Category: Biology Dictionary D

Dynamic Equilibrium Definition A system in dynamic equilibrium will have small changes that sum together to produce no net change. Many biological systems are in dynamic equilibrium, from the water inside a cell, to the dynamic equilibrium experienced by populations of predators and prey. Dynamic equilibrium is different from a static equilibrium, in which the parts […]

Dorsal Cavity Definition The dorsal cavity, or dorsal body cavity, is a fluid filled space which surrounds the brain and spinal cord of vertebrates. The dorsal cavity is usually considered as two semi-separate spaces, the cranial cavity and the spinal cavity, housing the brain and spinal cord, respectively. However, the fluid in the dorsal cavity connects between the brain […]

Dominant Trait Definition A dominant trait is an inherited characteristic that appears in an offspring if it is contributed from a parent through a dominant allele. Traits, also known as phenotypes, may include features such as eye color, hair color, immunity or susceptibility to certain diseases and facial features such as dimples and freckles. In sexually reproducing […]

Dominant Allele Definition A dominant allele is a variation of a gene that will produce a certain phenotype, even in the presence of other alleles. A dominant allele typically encodes for a functioning protein. The allele is dominant because one copy of the allele produces enough enzyme to supply a cell with plenty of a […]

Domain Definition In biology, a domain refers to the largest of all groups in the classification of life. There are currently 3 agreed groups at this level, the Archaea domain, Bacteria domain, and Eukarya domain. Each domain contains a collection of organisms with similar properties and evolutionary histories, as scientists have organized them. It should be noted that while the three […]

DNA Sequencing Definition DNA sequencing is the process of determining the sequence of nucleotides within a DNA molecule. Every organism’s DNA consists of a unique sequence of nucleotides. Determining the sequence can help scientists compare DNA between organisms, which can help show how the organisms are related. DNA Sequencing Overview This means that by sequencing […]

DNA Fingerprinting Definition DNA fingerprinting is a method used to identify living things based on samples of their DNA. Instead of looking at the whole sequence of a person’s DNA, these techniques look at the presence or absence of common markers that can be quickly and easily identified. DNA Fingerprinting Explained The process is sometimes […]

DNA Definition Deoxyribonucleic acid, or DNA, is a biological macromolecule that carries hereditary information in many organisms. DNA is necessary for the production of proteins, the regulation, metabolism, and reproduction of the cell. Large compressed DNA molecules with associated proteins, called chromatin, are mostly present inside the nucleus. Some cytoplasmic organelles like the mitochondria also […]

Divergent Evolution Definition Divergent evolution is the process whereby groups from the same common ancestor evolve and accumulate differences, resulting in the formation of new species. Divergent evolution may occur as a response to changes in abiotic factors, such as a change in environmental conditions, or when a new niche becomes available. Alternatively, divergent evolution may take place in […]

Disruptive Selection Definition Disruptive selection is an evolutionary force that drives a population apart. The disruptive selection will cause organsisms with intermediate traits to reproduce less, and will allow those organisms with extreme traits to reproduce more. This causes the alleles for the extreme traits to increase in frequency. Over time, and with enough disruptive […]