Week 5 (up to midterm)

Question 1

describe mycobacteria

Answer 1

-complex cell envelope with characteristics of both gram positive and negative, but classified as gram positive
-extreme resistance to environment
-hydrophobic mycromembrane: rich in mycolic acids, mycolic and peptidoglycan held together by polysaccharide, stained with acid-fast stain

pros: thick, waxy, outer mycomembrane
cons: grows slowly, energetically expensive to maintain

Question 2

describe the S layer

Answer 2

-in almost all archaea and some bacteria
-consists of single layer of proteins
-very ordered array
-encloses entire cell surface
-diverse functions: can flex, central pores allow movement of molecules, extra external protective layer

Question 3

Archaeal cell wall

Answer 3

-semi-rigid structure
-variety of cell walls, some lack entirely
-most have proteinacious S-layer anchored to cell membrane
-few have pseudopeptidoglycan

Question 4

describe capsules

Answer 4

-difficult to stain, forms halo around cells
-additional cell capsule exterior to cell wall
-consists of polysaccharides and glycoproteins loosely bound to cell envelope
-protects against immune system, assists with adherence, protects from dehydration by binding with water and forming hydration

Question 5

describe the phyla cyanobacteria

Answer 5

-photoautotrophic prokaryotes that produce oxygen
-contains chlorophyll and associated pigments

Question 6

specialized structures in cyanobacteria

Answer 6

-thylakoids
-specialized microcompartments
-gas vesicles

Question 7

describe thylakoids

Answer 7

-only available in gram-negative phototrophs
-specialists systems of extensively folded lamelle (sheets) of membranes
-packed with chlorophyll, photosynthetic proteins and electron carriers
-maximizes photosynthetic capabiltiy

Question 8

describe specialized protein micro compartments (ex: carboxysomes)

Answer 8

-carbon fixing enzyme (rubisco)
-in gram negatives
-polyhedral-shaped selectively permeable protein shell with carbon-fixing enzymes

Question 9

describe gas vesicles

Answer 9

-protein tubes packed as hexagonal arrays
-captures gas produced from metabolism
-allows microbes to float (necessary for phootsynthesis)

Question 10

classifications based on environmental conditions (TEMP)

Answer 10

-hyperthermophile (above 80 °C)
-thermophile (50-80 °C)
-mesophile (15-45 °C)
-psychrophile (below 15 °C)

Question 11

classifications based on environmental conditions (pH)

Answer 11

-alkaphile (above 9)
-neutrophile (5-8)
-acidophile (below 3)

Question 12

classifications based on environmental conditions (osmolarity)

Answer 12

-halophile (high salt)
-halotolerant (high salt not required)

Question 13

classifications based on environmental conditions (oxygen)

Answer 13

-strict aerobe (only in O2)
-facilitative microbe (with or without)
-microaerophile (small amounts)
-strict anaerobe (only without O2)

Question 14

classifications based on environmental conditions (pressure)

Answer 14

-barophile (high pressure above 380 atm)
-barotolerant (between 10-500 atm)

Question 15

explain aerobic and anaerobic respiration

Answer 15

aerobic: O2 as electron acceptor, has enzyme able to detoxify and neutralize reactive oxygen species

anaerobic: anything other than O2, lacks these enzymes

Question 16

describe the phyla proteobacteria

Answer 16

-has 5 major classes, alpha -, beta, gamma -, delta -, epilson-proteobacteria
-triple-layered gram negative cell envelope, outer membrane, thin peptidoglycan periplasm
-diverse metabolism (fermentation, anaerobic/aerobic)

Question 17

alpha proteobacteria

Answer 17

-endosymbionts (nitrogen fixers and plant roots include rhizobium)
-rod-shaped
-aerobic
-bacteria lose cell wall, becomes rounded bacteroids specialized for N2 fixation
-host cell provides nutrients

Question 18

gamma proteobacteria

Answer 18

-includes enteric bacteria that colonize colon
-gram negative rods, flagella , facilitative anaerobes and fermentation
-includes species pathogenic to humans

Question 19

phyla bacteriodetes

Answer 19

-non-spore forming gram negative
-aerobic and anaerobic
some opportunistic pathogens (no harm to host if controlled)

Question 20

describe phylum firmicutes

Answer 20

-low GC species
-rod-shape cells
-can be aerobe or facultative anaerobe
-vegetative cells develop endospores in times of stress that swell
-non-spore forming can be staphylococcus (cocci in clusters) or streptococcus (cocci in chains)

Question 21

describe the phylogeny of archaea domain

Answer 21

-many phyla based on small subunit rRNA and genome sequences
-extremophiles

Question 22

Euryarchaeota (phylum): methanogens

Answer 22

-many polyphyletic clades
-energetic role in ecosystem for anaerobic removal of H2, produces methane
-found in soils, wetland
-trapped in ice as methane hydrate under oceans in permafrost, when melted releases methane
-pseudopeptidoglycan
-morphologically diverse

Question 23

Euryarchaeota: thermophiles

Answer 23

-temps between 50-80 degrees, bacteria or archaea
-Habitat often represent multiple extreme conditions
-ex: Pyrococcus furiosus: Lives in deep-sea hydrothermal vents
Hyperthermophile + barophile
Survive at temps above 70, prefers 100
An anaerobe that metabolizes sulfur to
H2S

Question 24

use of archaea in biotechnology

Answer 24

• Extremophiles make enzymes with ranges of stability “extremozymes”
  
  • Archaea lipids for vaccine adjuvants
    Archaea are source of antibiotic classes being explored by pharmaceutical industry