Chapter 4: A tour of the cell

Question 1

cytoskeleton

Answer 1

A network of protein fibers in the cytoplasm of a eukaryotic cell; includes microfilaments, intermediate filaments, and microtubules.

Question 2

vesicle

Answer 2

a sac made of membrane in the cytoplasm of a eukaryotic cell.

Question 3

ribosome

Answer 3

a cell structure consisting of RNA and protein organized into two subunits and functioning as the site of protein synthesis in the cytoplasm. The ribosomal subunits are constructed in the nucleolus.

Question 4

endomembrane system

Answer 4

a network of membranes inside and around a eukaryotic cell, related either through direct physical contact or by the transfer of membranous vesicles.

Question 5

glycoprotein

Answer 5

a macromolecule consisting of one or more polypeptides linked to short chains of sugars.

Question 6

intermediate filament

Answer 6

an intermediate-sized protein fiber that is one of the three main kinds of fibers making up the cytoskeleton of eukaryotic cells. Intermediate filaments are rope like, made of fibrous proteins

Question 7

thylakoid

Answer 7

one of a number of disk-shaped membranous sacs inside a chloroplast. Thylakoid membranes contain chlorophyll and the enzymes of the light reactions of photosynthesis. A stack of thylakoids is called a granum.

Question 8

scanning electron microscope (SEM)

Answer 8

a microscope that uses an electron beam to study the surface architecture of a cell or other specimen

Question 9

plasma membrane

Answer 9

the membrane that sets a cell off from its surroundings and acts as a selective barrier to the passage of ions and molecules into and out of the cell; consists of a phospholipid bilayer in which are embedded molecules of protein and cholesterol.

Question 10

chromosome

Answer 10

a threadlike, 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. Chromosomes consist of chromatin, a combination of DNA and protein.

Question 11

eukaryotic cell

Answer 11

a type pf cell that has a membrane-enclosed nucleus and other membrane-enclosed organelles. All organisms except bacteria and archaea are composed of eukaryotic cells.

Question 12

transport vesicle

Answer 12

a tiny membranous sac in a cell’s cytoplasm carrying molecules produced by the cell. The vesicle buds from the endoplasmic reticulum or Golgi and eventually fuses with another membranous organelle or the plasma membrane, releasing its contents.

Question 13

flagellum

Answer 13

(plural, flagella) 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 1 2 arrangement of microtubules covered by the cell’s plasma membrane.

Question 14

crista

Answer 14

(plural, cristae) an infolding of the inner membrane of a mitochondrion in which is embedded the electron transport chain and the enzyme catalyzing the synthesis of ATP

Question 15

plasmodesma

Answer 15

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

Question 16

golgi apparatus

Answer 16

an organelle in eukaryotic cells consisting of stacks of membranous sacs that modify, store, and ship products of the endoplasmic reticulum.

Question 17

central vacuole

Answer 17

a membrane-enclosed sac occupying most of the interior of a mature plant cell, having diverse roles in reproduction, growth, and development

Question 18

prokaryotic cell

Answer 18

a type of cell lacking a membrane-enclosed nucleus and other membrane-enclosed organelles; found only in the domains Bacteria and Archaea.

Question 19

extracellular matrix (ECM)

Answer 19

a substance in which the cells of an animal tissue are embedded; consists of protein and polysaccharides

Question 20

organelle

Answer 20

a membrane-enclosed structure with a specialized function within a cell

Question 21

nucleus

Answer 21

(plural, nuclei) 1) an atom’s central core, containing protons and neutrons. 2) The genetic control center of a eukaryotic cell.

Question 22

endoplasmic reticulum (ER)

Answer 22

an extensive membranous network in a eukaryotic cell, continuos with the outer nuclear membrane and composed of ribosome-studded (rough) and ribosome-free (smooth) regions.

Question 23

microtubule

Answer 23

The thickest of the three main kinds of fibers making up the cytoskeleton of a eukaryotic cell; a straight, hollow tube made of globular proteins called tubulins. Microtubules form the basis of the structure and movement of cilia and flagella.

