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Chapter 4: Cells: The Working Units of Life
Terms in this set (50)
A protein that makes up the cytoskeletal microfilaments in eukaryotic cells and is one of the two contractile proteins in muscle. (See also myosin.)
The programmed destruction of a cellâ€™s components.
Specialized structures associated with the plasma membranes of epithelial cells. Some contribute to cell adhesion, others to intercellular communication.
Lipid bilayer also containing proteins and other molecules that encloses the cytoplasm of the cell and separates it from the surrounding environment.
States that cells are the basic structural and physiological units of all living organisms, and that all cells come from preexisting cells.
A relatively rigid structure that encloses cells of plants, fungi, many protists, and most prokaryotes, and which gives these cells their shape and limits their expansion in hypotonic media.
An organelle bounded by a double membrane containing the enzymes and pigments that perform photosynthesis. Chloroplasts occur only in eukaryotes.
The nucleic acidâ€"protein complex that makes up eukaryotic chromosomes.
In bacteria and viruses, the DNA molecule that contains most or all of the genetic information of the cell or virus. In eukaryotes, a structure composed of DNA and proteins that bears part of the genetic information of the cell.
Hairlike organelle used for locomotion by many unicellular organisms and for moving water and mucus by many multicellular organisms. Generally shorter than a flagellum.
A fibrous protein found extensively in bone and connective tissue.
The contents of the cell, excluding the nucleus.
The network of microtubules and microfilaments that gives a eukaryotic cell its shape and its capacity to arrange its organelles and to move.
The fluid portion of the cytoplasm, excluding organelles and other solids.
A system of intracellular membranes that exchange material with one another, consisting of the Golgi apparatus, endoplasmic reticulum, and lysosomes when present.
endoplasmic reticulum (ER)
A system of membranous tubes and flattened sacs found in the cytoplasm of eukaryotes. Exists in two forms: rough ER, studded with ribosomes; and smooth ER, lacking ribosomes.
Organisms whose cells contain their genetic material inside a nucleus. Includes all life other than the viruses, archaea, and bacteria. (Contrast with prokaryotes.)
A material of heterogeneous composition surrounding cells and performing many functions including adhesion of cells.
Long, whiplike appendage that propels cells. Prokaryotic flagella differ sharply from those found in eukaryotes.
A protein to which sugars are attached.
An organelle found in plants, in which stored lipids are converted to carbohydrates.
A system of concentrically folded membranes found in the cytoplasm of eukaryotic cells; functions in secretion from the cell by exocytosis.
Components of the cytoskeleton whose diameters fall between those of the larger microtubules and those of the smaller microfilaments.
An intracellular membrane.
A membrane-enclosed organelle originating from the Golgi apparatus and containing hydrolytic enzymes. (Contrast with secondary lysosome.)
In eukaryotic cells, a fibrous structure made up of actin monomers. Microfilaments play roles in the cytoskeleton, in cell movement, and in muscle contraction.
Tubular structures found in centrioles, spindle apparatus, cilia, flagella, and cytoskeleton of eukaryotic cells. These tubules play roles in the motion and maintenance of shape of eukaryotic cells.
An organelle in eukaryotic cells that contains the enzymes of the citric acid cycle, the respiratory chain, and oxidative phosphorylation.
Specialized proteins that use energy to change shape and move cells or structures within cells.
The region that harbors the chromosomes of a prokaryotic cell. Unlike the eukaryotic nucleus, it is not bounded by a membrane.
A small, generally spherical body found within the nucleus of eukaryotic cells. The site of synthesis of ribosomal RNA.
(1) In cells, the centrally located compartment of eukaryotic cells that is bounded by a double membrane and contains the chromosomes. (2) In the brain, an identifiable group of neurons that share common characteristics or functions.
Any of the membrane-enclosed structures within a eukaryotic cell. Examples include the nucleus, endoplasmic reticulum, and mitochondria.
An organelle that houses reactions in which toxic peroxides are formed and then converted to water.
One of two major classes of white blood cells; one of the nonspecific defenses of animals; ingests invading microorganisms by phagocytosis.
Endocytosis by a cell of another cell or large particle.
Membrane-enclosed vesicle inside a cell that results from infolding of the cell membrane and enclosing a particle to be taken into the cell.
A cytoplasmic strand connecting two adjacent plant cells.
Unicellular organisms that do not have nuclei. (Contrast with eukaryotes.)
A glycoprotein containing a protein core with attached long, linear carbohydrate chains.
A small particle in the cell that is the site of protein synthesis.
rough endoplasmic reticulum (RER)
The portion of the endoplasmic reticulum whose outer surface has attached ribosomes. (Contrast with smooth endoplasmic reticulum.)
Membrane-enclosed organelle formed by the fusion of a primary lysosome with a phagosome, in which macromolecules taken up by phagocytosis are hydrolyzed into their monomers. (Contrast with lysosome.)
smooth endoplasmic reticulum (SER)
Portion of the endoplasmic reticulum that lacks ribosomes and has a tubular appearance. (Contrast with rough endoplasmic reticulum.)
surface area-to-volume ratio
For any cell, organism, or geometrical solid, the ratio of surface area to volume; this is an important factor in setting an upper limit on the size a cell or organism can attain.
A flattened sac within a chloroplast. Thylakoid membranes contain all of the chlorophyll in a plant, in addition to the electron carriers of photophosphorylation. Thylakoids stack to form grana.
A protein that polymerizes to form microtubules.
Membrane-enclosed organelle in plant cells that can function for storage, water concentration for turgor, or hydrolysis of stored macromolecules.
Within the cytoplasm, a membrane-enclosed compartment that is associated with other organelles; the Golgi complex is one example.