The Cell Flashcards
Cytosol
Semi-fluid medium found in cytoplasm
Cytoplasm
The region between nucleus and cell membrane
Light Microscope (LM)
Lenses bend visible light to magnify images of specimens
Organelle
Any of several membrane-enclosed structures with specialized functions, suspended in the cytosol of eukaryotic cells
Electron microscope (EM)
Uses magnets to focus an electron beam on or through a spectrum, greater resolution than LM
Scanning electron microscope (SEM)
Uses an electron bean to scan the surface of the sample coated with metal atoms, to study details of it’s topography
Transmission electron microscope (TEM)
Passes an electron beam through very thin sections stained with metal atoms and is primarily used to study the internal ultrastructure of cells
Cell Fractionation
The disruption of a cell and separation of its parts by centrifugation at successively higher speeds
Eukaryotic cell
Type of cell with membrane-enclosed nucleus and membrane-enclosed organelles.
Prokaryotic cell
No nucleus.
DNA is in an unbound region called the nucleoid.
No membrane-bound organelles.
Cytoplasm bound by the plasma membrane.
Nucleoid
A non-membrane-bounded region in a prokaryotic cell where the DNA is concentrated.
Plasma membrane
The membrane at the boundary of every cell that acts as a selective barrier, regulating the cell’s chemical composition.
Nucleus
An atom’s central core, containing protons and neutrons; the organelle of a eukaryotic cell that contains the genetic material in the form of chromosomes, made up of chromatin; a cluster of neutrons.
Nuclear envelope
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. Two lipid bilayers.
Nuclear lamina
A netlike array of protein filaments that lines the inner surface of the nuclear envelope and helps maintain the shape of the nucleus.
Chromosome
A cellular structure carrying genetic material, found in the nucleus of eukaryotic cells. Each chromosome consists of one very long DNA molecule and associated proteins
Chromatin
The complex of DNA and proteins that makes up eukaryotic chromosomes. When the cell is not dividing, chromatin exists in its dispersed form, as a mass of very long, thin fibers that are not visible with a light microscope.
Nucleolus
A specialized structure in the nucleus, consisting of chromosomal regions containing ribosomal RNA (rRNA) genes along with ribosomal proteins imported from cytoplasm; site of rRNA synthesis and ribosomal subunit assembly.
Ribosome
A complex of rRNA and protein molecules that function as a site of protein synthesis in the cytoplasm; consists of a large and small subunit. In eukaryotic cells, each subunit is assembled in the nucleolus. Free ribosome found in cytosol. Bound ribosomes attached to ER.
Endomembrane system
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 ER, the Golgi apparatus, lysosomes, vesicles, and vacuoles.
Vesicle
A membranous sac in the cytoplasm of a eukaryotic cell
Endoplasmic Reticulum (ER)
An extensive membranous network in eukaryotic cells, continuous with the outer nuclear membrane and composed of ribosome-studded (rough) and ribosome-free (smooth) regions.
Smooth ER
The portion of the ER that is free of ribosomes. Functions: synthesizes lipids, phospholipids, and steroids (hormones). Participates in carbohydrate metabolism. Detoxifies drugs & poisons. Stores calcium ions for muscle contraction.
Rough ER
The portion of the ER with ribosomes attached. Functions: protein synthesis. Membrane production.
Glycoprotein
A protein with one or more covalently attached carbohydrates.
Transport vesicle
A small membranous sac in a eukaryotic cell’s cytoplasm carrying molecules produced by the cell.
Golgi apparatus
An organelle in eukaryotic cells consisting of stacks of flat membranous sacs that modify, store, and route products of the ER and synthesize some products, notably noncellular carbohydrates. The cis face accepts transport vesicles from ER. The trans face pinches off vesicles.
Lysosome
A membrane-enclosed sac of hydrolytic enzymes (produced in rough ER) found in the cytoplasm of animal cells and some protists. Contains a stockpile of digestive enzymes, important in breaking down nutrients, destroying bacteria, recycling, and development.
Phagocytosis
A type of endocytosis in which large particulate substances or small organisms are taken up by a cell. It’s carried out by some protists and by certain immune cells of animals (in mammals, mainly macrophages, neutrophilis, and dendritic cells)
Vacuole
A membrane-bounded vesicle whose specialized function varies in different kinds of cells.
Food vacuole
A membranous sac formed by phagocytosis of microorganisms or particles to be used as food by the cell.
Contractile vacuole
A membranous sac formed that helps move excess water out of certain freshwater protists.
Central vacuole
In a mature plant cell, a large membranous sac with diverse roles in growth, storage, and sequestration of toxic substances.
Mitochondria
An organelle in eukaryotic cells that serves as the site of cellular respiration; uses oxygen to break down organic molecules and synthesize ATP.
Chloroplast
An organelle found in plants and photosynthetic protists that absorbs sunlight and uses it to drive the synthesis of organic compounds from carbon dioxide.
Endosymbiont theory
The theory that mitochondria and plastids, including chloroplasts, originated as prokaryotic cells engulfed by an ancestral eukaryotic cell. The engulfed cell and its host cell then evolved into a single organism.
Cristae
An infolding of the inner membrane of mitochondrion. The inner membrane houses electron transport chains and molecules of the enzyme catalyzing the synthesis of ATP (ATP synthase)
Mitochondrial matrix
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.
Thylakoid
A flattened, membranous sac inside a chloroplast. Often exist in stacks called grana that are interconnected; their membranes contain molecular “machinery” used to convert light energy to chemical energy.
Granum
A stack of membrane-bounded thylakoids in the chloroplast. Grana function in the light reactions of photosynthesis.
