Ch. 6 - A Tour of the Cell Flashcards
An optical instrument with lenses that refract (bend) visible light to magnify images of specimens.
Light Microscope (LM)
Any of several membrane-enclosed structures with specialized functions, suspended in the cytosol of eukaryotic cells.
Organelle
A microscope that uses magnets to focus an electron beam on or through a specimen, resulting in a practical resolution that is 100-fold greater than that of a light microscope using standard techniques.
Electron Microscope (EM)
A microscope that uses an electron beam to scan the surface of a sample, coated with metal atoms, to study details of its topography.
Scanning Electron Microscope (SEM)
A microscope that passes an electron beam through very thin sections stained with metal atoms and is primarily used to study the internal structure of cells.
Transmission Electron Microscope (TEM)
The disruption of a cell and separation of its parts by centrifugation at successively higher speeds.
Cell Fractionation
The semifluid portion of the cytoplasm.
Cytosol
A type of cell with a membrane-enclosed nucleus and membrane-enclosed organelles.
Eukaryotic Cell
A type of cell lacking a membrane-enclosed nucleus and membrane-enclosed organelles.
Prokaryotic Cell
A non-membrane-enclosed region in a prokaryotic cell where its chromosome is located.
Nucleoid
The contents of the cell bounded by the plasma membrane; in eukaryotes, the portion exclusive of the nucleus.
Cytoplasm
The membrane at the boundary of every cell that acts as a selective barrier, regulating the cell’s chemical composition.
Plasma Membrane
(1) An atom’s central core, containing protons and neutrons. (2) The organelle of a eukaryotic cell that contains the genetic material in the form of chromosomes, made up of chromatin. (3) A cluster of neurons.
Nucleus
In a eukaryotic cell, the double membrane that surrounds the nucleus, perforated with pores that regulate traffic with the cytoplasm. The outer membrane is continuous with the endoplasmic reticulum.
Nuclear Envelope
A netlike array of protein filaments that lines the inner surface of the nuclear envelope and helps maintain the shape of the nucleus.
Nuclear Lamina
A cellular structure consisting of one DNA molecule and associated protein molecules. (In some contexts, such as genome sequencing, the term may refer to the DNA alone).
Chromosome
The complex of DNA and proteins that makes up eukaryotic chromosomes.
Chromatin
A specialized structure in the nucleus, consisting of chromosomal regions containing ribosomal RNA (rRNA) genes along with ribosomal proteins imported from the cytoplasm; site of rRNA synthesis and ribosomal subunit assembly.
Nucleolus
A complex of rRNA and protein molecules that functions as a site of protein synthesis in the cytoplasm; consists of a large and a small subunit. In eukaryotic cells, each subunit is assembled in the nucleolus.
Ribosome
The collection of membranes inside and surrounding a eukaryotic cell, related either through direct physical contact or by the transfer of membranous vesicles; includes the plasma membrane, the nuclear envelope, the smooth and rough endoplasmic reticulum, the Golgi apparatus, lysosomes, vesicles, and vacuoles.
Endomembrane System
A membranous sac in the cytoplasm of a eukaryotic cell.
Vesicle
An extensive membranous network in eukaryotic cells, continuous with the outer nuclear membrane and composed of ribosome-studded (rough) and ribosome-free (smooth) regions.
Endoplasmic Reticulum (ER)
That portion of the endoplasmic reticulum that is free of ribosomes.
Smooth ER
That portion of the endoplasmic reticulum with ribosomes attached.
Rough ER
A protein with one or more covalently attached carbohydrates.
Glycoprotein
A small membranous sac in a eukaryotic cell’s cytoplasm carrying molecules produced by the cell.
Transport Vesicle
An organelle in eukaryotic cells consisting of stacks of flat membranous sacs that modify, store, and route products of the endoplasmic reticulum and synthesize some products, notably noncellulose carbohydrates.
Golgi Apparatus
A membrane-enclosed sac of hydrolytic enzymes found in the cytoplasm of animal cells and some protists.
Lysosome
A type of endocytosis in which large particulate substances or small organisms are taken up by a cell. It is carried out by some protists and by certain immune cells of animals (in mammals, mainly macrophages, neutrophils, and dendritic cells).
Phagocytosis
A membrane-bounded vesicle whose specialized function varies in different kinds of cells.