Question 24

microfilament

Answer 24

the thinnest of the three main kinds of protein fibers making up the cytoskeleton of a eukaryotic cell; a solid, helical rod composed of the globular protein actin.

Question 25

lysosome

Answer 25

a digestive organelle in eukaryotic cells; contains hydrolytic enzymes that digest the cell’s food and wastes.

Question 26

micrograph

Answer 26

a photograph taken through a microscope

Question 27

peroxisome

Answer 27

an organelle containing enzymes that transfer hydrogen from various substrates to oxygen, producing and then degrading hydrogen peroxide

Question 28

cell theory

Answer 28

The theory that all living things are composed of cells and that all cells come from other cells.

Question 29

chromatin

Answer 29

the complex of DNA and proteins that constitutes eukaryotic chromosomes; often used to refer to the diffuse, very extended form taken by chromosomes when a cell is not dividing.

Question 30

cellular metabolism

Answer 30

the chemical activities of cells

Question 31

nuclear envelope

Answer 31

a double membrane, perforated with pores, which encloses the nucleus and separates it from the rest of the eukaryotic cell.

Question 32

nucleolus

Answer 32

a structure within the nucleus of a eukaryotic cell where ribosomal RNA is made and assembled with proteins imported from the cytoplasm to make ribosomal subunits.

Question 33

mitochondrion

Answer 33

(plural, mitochondria) an organelle in eukaryotic cels where cellular respiration occurs. Enclosed by two concentric membranes, it is where most of the cell’s ATP is made.

Question 34

cilia

Answer 34

a short cellular appendage specialized for locomotion formed from a core of nine outer doublet microtubules and two single microtubules covered by the cell’s plasma membrane.

Question 35

granum

Answer 35

(plural, grana) a stack of hollow disks formed of thylakoid membrane in a chloroplast. Grana are the sites where light energy is trapped by chlorophyll and converted to chemical energy during the light reactions of photosynthesis.

Question 36

electron microscope (EM)

Answer 36

An instrument that focuses an electron beam through, or onto the surface of, a specimen. An electron microscope achieves a hundredfold greater resolution than a light microscope.

Question 37

transmission electron microscope (TEM)

Answer 37

A microscope that uses an electron beam to study the internal structure of thinly sectioned specimens.

Question 38

vacuole

Answer 38

a membrane-enclosed sac that is part of the endomembrane system of a eukaryotic cell, having diverse functions.

Question 39

centriole

Answer 39

a structure in an animal cell composed of cylinders of microtubule triplets arranged in a 9 and 0 pattern. An animal usually has a centrosome with a pair of centrioles involved in a cell division.

Question 40

nucleoid

Answer 40

a dense region of DNA in a prokaryotic cell

Question 41

rough ER

Answer 41

a network of interconnected membranous sacs in a eukaryotic cell’s cytoplasm. Rough ER membranes are studded with ribosomes that make membrane proteins and secretory proteins.

Question 42

stroma

Answer 42

The fluid of the chloroplast surrounding the thylakoid membrane; involved in the synthesis of organic molecules from carbon dioxide and water; Sugars are made in the stroma by the enzymes of the calvin cycle.

Question 43

mitichondrial matrix

Answer 43

the fluid contained within the inner membrane of a mitochondrion.

Question 44

light microscope (LM)

Answer 44

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.

Question 45

cytoplasm

Answer 45

Everything inside a cell between the plasma membrane and the nucleus; consists of a semifluid medium and organelles.

Question 46

endosymbiosis

Answer 46

A process by which the mitochondria and chloroplasts of eukaryotic cells probably evolved from symbiotic associations between small prokaryotic cells living inside larger cells.

Question 47

cell wall

Answer 47

a protective layer external to the plasma membrane in plant cells, bacteria, fungi, and some protists; protects the cell and helps maintain its shape.

Question 48

chloroplast

Answer 48

an organelle found in plants and photosynthetic protists that absorbs sunlight and uses it to drive the synthesis of organic molecules (sugars) from carbon dioxide and water.