Inheritance

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Hey, to me inheritance is one of the hardest topics in the syllabus, from the B2 section. I havent even studied it in class yet, but as the exams are close I thought it would be a good idea to start learning it. So anyone can post any facts here that they know about the inheritance topic and we will see how far we get :D

Posted: 23-12-09 13:31 by I P B

Alleles are different forms of a gene, they can either be dominant or recessive.

  • the characteristic controlled by a dominant allele develops if the allele is present on one or both chromosomes in a pair
  • the characteristic controlled by a recessive allele develops only if the allele is present on both chromosomes in a pair

For example, the allele for brown eyes is dominant, while the allele for blue eyes is recessive. An individual who inherits one or two alleles for brown eyes will have brown eyes. An individual will only have blue eyes if they inherit two copies of the allele for blue eyes.

Huntington’s disease is a disorder of the nervous system that is caused by a dominant allele. Cystic fibrosis is a disorder of the cell membranes caused by a recessive allele

Posted: 23-12-09 21:32 by RATM33

Thats all you really need to know I think, well, that and the genetic diagrams, which you really need to practice, because I went wrong here in my B2

Posted: 23-12-09 21:34 by RATM33

Wow, thats a lot of detail, thankyou very much! You really are a life saver :D The genetic diagrams, how would we practice those? Oh, and merry christmas for the 25th, since im guessing you wont be back online till then! :D

Posted: 23-12-09 22:03 by I P B

lol, thanks, you too :)

im not sure exactly lol :S, try some examples from past papers and stuff

try question 3 in this past paper (you might have done it before) - http://store.aqa.org.uk/qual/gcse/qp-ms/AQA-BLY2H-W-QP-JAN08.PDF

Posted: 24-12-09 14:49 by RATM33

Wow, thats great :D I havent done it before but will definitely have a go at it. Thankyou very much! And have a great holiday :D

Posted: 26-12-09 16:40 by I P B