What is today????

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What is today????

• Ummmmmm, what is it???
• VALEN-what?
• Oh okay
• HAPPY VALENTINES DAY!!!!!!
• Candy, Candy, Candy, Candy
• At the end of class if you are AWESOME!!!!!

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Mendels Laws of Heredity

• Why we look the way we look...

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Bell Ringer 2-14-13What is heredity?

• The passing on of characteristics (traits) from
  parents to offspring
• Genetics is the study of heredity

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Mendel used peas...

• They reproduce sexually
• They have two distinct, male and female, sex
  cells called gametes
• Their traits are easy to isolate

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Mendel crossed them

• Fertilization - the uniting of male and female
  gametes
• Cross - combining gametes from parents with
  different traits

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Questions

• What did Mendel cross?
• What are traits?
• What are gametes?
• What is fertilization?
• What is heredity?
• What is genetics?

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What Did Mendel Find?

• He discovered different laws and rules that
  explain factors affecting heredity.

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Rule of Unit Factors

• Each organism has two alleles for each trait
• Alleles - different forms of the same gene
• Genes - located on chromosomes, they control how
  an organism develops

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Rule of Dominance

• The trait that is observed in the offspring is
  the dominant trait (uppercase)
• The trait that disappears in the offspring is the
  recessive trait (lowercase)

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Law of Segregation

• The two alleles for a trait must separate when
  gametes are formed
• A parent randomly passes only one allele for each
  trait to each offspring

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Law of Independent Assortment

• The genes for different traits are inherited
  independently of each other.

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Questions...

• How many alleles are there for each trait?
• What is an allele?
• How many alleles does a parent pass on to each
  offspring for each trait

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Questions...

• What do we call the trait that is observed?
• What case (upper or lower) is it written in?
• What about the one that disappears?
• What case is it written in?

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Phenotype Genotype

• Phenotype - the way an organism looks
• red hair or brown hair
• genotype - the gene combination of an organism
• AA or Aa or aa

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Heterozygous Homozygous

• Heterozygous - if the two alleles for a trait are
  different (Aa)
• Homozygous - if the two alleles for a trait are
  the same (AA or aa)

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Dihybrid vs Monohybrid

• Dihybrid Cross - crossing parents who differ in
  two traits (AAEE with aaee)
• Monohybrid Cross - crossing parents who differ in
  only one trait (AA with aa)

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Questions...

• What is the phenotype?
• What is the genotype?
• What is homozygous?
• What is heterozygous?
• What is monohybrid crossing?