introduction

Question 1

stromatolites

Answer 1

a laminated microbial mat
which can become fossilized and is typically
built from layers of filamentous
microorganisms

Question 2

banded iron formation

Answer 2

iron oxide–rich
ancient sedimentary rocks containing
zones of oxidized iron (Fe3+) formed
by oxidation of Fe2+ by O2 produced
by cyanobacteria

Question 3

phylogeny

Answer 3

evolutionary history

Question 4

ribosomal RNA (rRNA)

Answer 4

RNA molecules
found in the small and large subunits of the
ribosome

Question 5

recombination

Answer 5

resorting or rearrangement of DNA fragments resulting in a new
sequence

Question 6

archaellum

Answer 6

a long, thin cellular appendage
present in many Archaea that rotates and is
responsible for swimming motility

Question 7

basal body

Answer 7

the “motor” portion of the
bacterial flagellum, embedded in the
cytoplasmic membrane and cell wall

Question 8

capsule

Answer 8

a polysaccharide or protein
outermost layer, usually rather slimy,
present on some bacteria

Question 9

chemotaxis

Answer 9

directed movement of
an organism toward (positive chemotaxis)
or away from (negative chemotaxis) a
chemical gradient

Question 10

cristae

Answer 10

the internal membranes of a
mitochondrion

Question 11

cytoskeleton

Answer 11

the cellular scaffolding typical
of eukaryotic cells in which microtubules,
microfilaments, and intermediate filaments
define the cell’s shape

Question 12

dipicolinic acid

Answer 12

a substance unique to
endospores that confers heat resistance on
these structures

Question 13

endospore

Answer 13

a highly heat-resistant,
thick-walled, differentiated structure
produced by certain gram-positive Bacteria

Question 14

gas vesicles

Answer 14

gas-filled cytoplasmic structures
bounded by protein and conferring
buoyancy on cells

Question 15

histones

Answer 15

highly basic proteins that compact
and wind DNA in the nucleus of eukaryotic
cells

Question 16

hydrogenosome

Answer 16

an organelle of
endosymbiotic origin present in certain
microbial eukaryotes that oxidizes pyruvate
to H2, CO2, and acetate, and couples this to
ATP synthesis

Question 17

intermediate filament

Answer 17

a filamentous
polymer of fibrous keratin proteins,
supercoiled into thicker fibers, that functions
in maintaining cell shape and the positioning
of certain organelles in the eukaryotic cell

Question 18

lipopolysaccharide

Answer 18

a combination
of lipid with polysaccharide and protein
that forms the major portion of the outer
membrane in gram-negative Bacteria

Question 19

lysosome

Answer 19

an organelle containing digestive
enzymes for hydrolysis of proteins, fats, and
polysaccharides

Question 20

magnetosome

Answer 20

a particle of magnetite
(Fe3O4) enclosed by a nonunit membrane in
the cytoplasm of magnetotactic Bacteria

Question 21

microfilament

Answer 21

a filamentous polymer of
the protein actin that helps maintain the
shape of a eukaryotic cell

Question 22

microtubule

Answer 22

a filamentous polymer of
the proteins α-tubulin and β-tubulin that
functions in eukaryotic cell shape and
motility

Question 23

outer membrane

Answer 23

e a phospholipid- and
polysaccharide-containing unit membrane
that lies external to the peptidoglycan layer
in cells of gram-negative Bacteria

Question 24

periplasm

Answer 24

a gel-like region between the outer
surface of the cytoplasmic membrane and
the inner surface of the lipopolysaccharide
layer of gram-negative Bacteria

Question 24

peptidoglycan

Answer 24

a polysaccharide composed of alternating repeats of N-acetylglucosamine and N-acetylmuramic acid arranged in adjacent layers and cross-linked by short peptides

Question 25

peritrichous flagellation

Answer 25

having flagella located in many places around the surface of the cell

Question 26

phototaxis

Answer 26

movement of an organism toward light

Question 27

pili

Answer 27

thin, filamentous structures that extend from the surface of a cell and, depending on type, facilitate cell attachment, genetic exchange, or twitching motility

Question 28

polar flagelation

Answer 28

having flagella emanating from one or both poles of the cell

Question 29

PHB (poly beta hydroxybutyric acid)

Answer 29

a common storage material of prokaryotic cells consisting of a polymer of β-hydroxybutyrate or another β-alkanoic acid or mixtures of β-alkanoic acids

Question 30

S layer

Answer 30

an outermost cell surface layer composed of protein or glycoprotein present on some Bacteria and Archaea

Question 31

stroma

Answer 31

the lumen of the chloroplast, surrounded by the inner membrane

Question 32

teichoic acid

Answer 32

a phosphorylated polyalcohol found in the cell wall of some gram-positive Bacteria

Question 33

thylakoid

Answer 33

a membrane layer containing the photosynthetic pigments in chloroplasts