Question

1. in the appropriate space in table 1 below, record the results you expect to obtain after incubation. use (+) for bacterial growth (i.e., resistance to the antibiotic) and (-) for lack of growth (i.e., sensitivity to the antibiotic). in the space below the table, explain your reasoning. table 1. growth of e. coli strains i and ii on plates used to confirm the strains’ resistance or sensitivity to streptomycin and ampicillin.

Explanation:

Step1: Analyze LB plates

LB is a general - purpose growth medium. Both strains are expected to grow (denoted by +) as there are no antibiotics present to inhibit growth. Observed results match expectations.

Step2: Analyze LB+str plates

Strain I has resistance to streptomycin (str), so it is expected to grow (+). Strain II is sensitive to str, so it is expected to not grow (-). Observed results match expectations.

Step3: Analyze LB+amp plates

Strain I is sensitive to ampicillin (amp), so it is expected to not grow (-). Strain II has resistance to amp, so it is expected to grow (+). Observed results match expectations.

Step4: Analyze LB+str+amp plates

Strain I has resistance to str but is sensitive to amp, so it cannot grow in the presence of both antibiotics (observed -). Strain II has resistance to amp but is sensitive to str, so it cannot grow in the presence of both antibiotics (observed -), but the expected result for Strain II was + assuming it could handle the combination based on individual resistances, which indicates a possible error in the assumption or experimental conditions.

Answer:

The reasoning for expected results is based on the individual resistances and sensitivities of E. coli strains I and II to streptomycin and ampicillin. The observed results mostly match the expected results, except for Strain II on the LB+str+amp plate where there may be an error in the experimental setup or assumptions about combined - antibiotic resistance.