MCB 100 Final Exam UIUC Questions and Correct Answers
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Course
MCB 100
Institution
MCB 100
Similarities between Archaea and bacteria -Prokaryotic cell - no nuclear membrane,one circular chromosome - 70S ribosomes - most have cell walls - some species stain purple and others end up red in the Gram stain
Differences between Archaea and bacteria - Ribosomal RNA sequence data - Archaeal cel...
MCB 100 Final Exam UIUC Questions
and Correct Answers
Similarities between Archaea and bacteria ✅-Prokaryotic cell
- no nuclear membrane,one circular chromosome
- 70S ribosomes
- most have cell walls
- some species stain purple and others
end up red in the Gram stain
Differences between Archaea and bacteria ✅- Ribosomal RNA sequence data
- Archaeal cell walls lack peptidoglycan (no N-acetyl muramic acid).
- Archaeal cytoplasmic membrane lipids have branched chain fatty acids that may
extend through the membrane.
- The initial amino acid in protein synthesis in Archaea is methionine rather than formyl-
methionine, which is used in bacteria.
- Archaeal RNA polymerase is similar to eukaryotic RNA pol II.
- Archaeal flagella are simple protein threads that rotate like those of bacteria, but they
are very different. Archaea flagella are not hollow tubes, they are solid. Assembly differs
from bacterial flagella too.
Pseudomurein ✅a cell wall polymer found in some species of Archaea that is similar to
peptidoglycan in that it consists of sugar chains that are cross linked by amino acid
chains
Methanogens ✅Methanogens are obligate anaerobes
that produce methane - CH4 .
Halophiles ✅Their habitats are more than 9% NaCl
(sea water is 0.9%)
Some survive in 35% NaCl
Many make red-orange pigments that absorb light energy and protect from UV.
Example: Halobacterium, Halococcus
Halophiles ✅Lack chlorophylls or bacteriochlorophylls
Makes Bacteriorhodopsins
(purple-red pigments, rhodo = red)
Low G + C Gram-positive Bacteria (Firmicutes) ✅Clostridium Bacillus
Mycoplasma Listeria
High G + C Gram-positive Bacteria (Actinobacteria) ✅Corynebacterium
Mycobacterium
Actinomycetes
Clostridium ✅club-shaped
- Anaerobes (many are obligate anaerobes that die in the presence of O2)
- Produce heat resistant endospores
- They have a wide variety of fermentative pathways
such as acetone-butanol production
- Many produce and excrete potent toxins
Clostridium botulinum ✅Anaerobic, spore forming, gram + rod
Botulism: severe form of food poisoning
Improperly canned non-acidic food
Neurotoxin
Headache, double vision, flaccid paralysis
Clostridium tetani ✅natural habitat is anaerobic
soil layers and sediments
- produces a toxin that causes
rigid paralysis
- infects wounds and
produces toxin in vivo
- tetanus vaccine is a toxoid
that provides immunity to toxin
Clostridium perfringens ✅- spores are common in soil
- wound infection
- causes gas gangrene
- produces a number of necrotizing
toxins that kill tissues
Clostridium difficile ✅- may be found in low numbers in the human gut
- naturally resistant to several antibiotics
- may multiply in patients on antibiotic therapy
- produces toxins
- may cause antibiotic induced diarrhea
Clostridium difficile ✅Found in soil, animal feces, meat & poultry contaminated at
slaughter
, Clostridium difficile ✅is a major cause of colitis following antibiotic use, especially in
hospitals.
Clostridium difficile ✅colonizes the colon
Symptoms are: watery diarrhea, with no blood.
To treat, stop antibiotic therapy, give probiotics
Bacillus anthracis ✅- primarily a herbivore disease (sheep and cattle especially)
- problem in nations where animal vaccination is not practical
- virulence factors include: a capsule made of glutamic acid
and toxins
Inhalation Anthrax ✅initial flu like symptoms
- treatment is often too late to save the patient because the toxins are enzymes, even if
the bacteria are killed the toxins keep onworking to kill the patient
- very high mortality rate in untreated cases
Cutaneous Anthrax ✅- infects minor wounds
- necrotic effects on surrounding tissues
- AKA: wool sorter's disease
- untreated mortality rate is 20%
Gastrointestinal Anthrax ✅infects gut, due to eating contaminated meat
Bacillus stearothermophilus ✅a thermophile that is involved in hay spoilage
(Wet hay can lead to barn fires due to the heat released by
microbial metabolism.)
Bacillus thuringiensis ✅produces a toxin that kills
insects but does not harm
mammals,
- used as an organic method of
controlling insect pests
Bacillus licheniformis ✅synthesizes bacitracin - an antibiotic that inhibits peptidoglycan
synthesis by interfering with the movement of precursor groups through the cell
membrane to the cell wall
- a common soil bacterium capable of reducing nitrate
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