patterns of inheritance i n humans
DESCRIPTION
Patterns of Inheritance i n Humans. Pedigree. Geneticists study the inheritance of certain traits by using a Pedigree A pedigree is a visual representation of a family and shows inheritance patterns over several generations. Can be used to determine genotype Why do we need pedigrees?. - PowerPoint PPT PresentationTRANSCRIPT
![Page 1: Patterns of Inheritance i n Humans](https://reader036.vdocument.in/reader036/viewer/2022062501/5681671f550346895ddba03f/html5/thumbnails/1.jpg)
Patterns of Inheritancein Humans
![Page 2: Patterns of Inheritance i n Humans](https://reader036.vdocument.in/reader036/viewer/2022062501/5681671f550346895ddba03f/html5/thumbnails/2.jpg)
Pedigree• Geneticists study the inheritance of certain traits
by using a Pedigree
• A pedigree is a visual representation of a family and shows inheritance patterns over several generations.
• Can be used to determine genotype
• Why do we need pedigrees?
![Page 3: Patterns of Inheritance i n Humans](https://reader036.vdocument.in/reader036/viewer/2022062501/5681671f550346895ddba03f/html5/thumbnails/3.jpg)
![Page 4: Patterns of Inheritance i n Humans](https://reader036.vdocument.in/reader036/viewer/2022062501/5681671f550346895ddba03f/html5/thumbnails/4.jpg)
Autosomal Inheritance
• Most traits and genetic disorders are coded on autosomal chromosomes.
• Traits and disorders can be autosomal dominant or autosomal recessive.
![Page 5: Patterns of Inheritance i n Humans](https://reader036.vdocument.in/reader036/viewer/2022062501/5681671f550346895ddba03f/html5/thumbnails/5.jpg)
Huntington’s Disease
• Autosomal Dominant• Causes Brain to deteriorate over 15 years
![Page 6: Patterns of Inheritance i n Humans](https://reader036.vdocument.in/reader036/viewer/2022062501/5681671f550346895ddba03f/html5/thumbnails/6.jpg)
Cystic Fibrosis
• Autosomal Recessive• Mucus buildup causes breathing and digestive
problems.
![Page 7: Patterns of Inheritance i n Humans](https://reader036.vdocument.in/reader036/viewer/2022062501/5681671f550346895ddba03f/html5/thumbnails/7.jpg)
Moving Beyond Mendel
• Mendel’s experiments only considered traits to be dominant or recessive
• Sometimes both traits are expressed and sometimes the trait is an intermediate of the parental traits
![Page 8: Patterns of Inheritance i n Humans](https://reader036.vdocument.in/reader036/viewer/2022062501/5681671f550346895ddba03f/html5/thumbnails/8.jpg)
Incomplete Dominance
• A situation when neither allele for a trait can completely mask the other.
• Heterozygote's have a phenotype in-between that of their parents
![Page 9: Patterns of Inheritance i n Humans](https://reader036.vdocument.in/reader036/viewer/2022062501/5681671f550346895ddba03f/html5/thumbnails/9.jpg)
Codominance
• Both alleles are fully expressed
![Page 10: Patterns of Inheritance i n Humans](https://reader036.vdocument.in/reader036/viewer/2022062501/5681671f550346895ddba03f/html5/thumbnails/10.jpg)
Codominance in Humans
• Ex: Sickle Cell Anemia
• Homozygous recessive individuals have all sickle cells while Heterozygotes have sickle cells and normal cells.
• Heterozygotes have resistance to malaria.
![Page 11: Patterns of Inheritance i n Humans](https://reader036.vdocument.in/reader036/viewer/2022062501/5681671f550346895ddba03f/html5/thumbnails/11.jpg)
Heterozygous Advantage
• This is a situation where Heterozygotes have an advantage over homozygous dominant and homozygous recessive.
• Why would having the Sickle Cell trait be an advantage?
![Page 12: Patterns of Inheritance i n Humans](https://reader036.vdocument.in/reader036/viewer/2022062501/5681671f550346895ddba03f/html5/thumbnails/12.jpg)
Multiple Alleles
• Many traits in Humans and other species are a result of interactions between more than 2 alleles on a specific gene.
• That is, there are more than just two possible phenotypes and genotypes.
![Page 13: Patterns of Inheritance i n Humans](https://reader036.vdocument.in/reader036/viewer/2022062501/5681671f550346895ddba03f/html5/thumbnails/13.jpg)
ABO Blood type
• In Humans, Blood Type is determined by the interaction of 3 blood type alleles.
• IA IB and i
![Page 14: Patterns of Inheritance i n Humans](https://reader036.vdocument.in/reader036/viewer/2022062501/5681671f550346895ddba03f/html5/thumbnails/14.jpg)
Polygenic Inheritance
• Some traits show continuous variation and will vary gradually from one extreme to another
• Traits like these are usually controlled by more than one gene and are called Polygenic Traits
• The group of genes that all contribute to the phenotype are called polygenes.
![Page 15: Patterns of Inheritance i n Humans](https://reader036.vdocument.in/reader036/viewer/2022062501/5681671f550346895ddba03f/html5/thumbnails/15.jpg)
Skin Colour
• Only the dominant forms of the gene will contribute to the phenotype.