.
i have green eyes and freckles but not red hair
i've heard that they are caused by a thing called pheomelanin
Answer
Melanin exists in two forms in human skin and hair: eumelanin, which is a brown-black color and phomelanin, which is a yellow-red color. The relative ratio controls hair/skin color. People who donât have red hair convert most of their phomelanin to eumelanin. No phomelanin left means no red coloration left in the hair.
Since every person inherit two copies of a gene you may have a dominant version and a recessive. A possible indicator of the red recessive gene's presence can be freckles. However people can have freckles who do not carry the recessive for red hair due to other genetic skin influences.
Green eye color is due to EYCL2 or eye color 2 gene. The dominant form encodes green eyes and the recessive encodes blue. This gene is recessive to EYCL1 that produces brown or blue. Both genes together regulate the amount of melanin present in the iris. More melanin means darker eye color. Your EYCL1 must be for blue (meaning less melanin) for you to have green eyes.
Interactive site to play with eye color genetics
http://www.athro.com/evo/gen/genefr2.html
Eye color genetics
http://www.thetech.org/genetics/ask.php?id=203
http://www.hhmi.org/cgi-bin/askascientist/highlight.pl?kw=&file=answers%2Fgenetics%2Fans_044.html
The critical gene involved in the conversion of melanin in skin and hair is MC1R. This gene encodes for a protein that ensures the phomelanin is converted.
Red haired people have less of the MC1R protein because they inherit copies that are not translated into protein very frequently if at all. There are actually has 7-9 known levels of MC1R production to account for different amounts of redness being left in hair.
It may seem odd that a gene is translated to protein at different rates in different people but this is the kind of variation that is meant when you hear things about genetic variability in a species. It isn't just an 'on' or 'off' switch. There can be a broad range of expression in some genes where one person expresses more than another as an inherited trait. The gene itself encodes for the same protein but the rate the protein is made is varied between people.
Melanin exists in two forms in human skin and hair: eumelanin, which is a brown-black color and phomelanin, which is a yellow-red color. The relative ratio controls hair/skin color. People who donât have red hair convert most of their phomelanin to eumelanin. No phomelanin left means no red coloration left in the hair.
Since every person inherit two copies of a gene you may have a dominant version and a recessive. A possible indicator of the red recessive gene's presence can be freckles. However people can have freckles who do not carry the recessive for red hair due to other genetic skin influences.
Green eye color is due to EYCL2 or eye color 2 gene. The dominant form encodes green eyes and the recessive encodes blue. This gene is recessive to EYCL1 that produces brown or blue. Both genes together regulate the amount of melanin present in the iris. More melanin means darker eye color. Your EYCL1 must be for blue (meaning less melanin) for you to have green eyes.
Interactive site to play with eye color genetics
http://www.athro.com/evo/gen/genefr2.html
Eye color genetics
http://www.thetech.org/genetics/ask.php?id=203
http://www.hhmi.org/cgi-bin/askascientist/highlight.pl?kw=&file=answers%2Fgenetics%2Fans_044.html
The critical gene involved in the conversion of melanin in skin and hair is MC1R. This gene encodes for a protein that ensures the phomelanin is converted.
Red haired people have less of the MC1R protein because they inherit copies that are not translated into protein very frequently if at all. There are actually has 7-9 known levels of MC1R production to account for different amounts of redness being left in hair.
It may seem odd that a gene is translated to protein at different rates in different people but this is the kind of variation that is meant when you hear things about genetic variability in a species. It isn't just an 'on' or 'off' switch. There can be a broad range of expression in some genes where one person expresses more than another as an inherited trait. The gene itself encodes for the same protein but the rate the protein is made is varied between people.
Red Hair genetics Question?
gwynn
So I have medium/dark brown hair. I have 2 sisters who are red hair, fair skinned. We have the same parents, my mom was blonde and my dad strawberry blonde. How did I get such dark hair?
Answer
The genetics behind red hair inheritance is a little different than the inheritance of other traits. With red hair a person can inherit the trait even if both parents do not exhibit the trait which is not entirely true in your case because your dad has strawberry blonde hair which is a variation of red headedness. Inheriting red hair is controlled by the melanocortin-1 receptor (MC1R) gene. Which essentially regulates the amounts of melanin in the body. This is why consequentially people with red hair tend to also have fair skin, freckles and a variety of other pigment related traits characteristic of people of irish, scandinavian or higher latitude populations and their decedents. In people with this gene they tend to have more of the pigment pheomelanin than do people with other hair colors who tend to have more eumelanin instead. Both of your parents are likely to be carriers of the MC1R gene but do not have read hair because the necessary mutations that need to occur on the chromosome haven't occurred. Since your mom is blonde it is most likely that you inherited your dark hair from your dad. A number of genes determine hair color and chances are you are a carrier of the gene for red hair as well.
The genetics behind red hair inheritance is a little different than the inheritance of other traits. With red hair a person can inherit the trait even if both parents do not exhibit the trait which is not entirely true in your case because your dad has strawberry blonde hair which is a variation of red headedness. Inheriting red hair is controlled by the melanocortin-1 receptor (MC1R) gene. Which essentially regulates the amounts of melanin in the body. This is why consequentially people with red hair tend to also have fair skin, freckles and a variety of other pigment related traits characteristic of people of irish, scandinavian or higher latitude populations and their decedents. In people with this gene they tend to have more of the pigment pheomelanin than do people with other hair colors who tend to have more eumelanin instead. Both of your parents are likely to be carriers of the MC1R gene but do not have read hair because the necessary mutations that need to occur on the chromosome haven't occurred. Since your mom is blonde it is most likely that you inherited your dark hair from your dad. A number of genes determine hair color and chances are you are a carrier of the gene for red hair as well.
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