Making a Pedigree Chart

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Making a Pedigree Chart
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Quick Review

• Genotype what genes someone has
• Genes are usually represented by a letter, a
  capital letter for the dominant trait, a small
  case for the recessive.
• Ex. Tongue Rolling is dominant, so we use R to
  represent the tongue rolling
• Inability to roll your tongue is recessive so we
  use r to represent the non-rolling gene
• For every trait, you get a gene from each parent.

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Genotypes and Phenotypes

• Mom and Dad are Rr-that is their genotype, they
  can also be described as heterozygous-they have 1
  of each gene
• What is their PHENOTYPE?
• The youngest son has a genotype of rr-he is
  Homozygous recessive-2 copies of the recessive
  gene
• His phenotype?

tongue rollers
Rr
Rr
I cant Roll my Tongue!
Rr
rr
non-roller
Rr
Rr
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Some common dominant and recessive traits

• Widows peak is dominant.
• You can be homozygous dominant (WW) or
  heterozygous (Ww) and you will have widows peak
• What is your genotype and phenotype if youre
  homozygous recessive?

ww, no widow's peak
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What is a Pedigree and why do we use them?
1) A pedigree is a chart of the genetic history
of a family over several generations.
2) A genetic counsellor will use pedigree charts
to help determine the distribution of a disease
in an affected family.
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Making a Pedigree Chart

• Pedigree charts are made to chart family history
  and see how traits are passed.
• What generations are these?

I
II
III
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Organizing the pedigree chart

• 3) Generations are identified by Roman numerals

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Organizing the pedigree chart

• 4) Individuals in each generation are numbered
  from left to right.

3
4
5
6
7
2
1
9
Symbols Used-write it down!

• Shade individuals that have the trait youre
  studying
• Boyssquares (Lucy always calls Charlie Brown a
  block head)
• Girls-circles
• Shaded small circle-is a deceased affected
  infant female
• Shaded small square
• is a deceased affected infant male

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• Married-connected at side
• Siblings-connected at TOP not at the side
  (hopefully not siblings AND married)
• Oldest child-to the left
• Question-if shaded individuals in this pedigree
  have blue eyes, what is the GENOTYPE of the
  parents?

both must be Bb
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Other

• Divorced, separated
• Deceased
• Twins(maternal or identical)
• Twins(fraternal)

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Whats going on?Shadedblue eyes

• 1 and 2 split after having 4, 2 then had kids
  with 3 and split with her too after 5-9 were born
• Genotypes of 1, 4,7?
• Genotypes of 2 3?
• Genotypes of 5,6, 8, 9, 10, 11, 12?

1
2
3
bb
Bb
6
10
4
5
7
8
9
could be BB or Bb
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11
III
In what generation are there twins?
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Time to practice

• Complete the practice worksheet on pedigrees in
  class (we will review)

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Make your own pedigree

• Using your own family, make your own pedigree
  chart
• Must at LEAST include grandparents, parents,
  your generation
• Pick one easy dominant or recessive trait and
  shade individuals that have it. You can guess
  who has it if you dont know for sure. (Dont
  pick a trait that EVERYONE in your family has)
• Label the Genotypes of everyone in your family
• Label yourself, grandparents, cousins, etc
• Put a key on the pedigree so I know what shaded
  means. Ex.-shaded people have 3 heads