Lecture 1 Glossary Carbohydrate An organic molecule containing

Lecture (1) Glossary

Carbohydrate An organic molecule containing carbon , hydrogen, and oxygen in a ratio of 1: 2: 1. the carbohydrate class of molecules is subdivided into monosaccharides, disaccharids, and polysaccharides.

Cholesterol A twenty-seven-carbon steroid that serves as the precursor for steroid hormones.

Cytoplasm The semifluid part of the cell between the cell membrane and the nucleus, exclusive of membrane-bound organelles. It contains many enzymes and structural proteins.

Cytoplasm

DNA Deoxyribonucleic acid. A nucleic acid composed of nucleotide bases and deoxyribose sugar that contains the genetic code

Endocytosis The cellular uptake of particles that are too large to cross the cell membrane. This occurs by invagination of the cell membrane until a membrane-enclosed vesicle is pinched off within the cytoplasm.

Endoplasmic Reticulum An extensive system of membrane-enclosed cavities within the cytoplasm of the cell. Those with ribosomes on their surface are called rough endoplasmic reticulum and participate in protein synthesis.

Endoplasmic Reticulum

Enzyme A protein catalyst that increases the rate of specific chemical reactions.

Exocytosis The process of cellular secretion in which the secretory products are contained within a membrane-enclosed vesicle. The vesicle fuses with the cell membrane so that the lumen of the vesicle is open to the extracellular environment

Golgi Apparatus A network of stacked, flattened membranous sacs within the cytoplasm of cells. Its major function is to concentrate and package proteins within vesicles that bud off from it.

Lipid An organic molecule that is nonpolar, and thus insoluble in water. Lipids include triglycerides, steroids, and phospholipids.

Lysosome An organelle containing digestive enzymes that is responsible for intracellular digestion

Lysosome

Nucleus The organelle, surrounded by a double saclike membrane called the nuclear envelope, that contains the DNA and genetic information of the cell.

Phagocytosis Cellular eating: the ability of some cells to engulf large particles and digest these particles by merging the food vacuole in which they are contained with a lysosome containing digestive enzymes.

Phospholipid A lipid containing a phosphate group. Phospholipid molecules are polar on one end and nonpolar on the other end. They make up a large part of the cell membrane and function in the lung alveoli as surfactants

Protein The class of organic molecules composed of large polypeptides, in which over a hundred amino acids are bonded together by peptide bond.

Ribosome A cytoplasmic organelle composed of protein and ribosomal RNA that is responsible for the translation of messenger RNA and protein synthesis.

RNA Ribonucleic acid. A nucleic acid consisting of the nitrogenous bases adenine, guanine, cytosine, and uracil; the sugar ribose; and phosphate groups, there are three types of RNA found in cytoplasm: messenger RNA (m. RNA), transfer RNA (t. RNA), and ribosomal RNA (r. RNA)

Urea The chief nitrogenous waste product of protein catabolism in the urine, formed in the liver from amino acids.