Patterns of Inheritance

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Chapter 9
Patterns of Inheritance
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Genetics

• Gregor Mendel
• Monk
• Garden peas
• True-breeding varieties
• Hybrids
• Cross
• P generation
• F1 generation
• F2 generation

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Genetics

• Genetic Hypotheses
• There are alternative forms of genes that account
  for variations in inherited characteristics.
• For each characteristic, an organism inherits two
  alleles, one from each parent.

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Genetics

• Genetic Hypotheses
• If the two alleles of an inherited pair differ,
  then one determines the organisms appearance and
  is called the dominant allele. The other has no
  noticeable affect and is called the recessive
  allele.
• A sperm or egg carries only one allele for each
  inherited trait because the pair separate during
  production of gametes.

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Genetic Crosses

• Monohybrid crosses
• Punnet Square
• One trait
• Genotype
• Homozygous dominant
• Homozygous recessive
• Heterozygous
• Phenotype

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Genetic Crosses

• Homologous Chromosomes
• Carry genes controlling the same trait.
• Loci- specific location of gene on a chromosome.
• Alleles are found on the same locus on homologous
  chromosomes.

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Genetic Crosses

• Dihybrid crosses
• Two traits
• Law of independent assortment

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Genetic Disorders

• Pedigree
• Recessive disorders (pg 163)
• Cystic fibrosis
• Inbreeding
• Dominant disorders

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Genetic Testing

• Fetal testing
• Amniocentesis
• Chorionic villus sampling
• Alpha-fetoprotein blood test

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Genetic Testing

• Fetal Imaging
• Ultrasound Imaging
• Fetoscopy
• Newborn Screening
• Blood tests
• PKU

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Incomplete Dominance

• Complete dominance
• Dominant gene always expressed
• Must be homozygous recessive for recessive gene
  expression
• Incomplete dominance
• 3rd phenotype is expressed.
• F2 generation genotypic and phenotypic ratio is
  always 121

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Multiple Alleles

• ABO blood grouping
• 3 alleles
• 4 phenotypes
• Type A
• Type B
• Type AB
• Type O
• 6 genotypes
• ii
• IAIA or IAi
• IBIB or Ibi
• IAIB Codominant

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Gene Expression

• Plieotropy
• Polygenic ingeritance
• Environment
• Linked genes

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Sex Determination

• Humans
• Insects
• Birds, butterflies, fish
• Chromosome number
• Plants

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Sex Linked Genes

• Red-Green Color Blindness
• Hemophilia
• Baldness
• Duchenne Muscular Dystrophy.