Gene Flow Definition The exchange of alleles between two or more populations is known as gene flow. In some cases, it is referred to as gene flow or allele migration. Despite the fact that migrating animals often carry new alleles from one population to another, gene flow cannot occur unless they interbreed with the new … Read more
Disaccharide Definition A disaccharide, also called a double sugar, is a molecule formed by two monosaccharides, or simple sugars. Three common disaccharides are sucrose, maltose, and lactose. They have 12 carbon atoms, and their chemical formula is C12H22O11. Other, less common disaccharides include lactulose, trehalose, and cellobiose. Disaccharides are formed through dehydration reactions in which … Read more
Definition A eukaryotic cell contains membrane-bound organelles such as a nucleus, mitochondria, and an endoplasmic reticulum. Organisms based on the eukaryotic cell include protozoa, fungi, plants, and animals. These organisms are grouped into the biological domain Eukaryota. Eukaryotic cells are larger and more complex than prokaryotic cells found in domains Archaea and Bacteria. Overview A … Read more
Definition Prophase I of meiosis I involves five stages during which alleles cross over and recombine to form non-identical haploid chromatids. Meiosis I begins with prophase I, followed by prophase II, anaphase I, anaphase II, metaphase I, and metaphase II. Prophase I Glossary of Terms The terms associated with Prophase I of meiosis I are … Read more
Vacuole Definition Vacuoles are organelles found in cells that store solutions or materials. The cell can phagocytoze, or engulf, solutions that have been created and are being stored or excreted. Vacuoles are simply chambers surrounded by a membrane, which prevents the cytosol from being exposed to the contents. Only certain molecules can pass through vacuoles … Read more
Daughter Cells Definition Daughter cells are produced after a single cell undergoes cell division. During mitosis, one pair of daughter cells is created after one round of DNA replication. During meiosis, a single round of DNA replication is followed by 2 rounds of cell division. This creates two sets of daughter cells, each of which … Read more
Calvin Cycle Definition In plants, the Calvin cycle involves chemical reactions that “fix” carbon from CO2 into three-carbon sugars. The three-carbon compounds can later be converted into amino acids, nucleotides, and more complex sugars such as starches by plants and animals. “Carbon fixation” is the process by which most new organic matter is created. Plants … Read more
Telophase Definition Telophase is the final stage in cell division. During telophase, the nuclear envelopes reform around the new nuclei in each half of the dividing cell. The nucleolus, or ribosome producing portions of the nucleus return. As the cell has finished moving the chromosomes, the main parts of the spindle apparatus fall depolymerize, or … Read more
Labia Definition Labia refers to a part of the female genital anatomy that comprises the external region of the vulva (shown below). There are two pairs of labia in human women, termed the labia minora and the labia majora. The labia minora are the inner folds of skin residing under the labia majora. The labia … Read more
Thymus Gland Definition The thymus gland is a secretory gland that has an important role in immune function. One of its main secretions is the hormone thymosin. Thymosin stimulates the maturation of T cells, which are derivatives of white blood cells that circulate our system. Thymus Gland Overview T cells help clear the body of … Read more