chapter 17 bacteria and archaea

Question 1

what are prokaryotes?

Answer 1

single-celled organism that lacks a nucleus and membrane-bounded organelles

Question 2

are bacteria and archaea prokaryotes?

Answer 2

yes

Question 3

when did prokaryotes evolve?

Answer 3

4 billion years ago

Question 4

what is used to distinguish between bacteria and archaea?

Answer 4

DNA sequences and chemical composition

Question 5

what do bacteria and archaea have in common?

Answer 5

prokaryotic, small, circular chromosome, predominantly unicellular, and some can fix nitrogen or grow at temperatures above 80 degrees C

Question 6

unique features of bacteria

Answer 6

cell wall typically composed of peptidoglycan, membrane based on fatty acids, some use chlorophyll, cannot generate methane, sensitive to streptomycin, and genes do not contain introns

Question 7

unique features of archaea

Answer 7

cell wall composed primarily of protein, membrane based on nonfatty acid lipids, do not use chlorophyll, some generate methane, insensitive to streptomycin, and genes may contain introns

Question 8

do bacteria and archaea have similar internal and external structures?

Answer 8

yes

Question 9

nucleoid

Answer 9

the region where the DNA resides

Question 10

ribosomes

Answer 10

use mRNA to synthesize proteins

Question 11

plasmids

Answer 11

circles of DNA apart from the chromosome

Question 12

cell membrane

Answer 12

the outer boundary of the cell; it regulates what can enter and exit the cell

Question 13

cell wall

Answer 13

outside the membrane. gives the cell its shape and protects it from osmotic pressure

Question 14

glycocalyx

Answer 14

Many (but not all) bacteria and archaea have a layer of proteins or polysaccharides surrounding the cell wall. This layer helps cells attach to surfaces, form biofilms, and evade the immune system

Question 15

pili

Answer 15

short, hairlike projections made of protein that enable cells to adhere to objects, surfaces, and other cells

Question 16

what are sex pili used for?

Answer 16

exchanging DNA with other cells

Question 17

flagella

Answer 17

long, whip-like extensions made of protein that rotate like propellers to help the cells move

Question 18

taxis

Answer 18

a response that enables cells to move toward or away from external stimuli

Question 19

gram positive cells have…

Answer 19

a thick peptidoglycan layer

Question 20

gram negative cell walls consist of…

Answer 20

a thin inner layer of peptidoglycan plus a protective outer membrane of lipid, polysaccharide, and protein

Question 21

3 most common shapes for bacteria

Answer 21

coccus (spherical), bacillus (rod-shaped), and spirillum (spiral)

Question 22

endospores

Answer 22

dormant, thick-walled structures that can survive harsh conditions
found in some types of gram-positive bacteria

Question 23

how are prokaryotes classified?

Answer 23

based on metabolism

Question 24

photoautotrophs

Answer 24

derive energy from the sun

Question 25

chemoautotrophs

Answer 25

acquire energy by oxidizing inorganic or organic chemicals

Question 26

what do aerobic prokaryotes require?

Answer 26

oxygen

Question 27

obligate aerobes

Answer 27

require oxygen to live

Question 28

obligate anaerobes

Answer 28

are killed by oxygen, so they only live in habitats that lack it

Question 29

facultative anaerobes

Answer 29

can live in aerobic or anaerobic environments

Question 30

vertical gene transfer

Answer 30

aka binary fission

asexual process that replicates DNA and distributes it to two cells

Question 31

horizontal gene transfer

Answer 31

a cell receives DNA from a cell that is not its ancestor

Question 32

the three ways horizontal transfer occurs

Answer 32

transformation, transduction, and conjugation

Question 33

transformation

Answer 33

a dying cell may release its genetic material as it bursts, and other cells absorb stray bits of DNA

Question 34

transduction

Answer 34

a virus transfers this combined DNA to a bacterial cell

Question 35

conjugation

Answer 35

one cell receives DNA via direct contact with another cell

Question 36

sex pilus

Answer 36

the appendage through which DNA passes from donor to recipient

Question 37

the largest group of gram-negative bacteria

Answer 37

proteobacteria

includes heterotrophic facultative anaerobes that live in our intestines and autotrophs that obtain energy from sulfur

Question 38

the first cells to release oxygen gas as a byproduct of photosynthesis

Answer 38

cyanobacteria

Question 39

ancient [blank] gave rise to chloroplasts during endosymbiosis

Answer 39

cyanobacteria

Question 40

members of this domain were first discovered in extreme habitats

Answer 40

archaea

many archaea are extremophiles