Genetics

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Genetics

• Mendels Laws of Heredity

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Genetics

• Heredity passing of characteristics from parents
  to offspring.
• Traits the characteristics that are passed to
  the offspring.

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Genetics

• Genetics the study of heredity
• Gregor Mendel
• considered the father of genetics
• Mendel worked with peas studying 7 different
  characteristics

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7 traits in Mendels peas

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Genetic Vocabulary

• Gametes male and female sex cells
• In plants
• male gametes are pollen.
• female gametes are eggs.

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Genetic Vocabulary

• Fertilization joining of the male and female
  gametes.
• Zygote the single cell that results from
  fertilization
• Pollination transferring pollen to the female
  reproductive organ.
• Gene segment of DNA that controls a trait.

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How did Mendel do it?

• Mendel worked carefully to pollinate the peas.
• Mendel studied one trait at a time.
• He worked with true breeding plants.

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Mendels crosses

• Mendel crossed a tall plant with a short plant
  to produce a hybrid.
• Hybrid offspring of parents with different forms
  of a trait.

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Identifying Generations

• Abbreviations are used for the generations.
• P1 original parents.
• F1 first generation.
• F2 second generation.

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Mendels Crosses

• Mendel crossed the offspring of the F1 with
  itself to produce the F2 generation.
• For each trait the ratio in the F2 was the same.

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Mendels Conclusions

• Mendel concluded that each trait was controlled
  by 2 factors.
• These factors are genes.
• Alleles alternate forms of a gene. Expressed as
  different letters.

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Dominant vs. Recessive

• Dominant an allele that will cover or mask
  another trait. It is written as a capital letter
  T
• Recessive trait that can be masked by another
  trait. It is written as a lower case t

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Genetics

• Genotype the genes present in an organism,
  expressed as 2 letters.
• Phenotype the way an organism looks or behaves

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Homozygous

• Homozygous an organism is homozygous for a trait
  if both alleles are the same.
• TT is homozygous dominant
• tt is homozygous recessive

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Heterozygous

• Heterozygous an organism is heterozygous for a
  trait if the 2 alleles are different.
• Tt is heterozygous for height.
• The dominant allele will be expressed.