1 / 12

12.2 Complex patterns of inheritance

12.2 Complex patterns of inheritance. Complex patterns of inheritance. Mendel’s experiments show simple inheritance with recessive and dominant alleles Some patterns of inheritance are more complex. Complex patterns of inheritance. Incomplete dominance Codominance Multiple alleles

keelie-nichols
Download Presentation

12.2 Complex patterns of 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. 12.2 Complex patterns of inheritance

  2. Complex patterns of inheritance • Mendel’s experiments show simple inheritance with recessive and dominant alleles • Some patterns of inheritance are more complex

  3. Complex patterns of inheritance • Incomplete dominance • Codominance • Multiple alleles • Sex-linked inheritance • Polygenic inheritance • Environmental factors

  4. Incomplete dominance • Phenotype of the heterozygote is in between the phenotypes of the homozygotes • RR=red pigment R1R1=white, no pigment RR1=pink

  5. Codominance • Phenotypes of both homozygotes are produced in heterozygote, both alleles are expressed equally • BB=black feather WW= white feather BW= checkered

  6. Multiple alleles • Traits controlled by more than two alleles • Each pigeon has two alleles for feather color, but there are many possible alleles

  7. Sex-linked inheritance • In humans have 46 chromosomes, 23 pairs • 22 pairs autosomes • one pair sex chromosomes, determine sex

  8. Sex-linked inheritance • Sex-linked traits are controlled by genes located on the sex chromosomes • Alleles are carried on the X chromosome, not the Y chromosome

  9. Polygenic inheritance • A trait that is controlled by more than one gene • Genes may be on different chromosomes • Each gene may have more than one allele • Trait usually expressed in a continuous range of variability

  10. Environmental factors • External • Gene may not be expressed due to temperature, nutrition, light, chemicals, infection • For example, this bacteria is different color when grown at different temperature

  11. Environmental factors • Internal • Males and females differ due to hormones • Age may change trait expression

  12. Complex patterns of inheritance • Mendel’s idea that heredity is a composite of many traits still holds • Later researchers have filled in details

More Related