Metabolism and Genetics

Question 1

Which 3 enzymes are essential for a bacteria to survive in AEROBIC environment?

Answer 1

Superoxide dismutase, Catalase, Peroxidase

Question 2

Which enzyme is found in bacteria that tolerate low amounts of oxygen (microaerophiles)?

Answer 2

SUPEROXIDE DISMUTASE (Microaerophiles: Streptococcus, Spirochetes, Borrelia, Treponema, Campylobacter, HELICOBACTER)

Question 3

Mycoplasma species are considered FACULTATIVE ANAEROBES except?

Answer 3

Mycoplasma pneumoniae (OBLIGATE AEROBE)

Question 4

Which are the three OBLIGATE ANAEROBES?

Answer 4

BACTERoides, ACTINomyces, CLOStridium (the mnemonic I use : OBLIGATE ANAEROBES are BACTERIA that ACT IN CLOSed environement)

Question 5

Based on oxygen requirement Lepstospira is classified as?

Answer 5

OBLIGATE AEROBE (Remember it loves to go to calf muscles where oxygen tension is high causing the classic pain in Leptospirosis. Other OBLIGATE Aerobes : NoCARDIA, Psedomonas, Legionella, Mycobacterium, Bacillus, Neisseria, Brucella, Bordetella)

Question 6

Give two bacterial species which are exclusively anaerobic but INSENSITIVE to the presence of oxygen.

Answer 6

Propionibacterium, Lactobacillus (Aerotolerant Anaerobes)

Question 7

These are EXTRACHROMOSOMAL pieces of DNA encoding exotoxins and certain enzymes that confer DRUG RESISTANCE.

Answer 7

PLASMIDS

Question 8

Relapsing fever is caused by a mechanism described as the movement of genes from inactive (storage ) sites into active sites of transcription. What do you call this mechanism? Which bacteria cause the relapsing fever?

Answer 8

Programmed rearrangement (responsible for ANTIGENIC VARIATION); Borrelia recurrentis

Question 9

What is the most comon mode of DNA TRANSFER between bacterial cells?

Answer 9

Conjugation (DNA transfer using sex pili)

Question 10

The transfer procedure where DNA is transferred by a VIRUS (phage) from one bacteria to another.

Answer 10

TRANSDUCTION

Question 11

Scarlet fever is caused by which toxin? This toxin is acquired by which transfer procedure, Conjugation, Transduction or Transformation?

Answer 11

Erythrogenic toxin; Transduction

Question 12

Griffith’s experiment where a nonencapsulated bacteria acquired capsule from killed capsulated bacteria describes which transfer mechanism?

Answer 12

TRANSFORMATION

Question 13

A mutation which leads to the expression of the same amino acid is called?

Answer 13

SILENT

Question 14

What are the 3 STOP codons?

Answer 14

UAA, UAG, UGA