metabolism [noun] A sequence of biochemical reactions in living organisms that converts food into energy used to drive other biological processes. Also, the sequence of transformations foreign compounds undergo inside a living cell.
acid [noun] Generally, a substance that reacts with bases to form a salt, several different definitions of acids have been proposed by different scientists (listed in parentheses). 1) (Arrhenius) a compound that releases hydrogen ions (H+) in solution; 2) (Brønsted-Lowry) a compound capable of donating hydrogen ions, 3) (Lewis) a compound that can accept a pair of electrons from a base.
fluid [adjective] Able to flow because the intermolecular forces allow the molecules to move around in relation to one another. Both liquids and gases are fluid.
Structure of Animal Cells
enzyme [noun] Molecules produced by living organisms that help catalyze biochemical reactions. Enzymes are predominantly protein or protein-based molecules and are highly specific in their mechanism of action as well as the reactants that they work upon (called substrates).
DNA [noun] Deoxyribonucleic acid. A double-stranded nucleic acid containing the sugar 2-deoxy-D-ribose. A constituent of cellular nuclear material responsible for encoding genetic information in most organisms. Specifically, a template for the synthesis of proteins and enzymes in most organisms.
RNA [noun] Ribonucleic acid. A single-stranded nucleic acid containing the sugar ribose. In most organisms, a molecule responsible for transfer of the genetic information encoded in DNA to the manufacture of proteins. In some organisms such as viruses RNA is the primary carrier of genetic information.
microtubule [noun] Microtubules are hollow cylinders of tubulin protein in the cytoplasm of all eukaryotic cells. As part of a cell's cytoskeleton, they shape and support it. Microtubules are also involved in the transport of materials inside of the cell. They serve as paths along which organelles with motor-equipped molecules can move. Microtubules participate in the separation of chromosomes during cell division (mitosis) and can act alone or form such complex structures as flagella and cilia.
A compartment used for storage of nutrients, water, and waste.
7. Cell Wall
Found in plants, fungi, and some protists, a structure outside of the plasma membrane that provides strength, support, and protection.
environment [noun] The conditions that surround and affect an organism.
cell [noun] The basic structural unit of all living things.
endomembrane system [noun] A network of membrane-bound organelles that exchange materials and function cooperatively. Components include the nuclear envelope, endoplasmic reticulum, Golgi apparatus, lysosome, vacuoles, and the plasma membrane.
algae [noun] (plural form of alga) Mostly aquatic plantlike organisms that range in size from one cell to large multi-celled seaweed and are photosynthetic.
protein [noun] Macromolecules that are polymers of individual amino acids arranged in a chain and joined together by peptide bonds (and so also referred to as polypeptides). A minimum polymer length of approximately 40 amino acid units appears to be a functional size limit, and polymers shorter than this limit are commonly referred to as peptides. Proteins comprise approximately 50% of the dry weight of cells and fill a number of purposes, both functional and structural.
molecule [noun] A particle formed by the chemical bonding of two or more atoms. The molecule is the smallest particle of a chemical compound that retains the chemical properties of the compound.
chromosome [noun] The organized genetic structure of DNA with associated proteins that contains the hereditary information necessary for reproduction, protein manufacture, and other functions.
organelle [noun] Structure or compartment within a cell that performs a specialized function such as respiration or photosynthesis. An organelle is analogous to an organ in your body: It has a specific form and function within a cell.
liquid [noun] The state of matter characterized by its condensed nature and ability to flow. Unlike gases, molecules within a liquid often experience some type of intermolecular interaction. Unlike solids, liquids do not have fixed shapes and take the shape of their container (as do gases). Compare with gas and solid.
network [noun] An interconnected system; an interrelated net-like arrangement of parts.
nutrient [noun] A chemical substance (e.g., minerals, vitamins, proteins) that is needed by an organism to survive and grow. See also: macronutrient and micronutrient.
adenosine triphosphate [noun] (ATP) Molecules that provide energy for important chemical reactions within the cell; the main energy currency of the cell.
vesicle [noun] A small sac containing fluid and other material.
energy [noun] An abstract property defined as the capacity to do work. The basic forms of energy include chemical, electrical, mechanical, nuclear, and radiant (light).
eukaryote [noun] A single- or multi-cellular organism whose cells contain a distinct nucleus that encloses the organism's genetic material.
phospholipid [noun] A lipid or glyceride that contains a phosphate group. The phosphate group imparts a polar side to the molecule, while the lipid end remains relatively non-polar. Phospholipids are the main form of lipid in cell membranes.
amino acid [noun] Biochemical molecules that contain at least one amine group (-NH2) and at least one carboxylic acid group (-COOH) and conform to the general formula NH2-R-COOH, where R is an organic molecule. Amino acids are essential basic building blocks of proteins.
sugar [noun] A water-soluble crystalline carbohydrate. There are many types of sugar of varying degrees of sweetness, including fructose, which occurs naturally in fruit, and lactose, which occurs naturally in milk.
nucleus [noun] 1. [Atomic] A tiny, dense positively charged mass at the heart of an atom. The nucleus is composed of protons and neutrons, and contains nearly all of the mass of the atom while occupying only a tiny fraction of the volume. 2. [Cellular] A generally spherical structure encased in a double membrane that is found in most living eukaryotic cells. The nucleus contains hereditary information and directs the growth, metabolism, reproduction, and functioning of the cell.
membrane [noun] A thin layer of tissue that forms a boundary of a cell or cell part.
synthesis [noun] The production of a chemical compound by combining simpler compounds or elements.