test for Monday -- ADDENDUM -- PLEASE MAKE NOTE OF THIS FOR TEST ON MONDAY!!!!!!

Hi there,

   I forgot to discuss these two terms (pleiotropy and polygenic inheritance) with you in class due to my extreme stress in coming back from Guatemala.  You are responsible for understanding this material!  I don't think these are very confusing, but please come to AFT for help tomorrow if you need it.  I'm sorry that I omitted this, I am overwhelmed by stress lately and it is causing me to make mistakes. Ms. Leary

Please notice that pleiotropy and polygenic inheritance are essentially the converse to each other.

pleiotropy = one gene influences multiple characteristics

Ex: sickle-cell anemia allele (SCA) is a recessive blood disease. People with SCA (homozygous recessive) experience many different affects from weakness to heart failure to brain damage to kidney failure.  Not everyone who has SCA will express all of these affects in their phenotype. There is no set way that SCA manifests in a person.

please see fig 9.14

polygenic inheritance = one characteristic affected by many genes

Ex: skin color…as far as we understand it now, looks like ≥ 3 genes control  skin color (A, B, and C). Someone who is AABBCC is very dark-skinned and someone who is aabbcc is very light skinned and then there is a huge gamut in between .

please see figure fig 9.15

ALSO NOTE: there are NO questions on mitosis or cancer on this test!!!!