CH 27: Archaea and Bacteria

Question 1

What are prokaryotes?

Answer 1

a paraphyletic group consisting of bacteria and archaea

-Both lack a membrane bound nucleus

Question 2

What was the Great Oxidation Event?

Answer 2

No Oxygen on earth until Cyanobacteria evolved ability to photosynthesize
-Oxygen is byproduct of photosynthesis and built up over millions of years

Question 3

Why are prokaryotes so diverse?

Answer 3

• Short Generation times
• Live in almost all habitats
• Horizontal Gene Transfer

Question 4

Which domain is Archaea more closely related to?

Answer 4

Eukarya

Question 5

What gives Archaea its resilience, making them extremophiles?

Answer 5

Ether bonded lipids more resistant to heat

-Lipids have extra double/triple bonds that maintain shape and don’t denature under high temp/pH

Question 6

What are extremophiles?

Answer 6

Organisms that can occupy habitats with extreme conditions

Question 7

What are the types of extromphiles?

Answer 7

High Salt Content - halophiles

High Temperatures - Hyperthermophiles

Question 8

What are the phyla that make up Domain Archaea?

Answer 8

1) Korachaeota
2) Nanoarchaeota
3) Thaumarchaeota
4) Crenarchaeota
5) Euryarchaeota

Question 9

What kinds of living conditions do bacteria live in?

Answer 9

Mst favor moderate conditions

• some are extremophiles
• Some form symbiotic relationships with Eukaryotes

Question 10

What are the Phyla we need to know for Domain Bacteria?

Answer 10

1. Chlamydiae: Chlamydia
2. Spirochaetes: Syphilis and Lyme disease
3. Actinobacteria: Tuberculosis
4. Cyanobacteria: O2 producers; blue-green algae; can cause toxic algal blooms
5. Proteobacteria: Large group; metabolically diverse; E. coli, influenza

Question 11

What are the characteristics of Phylum Cyanobacteria?

Answer 11

• Photosynthetic bacteria generates Oxygen
• Live in aquatic habitats, wetlands, arid soil surface
• Plant chloroplasts are derived from cyanobacteria
• Live as single cells, colonies or filaments
• Produce Organic Carbon and Fix Nitrogen

Question 12

What Major Subgroup of Phylum Proteobacteria had a large impact on humans?

Answer 12

α-proteobacteria

•Ancestors of mitochondria, Rhizobium, Agrobacterium

Question 13

What is horizontal gene transfer?

Answer 13

Movement of one or more genes from one species to another
•Contrasts with vertical gene transfer from parent to progeny
•Increases genetic diversity

Question 14

What are the mechanisms of horizontal gene transfer?

Answer 14

Transformation, Transduction, and Conjugation

Question 15

Explain the mechanism of horizontal gene transfer, transformation.

Answer 15

Transformation

•DNA fragment from donor cell released to environment & taken up by another bacterial cell

Question 16

Explain the mechanism of horizontal gene transfer, transduction.

Answer 16

Transduction
•Virus infects donor cell & bacterial chromosome fragments
•Phage transfers fragment DNA to a recipient cell

Question 17

Explain the mechanism of horizontal gene transfer, conjugation.

Answer 17

Conjugation
•Requires direct contact between bacteria cells
•One bacterium acts as a donor & transfers DNA to recipient cell

Question 18

What are the important concepts of Bacteria and Archaea?

Answer 18

• Both evolved from common ancestor
• Eukaryotic nucleus and cytoplasm likely arose in ancient archaeal organism
• Mitochondria and plastids originated from proteobacteria and cyanobacteria by endosymbiosis

Question 19

What are examples of more complex cell structures in bacteria?

Answer 19

Magnetosomes

• Magnetite Crystals
• Like compass that help bacteria find low O2 habitats

Gas Vesicle
-Adjust buoyancy

Question 20

What are the major shapes of Bacteria?

Answer 20

1) Sphere - cocci
2) Rods - bacilli
3) Comma - vibrios
4) Spiral - spriochaetes
5) Single Cells, pairs, or Filaments

Question 21

What is mucilage?

