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					                  Chapter 10: Patterns of Inheritance
     -Connect the concepts of probability and randomness to the study of heredity (genetics).
     -Contrast the blending hypothesis with the particulate hypothesis of inheritance.
     -Explore explanations of inheritance that are not supported by experimental results.
     -Describe some of the monk Mendel’s procedures for his plant-breeding experiments           10.1.

–Explain Mendel’s principle of segregation.
-Describe how the rules probability apply to genetics. (Use Punnett squares).
-Utilize the Belmonte-approved, 5-step method for solving genetics problems.
-Contrast and connect genotype and phenotype.
-Explain Mendel’s principle of independent assortment.
-Debate on the nature versus nurture conundrum.
-Predict the results of monohybrid crosses and use testcrosses to determine genotypes.
-Determine parental (P) traits by observing the traits of the F1 and F2 generations.               10.2

-Describe how alleles interact in intermediate inheritance.
–Describe inheritance patterns involving more than 2 (multiple) alleles.
-Explain how polygenic inheritance results in a wide range of phenotypes.
-Describe how environmental conditions can affect phenotypic expression.                           10.3

-Summarize the chromosome theory of inheritance.
-Recognize and explain exceptions to Mendel’s principle of independent assortment.
-Understand how meiosis accounts for many of Mendel’s principles.
-Explain how crossing over generates new combinations of alleles.
-Understand how the probability of crossover between 2 genes depends on distance between them.           10.4

-Explain how sex-linked genes produce different inheritance patterns in males and females.
-Explain why sex-linked disorders are more common in males.
-Analyze and understand some of Morgan’s fruit fly crosses.
-Dominate all opposition in Get the Point!!                                                              10.5
      10.1 Mendel and Pea Plants
• Connect the concepts of
  probability and randomness to
  the study of heredity (genetics).
• Contrast the blending
  hypothesis with the particulate
  hypothesis of inheritance.
• Explore explanations of inheritance
  that are not supported by
  experimental results.
• Describe some of Mendel’s
  procedures for his plant-breeding
The Blending Hypothesis
of Inheritance
• For centuries, plant and animal
  breeders had many questions about
  the inheritance of flower colors, fur
  length, and other characters of
  organisms. Observations alone
  could not answer all these
• Then an Austrian monk named
  Gregor Mendel devised a series of
  experiments that revealed the basic
  rules underlying patterns of
             • A trait is a variation of a
               particular character. For
               example, one plant might
               have the trait of red flowers,
               while another might have the
               trait of yellow flowers.
             • In the early 1800s, biologists
         +     proposed the blending
               hypothesis to explain
               how offspring inherit traits
               from both parents. For
               example, suppose a red-
yields         flowered plant were crossed
               with a yellow-flowered plant
               of the same species.
             • According to the blending
               hypothesis, the red and
               yellow hereditary material in
               the offspring would blend,
               producing orange-flowered
               plants—like blending red and
               yellow paint to make orange
               paint. Based on this
               hypothesis, all offspring of
               orange-flowered plants would
               also have orange flowers.
         The Blending Hypothesis
                        (is not supported)
But people observed many exceptions to blending. For example, red-
   flowered parents sometimes produced yellow-flowered offspring.
  The blending hypothesis was eventually discarded because it could
      not explain how traits that disappear in one generation can
                        reappear in later ones.

Mendel's Plant Breeding Experiments
• In the 19th century (1800’s), most
  biologists worked by observing and
  describing nature. Gregor Mendel was
  one of the first to apply an experimental
  approach to the question of inheritance.
  His work eventually gave rise to
  genetics, the study of heredity.
• For 7 years, Mendel bred pea plants and
  recorded inheritance patterns in the
  offspring. Based on his results, he
  developed a particulate hypothesis of
• This hypothesis states that parents pass
  on to their offspring separate and distinct
  factors (today called genes) that are
  responsible for inherited traits.
• Mendel stressed that these heritable
  factors retain their identity generation       Heredity/Inheritance
  after generation. In other words, genes
  are more like marbles of different colors
  than paints. Just as marbles retain their     How parents pass their
  individual colors, genes retain their own
  identities.                                   traits to their offspring
Pea Plant Life Cycle
7 Pea Plant Traits studied by Mendel
                                100% YIELDS

• Mendel's 1st step was to identify pea plants that were true-
  breeding. (When self-fertilized, a true-breeding or purebred plant
  produces offspring identical in appearance to itself generation after
• For instance, Mendel identified a purple-flowered pea plant that,
  when self-fertilized, always produced offspring plants that had
  purple flowers.
• To test the particulate hypothesis, Mendel crossed true-
  breeding plants that had two distinct and contrasting traits—for
  example, purple or white flowers. These contrasting pea varieties
  served as parents for the next generation.
• In a method called cross-fertilization, or cross, sperm from the
  pollen of one flower fertilizes the eggs in the flower of a different
  plant. The fertilized eggs developed into embryos within seeds
  (peas) that Mendel planted.
• The seeds grew into offspring that eventually produced their own
  flowers. What color were their flowers?...Hmmmmm…
                       To prevent self-
                       1. Mendel snipped off all of the
                          anthers from the plant parent’s
                          (P) purple flower.
                       2. He then used a brush to snag
                          pollen from the other plant
                          parent’s white flower and
                          rubbed it on the sticky stigma
                          of the purple parent.

What color were the
progeny flowers from
    this cross?
• Mendel was a curious monk. He wondered, if a
  purple-flowered pea plant were fertilized with
  pollen from a white-flowered plant, what
  color flowers would the offspring have?



   10.1 Online Review

•Flower Parts/Pollination Activity 1, 2, 3, 4
•From Flowers to Fruits
•Genetics Timeline 1, 2, 3
•Genetics Timeline Activity
•Blending Hypothesis Overview 1, 2
•DNA From The Beginning
•Flower Quiz 1, 2, 3
•Pollination Quiz 1, 2
Back to Mr. Belmonte’s Biology

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