Chapter 27: Bacteria and Archaea(3)

Question 1

What are the diverse nutritional and metabolic adaptations that have evolved in Prokaryotes?

Answer 1

• Phototrophs obtain energy from light

– Chemotrophs obtain energy from chemicals

– Autotrophs use CO2 as a carbon source

– Heterotrophs require an organic nutrient to make organic compounds e.g. glucose

Question 2

Explain prokaryotic metabolism concerning O2.

Answer 2

– Obligate aerobes require O2 for cellular respiration
– Obligate anaerobes are poisoned by O2 and use fermentation or anaerobic respiration
– Facultative anaerobes can survive with or without O2

Question 3

Nitrogen is essential for the production of _____ and _______.

Answer 3

Nitrogen is essential for the production of amino acids and nucleic acids

Question 4

How do some prokaryotes metabolize nitrogen?

Answer 4

In nitrogen fixation, some prokaryotes convert atmospheric nitrogen (N2) to ammonia (NH3).

Question 5

Explain the metabolic cooperation involved in cyanobacterium Anabaena.

Answer 5

In the cyanobacterium Anabaena,

– photosynthetic cells
– specialized nitrogen-fixing cells called heterocysts exchange metabolic products

Question 6

What are the major groups of bacteria?

Answer 6

1. Proteobacteria
2. Chlamydias
3. Spirochetes
4. Cyanobacteria
5. Gram-positive bacteria

(PiCS Come on instGRAM)

Question 7

Metabolic cooperation between different prokaryotic species often occurs in surface-coating colonies known as
_________.

Answer 7

Metabolic cooperation between different prokaryotic species often occurs in surface-coating colonies known as biofilms

Question 8

Explain the traits of proteobacteria and its sub-groups.

Answer 8

Proteobacteria
* These gram-negative bacteria include
– photoautotrophs,
– chemoautotrophs, and
– heterotrophs

• Can be aerobic or anaerobic

SUB-GROUPS:-
Alpha
Beta
Gamma
Delta
Epsilon

Question 9

What are the characteristics of alpha-proteobacteria?

Answer 9

Alpha-Proteobacteria
* Many species of alpha-proteobacteria are closely associated with eukaryotic hosts

• It is hypothesized that mitochondria evolved from aerobic alpha-proteobacteria through endosymbiosis.
  (A symbiotic relationship where one organism lives inside the other is known as endosymbiosis)

Question 10

Give two examples of alpha-proteobacteria.

Answer 10

• Rhizobium, which forms root nodules in legumes and fixes atmospheric N2

– Agrobacterium, which produces tumors in plants and is used in genetic engineering

Question 11

What are the characteristics of beta-proteobacteria?

Answer 11

• Soil bacteria that play an important role in nitrogen recycling by oxidizing ammonia to nitrate
• ex: Nitrosomonas

Question 12

What are the characteristics of gamma-proteobacteria?

Answer 12

• This subgroup’s auto-trophic members include sulfur bacteria which obtain energy by oxidizing H2S, producing sulphur as a waste product
• Heterotrophic members of the group also include pathogens such as Legionella, Salmonella, and Vibrio cholerae

Question 13

What are the characteristics of chlamydias?

Answer 13

• These are parasites that live within animal cells
• Chlamydia trachomatis causes blindness and nongonococcal urethritis by sexual transmission

Question 14

What are the characteristics of spirochetes?

Answer 14

• These bacteria are helical heterotrophs
• Some are parasites, including
  – Treponema pallidum, which causes syphilis, and
  – Borrelia burgdorferi, which causes Lyme disease

Question 15

What are the characteristics of cyanobacteria?

Answer 15

• These are photoautotrophs that generate O2
• Plant chloroplasts likely evolved from cyanobacteria by the process of endosymbiosis

Question 16

What are the types of gram-positive bacteria?

Answer 16

Gram-positive bacteria include
– Actinomycetes, which decompose soil
– Bacillus anthracis, the cause of anthrax
– Clostridium botulinum, the cause of botulism

Question 17

What are the smallest known cells (gram-positive bacteria)?

Answer 17

Mycoplasmas

Question 18

What are the archaea that live in extreme places called and what are the types?

Answer 18

Some archaea live in extreme environments and are called extremophiles

• Extreme halophiles live in highly
  saline environments
• Extreme thermophiles thrive in
  very hot environments

Question 19

What are methanogens?

Answer 19

Methanogens live in swamps and marshes and produce methane as a waste product

– Methanogens are strict anaerobes and are poisoned by O2

Question 20

What are the crucial roles played by prokaryotes in the biosphere?

Answer 20

• Prokaryotes play a major role in the recycling of chemical elements between living and nonliving components of ecosystems.
• Chemoheterotrophic prokaryotes function as decomposers, breaking down dead organisms and waste products

Question 21

What is the impact of bacteria on soil nutrient availability?

Answer 21

• Prokaryotes can sometimes increase the availability of nitrogen, phosphorus, and potassium for plant growth
• In other instances, they can “immobilize” or decrease the availability of key plant nutrients