Genetics Archive
Mitosis is a type of cell division in which one cell (the mother) divides to produce two new cells (the daughters) that are genetically identical. The mitosis is a part of somatic cell division which includes the division of the …
The X and Y chromosomes are divided into two regions homologous and differential regions. In humans the homologous regions contain DNA sequences that are substantially similar on both sex chromosomes. The differential regions contain genes that have no counterparts …
Genes act by controlling cellular chemistry. Early in the twentieth century, Archibald Garrod, an English physician, made the first observation supporting this insight. Garrod noted that several recessive human diseases show defects in what is called metabolism, the general set of chemical …
Human matings, like those of experimental organisms, provide many examples of single-gene inheritance. However, controlled experimental crosses cannot be made with humans, and so geneticists must resort to scrutinizing medical records in the hope that informative matings have been made (such …
The first problem in understanding DNA replication was to figure out whether the mechanism of replication was semiconservative, conservative, or dispersive. In 1958, two young scientists, Matthew Meselson and Franklin Stahl, set out to discover which of these possibilities correctly …
The copying mechanism to which Watson and Crick referred is called semiconservative. The sugar-phosphate backbones are represented by thick ribbons, and the sequence of base pairs is random. Let’s imagine that the double helix is like a zipper that unzips, …
Before we see how Watson and Crick solved the structure of DNA, let’s review what was known about genes and DNA at the time that they began their historic collaboration: 1. Genes— the hereditary “factors” described by Mendel—were known to …
The seven characters in pea plants that Mendel chose to study extensively all exhibited dominance, but Mendel did realize that not all characters have traits that exhibit dominance. He conducted some crosses concerning the length of time that pea plants …
There is a wide variety of sex determining mechanisms, but three patterns are more common. XO-XX Type This pattern of sex determination is found is grass hopper and Protenor bug. Male is XO, because it has only one X chromosome. …
Most animals and many plants show sexual dimorphism; in other words, individuals are either male or female. In most of these cases, sex is determined by a special pair of sex chromosomes. Discovery T. H. Morgan was an American geneticist. …