Chapter 27: Bacteria and Archaea Flashcards Preview

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Flashcards in Chapter 27: Bacteria and Archaea Deck (18)
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1

Bacteria Overview

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

2

Bacteria Shape

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

3

Cell Wall structures

  • have a cell wall
  • categorized by composition
    • Peptidoglycan

4

Gram Stains

  • 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

5

Cell Surface Structure

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

6

Endospore

  • Protective coat
  • Surrounds DNA
  • dormant for centuries

7

​Fimbriae

Hairlike; allows for adherence

 

8

Flagella

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

 

9

​Prokaryotic Genome

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

 

10

Prokaryotic Reproduction

reproduce by binary fission

11

​Genetic Variation

  • 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

12

Nutritional Modes

Genetic Diversity allows for modes of nutrition

13

Metabolism 

  • 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

14

​Phylogeny

is tentative; based on molecular systematics

 

15

Domain Bacteria

 

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

 

 

 

 

16

Domain Archaea

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

17

Prokaryotes in Ecosystem

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

 

 

18

Impacts on Humans

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