Chapter 4: A Tour Of The Cell Flashcards
Light microscope
An optical instrument with lenses that refract (bend) visible light to magnify images and project them into a viewer’s eye or onto photographic film.
Electron microscope (EM)
A microscope that uses magnets to focus an electron beam through, or onto the surface of, a specimen. An electron microscope achieves a hundredfold greater resolution than a light microscope.
Cell theory
The theory that all living things are composed of cells and that all cells come from other cells.
Scanning electron microscope (SEM)
A microscope that uses an electron beam to study the surface details of a cell or other specimens.
Transmission electron microscope (TEM)
A microscope that uses an electron beam to study the internal structure of thinly sectioned specimens.
Plasma membrane
The membrane at the boundary of every cell that acts as a selective barrier to the passage of ions and molecules into and out of the cell; consists of a phospholipid belayer with embedded proteins
Prokaryotic cell
A type of cell lacking a membrane- enclosed nucleus and other membrane-enclosed organelles; found only in the domains Bacteria and Archaea.
Eukaryotic cells
A type of cell that has a membrane- enclosed nucleus and membrane-enclosed organelles. All organisms except bacteria and archaea are composed of eukaryotic cells.
Cytosol
The semi fluid portion of the cytoplasm.
Chromosomes
A gene-carrying structure found in the nucleus of a eukaryotic cell and most visible during mitosis and meiosis; also the main gene-carrying structure of a prokaryotic cell. A chromosome consist of one very long DNA molecule and associated proteins.
Ribosomes
A cell structure consisting of RNA and Protein organized into two subunits and functioning as the site of protein synthesis in the cytoplasm. In eukaryotic cells, the ribosomal subunits are constructed in the nucleolus.
Cytoplasm
The contents of a eukaryotic cell between the plasma membrane and the nucleus; consists of a semifluid medium and organelles; can also refer to the interior of a prokaryotic cell.
Nucleoid
A non-membrane bounded region in a prokaryotic cell where the DNA is concentrated.
Flagellum
A long cellular appendage specialized for locomotion. The flagella of prokaryotes and eukaryotes differ in both structure and function. Like cilia, eukaryotic flagella have a “9+2” arrangement of microtubules covered by the cell’s plasma membrane.
