Chapter 27 - Bacteria and Archaea

Question 1

Prokaryotes -

Answer 1

the single-celled organisms that make up domains Bacteria and Archaea, can thrive in a wide range of extreme environments

Question 2

A key feature of nearly all prokaryotic cells is the ____ ____, which maintains cell shape, protects the cell, and prevents it from bursting in a hypotonic environment

Answer 2

cell wall

Question 3

Peptidoglycan -

Answer 3

most bacterial cell walls contain this polymer which is composed of modified sugars cross-linked by short polypeptides

Question 4

Gram-positive bacteria -

Answer 4

have relatively simple walls composed of a thick layer of peptidoglycan

Question 5

Gram-negative bacteria -

Answer 5

have less peptidoglycan and are structurally more complex, with an outer membrane that contains lipopolysaccharides (carbohydrates bonded to lipids).

Question 6

A capsule -

Answer 6

the cell wall of many prokaryotes surrounded by a sticky layer of polysaccharide or protein

Question 7

Endospores -

Answer 7

bacteria develop resistant cells when they lack water or essential nutrients. The original cell produces a copy of its chromosome and surrounds that copy with a multilayered structure, forming the _______

Question 8

Fimbriae -

Answer 8

hairlike appendages that some prokaryotes use to stick to their substrate or to one another

Question 9

Pili (singular, pilus) -

Answer 9

appendages that pull two cells together prior to DNA transfer from one cell to the other

Question 10

Taxis -

Answer 10

a directed movement toward or away from a stimulus

Question 11

Chemotaxis -

Answer 11

where prokaryotes change their movement pattern in response to chemicals

Question 12

The genome of a prokaryote is structurally different from a eukaryotic genome and in most cases has considerably ____ DNA

Answer 12

less

Question 13

Nucleoid -

Answer 13

a region of cytoplasm that is not enclosed by a membrane, since prokaryotes lack a nucleus their chromosomes are condensed here

Question 14

Plasmids -

Answer 14

small rings of independently replicating DNA molecules

Question 15

Prokaryotic species three key features of their biology:

Answer 15

small, reproduce by binary fission, and often have short generation times

Question 16

Genetic recombination -

Answer 16

the combining of DNA from two sources

Question 17

Transformation -

Answer 17

the genotype and possibly phenotype of a prokaryotic cell are altered by the uptake of foreign DNA from its surroundings

Question 18

Transduction -

Answer 18

phages (short for “bacteriophages,” the viruses that infect bacteria) carry prokaryotic genes from one host cell to another

Question 19

Conjugation -

Answer 19

DNA is transferred between two prokaryotic cells (usually of the same species) that are temporarily joined. In bacteria, the DNA transfer is always one-way: One cell donates the DNA, and the other receives it

Question 20

F factor -

Answer 20

a particular piece of DNA that determines the ability to form pili and donate DNA during conjugation

Question 21

R plasmids -

Answer 21

carry “resistance genes” that code for enzymes that specifically destroy or otherwise hinder the effectiveness of certain antibiotics

Question 22

Chemotrophs -

Answer 22

organisms that obtain energy from chemicals

Question 23

Phototrophs -

Answer 23

organisms that obtain energy from light

Question 24

Autotrophs -

Answer 24

organisms that need only CO2 or related compounds as a carbon source

Question 25

Heterotrophs -

Answer 25

organisms that require at least one organic nutrient, such as glucose, to make other organic compounds

Question 26

Obligate aerobes -

Answer 26

use O2 for cellular respiration and cannot grow without it

Question 27

Obligate anaerobes -

Answer 27

poisoned by O2

Question 28

Anaerobic respiration -

Answer 28

where chemical energy is extracted, substances other than O2, such as nitrate ions (NO-3) or sulfate ions (SO4 -2), accept electrons at the “downhill” end of electron transport chains

Question 29

Facultative anaerobes -

Answer 29

use O2 if it is present but can also carry out fermentation or anaerobic respiration in an anaerobic environment

Question 30

Nitrogen fixation -

Answer 30

converting atmospheric nitrogen to ammonia

Question 31

Biofilms -

Answer 31

metabolic cooperation among the cells of one or more prokaryotic species occurring in surface-coating colonies which secrete signaling molecules that recruit nearby cells, causing the colonies to grow

Question 32

Extremophiles -

Answer 32

prokaryotes assigned to domain Archaea that live in environments so extreme that few other organisms can survive there

Question 33

Extreme halophiles -

Answer 33

live in highly saline environments

Question 34

Extreme thermophiles -

Answer 34

thrive in very hot environments

Question 35

Methanogens -

Answer 35

archaea that release methane as a by-product of how they obtain energy

Question 36

decomposers -

Answer 36

break down dead organisms as well as waste products and thereby unlocking supplies of carbon, nitrogen, and other elements

Question 37

Symbiosis -

Answer 37

an ecological relationship in which two species live in close contact with each other

Question 38

Exotoxins -

Answer 38

proteins secreted by certain bacteria and other organisms

Question 39

Endotoxins -

Answer 39

lipopolysaccharide components of the outer membrane of gram-negative bacteria, released only when the bacteria die and their cell walls break down

Question 40

Bioremediation -

Answer 40

the use of organisms to remove pollutants from soil, air, or water