Biol 1406 Chapter 6 Vocab

Front 1

actin

Back 1

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.

Front 2

basal body

Back 2

A eukaryotic cell structure consisting of a 9 + 0 arrangement of microtubule triplets. The basal body may organize the microtubule assembly of a cilium or flagellum and is structurally very similar to a centriole.

Front 3

capsule

Back 3

(1) A sticky layer that surrounds the cell wall of some prokaryotes, protecting the cell surface and sometimes helping to glue the cell to surfaces.
(2) The sporangium of a bryophyte (moss, liverwort, or hornwort).

Front 4

cell fractionation

Back 4

The disruption of a cell and separation of its parts by centrifugation.

Front 5

central vacuole

Back 5

A membranous sac in a mature plant cell with diverse roles in reproduction, growth, and development.

Front 6

centriole

Back 6

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 a pair of centrioles.

Front 7

centrosome

Back 7

Structure present in the cytoplasm of animal cells, important during cell division; functions as a microtubule-organizing center. A centrosome has two centrioles.

Front 8

chloroplast

Back 8

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.

Front 9

chromatin

Back 9

The complex of DNA and proteins that makes up a eukaryotic chromosome. 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.

Front 10

chromosome

Back 10

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. (A bacterial chromosome usually consists of a single circular DNA molecule and associated proteins. It is found in the nucleoid region, which is not membrane bounded.) See also chromatin.

Front 11

cilium

Back 11

A short cellular appendage containing microtubules. A motile cilium is specialized for locomotion and 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. A primary cilium is usually nonmotile and plays a sensory and signaling role; it lacks the two inner microtubules (the “9 + 0” arrangement). (plural, cilia)

Front 12

collagen

Back 12

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.

Front 13

contractile vacuole

Back 13

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

Front 14

crista

Back 14

An infolding of the inner membrane of a mitochondrion that houses electron transport chains and molecules of the enzyme catalyzing the synthesis of ATP (ATP synthase).

Front 15

cytoplasm

Back 15

The contents of the cell, exclusive of the nucleus and bounded by the plasma membrane.

Front 16

cytoplasmic streaming

Back 16

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

Front 17

cytoskeleton

Back 17

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

Front 18

cytosol

Back 18

The semifluid portion of the cytoplasm.

Front 19

desmosome

Back 19

A type of intercellular junction in animal cells that functions as a rivet.

Front 20

dynein

Back 20

In cilia and flagella, a large contractile protein extending from one microtubule doublet to the adjacent doublet. ATP hydrolysis drives changes in dynein shape that lead to bending of cilia and flagella.

Front 21

electron microscope (EM)

Back 21

A microscope that uses magnets to focus an electron beam on or through a specimen, resulting in resolving power a thousandfold greater than that of a light microscope.

Front 22

endomembrane system

Back 22

The collection of membranes inside and around a eukaryotic cell, related either through direct physical contact or by the transfer of membranous vesicles; includes the smooth and rough endoplasmic reticulum, the Golgi apparatus, lysosomes, and vacuoles.

Front 23

endoplasmic reticulum (ER)

Back 23

An extensive membranous network in eukaryotic cells, continuous with the outer nuclear membrane and composed of ribosome-studded (rough) and ribosome-free (smooth) regions.

Front 24

eukaryotic cell

Back 24

A type of cell with a membrane-enclosed nucleus and membrane-enclosed organelles. Organisms with eukaryotic cells (protists, plants, fungi, and animals) are called eukaryotes.

Front 25

extracellular matrix (ECM)

Back 25

The substance in which animal cells are embedded, consisting of protein and polysaccharides synthesized and secreted by cells.

Front 26

fibronectin

Back 26

A glycoprotein that helps animal cells attach to the extracellular matrix.

Front 27

flagellum

Back 27

A long cellular appendage specialized for locomotion. Like motile cilia, eukaryotic flagella have a core with nine outer doublet microtubules and two inner single microtubules ensheathed in an extension of the plasma membrane. Prokaryotic flagella have a different structure. (plural, flagella)

Front 28

food vacuole

Back 28

A membranous sac formed by phagocytosis of microorganisms or particles to be used as food by the cell.

Front 29

gap junction

Back 29

A type of intercellular junction in animals that allows the passage of materials between cells.

Front 30

glycoprotein

Back 30

A protein with one or more carbohydrates covalently attached to it.

Front 31

Golgi apparatus

Back 31

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.

Front 32

granum

Back 32

A stack of membrane-bounded thylakoids in the chloroplast. Grana function in the light reactions of photosynthesis. (plural, grana)

Front 33

integrin

Back 33

in animal cells, a transmembrane receptor protein that interconnects the extracellular matrix and the cytoskeleton.

