What are genetic pedigree diagrams Show how an inherited trait characteristic runs in a group of related individuals You might have to interpret genetic diagrams to work out the genotypes or potential phenotypes of individuals ID: 428970
Download Presentation The PPT/PDF document "Genetic Pedigree Diagrams" is the property of its rightful owner. Permission is granted to download and print the materials on this web site for personal, non-commercial use only, and to display it on your personal computer provided you do not modify the materials and that you retain all copyright notices contained in the materials. By downloading content from our website, you accept the terms of this agreement.
Slide1
Genetic Pedigree DiagramsSlide2
What are genetic pedigree diagrams?
Show how an inherited trait (characteristic) runs in a group of related individuals. You might have to interpret genetic diagrams to work out the genotypes or potential phenotypes of individuals. Slide3
Cystic Fibrosis
Inherited disorder that causes the production of a thick mucus, which affects the lungs and digestive system.
It is caused by a faulty recessive allele (f).
A person with CF is homozygous from the allele (ff).
(Ff) is a carrier of CF.Slide4
1
2
3
5
6
4
Unaffected male
Unaffected Female
Male with CF
Female with CF
Key shows what the shapes represent
Two parents are joined by a horizontal line
Vertical line goes from parents to children
Children have a vertical line above them
This female is CF (ff), but neither of her parents do. She must have inherited an f allele from each parent, so both parents must be carriers (Ff).
This male has CF (ff), like his mother (ff). He's inherited an f allele from each parent, so his father must be a carrier (Ff). Slide5
Possible Question
Work out the chances of the next child born to individuals 4 and 5 having CF. Slide6
Question
Huntington's disease is caused by a dominant allele. The genetic pedigree diagram shows the inheritance of Huntington's disease in one family.
1
3
2
4
5
What is the genotype of individual 1?
What would the possible genotypes of the offspring produced by a cross between individuals 3 and 5?
Affected female
Unaffected MaleSlide7
Answers
Heterozygous, e.g.
Hh
The cross between individual 1 and 2 has produced one affected child. As the unaffected child must have two recessive alleles, one from each parent, individual 1 must have one recessive allele and one dominant allele (
Hh
) to have the disorder and pass on an unaffected allele.
Heterozygous (
Hh
) and Homozygous recessive (
hh
).
Individual 5 is unaffected so must be homozygous recessive (
hh). Individual 3 has the disorder so must have at least one dominant allele, but they must also have one recessive allele from their unaffected parent (individual 2), so must be heterozygous (
Hh)