1 / 5

Polygenetic Inheritance

Polygenetic Inheritance. Skin color. Melanin, its only skin deep…. Differences in skin color are largely due to the amounts of melanin. A dark pigment produced by skin cells. At least 3 genes control synthesis of melanin. Each one has two forms: An allele for high melanin production

bobby
Download Presentation

Polygenetic Inheritance

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Polygenetic Inheritance Skin color

  2. Melanin, its only skin deep… • Differences in skin color are largely due to the amounts of melanin. • A dark pigment produced by skin cells. • At least 3 genes control synthesis of melanin. • Each one has two forms: • An allele for high melanin production • Dark skin (ABC) • And allele for low melanin production • Light skin (abc)

  3. Each dark skin allelle (ABC) in the genotype adds a small but equal amount of pigment. • There are 7 different shades of skin color, ranging from very dark (AABBCC) to very light (aabbcc). • Most individuals produce medium amounts of melanin and are intermediate skin color (AaBbCc)

  4. Punnett Square • How many possible shade of skin color? • 7, AaBbCc x AaBbCc • The offspring of this cross exhibit seven shades of skin color based on the number of dark-skin alleles in each genotype. • How many genes regulate melanin production? • 3 • How many forms of the gene are present? • 2, dark-allele & light-skin allele • Complete the table to determine the number of offspring with each skin color. • How many of these 64 possible offspring have skin darker than their parents? • 3 genes has two alleles. Are the dark-skin alleles dominant to the light-skin alleles? • no • What environmental factors would influence gene expressions?? • Sunlight, nutrition

  5. What would an individual with the aabbcc genotype look like? • A very fair haired, pale skinned individual, like Northern Europeans.

More Related