possible short answer questions

know the phases of bacterial growth and be able to identify these phases on a graph

define biofilm and understand its importance to bacterial growth and human health

• Biofilm - microbial communities that form slime layers and adhere to surfaces

  • Bacteria communicate to attract other bacterial cells

  • Share nutrients

  • Shelters bacteria from harmful environmental factors (antibiotics, antiseptics, immune system)

know the factors that will affect microbial death rate when surfaces are chemically treated

• Amount of microorganisms on the surface - more = harder to kill

• Type of microorganisms on the surface - some are harder to kill

• presence/absence of organic material - limits effectiveness of chemical

• Temperature of the environment - chemicals work better in warm environment

know what type of microorganisms are the most difficult to kill with disinfectant

Endospore - endospores allow bacteria to survive in harsh conditions

Prions - no nucleic acid so bacteria can survive many disinfecting techniques

Understand the bacterial operon and how it controls gene expression; know the difference between an inducible gene and a repressible gene and how gene expression benefits bacteria

A bacterial operon is a group of genes controlled together to turn gene expression on or off. An inducible operon is usually off but turns on when needed, such as the lac operon. A repressible operon is usually on but turns off when enough product is available such as the trp operon. Gene regulation benefits bacteria by saving energy and helping them adapt to environmental changes.

Define mutation and mutagen and understand the different types of mutations

*still needs to be updated

• Mutation: a change in the DNA sequence

• Mutagen: an agent that causes or increased mutations, such as UV radiation or certain chemicals

Understand the principle of the Ames test

The Ames test determines whether a chemical may cause mutations. It uses mutant bacteria that cannot make histidine. If the chemical causes reverse mutations, the bacteria regains the ability to make histidine and grow on a medium without it. More bacterial colonies than the control suggests the chemical may be mutagenic.