Mendelian Genetics

Overview A Punnett square displays the possible genotypes offspring can inherit from two parental genotypes. If a trait’s inheritance pattern …

Overview In the 1850s and 1860s, Gregor Mendel investigated inheritance by performing monohybrid crosses in pea plants. He crossed two plants that were …

Overview To determine whether traits are inherited together or separately, Gregor Mendel crossed pea plants that differed in two traits. These parental …

Trihybrid Crosses Some of Mendel’s crosses examined three pairs of contrasting characteristics. Such a cross is called a trihybrid cross. A …

While Mendel’s Law of Segregation states that the two alleles for one gene are separated into different gametes, a different question of how …

The chi-square test is a statistical hypothesis test. It is used to check whether there is a significant difference between an expected value and an …

Overview A pedigree is a diagram displaying a family’s history of a trait. Analyzing pedigrees can reveal (1) whether a trait is dominant or …

The Concept of Multiple Allelism Multiple allelism describes genes that exist in three or more allelic forms. Although diploid organisms, like humans, …

Gregor Mendel's work (1822 – 1884) was primarily focused on pea plants. Through his initial experiments, he determined that every gene in a diploid …

Agouti: A Lethal Allele Lucien Cuénot discovered lethal alleles in 1905 while studying the inheritance of coat color in mice. The agouti gene is …

When more than one gene is responsible for a given phenotype, the trait is considered polygenic. Human height is a polygenic trait. Studies have uncovered …

Although the genetic makeup of an organism plays a major role in determining the phenotype, there are also several environmental factors, such as …

Among mammals, the gender of an organism is determined by the sex chromosomes. Humans have two sex chromosomes, X and Y. Every human diploid cell has 22 …

The Y chromosome is a sex chromosome found in several vertebrates and mammals, including humans. In addition to 22 pairs of autosomes, the human …

In most organisms, sex is determined by the ratio of X and Y chromosomes. However, in some organisms, such as Drosophila and C.elegans, sex is determined …

In most mammalian species, females have two X sex chromosomes and males have an X and Y. As a result, mutations on the X chromosome in females may be …

Like autosomes, sex chromosomes contain a variety of genes necessary for normal body function. When a mutation in one of these genes results in biological …

In animals, gender is determined by the number and type of sex chromosome. For example, human females have two X chromosomes, and males have one X and one …

The human X chromosome contains over ten times the number of genes as in the Y chromosome. Since males have only one X chromosome, and females have two, …

Human blood is classified into different types based on the presence of antigens on the red blood cell's surface and antibodies in the plasma. Proper …

Blood transfusion is a therapeutic measure to restore the blood volume after extensive blood loss due to an accident or a medical procedure. Blood …