Organisms pass on their genetic information to the next generation by the transmission of their DNA. The study of the possible outcomes of these genetic recombinations of sexually reproducing organisms is called genetics. The University of Texas has some cool stuff about Gregor Mendel, who came up with a few LAWS of heredity based upon statistical evaluation of the traits of pea plants. Mendel did not know about DNA or chromosomes.
One trait will always be expressed (seen) in the phenotype as long as it is present. (found in the Genotype) ex. Brown Eyes
Each trait will separate or segregate individually. This assures that one allele (trait) will come from each parent. Segregation occurs during meiosis, the formation of the sex cells. (gametes)
Each trait will be inherited independently. They travel in little individual packets unique from other traits.
Mendel's Laws of Dominance, Segregation and Independent Assortment are illustrated by the Monohybrid Cross (Tt x Tt)
An alternative form of a gene. Examples: all the different eye colors in humans.
The genetic makeup of an organism (ex BB or Bb)
The physical traits we can see
REMEMBER: An organism must be pure (HOMOZYGOUS) in order for a recessive trait to be seen in the phenotype. Example: Blue eyes must be (bb)
About the year 1930 the Gene Chromosome Theory was postulated. Fruitfly , Drosophila melanogaster, showed different traits being transmitted on different chromosomes. This was the birth of modern genetics.
The variation within one species alone is tremendous. Take the species Canis familiaris: there are over 400 recognized breeds within this one species, the dog. Think of all the different types of dogs. It is remarkable that a Great Dane and a Pomeranian are in the same species. In the wild this variety within a single species would be an important factor in allowing the species to be able to survive even if there were drastic changes in the environment.
Both traits are expressed as in the Roan cattle, Red with white spots.
Traits are blended as in the 4 o'clock flower. (Red + White = Pink)
AA Ao BB Bo oo AB This will help you to learn why you have a certain blood type.Dennis Oneill's Blood Type Link
Weird Terminology in the Regents Exam where the O allele is represented by i so Type O = ii type Ao = Ai Type Bo = Bi
It will “split” in half and replicate itself. Half the “ladder” is the old DNA strand half is the new.
DNA stores the code for each protein that is synthesized on a ribosome.
Sex Linked Traits Travel on the Sex Chromosomes.
Example is Hemophilia on the "X" chromosome
DNA Used in a Bacterial Transformation to Produce Human Insulin. We can add the human gene to bacteria to “trick” it into producing insulin for us.
This how we find the father in a paternity suit or the murderer from DNA left at a crime scene.
Was designed to map the codes and functions of all the human genes.
Describe how mRNA acts as a messenger and as a tRNA acts as a translator during protein synthesis.