chapter 4: a tour of the cell

Question 1

organelles

Answer 1

membrane-enclosed compartments

Question 2

cytosol

Answer 2

semifluid substance in all cells

Question 3

eukaryotic cell

Answer 3

cell that has a nucleus, an organelle that is bounded by a double membrane; most of its DNA is in the nucleus

Question 4

prokaryotic cell

Answer 4

cell that does not have a nucleus; DNA is in the nucleoid

Question 5

nucleoid

Answer 5

an unbound region that has prokaryotic cells’ DNA

Question 6

cytoplasm

Answer 6

the substance between a cell’s plasma membrane, including the organelles

Question 7

plasma membrane

Answer 7

a selective barrier that allows passage of oxygen, nutrients, and waste to service the volume of every cell

Question 8

nucleus

Answer 8

organelle that contains most of the cell’s genes and is usually the most conspicuous organelle

Question 9

nuclear envelope

Answer 9

membrane barrier that encloses the nucleus, separating it from the cytoplasm; double membrane, with each membrane consisting of a lipid bilayer

Question 10

nuclear lamina

Answer 10

network of protein filaments that maintain the shape of the nucleus

Question 11

chromosomes

Answer 11

discrete units of organized DNA

Question 12

chromatin

Answer 12

the DNA and proteins of chromosomes together (DNA wrapped around proteins)

Question 13

nucleolus

Answer 13

a spherical structure located within the nucleus that synthesizes ribosomal RNA

Question 14

ribosomes

Answer 14

organelles that synthesize proteins by reading mRNA and translate the genetic codes into amino acids

Question 15

components of the endomembrane system

Answer 15

nuclear envelope, endoplasmic reticulum, golgi apparatus, lysosomes, vacuoles, plasma membrane

Question 16

vesicles

Answer 16

membrane-bound sacs that store, transport, and communicate materials within and outside of cells

Question 17

endoplasmic reticulum (ER)

Answer 17

a network of interconnected membranes within a eukaryotic cell that plays a crucial role in protein synthesis and processing, as well as lipid production; continuous with the nuclear envelope

Question 18

smooth ER

Answer 18

lacks ribosomes; synthesizes lipids, metabolizes carbohydrates, detoxifies drugs and poisons, stores calcium ions

Question 19

glycoproteins

Answer 19

proteins covalently bonded to carbohydrates

Question 20

rough ER

Answer 20

surface is studded with ribosomes; ribosomes secrete glycoproteins, distributes transport vesicles, is a membrane factory for the cell

Question 21

transport vesicles

Answer 21

proteins surrounded by membranes

Question 22

golgi apparatus

Answer 22

organelle that prepares proteins and lipids for use inside and outside the cell; consists of flattened membranous sacs called cisternae; modifies products of the ER, manufactures certain molecules, sorts and packages materials into transport vesicles

Question 23

lysosome

Answer 23

a membranous sac of hydrolytic enzymes that can digest macromolecules

Question 24

phagocytosis

Answer 24

a process in which a cell uses its plasma membrane to engulf another cell; this forms a food vacuole

Question 25

vacuoles

Answer 25

large vesicles derived from the endoplasmic reticulum and Golgi apparatus

Question 26

food vacuole

Answer 26

membrane-bound organelle in eukaryotic cells that digests food particles; formed by phagocytosis

Question 27

contractile vacuoles

Answer 27

pump excess water out of cells; found in many freshwater protists

Question 28

central vacuoles

Answer 28

serve as a repository for inorganic ions, including potassium and chloride

Question 29

mitochondria

Answer 29

the sites of cellular respiration, a metabolic process that uses oxygen to generate ATP

Question 30

chloroplasts

Answer 30

the sites of photosynthesis

Question 31

endosymbiont theory

Answer 31

theory that states organelles like mitochondria and chloroplasts were once free-living cells that joined the other cell as parasites or by being eaten

Question 32

cristae

Answer 32

folds in the inner mitochondrial membrane

Question 33

mitochondrial matrix

Answer 33

the space within the inner membrane of a mitochondrion

Question 34

thylakoids

Answer 34

membranous sacs in the chloroplast

Question 35

granum

Answer 35

stacks of thykaloids

Question 36

plastids

Answer 36

group of plant organelles; includes chloroplasts

Question 37

peroxisomes

Answer 37

specialized metabolic compartments bounded by a single membrane

Question 38

cytoskeleton

Answer 38

a network of fibers extending throughout the cytoplasm

Question 39

motor proteins

Answer 39

a class of molecular motors that can move along the cytoskeleton of cells

Question 40

microtubules

Answer 40

hollow rods constructed from globular protein dimers called tubulin; they shape and support the cell, guide movement of organelles, separate chromosomes during cell division

Question 41

centrosome

Answer 41

region near the nucleus that produces and grows microtubules

Question 42

centriole

Answer 42

paired barrel-shaped organelles located in the centrosome; each barrel has nine triplets of microtubules arranged in a ring

Question 43

cilia

Answer 43

hair-like organelles that extend from the surface of cells; moves like oars on a boat. occur in large numbers on cell surfaces

Question 44

flagella

Answer 44

hair-like appendages that help cells move; moves like a propeller on a boat. limited to one or a few per cell

Question 45

basal body

Answer 45

anchors the cilium or flagellum

Question 46

dynein

Answer 46

motor protein that drives the bending movements of a cilium or flagellum

Question 47

microfilaments

Answer 47

thin solid rods, built from molecules of globular actin subunits

Question 48

actin

Answer 48

protein that is an important contributor to the contractile property of muscle and other cells

Question 49

myosin

Answer 49

motor protein that interacts with microfilaments that function in cellular motility

Question 50

intermediate filaments

Answer 50

a type of cytoskeleton element that provide mechanical strength to cells and tissues; larger than microfilaments but smaller than microtubules; reinforce cell shape and fix organelles in place

Question 51

cell wall

Answer 51

an extracellular structure that distinguishes plant cells from animal cells

Question 52

primary cell wall

Answer 52

relatively thin and flexible

Question 53

middle lamella

Answer 53

thin layer between primary walls of adjacent cells

Question 54

secondary cell wall

Answer 54

added between the plasma membrane and the primary cell wall

Question 55

extracellular matrix (ECM)

Answer 55

a network of proteins and other molecules that surrounds and supports cells and tissues in the body; made up of glycoproteins such as collagen, proteoglycans, and fibronectin

Question 56

integrins

Answer 56

cell-surface receptor proteins in the plasma membrane that ECM proteins bind to