Front 34

intermediate filament

Back 34

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

Front 35

light microscope (LM)

Back 35

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

Front 36

lysosome

Back 36

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

Front 37

microfilament

Back 37

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 known as an actin filament.

Front 38

microtubule

Back 38

A hollow rod composed of tubulin proteins that make up part of the cytoskeleton in all eukaryotic cells and is found in cilia and flagella.

Front 39

middle lamella

Back 39

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

Front 40

mitochondrial matrix

Back 40

The compartment of the mitochondrion enclosed by the inner membrane and containing enzymes and substrates for the citric acid cycle.

Front 41

mitochondrion

Back 41

An organelle in eukaryotic cells that serves as the site of cellular respiration. (plural, mitochondria)

Front 42

motor protein

Back 42

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

Front 43

nuclear envelope

Back 43

The double membrane in a eukaryotic cell that encloses the nucleus, separating it from the cytoplasm.

Front 44

nuclear lamina

Back 44

A netlike array of protein filaments lining the inner surface of the nuclear envelope; it helps maintain the shape of the nucleus.

Front 45

nucleoid

Back 45

A dense region of DNA in a prokaryotic cell.

Front 46

nucleolus

Back 46

A specialized structure in the nucleus, consisting of chromatin regions containing ribosomal RNA genes along with ribosomal proteins imported from the cytoplasmic site of rRNA synthesis and ribosomal subunit assembly. (plural, nucleoli)
See also ribosome.

Front 47

nucleus

Back 47

(1) An atom’s central core, containing protons and neutrons.
(2) The chromosome-containing organelle of a eukaryotic cell.
(3) A cluster of neurons.

Front 48

organelle

Back 48

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

Front 49

peroxisome

Back 49

An organelle containing enzymes that transfer hydrogen (H2) from various substrates to oxygen (O2), producing and then degrading hydrogen peroxide (H2O2).

Front 50

phagocytosis

Back 50

A type of endocytosis in which large particulate substances 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).

Front 51

plasma membrane

Back 51

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

Front 52

plasmodesma

Back 52

An open channel in the cell wall of a plant through which strands of cytosol connect from an adjacent cell. (plural, plasmodesmata)

Front 53

plastid

Back 53

One of a family of closely related organelles that includes chloroplasts, chromoplasts, and amyloplasts (leucoplasts). Plastids are found in cells of photosynthetic organisms.

Front 54

primary cell wall

Back 54

In plants, a relatively thin and flexible layer first secreted by a young cell.

Front 55

prokaryotic cell

Back 55

A type of cell lacking a membrane-enclosed nucleus and membrane-enclosed organelles. Organisms with prokaryotic cells (bacteria and archaea) are called prokaryotes.

Front 56

proteoglycan

Back 56

A glycoprotein consisting of a small core protein with many carbohydrate chains attached, found in the extracellular matrix of animal cells. A proteoglycan may consist of up to 95% carbohydrate.

Front 57

pseudopodium

Back 57

A cellular extension of amoeboid cells used in moving and feeding. (plural, pseudopodia)

Front 58

ribosomal RNA (rRNA)

Back 58

The most abundant type of RNA, which together with proteins makes up ribosomes.

Front 59

ribosome

Back 59

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. See also nucleolus.

Front 60

rough ER

Back 60

That portion of the endoplasmic reticulum studded with ribosomes.

Front 61

scanning electron microscope (SEM)

Back 61

A microscope that uses an electron beam to scan the surface of a sample to study details of its topography.

Front 62

secondary cell wall

Back 62

In plants, a strong and durable matrix often deposited in several laminated layers for cell protection and support.

Front 63

smooth ER

Back 63

That portion of the endoplasmic reticulum that is free of ribosomes.

Front 64

stroma

Back 64

Within the chloroplast, the dense fluid of the chloroplast surrounding the thylakoid membrane; involved in the synthesis of organic molecules from carbon dioxide and water.

Front 65

thylakoid

Back 65

A flattened membranous sac inside a chloroplast. Thylakoids exist in an interconnected system in the chloroplast and contain the molecular “machinery” used to convert light energy to chemical energy.

Front 66

tight junction

Back 66

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

Front 67

transmission electron microscope (TEM)

Back 67

A microscope that passes an electron beam through very thin sections and is primarily used to study the internal ultrastructure of cells.

Front 68

transport vesicle

Back 68

A tiny membranous sac in a cell’s cytoplasm carrying molecules produced by the cell.

Front 69

vacuole

Back 69

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

Front 70

vesicle

Back 70

A sac made of membrane in the cytoplasm.