Chapter 6 Vocabulary Remote

Plasmodesma

Plasmodesma

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.

smooth ER

That portion of the endoplasmic reticulum that is free of ribosomes

transport vesicle

A small membranous sac in a eukaryotic cell's cytoplasm carrying molecules produced by the cell

vacuole

A membrane-bounded vesicle whose specialized function varies in different kinds of cells

Vesicle

A membranous sac in the cytoplasm of a eukaryotic cell

tight junction

A type of intercellular junction between animal cells that prevents the leakage of material through the space between cells.

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

rough ER

That portion of the endoplasmic reticulum with ribosomes attached

scanning electron microscope (SEM)

A microscope that uses an electron beam to scan the surface of a sample, coated with metal atoms, to study details of its topography.

secondary cell wall

In plant cells, a strong and durable matrix that is often deposited in several laminated layers around the plasma membrane and provides protection and support

Pseudopodium

A cellular extension of amoeboid cells used in moving and feeding

Ribosome

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.

Proteoglycan

A large molecule consisting of a small core protein with many carbohydrate chains attached, found in the extracellular matrix of animal cells

primary cell wall

In plants, a relatively thin and flexible layer that surrounds the plasma membrane of a young cell.

prokaryotic cell

A type of cell lacking a membrane-enclosed nucleus and membrane-enclosed organelles.

plastid

One of a family of closely related organelles that includes chloroplasts, chromoplasts, and amyloplasts.

Mitochondrion

An organelle in eukaryotic cells that serves as the site of cellular respiration

Organelle

Any of several membrane-enclosed structures with specialized functions, suspended in the cytosol of eukaryotic cells

phagocytosis

A type of endocytosis in which large particulate substances or small organisms are taken up by a cell.

plasma membrane

The membrane at the boundary of every cell that acts as a selective barrier, regulating the cell's chemical composition

Peroxisome

An organelle containing enzymes that transfer hydrogen atoms from various substrates to oxygen (O2), producing and then degrading hydrogen peroxide (H2O2).

nucleoid

A non-membrane-enclosed region in a prokaryotic cell where its chromosome is located.

Nucleus

The organelle of a eukaryotic cell that contains the genetic material in the form of chromosomes, made up of chromatin.

Nucleolus

A specialized structure in the nucleus, site of rRNA synthesis and ribosomal subunit assembly.

nuclear envelope

In a eukaryotic cell, the double membrane that surrounds the nucleus, perforated with pores that regulate traffic with the cytoplasm.

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

Myosin

A type of motor protein that associates into filaments that interact with actin filaments to cause cell contraction

motor protein

A protein that interacts with cytoskeletal elements and other cell components, producing movement of the whole cell or parts of the cell

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

desmosome

A type of intercellular junction in animal cells that functions as a rivet, fastening cells together

microfilament

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

lysosome

A membrane-enclosed sac of hydrolytic enzymes found in the cytoplasm of animal cells and some protists

microtubule

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.

middle lamella

In plants, a thin layer of adhesive extracellular material, primarily pectins, found between the primary walls of adjacent young cells

light microscope (LM)

An optical instrument with lenses that refract (bend) visible light to magnify images of specimens.

intermediate filament

A component of the cytoskeleton that includes filaments intermediate in size between microtubules and microfilaments

integrin

In animal cells, a transmembrane receptor protein with two subunits that interconnects the extracellular matrix and the cytoskeleton

glycoprotein

A protein with one or more covalently attached carbohydrates

Granum (plural, grana)

A stack of membrane-bounded thylakoids in the chloroplast. Grana function in the light reactions of photosynthesis

flagellum (plural, flagella)

A long cellular appendage specialized for locomotion.

gap junction

A type of intercellular junction in animal cells, consisting of proteins surrounding a pore that allows the passage of materials between cells

Golgi apparatus

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

extracellular matrix (ECM)

The meshwork surrounding animal cells, consisting of glycoproteins, polysaccharides, and proteoglycans synthesized and secreted by cells

fibronectin

An extracellular glycoprotein secreted by animal cells that helps them attach to the extracellular matrix

eukaryotic cell

A type of cell with a membrane-enclosed nucleus and membrane-enclosed organelles.

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 endoplasmic reticulum, the Golgi apparatus, lysosomes, vesicles, and vacuoles

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

electron microscope (EM)

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.

contractile vacuole

A membranous sac that helps move excess water out of certain freshwater protists

Cytoplasm

The contents of the cell bounded by the plasma membrane; in eukaryotes, the portion exclusive of the nucleus

cytoplasmic streaming

A circular flow of cytoplasm, involving interactions of myosin and actin filaments, that speeds the distribution of materials within cells.

Cytoskeleton

A network of microtubules, microfilaments, and intermediate filaments that extend throughout the cytoplasm and serve a variety of mechanical, transport, and signaling functions

cytosol

The semifluid portion of the cytoplasm

crista

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

actin

A globular protein that links into chains, two of which twist helically about each other, forming microfilaments (actin filaments) in muscle and other kinds of cells.

cell fractionation

The disruption of a cell and separation of its parts by centrifugation at successively higher speeds

cell wall

A protective layer external to the plasma membrane in the cells of plants, prokaryotes, fungi, and some protists.

central vacuole

In a mature plant cell, a large membranous sac with diverse roles in growth, storage, and sequestration of toxic substances

centriole

A structure in the centrosome of an animal cell composed of a cylinder of microtubule triplets arranged in a "9 + 0" pattern. A centrosome has two.

centrosome

A structure present in the cytoplasm of animal cells that functions as a microtubule-organizing center and is important during cell division. It has two centrioles.

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 and water

Chromatin

The complex of DNA and proteins that makes up eukaryotic chromosomes. When the cell is not dividing, it exists in its dispersed form, as a mass of very long, thin fibers that are not visible with a light microscope.

Chromosome

A cellular structure consisting of one DNA molecule and associated protein molecules.

cilium (plural, cilia)

A short appendage containing microtubules in eukaryotic cells.

collagen

A glycoprotein in the extracellular matrix of animal cells that forms strong fibers, found extensively in connective tissue and bone; the most abundant protein in the animal kingdom