, different traits
  15. Phenylketonuria (PKU)
    characterized by the inability of the body to utilize the essential amino acid phenylalanine