Online Lab 2 Unit 1

Genetic Inheritance

Every generation receives a set of genes from each parent. These genes have been passed down from each generation and slowly evolve and change each time two different organisms get together to produce offspring. This is referred to as genetic inheritance and is very important because it what makes you who you are and is why you are so much like you parents. Every human has evolved to have; two hands, two feet, eyes, toes, and fingers the basic characteristics, but depending on what was genetically inherited is what determines if you have long or short fingers and toes, blue or brown eye, or straight versus curly hair. These are a few of the many characteristics that are passed on to each offspring. Some traits that are passed on are not always good like tay-sachs disease, downs syndrome, baldness, and color blindness. While some traits are better than others they all make up who you are and become.

The following general terms help to understand genetic inheritance. A genotype is the actual genetic makeup of a person that is coded into the DNA of an organism, it’s a specific trait or an entire set of traits. A phenotype though is the appearance of an organism caused by the genotype and the environment. Alternative forms of a gene having the same position on a pair of chromosomes that control the same trait are called alleles. Alleles always come in pairs, dominant alleles are demonstrated by upper case letters and recessive alleles are represented by lower case letters. When two organisms breed to produce offspring a cross is the result. Dominant and recessive alleles that are inherited determine the phenotype. It takes two recessive traits to take presidency over a dominant trait. Whether is a dominant trait or recessive trait is passed depends if the parents are homozygous dominant, homozygous recessive or heterozygous. A homozygous parent will have two of the same type of alleles. Homozygous dominant means both alleles are the dominant trait represented by capital letters like EE. Homozygous recessive is when both alleles are a recessive trait represented by lower case letters like ee. While a heterozygous parent will have both a dominant and a recessive trait represented by an upper and lower case letter, Ee.

This picture is of two dragons that have different alleles inheritad by their parents. My dragon is the red dragon who inherited the recessive allele for horns (hh) so he did not inherit horns. The red dragon inherited the alleles LL so he developed legs unlike the blue dragon. By changing the alleles that were passed on when the parents genotypes crossed the dragons will look the same, having the same phenotype which is shown below.

The dominant and recessive alleles were changed to make those of the first dragon. By doing this they both have the same genotype and phenotype and look the same.

This punnett square demonstrates how homozygous parents alleles cross. The object was to make a cross between a homozygous dominant long-winged fly and a homozygous recessive vestigial-winged fly to determine what offspring they will produce. The homozygous dominant fly has alleles LL and is placed along the top of the punnett square. The homozygous recessive fly has alleles ll and are along the side of the punnett square. To determine the offspring the alleles are crossed which is shown inside the punnett square. The offspring produced are 4 heterozygous long-winged flyies.

In conclusion I hope these three diagrams showed how genotypes, can be manipulated to make organisms look the same and how alleles come in pairs and determine what an organisms develops and how they look based on what is genetically inherited by their parents. Both parents have homozygous dominant or recessive or heterozygous genotypes that are pass down there off spring. Like demonstrated in the punnett square all four offspring were long-winged flies. This does not mean that all offspring will look alike. That punnett square was only demonstrating what type of wings were going to be inherited. This process of crossing alleles takes place for every genotype. Which is what makes every individual unique.

Work Cited
http://biologica.concord.org/webtest1/web_labs_genophenotype.htm (dragon lab)
http://www.mhhe.com/biosci/genbio/virtual_labs/BL_05/BL_05.html (punnette square)