Mendel

Mendelian square

This subject was my favorite. We covered Mendel’s first law of genetics, as well as going over how to do Mendel’s square. Mendel’s first law states: Allele pairs separate during gamete formation, and randomly unite at fertilization. An example of this are out genes. A mother can have fraternal twins who are girls and even though they have the same dad and were born on the same day, they would looks completely different. This is because When the egg is fertilized instead of one single sperm entering the egg, two sperms make their way in. The offspring gets 50% if their genetic makeup from their mother and 50% from their father.  Even though they have the same parents they will look completely different because of the new combinations that will be forming throughout the 9 months. To predict what the children may look like, people use Mendelian square.

Ex:

A mother is having a baby and she has cheek freckles. The father of her baby also has cheek freckles. Cheek freckles are dominate, CC or Cc.

     C                      c

C  CC	Cc
C  CC	Cc

Looking at this example, no matter what the child will have check freckles since it is dominant in both the mother and the father.  

Mendelians square is not can not account for all of our traits. For example, it does not account for incomplete dominance, co-dominance, multiple alleles, polygenic/multiple gene inheritance, linkage, nondisjunction and sex influenced traits.

One example of an inheritance that can not be explained my Mendel’s model is blending inheritance. Blending inheritance is when when traits were determined, randomly, from a range of bounded by the homologous traits found in the parents. An example would be the kids hight. The mom might be really short and the dad is tall so there are different possibilities of the height of the offspring.

I also learned about Chi square distribution. The equation is ∑ (O-E)/E

You use this to calculate if a trait in a population is by chance or not by chance.