ATP
a nucleotide derived from adenosine that occurs in muscle tissue; the major source of energy for cellular reactions
cell
(biology) the basic structural and functional unit of all organisms; they may exist as independent units of life (as in monads) or may form colonies or tissues as in higher plants and animals
cell membrane
a thin membrane (a double layer of lipids) enclosing the cytoplasm of a cell; proteins in the membrane control passage of ions (like sodium or potassium or calcium) in and out of the cell
cell wall
a rigid layer of polysaccharides enclosing the membrane of plant and prokaryotic cells; maintains the shape of the cell and serves as a protective barrier
cellular respiration
the metabolic processes whereby certain organisms obtain energy from organic molecules; processes that take place in the cells and tissues during which energy is released and carbon dioxide is produced and absorbed by the blood to be transported to the lungs
chlorophyll
any of a group of green pigments found in photosynthetic organisms; there are four naturally occurring forms
chloroplast
plastid containing chlorophyll and other pigments; in plants that carry out photosynthesis
chromosome
a threadlike strand of DNA in the cell nucleus that carries the genes in a linear order
cytoplasm
the protoplasm of a cell excluding the nucleus; is full of proteins that control cell metabolism
diffusion
the act of dispersing or diffusing something
DNA
(biochemistry) a long linear polymer found in the nucleus of a cell and formed from nucleotides and shaped like a double helix; associated with the transmission of genetic information
mitochondrion
an organelle containing enzymes responsible for producing energy
mitosis
cell division in which the nucleus divides into nuclei containing the same number of chromosomes
nucleus
a part of the cell containing DNA and RNA and responsible for growth and reproduction
organelle
a specialized part of a cell; analogous to an organ
osmosis
(biology, chemistry) diffusion of molecules through a semipermeable membrane from a place of higher concentration to a place of lower concentration until the concentration on both sides is equal
permeable
allowing fluids or gases to pass or diffuse through
photosynthesis
synthesis of compounds with the aid of radiant energy (especially in plants)
ribosome
an organelle in the cytoplasm of a living cell; they attach to mRNA and move down it one codon at a time and then stop until tRNA brings the required amino acid; when it reaches a stop codon it falls apart and releases the completed protein molecule for use by the cell
RNA
(biochemistry) a long linear polymer of nucleotides found in the nucleus but mainly in the cytoplasm of a cell where it is associated with microsomes; it transmits genetic information from DNA to the cytoplasm and controls certain chemical processes in the cell
semipermeable membrane
a membrane (as a cell membrane) that allows some molecules to pass through but not others
vacuole
a tiny cavity filled with fluid in the cytoplasm of a cell
