One of the two major proteins of muscle; it makes up the thin filaments. Forms the microfilaments found in most eukaryotic cells
Centriole found at the base of a eukaryotic flagellum or cilium.
The theory, well established, that all organisms consist of cells, and that all cells come from preexisting cells.
A relatively rigid structure that encloses cells of plants, fungi, many protists, and most prokaryotes. Gives these cells their shape and limits their expansion in hypotonic media.
A paired organelle that helps organize the microtubules in animal and protist cells during nuclear division.
Any of a few green pigments associated with chloroplasts or with certain bacterial membranes; responsible for trapping light energy for photosynthesis.
An organelle bounded by a double membrane containing the enzymes and pigments that perform photosynthesis.
The nucleic acid-protein complex found in 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.
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 protein that plays a part in the movement of eukaryotic flagella and cilia by means of conformational changes.
Endoplasmic reticulum plus Golgi apparatus; also lysosomes, when present. A system of membranes that exchange material with one another.
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.
Two species living together, with one living inside the body (or even the cells) of the other.
Organisms whose cells contain their genetic material inside a nucleus. Includes all life other than the viruses, archaea, and bacteria.
In animal tissues, a material of heterogeneous composition surrounding cells and performing many functions including adhesion of cells.
Long, whiplike appendage that propels cells.
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 cell by exocytosis
Within a chloroplast, a stack of thylakoids.
Cytoskeletal component with diameters between the larger microtubules and smaller microfilaments.
Motor protein having the capacity to attach to organelles or vesicles and move them along microtubules of the cytoskeleton.
membrane-enclosed organelle found in eukaryotic cells (other than plants). Lysosomes contain a mixture of enzymes that can digest most of the macromolecules found in the rest of the cell.
Minute fibrous structure generally composed of actin found in the cytoplasm of eukaryotic cells. They play a role in the motion of cells.
Minute 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.
One of the two major proteins of muscle, it makes up the thick filaments.
The surface, consisting of two layers of membrane, that encloses the nucleus of eukaryotic 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.
The fluid material within the nuclear envelope of a cell, as opposed to the chromosomes, nucleoli, and other particulate constituents.
In cells, the centrally located compartment of eukaryotic cells that is bounded by a double membrane and contains the chromosomes
Organized structures that are found in or on cells. Examples: ribosomes, nuclei, mitochrondria, chloroplasts, cilia, and contractile vacuoles
An organelle that houses reactions in which toxic peroxides are formed. The peroxisome isolates these peroxides from the rest of the cell.
A white blood cell that ingests microorganisms by endocytosis.
Metabolic processes, carried out by green plants, by which visible light is trapped and the energy used to synthesize compounds such as ATP and glucose.
The membrane that surrounds the cell, regulating the entry and exit of molecules and ions. Every cell has a plasma membrane.
Organelle in plants that serves for food manufacture (by photosynthesis) or food storage; bounded by a double membrane.
Organisms whose genetic material is not contained within a nucleus: the bacteria and archaea. Considered an earlier stage in the evolution of life than the eukaryotes.
Aggregates of abiotically produced molecules that cannot reproduce but do maintain internal chemical environments that differ from their surroundings.
Cellular respiration; the catabolic pathways by which electrons are removed from various molecules and passed through intermediate electron carriers to O2, generating H2O and releasing energy.
A small organelle that is the site of protein synthesis.
That portion of the endoplasmic reticulum whose outer surface has attached ribosomes
The fluid contents of an organelle such as a chloroplast
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.
The living together of two or more species in a prolonged and intimate ecological relationship.
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.
protein that polymerizes to form microtubules.
A liquid-filled, membrane-enclosed compartment in cytoplasm; may function as digestive chambers, storage chambers, waste bins
A membrane enclosed compartment within the cytoplasm.