Yellow Pods Lab

GENETIC CROSSES An “X” is used to indicate that two individuals have been mated together. The parents are designated as P (for parental) and the offspring as F (for filial). When several generations are involved, subscripts are added to designate the generations. P1 give rise to F1 (first filial) progeny. If the F1 are crossed together they become P2 and their progeny F2. A cross between members of the F1 and members of the P1 is a backcross. A cross between members of the F1 and the true breeding recessive P1 is a test cross. MONOHYBRID CROSS The simplest form of a cross is a monohybrid cross, which analyses a single trait and its associated variations. The diagram below shows the

The “Brassica rapa” is a fast plant known as the field mustard. This plant is well known for its rapid growing rate, which makes it an easy breeding cycle and easy to pollinate. In giving so this makes “Brassica rapa” a great participant for testing Gregor Mendel’s theories of inheritance. The “Brassica rapa” acts like a test subject in testing cross-pollination giving the understanding to the dominant allele of colored stems. There are different colors that are visible on the stem that are above the soil; the colors vary from green to purple. P1 seed was ordered, germinated and cross-pollinated until germination of the next off spring of plants were also done. It was

This Punnet Square represents the F1 offspring breeding with each other to create more offspring. This second set of offspring is the F2 generation. If both parents are heterozygous dominant, then the offspring expected would be: 50% heterozygous dominant, 25% homozygous dominant and 25% homozygous recessive.

Gregor Mendel theorized that certain combinations of alleles in a genotype would result in a specific ratio of phenotypes expressed in each generation. For example, in the case of the dominant heterozygous anthocyanin genotype, the P1 with (ANL/anl) crossed with the P2 (ANL/anl) would result in a 1:2:1 ratio for genotypes (ANL/ANL), (ANL/anl) and (anl/anl). However,

Apply your understanding of how alleles assort and combine during reproduction to evaluate a scenario involving a monohybrid cross.

This lab had 2 exercises. Exercise 9.1 involved observing pictures of 60 F2 offspring and recording the phenotypes for 6 different traits. Exercise 9.2 required us to perform the “chi-square test” to determine whether the data we collected matches the standard Mendelian ratio.

You are also provided with a heterozygous female, and a homozygous recessive male for a genetic cross. In this particular female, all the dominant alleles are on one chromosome, and the recessive counterparts are on the other homologous chromosome. Due to a chromosomal condition, in the female no recombination occurs between the M and N loci. Normal recombination occurs between the L and M loci. Diagram this cross, and show the genotypes and frequencies of all offspring expected from this cross.

After analyzing the data present in the graph and tables for the monohybrid cross, we concluded that the phenotypic ratio is not a 3:1 but 1:1 ratio because it violates the mendelian law of equal segregation since we were focusing on the trait being sex linked. This is supported by research carried out by a scientist named Morgan T. H. in 1910 studied sex-limited inheritance in Drosophila for eye color. He verified his hypothesis by crossing red males (RWX) to white females (WWXX) and the results showed that all females were red-eyed and all males were white eyed. (Morgan, 1910) Compared to our results, although it wasn't exactly a 50:50 ratio it is significantly close enough to support the hypothesis that eye color is sex linked since males had more white eyes than females. The Dihybrid cross also supported the hypothesis of 9:3:3:1 ratio because compared to other research on dihybrid crosses with wild type and sepia eyes, ebony body the phenotypic ratio was the same because it followed the law of independent assortment that says that the inheritance of fone allele does not affect the other. Although that research, also looks at linkage, which we did account for in this specific lab experiment. (Marshall, 2008) So, it makes that our phenotypic ratio was valid in showing independent assortment of alleles in drosophila. Overall,

Gregor Mendel is known as the father of modern genetics because of the research and experiments he did by breeding pea plants and examining their physical appearances. He studied the plants seed color and shape, pod color and shape, and flower color and position. Mendel collected the seeds from pods produced after fertilizing two parent pea plants and then grew those seeds into new plants and observed how the offspring resembled or differed from the parents. After all of his experimentation, Mendel was able to conclude 3 principles. The principle of segregation, which meant that each organism has two alleles for each gene, one from each parent that separate

Three genotypes that can be associated with simple Mendelian traits are AA (homozygous dominant- dominant); Aa (heterozygous- dominant); aa (homozygous recessive- recessive).

Patterns of Dominance: Dominance isn’t black and white, or rather, recessive and dominant. In the real world, it’s a bit more complicated than that. There are a few different types of dominance. For starters, there’s incomplete dominance. Incomplete dominance is when neither allele is totally dominant, resulting in a mixture of the two alleles. (An allele is different alterations of the same gene.) And example of this would be flowers. Say you have a red rose and a white rose, the offspring of that rose can be more than just red or white, they can be a mixture of the two colors

Mendel's` Law of Segregation states that factors (alleles) segregated during gamete formation and recombined during fertilization. This means that the parent’s genes must segregate into haploid gametes so that their children have an equal chance of inheriting each gene from the parent, which results in a specific ratio of the likelihood of outcomes. During meiosis the alleles must have an equal chance to be passed on to the children as well. Mendel’s laws explain the behavior of the way genes are passed through children. In a punnett square the genotypes are split into separate alleles to reflect the law of segregation

Pairs of alternative traits were expressed in the F2 generation on the ratio of ¾ dominant to ¼ recessive (3:1 segregation ratio referred to as Mendelian ratio)

in the union of the sex cells. An addition was added to Mendel’s two inheritance laws. These

In this lab we considered Gregor Mendel theory of genetics. Mendel was a botanist and statistician. Mendel worked with garden peas to figure out their genetic pattern. The peas were also true-breed.1 The three principles that Mendel had for inheritance pattern are the principle of segregation, principle of dominance, and principle of independent assortment.2 The first principle of segregation means that the individual gets part of the trait from each parent that makes their traits.2 The second principle of dominance is that a trait may be present during the first generation, but doesn’t not mean it could be present in future generations and that the dominant allele is showed. The third principle of independent assortment is that it depends on the different units that are passed on that can decide your traits based on other traits that are given.2 This now goes into showing that variation of a gene is called an allele. This is now shown in a phenotype and genotype. A phenotype is showing he physical trait that we can see. A genotype is the showing of the genetic form that made that trait.3 Another term we used in this lab was homozygous which means you have two of the same alleles. The next term that was used is heterozygous which means that two different alleles were used. The term that was important that we used was a Punnett square. A Punnett square is way to be able to calculate the different potential outcomes of the genotypes graphically.3