| Term |
Definition |
| protein | a large organic molecule made of carbon, hydrogen, oxygen, nitrogen, and sometimes sulfur |
| enzyme | a protein that speeds up chemical reactions in the bodies of living things |
| carbohydrates | energy-rich organic compounds, such as sugars and starches, that are made of the elements carbon, hydrogen, and oxygen. They provide the raw materials to make parts of cells. |
| nucleic acid | a very large organic molecule made of carbon, oxygen, hydrogen, nitrogen, and phosphorus, that contains instructions that 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 in which they are highly concentrated to an area in which they are less concentrated |
| 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 energy |
| photosynthesis | the process by which plants and some other organisms capture light energy and use it to make food from carbon dioxide and water |
| pigment | a colored chemical compound that absorbs light |
| chlorophyll | a green pigment found in the chloroplasts of plants, algae, and some bacteria |
| chloroplast | a structure in the cells of plants and some other organisms that captures energy from sunlight and uses it to produce food |
| stomata | the small openings on the undersides of most leaves through which oxygen and carbon dioxide can move |
| respiration | the process by which cells break down simple food molecules to release the energy they contain |
| mitochondria | rod-shaped cell structures that produce most of the energy needed to carry out the cell's functions |
| fermentation | the process by which cells break down molecules to release energy without using oxygen |
| cell cycle | the regular sequence of growth and division that cells undergo |
| mitosis | the stage of the cell cycle during which the cell's nucleus divides into two new nuclei and one copy of the DNA is distributed into each daughter cell |
| interphase | the stage of the cell cycle that takes place before cell division occurs; during this stage, the cell grows, copies its DNA, and prepares to divide |
| chromosome | a rod-shaped cellular structure made of condensed chromatin; contains DNA, which carries the genetic information that controls inherited characteristics such as eye color and blood type |
| chromatid | one of the identical rods of a chromosome |
| replication | the process by which a cell makes a copy of the DNA in its nucleus |
| cytokinesis | the final stage of the cell cycle, in which the cell's cytoplasm divides, distributing the organelles into each of the two new cells |