Chapter 4 Vocabulary

Question 1

light microscope

Answer 1

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 2

magnification

Answer 2

an increase in the apparent size of an object

Question 3

resolution

Answer 3

a measure of the clarity of an image; the ability of an optical instrument to show 2 objects as separate

Question 4

cell theory

Answer 4

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

Question 5

electron microscope

Answer 5

an instrument that focuses an electron beam through, or onto the surface of a specimen. an electron microscope achieves a thousandfold greater resolution than a light microscope; the most powerful EM can distinguish objects as small as 0.2 nm

Question 6

scanning electron microscope

Answer 6

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

Question 7

transmission electron microscope

Answer 7

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

Question 8

prokaryotic cells

Answer 8

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

Question 9

eukaryotic cells

Answer 9

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

Question 10

plasma membrane

Answer 10

the thin layer of lipids and proteins 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 11

ribosome

Answer 11

a cell organelle consisting of RNA and protein organized into 2 subunits and functions as the site of protein synthesis in the cytoplasm. The ribosomal subunits are constructed in nucleolus

Question 12

nucleoid

Answer 12

the region in a prokaryotic cell consisting of a concentrated mass of DNA

Question 13

cell wall

Answer 13

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

Question 14

capsule

Answer 14

a sticky layer that surrounds the bacterial cell wall, protects the cell surface, and sometimes helps give the cell to surfaces

Question 15

pilus

Answer 15

A short projection on the surface of a prokaryotic cell that helps the prokaryote attach to other surfaces. specialized sex pili are used in conjugation to hold the mating cells together

Question 16

prokaryotic flagellum

Answer 16

a long surface projection that propels a prokaryotic cell through its liquid environment, totally different from the flagellum of a eukaryotic cell

Question 17

cytoplasm

Answer 17

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

Question 18

organelle

Answer 18

a structure with a specialized function within a cell

Question 19

cellular metabolism

Answer 19

the chemical activity of cells

Question 20

nucleus

Answer 20

genetic control center of eukaryotic cell

Question 21

chromatin

Answer 21

combination of DNA and proteins that constitutes chromosomes; often used to refer to the diffuse, very extended form taken by chromosomes when eukaryotic cell is no dividing

Question 22

chromosome

Answer 22

A thread-like, 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 prokaryotic cell. Consists of chromatin.

Question 23

nuclear envelope

Answer 23

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

Question 24

nucleolus

Answer 24

a structure within the nucleus of a eukaryotic cell where ribosomal RNA is made and assembled with proteins to make ribosomal subunits; consists of parts of the chromatin DNA, RNA transcribed from the DNA, and proteins imported from the cytoplasm

Question 25

granum

Answer 25

a stack of hollow disks formed of thylakoid membrane in a chloroplast. Grana ar the sites where light energy is trapped by chlorophyll and converted to chemical energy

Question 26

vesicles

Answer 26

sacs made of membrane

Question 27

endomembrane system

Answer 27

a network of membranous organelles that partition the cytoplasm of eukaryotic cells into functional compartments. some of the organelles are structurally connected to each other, whereas others are structurally separate but functionally connected by the traffic of membranous vesicles between them

Question 28

secretory protein

Answer 28

a protein (such as an antibody) that is secreted by a cell

Question 29

endoplasmic reticulum

Answer 29

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

Question 30

smooth ER

Answer 30

a network of interconnected membranous tubules in a eukaryotic cell's cytoplasm. smooth ER lacks ribosomes. enzymes embedded in smooth ER membrane function in the synthesis of certain kinds of molecules such as lipids

Question 31

rough ER

Answer 31

a network of interconnected membranous sacs in a eukaryotic cell's cytoplasm. Rough ER membranes are studded with tibosomes that make membrane and secratory proteins. the rough ER constructs membrane from phospholipids and proteins

Question 32

central vacuole

Answer 32

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

Question 33

chloroplast

Answer 33

an organelle found in plants and photosynthetic protists. enclosed by 2 concentric membranes, a chloroplast absorbs sunlight and uses it to power the synthesis of organic food molecules (sugars)

Question 34

cristae

Answer 34

folds of the inner membrane of mitochondrion. enzyme molecules embedded in cristae make ATP

Question 35

glycoprotein

Answer 35

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

Question 36

golgi apparatus

Answer 36

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

Question 37

intermembrane space

Answer 37

one of the two fluid filled internal compartments of the mitochondrion. the intermembrane space is the narrow region between inner and outer membranes

Question 38

lysosome

Answer 38

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

Question 39

stroma

Answer 39

a thick fluid enclosed by inner membrane of a chloroplast. sugars are made in the stroma by enzymes of calvin cycle

Question 40

transport vesicle

Answer 40

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

Question 41

vacuole

Answer 41

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

Question 42

anchoring junctions

Answer 42

a junction that connects tissue cells to each other (or to an extracellular matrix) and allows materials to pass from cell to cell

Question 43

basal body

Answer 43

a eukaryotic cell organelle consisting of a 9+0 arrangement of microtubule triplets, may organize the microtubule assembly of a cilium or flagellum, structurally identical to centriole

Question 44

cilium

Answer 44

a short appendage that propels some protists through water and moves fluid across the surface of many tissue cells in animals. in common with eukaryotic flagella, cilia have a (+2 arrangement of microtubules coverred by cell's plasma membrane

Question 45

cytoskeleton

Answer 45

a meshwork of fine fibers in the cytoplasm of a eukaryotic cell, includes microfilaments, intermediate filaments, and microtubules

Question 46

extracellular matrix

Answer 46

a substance in which the cells of an animal tissue are embedded, consisting of protein and polysaccharides

Question 47

flagellu,

Answer 47

longer, less numerous appendages on protists

Question 48

gap junctions

Answer 48

channels between adjacent tissue cells through which water and other small molecules pass freely

Question 49

intermediate filaments

Answer 49

an intermediate sized protein fiber that is one of the three main kinds of fibers making up cytoskeleton of eukaryotic cells. ropelike; made of fibrous proteins

Question 50

microfilament

Answer 50

the thinnest of the 3 main inds of protein fibers making up cytoskeleton of a eukaryotic cell; a solid, helical rod composed of the globular protein actin

Question 51

microtubules

Answer 51

the thickest of the 3 main kinds of fibers making up the cytoskeleton of a eukaryotic cell; a straight, hollow tube made of globular proteins called tubuluns. help form the basis of the structure and movement of cilia and flagella

Question 52

mitochondrial matrix

Answer 52

fluid contained within inner membrane of a mitochondrion

Question 53

mitochondrion

Answer 53

an organelle in eukaryotic cells where cellular respiration occurs. enclosed by 2 concentric membranes, it is where most of the cell's ATP is made

Question 54

plasmodesmota

Answer 54

open channels in a plant cell wall, through which strands of cytoplasm connect from adjacent walls

Question 55

tight junctions

Answer 55

a junction the binds tissue cells together in a leakproof sheet

Question 56

centriole

Answer 56

a structure in an animal cell composed of microtubule triplets arranged in a 9+0 pattern. an animal cell usually has a pair of centrioles within each of its centrosones