Lab 32 Questions

What factors influence the size of the zone of inhibition produced by a chemical?

1. Molecular weight of agent 2. Rate of difussion in the agar How well it diffuses into the agar, how long-lasting it is, solubility By the size of the molecule of the chemical used to kill the organism Smaller it is the faster it can be diffused out

Differentiate between antiseptic and disinfectant. Include examples of each in your answer. Indicate whether any chemicals can be used as both.

Antiseptic - inhibit microbial growth on living tissue; Ex. alcohol, betadine Disinfectant - chemical agents used on inanimate objects; Ex. bleach Disinfectants are too harsh to use on living tissue, but some antiseptics, such as alcohol, could be used as both.

How might the physical differences between gram-positive and gram-negative bacteria contribute to differences in chemical resistances?

Gram-negative may be more resistant to to that outer membrane that can keep chemicals from reaching the inside of the cell Gram negatives might be more resistent because they have extra protection.