Stroma
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.
Plastid
One of a family of closely related organelles that includes chloroplasts, chromoplasts, and amlyoplasts. Found in cells of photosynthetic eukaryotes.
Peroxisome
An organelle containing enzymes that transfer hydrogen atoms from various substrates to oxygen (O2), producing and the degrading hydrogen peroxide (H2O2)
Cytoskeleton
A network of microtubules, microfilaments, and intermediate filaments that extend throughout the cytoplasm and serve a variety of mechanical, transport, and signaling functions.
Microtubules
Thickest fiber. Made from globular protein tubulin. Straight, hollow fibers (25 nm diameter). Elongated/shortened by adding/removing tubulin units. Functions: cellular support, inner structure of cilia & flagella. Tracks for organelle movement. Separation of chromosomes during mitosis.
Microfilaments
Actin filaments. Made from globular protein G-actin. Solid rods (7 nm diameter). Functions: interact with myosin during muscle contraction. Involved in cell division, pseudopodia movement.
Intermediate filaments
Solid wound bundles of keratin subunits (8-12 nm diameter). More permanent. Functions: tension bearing filaments. Reinforce cell shape (e.g. nerve axons). Strengthen and line the nuclear envelope.
Motor protein
A protein that interacts with cytoskeletal elements and other cell components, producing movement of the whole cell or parts of the cell.
Centrosome
A structure present in the cytoplasm of animal cells that functions as a microtubule-organizing center and is important during cell division; has 2 centrioles.
Centriole
A structure in the centrosome of an animal cell composed of a cylinder of microtubule triplets arranged in a 9+0 pattern.
Flagella
A long cellular appendage specialized for locomotion. Like motile cilia, eukaryotic flagella have a core with 9 outer doublet microtubules and 2 inner single microtubules (the “9+2” arrangement) ensheathed in an extension of the plasma membrane.
Cilia
A short appendage containing microtubules in eukaryotic cells. A motile cillium is specialized for locomotion or moving fluid past the cell; formed from a core of 9 outer doublet microtubules and 2 inner single microtubules (the “9+2” arraignment) ensheathed in an extension of the plasma membrane. Primary cillium usually nonmotile and plays sensory and signaling role; lacks 2 inner microtubules (the “9+2” structure)
Power stroke
Cilium extended, stiff, fast movement. Plane of movement perpendicular to surface.
Recover stroke
Cilium bends forward, slow movement. Plane parallel to surface.
Undulatory (wave) movements
From cell to flagellar tip push cell. From tip to cell pull cell.
Basal body
A eukaryotic cell structure consisting of a “9+0” arrangement of microtubule triplets. The basal body may organize the microtubule assembly of a cilium of flagellum and is structurally very similar to a centriole.
Dynein
In cilia and flagella, a large motor protein extending from 1 microtubule doublet to the adjacent doublet. ATP hydrolysis drives changes in its shape that lead to bending of cilia and flagella.
Actin
A globular protein that links into chains, 2 of which twist helically about each other, forming microfilaments (actin filaments) in muscle and other kinds of cells.
Cortex
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; in plants, ground tissue and the dermal tissue in a root or eudicot stem.
Myosin
A type of motor protein that associates into filaments that interact with actin filaments to cause cell contraction.
Pseudopodia
A cellular extension of amoeboid cells used in moving and feeding.
Cytoplasmic streaming
A circular flow of cytoplasm, involving interactions of myosin and actin filaments, that speeds the distribution of materials within cells.
Cell wall
A protective layer external to the plasma membrane in the cells of plants, prokaryotes, fungi and some protists. Polysaccharides such as cellulose (in plants and some protists), chitin (in fungi), and peptidoglycan (in bacteria) are important structural components of them.
Primary cell wall
The level of protein structure referring to the specific linear sequence of amino acids.
Middle lamella
In plants, a thin layer of adhesive extracellular material, primarily pectins, found between the primary walls of adjacent young cells.
Secondary cell wall
Regions of repetitive coiling or folding of the polypeptide backbone of a protein due to hydrogen bonding between constituents of the backbone (not the side chains)
Extracellular matrix (ECM)
The meshwork surrounding animal cells, consisting of glycoproteins, polysaccharides and proteoglycans synthesized and secreted by the cells. Functions: provides support & anchorage. Acts as a “glue” to hold cells together. Allows cells to communicate with external environment.
Collagen
A glycoprotein in the extracellular matrix of animal cells that forms strong fibers, doing extensively in connective tissue and bone; the most abundant protein in the animal kingdom.
Proteoglycan
A large molecule consisting of a small core protein with many carbohydrate chains attached, found in the extracellular matrix of animal cells; may consist of up to 95% carbohydrate.
Integrin
In animal cells, a transmembrane receptor protein with 2 subunits that interconnects the extracellular matrix and the cytoskeleton.
Tight junction
A type of intercellular junction between animal cells that prevents the leakage of material through the spaces between cells.
Plasmodesmata
An open channel through the cell wall that connects the cytoplasm of adjacent plant cells, allowing water, small solutes, and some larger molecules to pass between the cells.
Desmosomes
A type of intercellular junction in animal cells that functions as a rivet, fastening cells together.
Gap junction
A type of intercellular connection in animal cells, consisting of proteins surrounding a pore that allows the passage of materials between cells.
Nucleic acid
A polymer (polynucleotide) consisting of many nucleotide monomers; serves as a blueprint for proteins and, through the actions of proteins, for all cellular activities. The two types are DNA and RNA.
Deoxyribonucleic acid (DNA)
A double-stranded, helical nucleic acid molecule capable of replicating and determining the inherited structure of a cells proteins.
