Biology Vocabulary 1

Cellulose

A carbohydrate that is a polymer composed of glucose units and that is the main component of the cell walls of most plants. It is insoluble in water and is used to make paper, cellophane, textiles, explosives, and other products.

Starch

A carbohydrate that is the chief form of stored energy in plants, especially wheat, corn, rice, and potatoes. Starch is a mixture of two different polysaccharides built out of glucose units, and forms a white, tasteless powder when purified. It is an important source of nutrition

Lipids

A group of organic molecules (see also organic molecule) that includes fats, oils, and waxes. Lipids do not dissolve in water. In animals, including humans, lipids store energy and form parts of cell structures, such as cell membranes.

Insulin

A hormone produced in the pancreas that regulates the amount of sugar in the blood by stimulating cells, especially liver and muscle cells, to absorb and metabolize glucose. Insulin also stimulates the conversion of blood glucose into glycogen and fat, which are the body's chief sources of stored carbohydrates.

Glucose

A monosaccharide sugar, C6H12O6, occurring widely in most plant and animal tissue. It is the principal circulating sugar in the blood and the major energy source of the body.

Glycogen

A polysaccharide stored in animal liver and muscle cells that is easily converted to glucose to meet metabolic energy requirements. Most of the carbohydrate energy stored in animal cells is in the form of glycogen.

Catalyst

A substance that starts or speeds up a chemical reaction while undergoing no permanent change itself. The enzymes in saliva, for example, are catalysts in digestion.

Hemoglobin

An iron-containing protein present in the blood of many animals that, in vertebrates, carries oxygen from the lungs to the tissues of the body and carries carbon dioxide from the tissues to the lungs. Hemoglobin is contained in the red blood cells of vertebrates and gives these cells their characteristic color

Carbohydrates

Any of a group of organic compounds that includes sugars, starches, celluloses, and gums and serves as a major energy source in the diet of animals. These compounds are produced by photosynthetic plants and contain only carbon, hydrogen, and oxygen, usually in the ratio 1:2:1.

Protein

Any of a large class of complex organic chemical compounds that are essential for life. Proteins play a central role in biological processes and form the basis of living tissues. They consist of long chains of amino acids connected by peptide bonds and have distinct and varied three-dimensional structures, usually containing alpha helices and beta sheets as well as looping and folded chains. Enzymes, antibodies, and hemoglobin are examples of proteins.

Steroid

Any of a large class of organic compounds having as a basis 17 carbon atoms arranged in four rings fused together.

Enzyme

Any of numerous proteins produced in living cells that accelerate or catalyze the metabolic processes of an organism.

Nucleic Acids

Organic molecule (see also organic molecule) found in the nuclei of cells. DNA and RNA, the best-known nucleic acids, govern heredity and the chemical processes in the cell.

Activation Energy

The least amount of energy needed for a chemical reaction to take place.

Phospholipids

any of a group of lipids that contain a phosphate ester as part of the structure and yield on hydrolysis phosphoric acid, an alcohol, fatty acid, and a nitrogenous base: found in all living cells

Denaturation

to change the structure of (a protein) by heat, acids, alkalies, etc., so that the original properties are greatly changed or eliminated