Genetics 1134 pt.1
Introduction to genetics:
The study of gene and it’s function. Basically there are 3 main branches which is Transmission genetics, Molecular level genetics and Population genetics.
Firstly, we would learn the basics of genetics in a reverse direction (back to front). We first study about the Mendelian theories which associates most with variation. Gregory Mendel is a very observant monk which conducted his experiment on the garden pea plant, Pisum Sativum. The father of genetics choose the garden pea as it’s easy to grow and will bear results in just a few months and can be artificially fertilized. He observed the variation of the distinct characteristics in the plant and deduce that a specific characteristics is controlled by a pair of genes. These pair of genes is controlled by a different type of alleles. The alleles have a dominant and recessive trait. The dominant allele obviously is dominant over the recessive trait. For example, an allele for tall is T and dwarf is t. T is dominant over t so the dwarf characteristics can only be shown in a homozygous state (the letter is same, ie. tt). Tall characteristics remain in heterozygous state as the allele T is dominant over the allele t.
Monohybrid cross is a hybridization between two parents where it only consist of one characteristics. For example:
Parents: TT x tt
F1 Generation: All Tt
This where Mendelian theory comes in. During mating, each allele will segregate independently and fuse with another allele. But there is a few exceptions which we would discuss later.
Usually for the convenience of calculating the possible genotype from the cross, we would use Punnett Square diagram. This is essentially useful in calculating the possible genotype in dihybrid cross.
That’s what I remembered so far without even looking at any references so there’s bound to be a lot of mistake in there…..for the explanation on the scientific terms here please kindly refer to wikipedia in the section Introduction to Genetics. D.F.J signing out for today…..