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Veridian Etoile
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Genetics... The Basics
Jul 18th, 2011 at 9:46pm
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This thread is to discuss genetics, from the basic genetics to the more advanced... Links to sites that have SCIENTIFICALLY PROVEN information on them, information, new discoveries and understanding how dominant and recessive genes work will be posted here.

This is to help others understand why something like Tourette Syndrome or Hemophilia will show up more in boys than girls, and why some genetic disorders are so rare or are very common. It will also explain why brown eyes are so common and how blue eyes are not for example.


I do ask that only links to sites outside of Sanctuary be posted, NO actual copy/paste of any material from any site please!! We respect copyright laws here and anyone who posts any material that is directly from another site word for word will have their post modified to remove the copy/pasted material and be given a gentle but firm reminder of our rule about respecting the copyright laws. You may post a synopsis of the site in your own words, but doing a copy/paste from any site is not permitted. Thank you.


So, how do genes work? The following site gives a pretty basic description of what genes are made of and how one gets 46 chromosomes.

http://kidshealth.org/teen/your_body/health_basics/genes_genetic_disorders.html

The site is aimed more toward a teen audience but it still explains a lot of things in a very clear, concise manner that is very easy to understand.

Okay, first of all, let's talk about dominant and recessive genes. The following is in my own words and stuff I remembered learning in high school biology. If I get too technical, someone PLEASE speak up so I can tone down the technical stuff!!

To understand how dominant and recessive genes work, we need to remember that we get TWO copies of every single gene on 44 of the 46 chromosomes we have in our bodies (the Y chromosome that boys have doesn't have as many genes on it as the X chromosome has, hence duplicates on 44 instead of 46).

Dominant genes will have their characteristic(s) show up even if only ONE copy of the gene is present. Brown eyes are an example of that, that particular eye color is a DOMINANT eye color. One could have the gene for brown eyes and the gene for blue eyes but said person will have brown eyes, for example. Dominant genes will be in about 75% of the people out there, due to most people having only one copy of it, but some have two copies of it.

Recessive genes will only have their characteristic(s) shown if a person has TWO copies of the gene... Blue eyes are an example, the blue eye gene is recessive. A person with blue eyes will ONLY have the genes for blue eyes because that gene is recessive. Recessive genes show up approximately 25% of the time, because that is the average that a person will get both genes to give them blue eyes.

This is a VERY basic chart (one I made myself) but it shows how brown eyes will show up even if a child gets a blue eyed gene. The brown eyed gene is represented by a capital B, due to it being dominant, and the blue eyed gene will be represented by a little b, due to it being recessive...

                                Father (Bb)

                                        B (brown eyed gene)      b (blue eye gene)

Mother (Bb)    


B (brown eyed gene)          BB child (brown eyes)     Bb (brown eyes)

b (blue eyed gene)              bB child (brown eyes)     bb (blue eyes)

In this particular case, there is a chance that 75% of their children would have brown eyes and a 25% chance that their children could have blue eyes.

I know this is not exactly the case a lot of the time, due to multiple genes working toward a characteristic like height, etc but there are a lot of characteristics in the human genome (genes) that are determined by only one gene.

That's it for today, I will do my best to keep this thread going with new information... Anyone is welcome to contribute and ask questions!! Smiley

  


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