Human Heredity by KOudP8X

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									      Chapter 12
Patterns of Heredity and
    Human Genetics
         Section 1
  Mendelian Inheritance of
      Human Traits
                 Pedigree
• A pedigree is a        • <>
  graphic
  representation of
  genetic inheritance.
• Symbols are used to
  show the trait being
  studied and family
  relationships
   Answer the following about the
         above pedigree

• a. What is the sex of I 1?
  ___________________
• b. How many children does IV 2 have?
  ___________
• c. How many children of IV 12 have
  cancer? ____________
• d. List all of the males who have polyps
  (carriers) __________
 Dominant Autosomal Heredity

• Follow Rule of Dominance
• Tongue curling
• Free earlobes
• Huntington’s disease
     Huntington’s Disease
• Lethal genetic disorder
  caused by rare autosomal
  dominant allele
• Nervous system disintegrates
  causing loss of control of
  limbs and mental
  deterioration.
     Huntington’s disease

• Since onset occurs
  between ages 30 and 50,
  this defect can be
  transmitted to new
  generations before the
  parent knows that he is a
  carrier.
        Huntington’s

• Genetic testing can
  determine if a person is a
  carrier.
• Carriers will get disease
  because allele is dominant.
www.about-dementia.com/huntingtons/hd-causes.php
Recessive Autosomal Heredity
• Genetic disorders caused by
  recessive alleles.
• Most genetic disorders are
  caused by this type of allele.
• Cystic fibrosis, sickle -cell
  anemia, Tay - Sachs disease,
  Phenylketonuria (PKU).
       Cystic Fibrosis
• Most common lethal genetic
  disorder in white Americans.
• Characterized by thick mucus
  in lungs and digestive tract.
• Food is not digested properly
• Breathing is difficult - frequent
  lung infections
        Tay- Sachs
• Absence of enzyme that breaks
  down a lipid that is produced and
  stored in the central nervous
  system. Lipid builds up in brain
  membranes
• Common in Eastern European
  Jews and Pennsylvania Dutch.
        Symptoms of
     Tay-Sachs Disease
• Blindness
• Progressive loss of
  movement
• Mental deterioration
• Death by age 5.
• See pg 312 for pedigree
    Phenylketonuria
        (PKU)
• Most common in people of
  Norwegian and Swedish
  descent.
• Caused by absence of
  enzyme that converts
  phenylalanine to tyrosine
  (amino acids).
   Symptoms of PKU
• New born appears normal.
• Once baby starts drinking
  milk, which is high in
  phenylalanine, damage
  occurs
        Symptoms
• Build up in phenylalanine
  causes severe central
  nervous system damage
  resulting in mental
  retardation.
   Treatment of PKU
• All newborns are tested for
  PKU.
• Changes in diet can prevent
  damage.
   New Problems With
         PKU
• If a homozygous recessive
  female becomes pregnant,
  high levels of
  phenylalanine in her blood
  can damage baby.

								
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