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Human Traits

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  • Gene: a region of DNA where a specific set of instructions for one trait is kept. We get some of our genes from our mother and some from our father... more
  • Inheritance: genetic information passed down from a parent.
  • Phenotype: the appearance of an individual resulting from the interaction between their genetic makeup and the environment. Phenotypic trait... more
  • Trait: characteristics of an organism that can be the result of genes and/or influenced by the environment. Traits can be physical like hair color or the shape and size of a plant leaf. Traits can also be behaviors such as birds building nests.

Below is a list of phenotypes easily identified in humans that follow the pattern of Mendelian inheritance. Look at yourself in the mirror to see if you carry the dominant or recessive alleles for these traits.

Mendelian Traits In Humans 

Cleft chin (dominant)     Chin without a cleft (recessive)

cleft chin

 

chin without cleft

Cheek dimples (dominant)

 No cheek dimples (recessive)

Cheek dimples

 

no cheek dimples

Free (dominant) earlobes Attached (recessive) earlobes

unattached earlobe

 

attached earlobe

Face freckles (dominant) No face freckles (recessive)

face freckles

 

no face freckles

No Hitchhiker's thumb (dominant)
 Hitchhiker's thumb (recessive)

hitckhiker's thumb

 

normal thumb

Widow's peak (dominant) No Widow's peak (recessive)

widow's peak hairline

 

flat hairline

The expression of traits, however, is often far more complicated than in those listed above or those which Mendel observed in his garden. Sometimes tens, or even hundreds of genes can play a role in just one trait! In some cases, genes can block or exaggerate processes in the cell which change the visible phenotype. In other cases, environment factors such temperature, light and nutrient levels influence the development of a phenotype. Below is a list of traits in humans involving interaction between multiple genes.

Non Mendelian Traits in Humans

Eye color      

black eyes

 

brown/black eyes

blue eyes

 

 

green eyes

 

Hair Color
 

 

red hair

 

black hair

brown hair

 

blonde hair

Ability to roll tongue
 

 

rolled tongue

 

not rolled tongue

 


Reference

List of Mendelian traits in humans. In Wikipedia. Retrieved July 20, 2010, from http://en.wikipedia.org/wiki/List_of_Mendelian_traits_in_humans

 

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