Early Life and the Diversification of Prokaryotes

Question 1

Photoautotrophs use

Answer 1

light as an energy source and CO2 as a carbon source

Question 2

Prokaryotes specialized internal membranes

Answer 2

form from infoldings of the plasma membrane and may function in cellular respiration or photosynthesis

Question 3

Characteristics of the clade Archaea?

Answer 3

• they have cell walls that lack peptidoglycan
• they are often found in harsh habitats
• have membrane enclosed organelles
• do not have a nuclear envelope
• they appear to be more closely related to eukaryotes than to bacteria
• they include (methanogens + extreme halophiles + extreme thermophile)

Question 4

Bacteria & Archaea Comparison

Answer 4

• only some archaea use CO2 to oxidize H2 releasing methane
• archaea and bacteria have different membrane lipids
• the cell walls of archaea lack peptidoglycan
• both generally lack membrane-enclosed organelles
• both have histones associated with DNA

Question 5

Endospore

Answer 5

• associated with the greatest ability to withstand unfavorable conditions

Question 6

How is prokaryotes placed into major clades within the domains Archaea and Bacteria?

Answer 6

molecular comparison

Question 7

Facultative anaerobes

Answer 7

can survive with or without oxygen

Question 8

Nitrogen Fixation

Answer 8

• converts N2 to ammonia
• making nitrogen available for incorporation into proteins and nucleic acids
• only obtains nitrogen from the atmosphere

Question 9

A Gram stain distinguishes bacteria based on a difference in their

Answer 9

cell walls

Question 10

Chemoautotrophs

Answer 10

oxidize inorganic substance for energy and use CO2 as a carbon source

Question 11

Bacterial Flagella

Answer 11

the mechanism of movement in bacterial flagella is different from that in protist flagella

Question 12

Prokaryotes Purpose

Answer 12

to recycle nutrients

Question 13

Sources of Genetic Variation in Bacterial Populations

Answer 13

• transduction
• conjugation
• mutation
• transformation

Question 14

Prokaryotes

Answer 14

• ## often form symbiotic associations with much larger organisms (hosts)

Question 15

What is the smaller organisms called in symbiotic relationships?

Answer 15

symbiont

Question 16

What is the larger organisms called in symbiotic relationships?

Answer 16

host

Question 17

Mutualism

Answer 17

an ecological interaction between two species in which both benefit
Ex. bioluminescent bacteria in fish
Ex. species of bacteria that live in the guts of animals

Question 18

Commensalism

Answer 18

an interaction in which one species benefits while the other is not harmed or helped in any significant way
Ex. oils that exude from your pores (providing food)

Question 19

Parasitism

Answer 19

• an interaction in which a parasite eats the cell contents + tissues or body fluids of its host
• harm but usually do not kill their host (or at least no immediately)

Question 20

Pathogens

Answer 20

are parasites that cause disease in their host

Question 21

Bacteria Ecological Roles

Answer 21

• gut mutualist
• bioluminescent bacteria in fish
• pathogen
• skin commensalism

Question 22

Many prokaryotes secrete a sticky capsule outside the cell wall that

Answer 22

seres as protection from host defenses and as glue for adherence

Question 23

Chlamydias

Answer 23

• intercellular parasites
• including a species that causes blindness and nongonococcal urethritis

Question 24

Proteobacteria

Answer 24

• diverse gram-negative bacteria
• including pathogens (as Salmonella & Helicobacter pylori)
• beneficial species (as Rhizobium)

Question 25

Spirochetes

Answer 25

• helical heterotrophs
• including pathogens that cause syphilis and Lyme disease

Question 26

Gram Positive Bacteria

Answer 26

• diverse group
• includes (actinomycetes + mycoplasmas)
• pathogens that cause (anthrax + botulism + tuberculosis)

Question 27

Chemoheterotrophic Prokaryotes

Answer 27

may function as decomposers to return chemical elements to an ecosystem