exceptions to mendel s rules n.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
Exceptions to Mendel’s Rules PowerPoint Presentation
Download Presentation
Exceptions to Mendel’s Rules

Loading in 2 Seconds...

  share
play fullscreen
1 / 8
abiola

Exceptions to Mendel’s Rules - PowerPoint PPT Presentation

171 Views
Download Presentation
Exceptions to Mendel’s Rules
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. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

  1. Exceptions to Mendel’s Rules Genetics

  2. Some Examples • Multiple Alleles: more than 2 in a population • Co-dominance: both alleles fully expressed • Incomplete Dominance: both exert some influence • Others: epistasis, pleitropy, polygenic inheritance, multifactorial

  3. Pleitropy • Single gene pair exerts multiple effects • Symptoms seem unrelated and are therefore hard to connect and diagnosis Some historians believe Lincoln had Marfan Syndrome, an autosomal dominant disorder of the connective tissue

  4. Epistasis • One gene pair influences the expression of another gene pair • In Labrador retrievers, two gene pairs determine coat color • One gene pair determines amount of melanin, the other determines distribution

  5. Polygenic Inheritance • Many genes; one effect • usually produce a range of phenotypes • Example: skin color • Controlled by 5 gene pairs • AABBCCDDEE = very dark • Aabbccddee = very light • Gene pairs influence the metabolic pathway

  6. Polygenic Inheritance • Probability is that more phenotypes will be in the middle • 50% chance of A or a if parent is heterozygous • Most are “average” • Bell shaped curve • May also be influenced by environment

  7. Bell Shaped Curve Height, skin color, intelligence, hair color, eye color are examples of CONTINUOUS VARIATION

  8. Also playing a role in continuous variation is environment • Himalayan rabbit fur color is influenced by temperature • An enzyme required to make melanin only works at low temperatures • How does environment influence human skin color?