Question

1. Which structures of a gram-positive bacterial cell would be susceptible to an extracellular enzyme that cleaves peptide-peptide bonds? Select all that apply

Flagellum

Murein

Fimbria

Polysaccharide capsule

Phospholipid bilayer

Teichoic acid

S-layer

2. Extremophiles are species that have optimal growth at “extreme”—to us!—environmental conditions that would kill or inhibit the growth of most species.

Based solely on your reading in the Microbe textbook, which of the following cellular features are adapted to allow organisms to thrive at extremes of temperature, osmotic pressure, hydrostatic pressure, or pH? Select all that apply.

Intracellular solutes

Morphology

Chromosome

Membranes

Proteins

3. Which statement(s) about bacterial growth is(are) TRUE? Select all that apply.

The generation time is dependent upon the growth conditions

Cells in lag phase are adapting to survive harsh conditions

Cells enter stationary phase when the toxic products accumulate

Cells may need to adapt to fresh growth media

4. Which measure of bacterial density excludes (does not detect) dead and non-culturable cells?

Select all that apply.

Flow cytometry

Turbidity measurement with a spectrophotometer

Counting the cells in a counting chamber device by phase contrast microscopy

Viable count

The phrase “bacterial growth” refers to an increase in cell size

Answer 1

Answer 1- flagellum, fimbrae, Murein and S-layer are made up of proteins, thus they are susceptible to enzymes that cleave peptide-peptide bond.

Answer 2-(d) protein

extremophiles survives in harsh conditions due to their amino acid composition that affects their protein folding ability.

Answer 3-true statements are

The generation time is dependent upon the growth conditions

Cells in lag phase are adapting to survive harsh conditions

Cells enter stationary phase when the toxic products accumulate

Answer 4- (c) Viability

(d) The phrase “bacterial growth” refers to an increase in cell size