Definition During genetic drift, certain genes are randomly selected in a population, which results in a change in allele frequency. In many cases, mutations in DNA do not affect the fitness of an organism. Simply by chance, genetic changes can increase or decrease in a population. Genetic Drift Explained Although variations of genes (also known … Read more
Genotype Definition The genotype of an organism is the chemical composition of its DNA, which gives rise to the phenotype, or observable traits of an organism. A genotype consists of all the nucleic acids present in a DNA molecule that code for a particular trait. The outward appearance, or phenotype, is the result of interactions … Read more
Anaphase Definition Anaphase is a stage during eukaryotic cell division in which the chromosomes are segregated to opposite poles of the cell. The stage before anaphase, metaphase, the chromosomes are pulled to the metaphase plate, in the middle of the cell. Although the chromosomes were heavily condensed in the start of cell division, they continue … Read more
Definition The trapezius muscle is a large, paired, flat, superficial muscle of the upper back and neck composed of three sets of fibers. Its job is to move the shoulder blades by way of elevation, rotation, and adduction according to the controlling fiber type. It is innervated by the cranial accessory nerve (CN XI) for … Read more
Lipid Bilayer Definition A lipid bilayer is a biological membrane consisting of two layers of lipid molecules. Each lipid molecule, or phospholipid, contains a hydrophilic head and a hydrophobic tail. The tail regions, being repelled by water and slightly attracted to each other, congregate together. This exposes the head regions to the outside, creating a … Read more
Taxonomy Definition Taxonomy is the branch of biology that classifies all living things. It was developed by the Swedish botanist Carolus Linnaeus, who lived during the 18th Century, and his system of classification is still used today. Linnaeus invented binomial nomenclature, the system of giving each type of organism a genus and species name. He … Read more
Phylum Definition Phylum is a taxonomic ranking that comes third in the hierarchy of classification, after domain and kingdom. Organisms in a phylum share a set a characteristics that distinguishes them from organisms in another phylum. The qualities that group animals into a phylum have changed throughout scientific history, as better methods have arisen to … Read more
Missense Mutation Definition A missense mutation is a type of point mutation in which a different amino acid is placed within the produced protein, other than the original. In the process of converting DNA into protein, the language of DNA must be translated into the language of proteins. During this process, a change in the … Read more
The Basics Horny Toads are a genus of lizard adapted to the desert that boasts a number of large horns on the backside of their skull. Horny toads are in the genus Phrynosoma – meaning “toad-bodied” – a reference to the very short tails of horny toads. There are around 22 different species, found mostly throughout … Read more
Simple Columnar Epithelium Definition Simple columnar epithelia are tissues made of a single layer of long epithelial cells that are often seen in regions where absorption and secretion are important features. The cells of this epithelium are arranged in a neat row with the nuclei at the same level, near the basal end. In a … Read more