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

Phagocytosis Definition Phagocytosis, or “cell eating”, is the process by which a cell engulfs a particle and digests it. The word phagocytosis comes from the Greek phago-, meaning “devouring”, and -cyte, meaning “cell”.  Cells in the immune systems of organisms use phagocytosis to devour bodily intruders such as bacteria, and they also engulf and get … Read more

Definition Cricoid cartilage is part of the larynx (just below the pharynx), and sits on a level plane just below the thyroid gland and thyroid cartilage. It is a circular piece of hyaline cartilage which wraps completely around the trachea, providing a place of attachment for various ligaments, muscles and other cartilage. Overview While the … Read more

Hermaphrodite Definition A hermaphrodite is an organism with both male and female genitalia. In sexually reproducing organisms, males have organs that produce male gametes, usually sperm. Females have different sexual organs that produce female gametes, usually called eggs. In sexually dimorphic organisms, each organism only has type of reproductive organs, and the population is divided … Read more

Overpopulation Definition Overpopulation refers to a population which exceeds its sustainable size within a particular environment or habitat. Overpopulation results from an increased birth rate, decreased death rate, the immigration to a new ecological niche with fewer predators, or the sudden decline in available resources.  Therefore, overpopulation describes a situation in which a population in … Read more

Microfilament Definition Microfilaments, also called actin filaments, are polymers of the protein actin that are part of a cell’s cytoskeleton. The cytoskeleton is the network of protein filaments that extends throughout the cell, giving the cell structure and keeping organelles in place.  Microfilaments are the smallest filaments of the cytoskeleton. They have roles in cell … Read more