Category: Biology Dictionary C

Carotenoids Definition and Function Carotenoids are a type of accessory pigment, created by plants to help them absorb light energy and convert it to chemical energy. There are two types of carotenoids, xanthophylls and carotenes, which differ only in their oxygen content. Carotenoids have a similar base structure consisting of 8 isoprene molecules. Isoprene molecules have 5 carbons, and 8 of…

Cardiac Muscle Definition Cardiac muscle, also known as heart muscle, is the layer of muscle tissue which lies between the endocardium and epicardium. These inner and outer layers of the heart, respectively, surround the cardiac muscle tissue and separate it from the blood and other organs. Cardiac muscle is made from sheets of cardiac muscle cells. These cells,…

Definition The cardiac cycle is the series of contractions in the heart that pressurize different chambers, causing blood to flood in one direction. There are two stages during the cardiac cycle. During diastole, the ventricles relax and fill with blood. The muscles contract during systole, pushing blood through the arteries. Cardiac Cycle Explained The cardiac cycle varies in…

Carcinoma Definition Carcinoma is a term used to describe cancer derived from epithelial cells that line various tissues throughout the body. In addition, malignant tumors that have an unknown primary origin, but share histological characteristics with epithelial cells (e.g., stratification, pseudostratification, cytokeratin production, mucin, etc.) are also classified as carcinomas. Depending on the location, carcinomas…

Carboxyl Group Definition A carboxyl group is one of many functional groups that attaches to larger molecules and gives them certain properties. The carboxyl group is seen in many organic molecules known as carboxylic acids, which have a variety of functions. The carboxyl group consists of a carbon, bonded to both an oxygen and a hydroxyl group. Hydroxyl groups are…

Carbonyl Group Definition A carbonyl group is a functional group characterized by a carbon atom double bonded to an oxygen, found within a larger carbon-based molecule. The electronegativity of oxygen creates a resonance hybrid structure in which the electrons are continuously redistributed. This allows the molecule to participate in more reactions. Carbonyl Group Overview The power of…

Carbon Cycle Definition The carbon cycle is the cycle by which carbon moves through our Earth’s various systems. The carbon cycle is influenced by living things, atmospheric changes, ocean chemistry, and geologic activity are all part of this cycle. The levels of carbon are at an all-time high, largely due to human activities. Carbon Cycle…

CAM Plants Definition CAM – short for “Crassulacean Acid Metabolism” – is a method of carbon fixation evolved by some plants in dry circumstances. In most plants, the stomata – which are like tiny mouths that take in oxygen all along the surfaces of their leaves – open during the day to take in CO2 and…

Calvin Cycle Definition The Calvin cycle is the cycle of chemical reactions performed by plants to “fix” carbon from CO2 into three-carbon sugars. Later, plants and animals can turn these three-carbon compounds into amino acids, nucleotides, and more complex sugars such as starches. This process of “carbon fixation” is how most new organic matter is created.…

Calmodulin Definition Calmodulin, or calcium-modulated protein, is a calcium-binding protein found in the cytoplasm of all eukaryotic cells. It interacts with many other proteins in the cell, and acts as a regulator or an effector molecule in a wide variety of cellular functions. These functions include things as diverse as regulation of the cell cycle,…