L18: Microbial Metabolism/Structures and Functions

Question 1

How do bacteria replicate?

Answer 1

Binary fission

Question 2

What is a typical bacterial growth curve?

Answer 2

• -Starts with lag phase, where no growth occurs
• -Exponential phase is where growth is increasing quickly
• -Stationary phase is when there is a stalling of growth
• -Decline is when growth declines due to lack of resources

Question 3

When are the best times to target bacteria?

Answer 3

During lag or exponential phases (at other times spores are being made and microbials are less effective)

Question 4

What determines growth in culture?

Answer 4

• -pH optimum
• -Aerobic vs. anaerobic
• -Nutrients/composition of media
• -Temperature

Question 5

Chemoheterotrophs

Answer 5

Use organic compounds as both their energy source and their carbon source; most pathogenic bacteria

Question 6

Aerobic

Answer 6

Exclusively utilizes respiration to meet its energy need

Question 7

Anaerobe

Answer 7

Exclusively utilizes fermentation to meet its energy needs (killed by oxygen)

Question 8

Catalase

Answer 8

Catalyzes the breakdown of H2O2 (often expressed by organisms that can grow in the presence of oxygen)

Question 9

Fermentation

Answer 9

Pyruvate is converted to various end products; end products can help identify bacteria

Question 10

Importance/generation of folate

Answer 10

Important for the synthesis of purines and thymidine; derived from para-aminobenzoic acid (PABA) in bacteria

Question 11

Gyrase

Answer 11

Required for unwinding/winding DNA in replication; the targets of quinolones

Question 12

Co-transcriptional translation

Answer 12

Transcription and translation are coupled; 70S ribosomes instead of 80S ribosome in humans

Question 13

2 important sugars of peptidoglycan

Answer 13

1. N-acetylglucosamine (NAG)

2. N-acetylmuramic acid (NAM)

Question 14

Transpeptidation

Answer 14

Occurs between the free amine of the diamino amino acid in the third position of the pentapeptide (or the N-terminus of the attached pentaglycine chain), and the D-alanine at the fourth position of the other peptide chain, releasing the D-alanine precursor

Question 15

Peptidoglycan synthesis

Answer 15

1. NAM and NAG get activated by UDP
2. Addition of amino acids to UDP-NAM to form NAM-pentapeptide, fueled by ATP
3. NAM-pentapeptide is transferred to bactoprenol phosphate and they’re joined by pyrophosphate bond
4. UDP transfers NAG to bactoprenol-NAM-pentapeptide
5. Bactoprenol carrier transports completed NAG-NAM-pentapeptide repeat unit across the membrane