alleles - One of a set of alternate forms of a gene. An example is the different alleles of eye color. Each of the different forms of the gene code for eye color, only each codes for a different color i.e. blue, brown, green.
centrifuge - a machine that rotates (spins) rapidly and uses centrifugal force to separate substances of different densities. You've used a centrifuge before. Have you ever watched a washing machine on spin cycle? A washing machine uses centrifugal force in the spin cycle to separate the water from your clothes.
chromosomes - The self- replicating genetic structures of cells containing the DNA that bears in its sequence the cell's array of genes. In prokaryotes (bacteria), chromosomal DNA is circular, and the entire genome is carried on one chromosome. Eukaryotic (mammalian and other higher organisms) genomes consist of a number of chromosomes whose DNA is associated with different kinds of proteins.
diffusion - molecules
have energy, so when they are dissolved in water
electric charges - atoms acquire an
electric charge when they have too many
electron micrograph - A picture taken by a very high powered microscope that magnifies enough to see large molecules. In both light and electron microscopes, illumination is provided by a source (lamp, filament in the electron gun) which is focused by a condenser lens onto the specimen. A first magnified image is formed by the objective lens. This image is further magnified by the projector lens onto a ground glass screen (light) or fluorescent screen (electrons). For a comprehensive comparison of microscope principles, click here.
fluid mosaic - the model used to describe the structure of cell membranes. Fluid- refers to the motion of the molecules in the membrane. The molecules are able to move, like molecules in a liquid, instead of being stationary, like molecules in a solid. Mosaic-something consisting of a variety of elements. In this case, a cell membrane is made up of several different kinds of lipids and proteins.
food chains - the sequence of food and nutrient distribution among different species. For example, small plant cells in water are eaten by small fish, small fish are eaten by big fish, big fish are eaten by people
heredity - the transmission of qualities from parent to offspring through the genes. Also see inherit.
immiscible - describes two or more liquids that will not mix together to form a single homogenous (unvarying) substance.
inherit - to receive a trait from a parent (or ancestor.) You inherit bodily traits such as eye color from your parents. Also see heredity.
intoxication - to make drunk with alcohol, drugs or other substances. When using intoxication to describe an effect of a substance on the body (the pathology of a substance) intoxication also means poison or to poison someone.
jaundice - a yellowing of the skin, usually showing up in the whites of the eyes, fingernails, and other lightly pigmented parts of the body surface. There are three main causes: 1) accumulation of a breakdown product (called bilirubin) of excessive destruction of red blood cells (bruises often have localized jaundice in the early stage of healing), 2) a failure of the liver to remove the normal amounts of bilirubin, or 3) failure of elimination of bilirubin via the bile that is normally made in the liver and dumped into the intestine as a waste product.
ketones - a class of body chemicals in which part of the molecule contains a carbon-oxygen bond (C= O).These form from the breakdown of fats and proteins in the liver. The can accumulate to toxic levels if the blood sugar falls too low (as in certain diabetes situations, starvation, or eating a high fat-low carbohydrate diet). They are toxic because they make the body fluids too acid for enzymes to work properly.
kinetic energy - energy associated with motion. A rock rolling down a hill has kinetic energy. Also see potential energy.
lipids - Lipids are also known as fats, but they include compounds of many different kinds. Chemically, these compounds are built on a backbone of glycerol, which was a three-carbon chain. Each carbon, in turn, bonds via an oxygen molecule to so-called fatty acids. Fatty acids have an acid group (COOH) at one end that is attached to a chain of carbons. Lipids differ mainly in the nature of the fatty acid chains.
molecules - When two or more atoms
bond together, they are called
nitrites - chemicals that contain a nitrogen and oxygen atom (NO) that are made from nitrates by microbes in the gut or soil. Nitrates provide the nitrogen content in fertilizer. Obviously, farm animals can be poisoned by eating fertilizer and even plants that have been over-fertilized. These are poisonous because they bind to hemoglobin and keep it from carrying oxygen in the blood. In large enough concentrations, nitrites and their reaction products can promote cancer. See http://www.epa.gov/safewater/dwh/c-ioc/nitrates.html for information on nitrites/nitrates in drinking water.
opacity - ability of material to stop light.
For example, muddy water is
organelles - Literally, the term means "little organs." Inside a cell, there are various little structures that perform specific functions, much like the multicellular organs of our body do. In the cell, these include generating energy (the organelle is the mitochondrion), making proteins (the organelles are ribosomes and Golgi apparatus), and others.
osmosis - the movement of a solvent (like water)
from an area of lesser to greater concentrations so that the solvent will be evenly
distributed. So for example, if you put a cell in pure water (that has no dissolved
chemicals in it), the water outside would move inside to increase the concentration
phagocytosis - the process by which certain cells destroy toxins and other organic matter by wrapping their cell membrane around it, and incorporating it into the phagocytic cell, where enzymes break down the chemicals and destroy them.
phosphate bonds (high energy) - adenosine diphosphate has two phosphate groups bonded like this: O - P - O - P. The ADP can capture external energy and store it in a third phosphate group. The bond that holds the third phosphate group to the molecule has high energy and can readily release it. A similar principle applies to other compounds that store energy in phosphate bonds.
phospholipids - Phospholipids are typical lipids, except that a phosphate group (POO4) is bonded to one end of one of the fatty acid chains. See lipids.
porous - containing pores, or holes that permit the movement of fluids or gases. An example of a porous material is a sponge. Porosity is the extent to which a substance contains pores. Swiss cheese has high porosity compared to cheddar.
potential energy - energy that an object (or piece of matter) has because of its position, or an arrangement of its parts (for example chemical bonds.) A rock at the top of a hill has potential energy. Also see kinetic energy.
proteins - molecules made of long strings of
repeating units, called amino acids.
substrate - fluid or solid in which an item is placed, or environment in which something may function. For example, a fish's substrate is water. In this case, the substrate that the protein is placed into is a jello-like gel. In chemistry, the substrate is also whatever is acted upon, for example, and antibody's substrate is the part of the germ it attacks.
sugar - compounds that contain only carbon,
hydrogen, and oxygen, usually in a ring