Gap junction definition Gap junction (also known as communicating junctions) refers to the type of cellular junction that allows passage of ions and small molecules between the cytoplasm of adjacent cells. This exchange is done through formation of a protein channel in cell plasma membrane. Cellular communication and cell junctions Formation of functional tissues and […]

Genetic Code Definition Genetic Code refers to the correspondence system between a codon and an amino acid. This code is universal, i.e., it is used by (practically) all existing species, and it is redundant, which means that the same amino acid is encoded by different codons. From DNA to Protein Based on the Biology Central […]

Genetics definition Genetics derives from ancient Greek genesis meaning “origin” and refers to the science that studies genes, heredity and diversity in living organisms. It is the branch of Biology that focuses on study of transmission of biological characteristics from parents to children, that is, from generation to generation over time. The functional unit responsible for […]

Hereditary diseases Hereditary diseases are diseases that follow inheritance patterns within families. Since there is inherent difficulty in studies of heredity in humans (due to the impossibility of controlling crosses, long generation time and small number of offspring), the study of hereditary diseases is done through the construction and analysis of an ‘heredogram’. Alternatively, studies […]

Homologous Genes definition Homology derives from the Greek homos (equals) and logos (relation) and refers to the relation existing between two structures (of different species) that share a common ancestor. Definition of homologous genes is based on the same, which states that two genes are homologous when their DNA sequence derives from a common origin, and […]

Intermediate Filaments definition Intermediate Filaments refers to filaments of fibrous proteins that form the cytoskeleton and give strength and mechanical strength to cells. Cytoskeleton Cytoskeleton is present in virtually all cells and is the cellular constituent responsible for maintaining cell’s shape and assisting in movement. Cytoskeleton consists of three types of filaments: actin filaments, intermediate […]

Interphase definition Interphase refers to the phase between two successive mitoses, during which chromosomes are relaxed and functionally active and where an intense metabolic activity takes place. It is the longest phase of cell cycle and is subdivided into G1 stage, S stage and G2 stage. Cell Cycle Cell cycle is divided into two successive […]

Lysosome definition Lysosome refers to the organelle present in eukaryotic cells which has as its main function the degradation of particles. Lysosome Characteristics Lysosomes are membrane-bound organelles present in eukaryotic cells, Figure 1. Inside, these organelles contain various hydrolytic enzymes, such as proteases, nucleases, lipases, phosphatases, among others. All hydrolytic enzymes present in lysosomes are […]

Metaphase definition Metaphase designates cell cycle phase in which chromosomes are in their most condensed state, aligned in cell equatorial plate. At this stage, chromosomes are attached to mitotic spindle, but have not yet segregated to cell opposite poles. Cell Cycle Cell basic function, which allows it to generate offspring exactly like itself, is the […]

Mitochondria definition Mitochondria refers to a cellular organelle responsible for production of energy (ATP) necessary for cell optimal functioning. Mitochondria origin and synthesis The existing theory suggests that mitochondria is a semiautonomous organelle, which was originated in endocytosis of a bacterium by an ancestral nucleated cell. This theory, not yet fully confirmed, is called the […]