Chapter 27: Bacteria and Archaea

Question 1

Bacteria Overview

​

Answer 1

• oldest most successful group
• unicellular
• lack nucleus, organelles
• found in all locations, diverse enviroments

Question 2

Bacteria Shape

Answer 2

• 3 common shapes
  
  1. Cocci (sphere)
  2. Bacilli (rod)
  3. Spirilla (spiral)

Question 3

Cell Wall structures

Answer 3

• have a cell wall
• categorized by composition
  
  • Peptidoglycan​

Question 4

Gram Stains

Answer 4

• Gram Positive: large amount of peptidoglycan that traps violet dye in the cytoplasm
• Gram Negative: has less peptidoglycan, and is located in a layer between the plasma membrane and an outer membrane

Question 5

Cell Surface Structure

Answer 5

• Capsule or slime layer
• covers cells wall
• used for
  
  • adherence
  • defensive shield

Question 6

Endospore

Answer 6

• Protective coat
• Surrounds DNA
• dormant for centuries

Question 7

​Fimbriae

Answer 7

Hairlike; allows for adherence

Question 8

Flagella

​

Answer 8

• Used for movement
• Demonstrate taxis
  
  • movement toward or away from stimulus

Question 9

​Prokaryotic Genome

Answer 9

• circular chromosomes, located in nucleoid region
• some also have small rings of DNA called plasmids

Question 10

Prokaryotic Reproduction

Answer 10

reproduce by binary fission

Question 11

​Genetic Variation

Answer 11

• ultimate source is mutations
• diversity is due to genetic recombination
• 3 mechanisms:
  
  1. Transformation - obtain DNA from environment
  2. Transduction - virus transfers genes b/w bacteria
  3. Conjugation - genes transferred b/w bacteria called horizontal gene transfer

Question 12

Nutritional Modes

Answer 12

Genetic Diversity allows for modes of nutrition

Question 13

Metabolism

Answer 13

• is the making and breaking of substances
• Various metabolism
  
  • Obligate Aerobes - require and use oxygen
  • Facultative anaerobes - can use or not use oxygen
  • Obligate anaerobes - poisoned by oxygen

Question 14

​Phylogeny

Answer 14

is tentative; based on molecular systematics

Question 15

Domain Bacteria

Answer 15

• 5 groups
  
  • Spirochetes
  • Chlamydias
  • Cyanobacteria (photoautotrophs)
• 2 Largest Groups:
  
  • Proteobacteria
  • Gram- Positive Bacteria

Question 16

Domain Archaea

Answer 16

• members can be in extreme environments
• Called extremophiles
  
  • extreme halophiles - high salt environment
  • extreme thermophiles - hot environment
• others live in moderate environments

Question 17

Prokaryotes in Ecosystem

Answer 17

• Have important roles
  
  • Decompose
    
    • recycle elements
  • Form symbiotic relationships
    
    • ​​mutualism
    • commensalism
    • parasitism

Question 18

Impacts on Humans

Answer 18

• Negative: cause half of human disease
  
  • exotoxins: secreted
  • endotoxins: released after death
• Positive: used to produce food
  
  • bioremediation - sewage, oil spills
  • vitamins, antibiotics