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| thin, flexible barrier around a cell; regulates what enters and leaves the cell |
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| strong supporting layer around the cell membrane in plants, algae, and some bacteria |
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| the center of the atom which contains the protons and neutrons; in cells, structure that contains the cell's genetic material (DNA) and controls the cell's activities |
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| material inside the cell membrane—not including the nucleus |
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| unicellular organism lacking a nucleus |
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| organism whose cells contain nuclei |
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| specialized structure that performs important cellular functions within a eukaryotic cell |
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| granular material visible within the nucleus; consists of DNA tightly coiled around proteins |
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| threadlike structure within the nucleus containing the genetic information that is passed from one generation of cells to the next |
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| small, dense region within most nuclei in which the assembly of proteins begins |
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| layer of two membranes that surrounds the nucleus of a cell |
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| network of protein filaments within some cells that helps the cell maintain its shape and is involved in many forms of cell movement |
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| small particle in the cell on which proteins are assembled; made of RNA and protein |
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| internal membrane system in cells in which lipid components of the cell membrane are assembled and some proteins are modified |
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| stack of membranes in the cell that modifies, sorts, and packages proteins from the endoplasmic reticulum |
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| cell organelle filled with enzymes needed to break down certain materials in the cell |
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| cell organelle that stores materials such as water, salts, proteins, and carbohydrates |
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| organelle found in cells of plants and some other organisms that captures the energy from sunlight and converts it into chemical energy |
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| cell organelle that converts the chemical energy stored in food into compounds that are more convenient for the cell to use |
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| diffusion of water through a selectively permeable membrane |
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| process by which molecules tend to move from an area where they are more concentrated to an area where they are less concentrated |
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| energy-requiring process that moves material across a cell membrane against a concentration difference |
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| movement of specific molecules across cell membranes through protein channels |
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| organized way of using evidence to learn about the natural world; also, the body of knowledge that scientists have built up after years of using this process |
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| use of one or more of the senses—sight, hearing, touch, smell, and sometimes taste—to gather information |
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| evidence; information gathered from observations |
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| logical interpretation based on prior knowledge and experience |
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| possible explanation for a set of observations or possible answer to a scientific question |
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| hypothesis (disproven) stating that life could arise from nonliving matter |
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| a test of the effect of a single variable by changing it while keeping all other variables the same |
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| factor in an experiment that a scientist purposely changes; also known as independent variable |
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| factor in an experiment that a scientist wants to observe, which may change in response to the manipulated variable; also known as a dependent variable |
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| well-tested explanation that unifies a broad range of observations |
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| science that seeks to understand the living world |
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| collection of living matter enclosed by a barrier that separates the cell from its surroundings; basic unit of all forms of life |
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| process by which cells from two different parents unite to produce the first cell of a new organism |
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| process by which a single parent reproduces by itself |
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| set of chemical reactions through which an organism builds up or breaks down materials as it carries out its life processes |
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| a signal to which an organism responds |
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| process by which organisms maintain a relatively stable internal environment |
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| decimal system of measurement based on certain physical standards and scaled on multiples of 10 |
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| device that produces magnified images of structures that are too small to see with the unaided eye |
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| compound light microscope |
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| microscope that allows light to pass through a specimen and uses two lenses to form an image |
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| microscope that forms an image by focusing beams of electrons onto a specimen |
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| group of cells grown in a nutrient solution from a single original cell |
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| technique in which cells are broken into pieces and the different cell parts are separated |
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| the center of the atom which contains the protons and neutrons; in cells, structure that contains the cell's genetic material (DNA) and controls the cell's activities |
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| negatively charged particle; located outside the atomic nucleus |
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| substance consisting entirely of one type of atom |
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| atom of an element that has a number of neutrons different from that of other atoms of the same element |
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| substance formed by the chemical combination of two or more elements in definite proportions |
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| link that holds together atoms in compounds |
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| bond formed when one or more electrons are transferred from one atom to another |
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| atom that has a positive or negative charge |
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| bond formed by the sharing of electrons between atoms |
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| smallest unit of most compounds |
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| a slight attraction that develops between the oppositely charged regions of nearby molecules |
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| attraction between molecules of the same substance |
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| attraction between molecules of different substances; in plants, attraction between unlike molecules |
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| material composed of two or more elements or compounds that are physically mixed together but not chemically combined |
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| mixture of two or more substances in which the molecules of the substances are evenly distributed |
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| substance that is dissolved in a solvent to make a solution |
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| substance in which a solute is dissolved to form a solution |
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| mixture of water and nondissolved materials |
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| measurement system used to indicate the concentration of hydrogen ions (H+) in solution; ranges from 0 to 14 |
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| compound that forms hydrogen ions (H+) in solution |
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| compound that produces hydroxide ions (OH+) in solution |
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| weak acid or base that can react with strong acids or bases to help prevent sharp, sudden changes in pH |
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| small unit that can join together with other small units to form polymers |
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| large compound formed from combinations of many monomers |
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| compound made up of carbon, hydrogen, and oxygen atoms; major source of energy for the human body |
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| large macromolecule formed from monosaccharides |
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| macromolecule made mainly from carbon and hydrogen atoms; includes fats, oils, and waxes |
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| macromolecule containing hydrogen, oxygen, nitrogen, carbon, and phosphorus |
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| monomer of nucleic acids made up of a 5-carbon sugar, a phosphate group, and a nitrogenous base |
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| single-stranded nucleic acid that contains the sugar ribose |
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| nucleic acid that contains the sugar deoxyribose |
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| macromolecule that contains carbon, hydrogen, oxygen, and nitrogen; needed by the body for growth and repair and to make up enzymes |
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| compound with an amino group (−NH2) on one end and a carboxyl group (−COOH) on the other end |
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| process that changes one set of chemicals into another set of chemicals |
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| element or compound that enters into a chemical reaction |
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| element or compound produced by a chemical reaction |
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| energy needed to get a reaction started |
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| substance that speeds up the rate of a chemical reaction |
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| protein that acts as a biological catalyst |
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| reactant of an enzyme-catalyzed reaction |
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