Genetics Lab

Introduction:
As individuals grow and develop they become more distinct as there genetic traits start to become visual. You can look at any one person and there parents and generally see more of a resemblance to one of the parents as to the other. These similarities for one parent as opposed to the other can easily be explained by the different genetic traits being passed on by the parents. Why is this important to the evolution of humans as a species. Many diseases have been linked to hereditary genes in either one parent or both. Understanding these hereditary links for diseases such as cancer can help scientists to possibly eliminate these genes from the gene pool. We have talked about evolution extensively in this class so far and evolution can also explain how some traits have become dominant in humans and others have not. If a trait is harmful to the human race then evolution says those individuals with these particular traits would die off over time and the individuals with healthy strong genes would continue to survive. My questions is if humans with out the help of scientific intervention could naturally eliminate some harmful genetic traits like cancer threw natural selection over a few hundred or thousand year period.

Terms
Genotype = The genotype is the actual genetic code which a parent passes on when there gamete (sex cell) with that individual parents 23 chromosomes merge with the other parents genetic code forming the zygote.
For Instance in our dragon lab the code for the dragon offspring to be blue was a lower case b. the “b” would represent the genotype code being passed on.
Phenotype = The phenotype is the physical representation of the genotype. In the dragon lab the genotype for blue skin was “b” and the phenotype was the blue color skin of the dragon.
Allele = Allele’s are the alternate form of a genotype. Allele’s come in pairs and are designated by letters, an uppercase letter indicates a dominant trait, and a lower case letter indicates a recessive trait. In the fly lab the allele’s for a black fly are a dominant trait so there allele code was two upper case LL’s. That particular fly could mate with any other fly and the offspring would still have the dominant trait of black color.
Cross = The term cross is used to show the combination of different allele’s being combined with the offspring. A cross between two parents with a homozygous dominant trait for wings in the dragon lab will produce offspring with wings. A cross between two parents with homozygous recessive genes for short tails will have offspring with all short tails. Finally a cross between two heterozygous dragons with genes for scales would produce a 3 to 1 ration in favor of the scales. If the dragons had 4 offspring three of them would have the trait for scales and one of them would have the recessive trait for no scales.
Dominant = A dominant gene is one that is going to be passed on to the offspring. No matter what the other parents genotype is for that particular trait, if one parent has a very dominant gene then the offspring will share that gene. Again the case of the fly lab there were two fly’s with gray bodies and one with a black body. The fly with the black body had an allele of LL indicating it was a dominant trait. By looking at the punnett square you can see all the offspring will have the dominant black colored body.
Recessive = A recessive gene is basically the opposite of the dominant gene. The only way a recessive gene will be passed on is when the paring of two parents both have at least one recessive gene for a particular trait. In our fly lab the we paired two heterozygous long-winged fly with gray bodies and a Ll as the allele. The offspring of this paring would have one individual would have three offspring with black bodies and one with a gray body. The gray bodied fly would have an allele of “ll” and that gene would still be recessive.

This picture shows two identical dragons. Both dragons have the same genetic makeup or genotypes as indicated by the chart on the right showing the letter codes for dominant and recessive allele‘s. On the chart the upper case letters indicate a homozygous dominant genotype, and the lower case letters show a homozygous recessive genotype.

This picture shows how the punnett square can predict what type of genetic crosses will occur when two fly’s with specific alleles have offspring. In this case both fly’s have heterozygous genotypes, so if the allele for a long wings is “L” and allele for short wings is “l” the offspring will be 3 to 1. Three of the zygote’s will have long wings (LL and Ll) and one of the zygote’s will have short wings (ll).

Conclusion:
Why does the child have red hair instead of black, or green eyes instead of brown. These features of a person are determined by the different genotypes being passed on from the parents and weather these traits are dominant or recessive. In my case I have wondered if the genotype for hair loss is dominant in myself or my brother. Both my parents have shown they have the genetic trait of hair loss. Is this specific trait for hair loss a dominant genotype? So far neither my brother or myself are showing signs of hereditary hair loss. For now I can only stand by helpless as genetics does its work, I know I either have the trait for hair loss or I don’t. After learning more about genetics I am somewhat disheartened because if both of my parents have hair loss then it would seem hair loss is a dominant trait, and in the future I can look forward to joining the millions of other Americans using Rogaine.