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Flashcards in Molecular Biology Deck (57)
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Define: Element

A substance that cannot be decomposed into simpler substances by chemical means, and is made up of atoms all with an identical number of protons.
(Elemnts cannot be broken down into other


Define: Trace Element

Any chemical Element that an organism needs very small quantities of to survive.


Define: Compound

A substance consisting of atoms or ions of two or more elements that are chemically bonded together.


Define: Atom

The smallest unit of matter indivisible by chemical means.


Define: Isotope

One of several nuclides having the same number of protons in their nuclei and hence having the same atomic number, but differing in the number of neutrons and therefore, in the mass number. Almost identical chemical properties exist between isotopes of a particular element.


Define: Radioactive Isotope

An atom in which the nucleus decays spontaneously shedding particles and releasing energy.


Define: Nucleus

The large, membrane-bounded organelle that contains the genetic material, in the form of multiple linear DNA molecules organized into structures called chromosomes.


Define: Ionic bond

An ionic bond is a chemical bond wherein there is a transfer of an electron from one atom to another. For an ionic bonding to occur there must be an electron donor (often a metal) and an electron acceptor (often a nonmetal).


Define: Covalent bond

A covalent bond is known for the sharing of electrons between two atoms. Rather than the process of giving and receiving, covalent bonding entails the sharing of electrons in pair(s).


Define: Hydrogen Bond

A type of chemical bond that is formed when the slightly positive hydrogen atom of a polar covalent bond forms an electrostatic link with the more electreonegative atom of a polar covalent bond in the same or another molecule.


Define: Polarity

The condition of having contrasting properties or direction


Define: Cohesion

The act, state or process of sticking together, as in intermolecular force that holds together alike molecules in a substance or the binding together of alike molecules.


Define: Solvent

A liquid in which substances (or solutes) are dissolved forming a solution.


Define: Solute

a component of a solution: in a solution, the dissolving substance is called a solvent whereas the dissolved substance is called a solute


Define: Solution

A type of homogenous mixture in which the particles of one or more substances (the solute) are distributed uniformly throughout another substance (the solvent).


Define: Hydrophobic

Lacking an affinity for water; insoluble in water; repelling water.


Define: Hydrophillic

A hydrophilic molecule or portion of a molecule is one whose interactions with water and other polar substances are more thermodynamically favorable than their interactions with oil or other hydrophobic solvents.


Define: Macromolecule

A large complex molecule, such as nucleic acids, proteins, carbohydrates, and lipids, with relatively large molecular weight


Define: Monomer

A monomer may combine with another monomer through chemical bonds to form a larger molecule, as in a polymer.


Define: Polymer

A compound made up of several repeating units (monomers) or protomers


Define: Dehydration reaction

A chemical reaction whereby a water molecule is lost, such as that during the synthesis of an organic compound


Define: Hydration Reaction

A chemical reaction in which water molecules combine with a substance.


Define: Monosaccharide

A simple sugar that constitutes the building blocks of a more complex form of sugars such as oligosaccharides and polysaccharides; examples are fructose, glucose, and ribose


Define: Disaccharide

A (carbohydrate) composed of two monosaccharides, thus yields two monosaccharide molecules on complete hydrolysis


Define: Polysaccharide

Any from the group of polymeric carbohydrates formed by long chains of repeating units linked together by glycosidic bonds


Define: Glycosidic bond

Glycosidic bond is a covalent bond that holds a carbohydrate (sugar) to another group that can or cannot be another sugar.


Define: Lipid

A fatty or waxy organic compound that is readily soluble in nonpolar solvent (e.g. ether) but not in polar solvent (e.g water), and whose major biological functions involve energy storage, structural component of cell membrane, and cell signaling


Define: Fat

A term largely applied to storage lipids in animal tissues that are usually solid at room temperature


Define: Phospholipid

A lipid with one or more phosphate groups attached to it.


Define: Steroid

Any of the group of fat-soluble organic compounds containing four rings arranged in a particular molecular configuration, produced either naturally (i.e. from the sterols lanosterol and cycloartenol) or synthetically.