Pedigrees Pedigrees study how a trait is passed from one generation to the next. Infers genotypes of...
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Transcript of Pedigrees Pedigrees study how a trait is passed from one generation to the next. Infers genotypes of...
![Page 1: Pedigrees Pedigrees study how a trait is passed from one generation to the next. Infers genotypes of family members Disorders can be carried on… – Autosomes.](https://reader036.fdocuments.us/reader036/viewer/2022081515/56649ebe5503460f94bc81b1/html5/thumbnails/1.jpg)
Pedigrees
• Pedigrees study how a trait is passed from one generation to the next.
• Infers genotypes of family members• Disorders can be carried on…
– Autosomes (22 pairs of chromosomes)– Sex Chromosomes (X or Y)– Number of Chromosomes (called N)
(either N > 46 > N)• Keep in mind: traits are influenced
heavily by non-genetic factors or environmental factors– Nutrition – Exercise– Toxins (mutagens)– Disease
![Page 2: Pedigrees Pedigrees study how a trait is passed from one generation to the next. Infers genotypes of family members Disorders can be carried on… – Autosomes.](https://reader036.fdocuments.us/reader036/viewer/2022081515/56649ebe5503460f94bc81b1/html5/thumbnails/2.jpg)
Parts of a Pedigree
• Squares are males (XY)• Circles are females (XX)• Horizontal lines connect breeding
couples• Vertical lines connect parents to
children• Shading means the individual has the
trait• Half shading or a dot means they
carry the gene called a “carrier”• No shading means the individual does
not have the trait• A diagonal line means death.• Roman numerals show generations• Numbers assign an individual to a
generation– Example: What happened to II, 4?
![Page 3: Pedigrees Pedigrees study how a trait is passed from one generation to the next. Infers genotypes of family members Disorders can be carried on… – Autosomes.](https://reader036.fdocuments.us/reader036/viewer/2022081515/56649ebe5503460f94bc81b1/html5/thumbnails/3.jpg)
Interpreting Pedigrees
• 1. Determine if the trait is dominant or recessive.– Every other
generation: It is recessive
– Every generation: It is Dominant
![Page 4: Pedigrees Pedigrees study how a trait is passed from one generation to the next. Infers genotypes of family members Disorders can be carried on… – Autosomes.](https://reader036.fdocuments.us/reader036/viewer/2022081515/56649ebe5503460f94bc81b1/html5/thumbnails/4.jpg)
Interpreting Pedigrees
• 2. Determine if the trait is autosomal or sex linked.– Affects males and females equally:
Autosomal (Aa)– Affects one sex more than the
other: especially MALES! Sex-linked (XCXc or XcY)
• Typically sex-linked disorders or traits are carried on the X chromosome– Females tend to “carry” a trait and
affect their sons.– Females get the trait from an
affected father or carrier/affected mother
– Affected males got it from their mother and give it to their daughters to “carry.”
![Page 5: Pedigrees Pedigrees study how a trait is passed from one generation to the next. Infers genotypes of family members Disorders can be carried on… – Autosomes.](https://reader036.fdocuments.us/reader036/viewer/2022081515/56649ebe5503460f94bc81b1/html5/thumbnails/5.jpg)
Recap on interpreting pedigrees1. Determine if it is dominant or recessive.2. Determine if it is autosomal or Sex-linked.3. Assign genotypes to affected (shaded) individuals first.
– If Autosomal then use two alleles to show inheritance. (AA, Aa or aa for example)
– In Sex-linked the shaded males will carry the gene (XcY) and be affected.
– In Sex-linked the females can be unaffected, affected or carriers and marked with a dot. (XCXc)
4. Assign remaining genotypes to unaffected individuals .– In Sex-linked the unshaded males will not carry the gene (XCY) and be
unaffected.
5. Double check your work, does the pedigree make sense?
![Page 6: Pedigrees Pedigrees study how a trait is passed from one generation to the next. Infers genotypes of family members Disorders can be carried on… – Autosomes.](https://reader036.fdocuments.us/reader036/viewer/2022081515/56649ebe5503460f94bc81b1/html5/thumbnails/6.jpg)
Your Turn!
Is this dominant or recessive? Is this Autosomal or Sex-linked? Assign genotypes to the pedigree to show the inheritance pattern.
![Page 7: Pedigrees Pedigrees study how a trait is passed from one generation to the next. Infers genotypes of family members Disorders can be carried on… – Autosomes.](https://reader036.fdocuments.us/reader036/viewer/2022081515/56649ebe5503460f94bc81b1/html5/thumbnails/7.jpg)
Check your work
Type of Inheritance? Autosomal dominant inheritance.
![Page 8: Pedigrees Pedigrees study how a trait is passed from one generation to the next. Infers genotypes of family members Disorders can be carried on… – Autosomes.](https://reader036.fdocuments.us/reader036/viewer/2022081515/56649ebe5503460f94bc81b1/html5/thumbnails/8.jpg)
Sex-Related Punnet Squares• The genes for these traits are on the X chromosome,
because boys only receive one X chromosome they are more likely to inherit disorders passed to them from their mother who would be a carrier.– Humans have 22 pairs of autosomes and 1 pair of
sex chromosomes – Males are XY
• Males donate their Y chromosome to their sons only and their X chromosome to their daughters.
• They determine the sex of the child!
– Females are XX• Females donate either one of their X chromosomes to
their sons and daughters• Many times in women the other X chromosome coils
up and deactivates to become a Barr body.• Hemophilia and Colorblindness are sex linked traits, the
punnett square shows how a woman who is a carrier passes the trait to her son, but not her daughters.
– In what only case could you have a daughter with hemophilia and/or colorblindness?
– She inherits a recessive from her mother and her father!
![Page 9: Pedigrees Pedigrees study how a trait is passed from one generation to the next. Infers genotypes of family members Disorders can be carried on… – Autosomes.](https://reader036.fdocuments.us/reader036/viewer/2022081515/56649ebe5503460f94bc81b1/html5/thumbnails/9.jpg)
Your Turn!• A mother whose
father had hemophilia marries a man without hemophilia.
• What is the probability they have children with the disorder?– Use H for normal and h
for hemophilia
![Page 10: Pedigrees Pedigrees study how a trait is passed from one generation to the next. Infers genotypes of family members Disorders can be carried on… – Autosomes.](https://reader036.fdocuments.us/reader036/viewer/2022081515/56649ebe5503460f94bc81b1/html5/thumbnails/10.jpg)
Check your work• First you should figure out
the genotypes of the parents. If the mother had a father with hemophilia, then she is a carrier XHXh and the father is normal since he does not have hemophilia himself. XHY
• They have a 50% chance of having a boy with hemophilia; 0% chance for a daughter with hemophilia.
![Page 11: Pedigrees Pedigrees study how a trait is passed from one generation to the next. Infers genotypes of family members Disorders can be carried on… – Autosomes.](https://reader036.fdocuments.us/reader036/viewer/2022081515/56649ebe5503460f94bc81b1/html5/thumbnails/11.jpg)
Your turn!
Is this dominant or recessive? Is this Autosomal or Sex-linked? Assign genotypes to the pedigree to show the inheritance pattern.
![Page 12: Pedigrees Pedigrees study how a trait is passed from one generation to the next. Infers genotypes of family members Disorders can be carried on… – Autosomes.](https://reader036.fdocuments.us/reader036/viewer/2022081515/56649ebe5503460f94bc81b1/html5/thumbnails/12.jpg)
Check your work.
Type of Inheritance? Sex linked Recessive