5'2 Traits and Inheritance

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5.2 Traits and Inheritance
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Genes and Alleles

• GENES instructions for an inherited trait
• Traits are controlled by genes
• There are genes for eye color, hair color, shape
  of earlobe, etc.
• ALLELES are the different forms a gene may have
  for a trait
• (ex. Blue, green, or brown eyes, attached or
  unattached earlobes, etc.)

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Genotype Phenotype

• GENOTYPE ? the genetic make-up of an organism
• PHENOTYPE ? An organisms appearance or the
  physical trait that shows as a result of a
  particular genotype

Black Black
BLACK
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Genotype Phenotype

• Black Red
• Brown Blonde
• Red Red
• Black Blonde
• Blonde - Blonde

• Black
• Brown
• Red
• Black
• Blonde

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• A Punnett square is a tool used to predict
  genetic results
• Scientists put the parents alleles on a Punnett
  square to predict possible outcomes

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• Scientists will use letters to represent the
  different alleles
• In this punnett square, P represents pink. It is
  capitalized because it is the dominant allele.
• A lower case p represents the recessive allele
  which is blue.

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Homozygous Heterozygous

• If an organism is homozygous ? it has two of the
  same alleles for a trait
• PP or pp
• Heterozygous organisms have 2 different alleles
  for a trait
• Pp

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Exceptions to Mendels Research

• Incomplete dominance when neither allele
  dominates the other
• When crossing a red snapdragon with a white
  snapdragon ? you get a pink snapdragon

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The End