Answer 21

Also called glycocalyx

-Very sticky composed of polysaccharides and/or proteins

Question 22

What are the functions of mucilage?

Answer 22

1) Evade host defenses
2) Hold colony together (biofilm)
3) Help aquatic bacteria float
4) Binds mineral nutrients
5) Defense against predators
6) Prevents UV damage

Question 23

What are biofilms?

Answer 23

Biofilms: aggregates of microorganisms that secrete adhesive mucilage & glue themselves to surfaces
•Help remain in favorable areas for growth

Question 24

What is quorum sensing?

Answer 24

given enough individuals, signaling molecules released by individuals cause collective behavior
•Moving to a common location
•Secreting mucilage

Question 25

What are the major forms of bacterial cell walls?

Answer 25

Gram-positive or Gram-negative | -differ in peptidoglycan thickness, staining properties & response to antibiotics

Question 26

What are the two methods of motility for bacteria?

Answer 26

Flagella and Pili

Question 27

What are flagella used for in bacteria?

Answer 27

* Important for swimming * Lack plasma membrane cover of proteins * Lack internal cytoskeleton of microtubules * Lack motor protein dynein * Eukaryotic flagella: repeatedly bend & straighten * Bacterial flagella: outboard motor

Question 28

What are pili used for in bacteria?

Answer 28

* Twitch or glide across surfaces * Threadlike structures on surface of cell * If nutrients are low bacteria glide together & form tiny tree like colonies * Important for reproduction

Question 29

How do bacteria reproduce?

Answer 29

Binary fission –divide by splitting in two 1. Circular DNA replicates within the cell 2. DNA molecules migrate to opposite ends of cell 3. Cell elongates 4. Cell constricts at middle, pinches off one cell can become millions in hours

Question 30

How do bacteria survive harsh conditions?

Answer 30

By forming akinetes and endospores

Question 31

What do all living cells require to build organic molecules?

Answer 31

Energy and a source of Carbon

Question 32

How can you classify bacteria and archaea?

Answer 32

Can be classified by: •Nutrition •Response to oxygen •Presence of specialized metabolic processes

Question 33

What is a heterotroph and what are its types?

Answer 33

Heterotrophs: organisms that require at least one organic compound, and often more Photoheterotroph: able to use light energy to make ATP but they must take in organic compounds from the environment Chemoorganotroph: must obtain organic molecules for both energy and carbon source

Question 34

What is an autotroph and what are its types?

Answer 34

Autotrophs: produce all or most of their own organic compounds Photoautotroph: Uses light as energy source for synthesis of organic compounds from CO2or H2S Chemoautotrophs: Use energy obtained from chemical modification of inorganic compounds to synthesize organic compounds

Question 35

How are bacteria/archaea classified by oxygen response?

Answer 35

* Obligate aerobes –require oxygen * Facultative aerobes –can use oxygen or not * Obligate anaerobes –cannot tolerate oxygen * Aerotolerantanaerobes –do not use oxygen but are not poisoned by it

Question 36

How are bacteria/archaea classified by special metabolism?

Answer 36

Diazotrophs–conduct nitrogen fixation •Enzyme nitrogenase converts inorganic nitrogen gas (N2) into ammonia (NH3) •Autotrophs need ammonia to make N containing compounds •Heterocysts–specialized cells for nitrogen fixation in cyanobacteria

Question 37

What are the Ecological role of bacteria?

Answer 37

Carbon cycle •Producers synthesize organic compounds used by other organisms as food •Decomposers break down dead organisms to release minerals for reuse * Methanogens make methane * Methanotrophs consume methane

Question 38

What are the symbiotic roles of bacteria?

Answer 38

* Symbiosis: An organism that lives in close association with one or more other organisms * Parasitism: One partner benefits at the expense of the other * Mutualism: Association is beneficial to both partners

Question 39

What are the symbiotic roles of bacteria?

Answer 39

* Syntrophy–some bacteria live together and supply each other with essential nutrients * Consortia–larger community of nutrient exchangers

Question 40

What is a pathogen?

Answer 40

Pathogen–parasitic microbe causes disease symptoms | •Organisms that obtain organic compounds from living hosts (parasites)