Vacuole
A membranous sac formed by phagocytosis of microorganisms or particles to be used as food by the cell.
Food Vacuole
A membranous sac that helps move excess water out of certain freshwater protists.
Contractile Vacuole
In a mature plant cell, a large membranous sac with diverse roles in growth, storage, and sequestration of toxic substances.
Central Vacuole
An organelle in eukaryotic cells that serves as the site of cellular respiration; uses oxygen to break down organic molecules and synthesize ATP.
Mitochondrion
An organelle found in plants and photosynthetic protists that absorbs sunlight and uses it to drive the synthesis of organic compounds from carbon dioxide and water.
Chloroplast
The theory that mitochondria and plastids, including chloroplasts, originated as prokaryotic cells engulfed by a host cell. The engulfed cell and its host cell then evolved into a single organism.
Endosymbiont Theory
An infolding of the inner membrane of a mitochondrion. The inner membrane houses electron transport chains and molecules of the enzyme catalyzing the synthesis of ATP (ATP synthase).
Crista (plural, Cristae)
The compartment of the mitochondrion enclosed by the inner membrane and containing enzymes and substrates for the citric acid cycle, as well as ribosomes and DNA.
Mitochondrial Matrix
A flattened, membranous sac inside a chloroplast; their membranes contain molecular “machinery” used to convert light energy to chemical energy.
Thylakoid
A stack of membrane-bounded thylakoids in the chloroplast. They function in the light reactions of photosynthesis.
Granum (plural, Grana)
The dense fluid within the chloroplast surrounding the thylakoid membrane and containing ribosomes and DNA; involved in the synthesis of organic molecules from carbon dioxide and water.
Stroma
One of a family of closely related organelles that includes chloroplasts, chromoplasts, and amyloplasts.
Plastid
An organelle containing enzymes that transfer hydrogen atoms from various substrates to oxygen gas (O2), producing and then degrading hydrogen peroxide (H2O2).
Peroxisome
A network of microtubules, microfilaments, and intermediate filaments that extend throughout the cytoplasm and serve a variety of mechanical, transport, and signaling functions.
Cytoskeleton
A protein that interacts with cytoskeletal elements and other cell components, producing movement of the whole cell or parts of the cell.
Motor Protein
A hollow rod composed of tubulin proteins that makes up part of the cytoskeleton in all eukaryotic cells and is found in cilia and flagella.
Microtubule
A structure present in the cytoplasm of animal cells that functions as a microtubule-organizing center and is important during cell division.
Centrosome
A structure in the centrosome of an animal cell composed of a cylinder of microtubule triplets arranged in a “9 + 0” pattern.
Centriole
A long cellular appendage specialized for locomotion.
Flagellum
A short appendage containing microtubules in eukaryotic cells.
Cilium
A short appendage containing microtubules specialized for locomotion or moving fluid past the cell; it is formed from a core of nine outer doublet microtubules and two inner single microtubules (the “9 + 2” arrangement) ensheathed in an extension of the plasma membrane.
Motile Cilium
A usually nonmotile short appendage containing microtubules that plays a sensory and signaling role; it lacks the two inner microtubules (the “9 + 0” arrangement).
Primary Cilium
A eukaryotic cell structure consisting of a “9 + 0” arrangement of microtubule triplets that may organize the microtubule assembly of a cilium or flagellum and is structurally very similar to a centriole.
Basal Body
In cilia and flagella, a large motor protein extending from one microtubule doublet to the adjacent doublet.
Dynein
A cable composed of actin proteins in the cytoplasm of almost every eukaryotic cell, making up part of the cytoskeleton and acting alone or with myosin to cause cell contraction; also called an actin filament.
Microfilament
A globular protein that links into chains, two of which twist helically about each other, forming microfilaments in muscle and other kinds of cells.
Actin
(1) The outer region of cytoplasm in a eukaryotic cell, lying just under the plasma membrane, that has a more gel-like consistency than the inner regions due to the presence of multiple microfilaments. (2) In plants, ground tissue that is between the vascular tissue and dermal tissue in a root or eudicot stem.
Cortex
A type of motor protein that associates into filaments that interact with actin filaments to cause cell contraction.
Myosin
A cellular extension of amoeboid cells used in moving and feeding.
Pseudopodium
