practical knowledge

Question 1

Why are human tears lytic and what is the target of the lytic chemical they contain?

Answer 1

They contain lysozyme

Lysozyme catalyzes the hydrolysis of 1,4-beta-linkages between N-acetylmuramic acid and N-acetyl-D glucosamine residues in peptidoglycan. This means that it is more effective against Gram-positive bacteria.

Question 2

What antibiotic is E coli not susceptible to and why?

Answer 2

Penicillin, which targets the formation of peptidoglycan cross-links in the bacterial cell wall. E. coli (a Gram negative) has less peptidoglycan in its cell wall so is less susceptible. It may also produce penicillinase enzymes to inhibit the drug.

Question 3

Which strains were Gram positive and which ones gram negative?

Answer 3

B.megaterium and S. aureus gram positive

E. coli and P.fluorescens gram negative

Question 4

Which strain is heat resistant?

Answer 4

B. megaterium