Ch 1 - The Fundamental Units of Life Flashcards
archaeon
microscopic organism that is a member of one of the two divisions of prokaryotes; often found in hostile environments such as hot springs or concentrated brine (see also bacterium)
bacterium
microscopic organism that is a member of one of the two division of prokaryotes; some species cause disease. the term is sometimes used to refer to any prokaryotic microorganism, although the world of prokaryotes also includes archaea, which are only distantly related to each other
cell
the basic unit from which a living organism is made; an aqueous solution of chemicals, enclosed by a membrane, that has an ability to self-replicate
chloroplast
specialized organelle in algae and plants that contains chlorophyll and serves as the site for photosynthesis
chromosome
long, threadlike structure composed of DNA and proteins that carries the genetic information of an organism; become visible as a distinct entity when a plant or animal cell prepares to divide
cytoplasm
contents of a cell that are contained within its plasma membrane but, in the case of eukaryotic cells, outside the nucleus
cytoskeleton
system of protein filaments in the cytoplasm of a eukaryotic cell that gives the cell shape and the capacity for directed movement. its most abundant components are actin filaments, microtubules and intermediate filaments.
cytosol
contents of the main compartment of the cytoplasm, excluding membrane-enclosed organelles such as endoplasmic reticulum and mitochondria. the cell fraction remaining after membranes, cytoskeletal components and other organelles have been removed
DNA
double stranded polynucleotide formed from two separate chains of covalently linked deoxyribonucleotide units. it serves as the cell’s store of genetic information that is transmitted from generation to generation.
electron microscope
instrument that illuminates a specimen using beams of electrons to reveal and magnify the structures of very small objects, such as organelles and large molecules
endoplasmic reticulum (ER)
labyrinthine membrane-enclosed compartment in the cytoplasm of eukaryotic cells where lipids and proteins are made
eukaryote
an organism whose cells have a distinct nucleus and cytoplasm
evolution
process of gradual modification and adaptation that occurs in living organisms over generations
fluorescence microscope
instrument used to visualize a specimen that has been labeled with a fluorescent dye; samples are illuminated with a wavelength of light that excite the dye, causing it to fluoresce
genome
the total genetic information carried by all the chromosomes of a cell or organism; in humans, the total number of nucleotide pairs in the 22 autosomes plus the X and Y chromosomes