Heredity is the passing on of traits from the parents to its offspring. Genes control all the traits that an organism receives. Genotype are the genes of an individual for a particular trait or traits, often designated by using letters to as identifiers such as using BB or Aa as an example. The different forms a gene may have for a trait are called alleles. There are two alleles for every trait. Alleles represent a genotype, or the genetic makeup of an organism for a trait. A phenotype is a physical trait that shows as a result of an organism's particular genotype. Organisms may look alike but have different genotypes. It is impossible to determine homozygous dominant and heterozygous genotypes visually.
As the example showed in our lab, Mendel's pea plants had two alleles for flower color—an allele for purple and an allele for white. Mendel crossed a purple-flowered pea plant with a white-flowered pea plant. All the offspring of this cross had purple flowers. Mendel determined that the purple flower allele was dominant because it covered up the white flower allele, which he called recessive. Phenotypes are the visible expression of a genotype such as a person having brown eyes or a dragon breathing fire. These are considered to be the dominant allele which is when the allele that exerts its phonotypic effect in the zygote masks the expression of the recessive allele. The recessive allele is still part of the genetic makeup of the zygote, but is masked by the more dominant allele.
Reginald Punnett an English Biologist developed a method for predicting which alleles can combine. It is called a Punnett square. In a Punnett square, dominant and recessive alleles are represented by letters. An uppercase letter represents a dominant allele, and a lowercase letter represents a recessive allele. Each cell in an organism's body contains two alleles for every trait. One allele is inherited from the mother and one allele is inherited from the father. An organism is homozygous if it has identical alleles for a particular trait. An organism is heterozygous if it has no identical alleles for a particular trait. There are three possible combinations of alleles of an organism for a particular trait: homozygous dominant (PP), heterozygous (Pp), and homozygous recessive (pp).
As the example showed in our lab, Mendel's pea plants had two alleles for flower color—an allele for purple and an allele for white. Mendel crossed a purple-flowered pea plant with a white-flowered pea plant. All the offspring of this cross had purple flowers. Mendel determined that the purple flower allele was dominant because it covered up the white flower allele, which he called recessive. Phenotypes are the visible expression of a genotype such as a person having brown eyes or a dragon breathing fire. These are considered to be the dominant allele which is when the allele that exerts its phonotypic effect in the zygote masks the expression of the recessive allele. The recessive allele is still part of the genetic makeup of the zygote, but is masked by the more dominant allele.
Reginald Punnett an English Biologist developed a method for predicting which alleles can combine. It is called a Punnett square. In a Punnett square, dominant and recessive alleles are represented by letters. An uppercase letter represents a dominant allele, and a lowercase letter represents a recessive allele. Each cell in an organism's body contains two alleles for every trait. One allele is inherited from the mother and one allele is inherited from the father. An organism is homozygous if it has identical alleles for a particular trait. An organism is heterozygous if it has no identical alleles for a particular trait. There are three possible combinations of alleles of an organism for a particular trait: homozygous dominant (PP), heterozygous (Pp), and homozygous recessive (pp).
This was a very interesting lab to me after just having a baby. It is quite fun to just see the different features he has inhereted from his father and I.
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