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Complex Inheritance of Human Traits

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Presentation on theme: "Complex Inheritance of Human Traits"— Presentation transcript:

1 Complex Inheritance of Human Traits

2 Codominance in Humans Phenotypes of both homozygotes are produced in the heterozygote Recall the checkered rooster Sickle-cell anemia

3 Sickle-cell Anemia Disorder where red blood cells are sickle shaped
Normally concave Shorter life span and can slow bloodflow or block small vessels 1 in 12 African Americans is heterozygous for the disorder


5 Malaria Sickle Cell

6 Multiple Alleles in Humans
Blood types Can be A, B, AB, or O

7 Type A The IA allele is dominant to i
IAi or IAIA will give you type A blood Surface protein A is produced

8 Type B The IB allele is also dominant to i
IBIB or IBi will =type B blood Surface protein B is produced.

9 Type AB The IA and IB alleles are codominant to each other
IAIB you will have type AB blood Will produce both surface proteins

10 Type O The i allele is recessive Produces no surface molecule
Homozygous ii you have blood type O


12 Sex-Linked Traits in Humans
Traits that are determined by genes that are carried on the sex chromosomes Most of these genes are located on the X chromosome


14 Red-green Color Blindness
People who have red-green color blindness can't differentiate these two colors


16 Hemophilia: An X-linked disorder
Blood fails to clot normally because of a deficiency or abnormality of one of the clotting factors 1 male in every has hemophilia but only about one in 100 million females Why?

17 Polygenic Inheritance in Humans
These kinds of traits usually represent a range of variation that is measurable Color variations in human eyes Skin color


19 Changes in Chromosome Numbers
Unusual numbers of autosomes Down syndrome: Trisomy 21 Unusual numbers of sex chromosomes Turner’s Syndrome and Klinefelter's Syndrome

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