Term | Definition |
cell | The basic unit of structure and function in living things. |
microscope | An instrument that makes small objects look larger. |
cell theory | A widely accepted explanation of the relationship between cells and living things. |
organelle | A tiny cell structure that carries out a specific function within the cell. |
cell wall | A rigid layer of nonliving material that surrounds the cells of plants and some other organisms. |
cell membrane | Acell structure that controls which substances can enter or leave the cell. |
nucleus | A cell structure that contains nucleic acids, the chemical instructions that direct all the cell's activities. |
cytoplasm | The region between the cell membrane and the nucleus; in organisms without a nucleus, the region located inside the cell membrane. |
mitochondria | Rod-shaped cell structures that convert energy in food molecules to energy the cell can use to carry its functions. |
endoplasmic reticulum | A cell structure that forms a maze of passageways in which proteins and other materials are carried from one part of the cell to another. |
| |
ribosome | A small grain-like structure in the cytoplasm of a cell where proteins are made. |
Golgi body | A structure in a cell that receives proteins and other newly formed materials from the endoplasmic reticulum, packages them, and distributes them to other parts of the cell. |
chloroplast | A structure in the cells of plants and som other organisms that captures energy from sunlight and uses it to produce food. |
vacuole | A sac inside a cell that acts as a storage area. |
lysosome | A small, round cell structure containing chemicals that break down large food particles into smaller ones. |
element | Any substance that cannot be broken down into simpler substances. |
compound | Two or more elements that are chemically combined. |
carbohydrate | Energy-rich organic compound,such as a sugar or starch, that is made of the elements carbon, hydrogen, and oxygen. |
protein | Large organic molecule made of carbon, hydrogen, oxygen, nitrogen, and sometimes sulfur. |
amino acid | A small molecule that is linked chemically to other amino acids to form proteins. |
enzyme | A type of protein that speeds up a chemial reaction in a living thing. |
lipid | Energy-rich organic compound, such as a fat, oil, or wax, that is made up of carbon, hydrogen, and oxygen. |
nucleic acid | Very large organic molecule made of carbon, oxygen, hydrogen, nitrogen, and phophorus, that contains the instructions cells need to carry out all the functions of life. |
DNA | Deoxyribonucleic acid; the genetic material that carries information about an organism and is passed from parent to offspring. |
RNA | Ribonucleic acid; a nucleic acid that plays an important role in the production of proteins. |
selectively permeable | A property of cell membranes that allows some substances to pass through, while others cannot. |
diffusion | The process by which molecules move from an area of higher concentration to an area of lower concentration. |
osmosis | The diffusion of water molecules through a selectively permeable membrane. |
passive transport | The movement of materials through a cell membrane without using energy. |
active transport | The movement of materials through a cell membrane using cellular energy. |