More on Genetics

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More on Genetics

• BY BRIANNA SHIELDS

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Do Now

• 1. How do you describe this genotype RR?
  (homozygous recessive, heterozygous, etc.)
• 2. If having hair in your ears is a dominant
  trait, and you have the gene combination Hh, will
  you have hair in your ears?
• 3. What do you call the physical appearance that
  an organism shows due to its gene combination
  (the way an organism looks)?

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GOAL

• To use punnett squares to predict the traits of
  offspring
• To become familiar with pedigree charts

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Review

• Brown eyes is dominant. Blue eyes is recessive.
  The mother is heterozygous and the father is
  heterozygous.
• What percentages of blue-eyed and brown eyed
  offspring will they get?

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Bb x Bb
B Brown bBlue
Genotypes 25 Homozygous Dominant BB 50
Heterozygous Bb 25 Homozygous Recessive bb
B
b
BB Bb
B
Bb bb
b
Phenotypes 75 Brown Eyed 25 Blue Eyed
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Review

• Having a short middle toe is a dominant trait.
  Having a long middle toe is recessive. If a
  heterozygous male and a homozygous recessive
  female have a child- what is the probability that
  the offspring will have a long middle toe?

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Mm x mm
M Short Middle Toe m Long Middle Toe
M
m
Genotypes 50 Heterozygous Mm 50 Homozygous
Recessive mm
Mm mm
m
Mm mm
m
Phenotypes 50 Short middle toe 50 Long middle
toe
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Create a punnett square

• A couple would like to have children- however,
  the husband has cystic fibrosis. Having cystic
  fibrosis is a recessive trait. The wife,
  however, does not have cystic fibrosis- but she
  is a carrier for the disease (she is
  heterozgyous). What are their chances for having
  a child with cystic fibrosis?

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Bb x bb
B Normal bCystic Fibrosis
B
b
Genotypes 50 Heterozygous Bb 50 Homozygous
recessive bb
Bb bb
b
Bb bb
b
Phenotypes 50 Carrier-Healthy 50 cystic fibrosis
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More Genetics Terms

• Carrier

• When an individual is heterozygous (carries the
  disease gene), although they dont actually have
  the disease (Cc).

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More Genetics Terms

• Pure Bred

• Homozygous recessive (bb) and Homozygous dominant
  (BB)
• AKA True breeders

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More Genetics Terms

• Hybrid

• Heterozygous individuals

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More Genetics Terms

• Sex Chromosomes

• Out of your 46 chromosomes - 2 of them are sex
  chromosomes
• Male XY
• Female XX

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Punnett Example XX x XY
X
X
Genotypes 50 XX 50 XY
XX XX
X
XY XY
Y
Phenotypes 50 Boy 50 Girl
X Female YMale
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Normal Human Karyotype
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Chromosome Disorders

• Turners Syndrome
• Monosomy X
• Female
• Short stature
• Skin folds on the neck
• Lack of sexual development
• Small, sterile, minor
• malformations

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Chromosome Disorders

• Klinefelters Syndrome XXY
• Male
• Chest malformations
• Poor sexual development
• Low fertility
• Decreased intelligence

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Chromosome Disorders

• XYY Syndrome
• Male prisoners
• Increased violence
• Above-average height
• Subnormal intelligence

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Chromosome Disorders

• XXX Syndrome
• Increased mental retardation
• Sterility
• Metafemale

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Chromosome Disorders

• Trisomy 21- extra chromosome
• Mental retardation
• Developmental Problems
• Characteristic features

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Chromosome Disorders Websites

• What Can Our Chromosomes Tell Us?
• Special Child Disorder Zone Archives

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Inheritance of Abnormal Genes
Is this a recessive or a dominant disease gene?
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Inheritance of Abnormal Genes
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Genetics Websites

• OLogy The Gene Scene
• DNA is an Instruction Manual
• Understanding Genetics Human Health and the ...
• Gene Safari

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Chromosomes in the Cell

• What Are Chromosomes?

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Pedigree Charts
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Genetics Assessment

• --gt Complete the Punnett Square Word Problems
• --gt Genetics Lab- Look at characteristics of
  classmates
• --gt Worksheet Should this Dog be Called Spot?
• Practicing Punnett Squares on the Internet

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DO NOW

• Get out your homework
• Go over your answers with your SEAT PARTNER
• If you arent done, FINISH IT!!
• We will go over the answers together in a few
  minutes