Microbiology - Chapter 3
1. What is the stimulus for chemotaxis?
Chemicals
2. What does the capsule typically look like on a stained smear when viewing under the light microscope?
Clear halos around the cells
Which of the following bacterial genera is described CORRECTLY?
Vibrio—club-shape INCORRECT
During bacterial conjugation, DNA can be transferred through a ______ from the donor to the recipient cell.
pilus
Which structure plays a direct role in the exchange of genetic material between bacterial cells?
pilus
The presence of variation in the size and shape of bacterial cells of the same species is known as _______.
pleomorphism
2. After Gram's iodine is added, what color do the cells appear under a light microscope?
All cells appear purple
1. What type of macromolecule makes up the bacterial capsule?
Carbohydrates
Which of the following cell arrangements is described CORRECTLY?
Diplococcus—pairs of spherical cells
4. True or False: The thinner peptidoglycan layer of gram-positive bacteria allows the crystal-violet-iodine complex to leave the cell.
False
Gram-positive bacteria have flagella with four basal body rings, while those of gram-negative bacteria have only two.
False
What motility structure is used for bacterial chemotaxis?
Flagella
3. A culture of Klebsiella colonies is smooth, indicating the presence of a capsule. A culture of Pseudomonas shows rough colonies. Based on this information alone, which species is likely to be more pathogenic?
Klebsiella
Choose the division that includes the archaea (archaebacteria).
Mendosicutes
Choose the substance or condition that triggers sporogenesis among endospore-forming bacteria.
Nutrient depletion
1. Why must fresh cells be used when performing a Gram stain?
Old cells may not Gram-stain properly.
Which of the following is involved in gliding motility in bacteria?
Specialized cell-surface proteins and slimy polysaccharides
A collection of bacterial cells that shares an overall similar pattern of traits different from other groups of bacteriais defined as a bacterial _________.
Species
Which of the following bacterial groups is described CORRECTLY?
Spirochetes—move by axial fibrils
If a few drops of nutrient solution are added to one side of a bacterium's environment, what will happen?
The bacterium will have longer runs towards the nutrient, but it will still tumble at times
What determines whether a bacterium "runs" or "tumbles" through its environment?
The direction of flagellar rotation
Which of the following statements about flagellar structure is TRUE?
The filament extends out of the cell
Why is the capsule considered a virulence factor?
The presence of the capsule allows a bacterium to evade the immune system and cause damage to the host
A spirochete moves in a screwlike manner that is mediated by axial fibrils located in the cell's periplasmic space.
True
Mycoplasma pneumoniae lacks a cell wall and is termed pleomorphic.
True
1. When is sporulation initiated by spore-forming bacteria?
When nutrients are depleted or conditions become adverse
The bacterial flagellum moves _______.
by rotation that is powered by the proton motive force
5. In the next phase of spore formation, ________ enters the cortex and ________ leaves the cortex.
calcium; water
Nanotubes are extensions of the _________ that can function in _________.
membrane; nutrient transfer
2. When spore formation begins, the vegetative cell is referred to as the ________.
mother cell
4. The cortex is formed from ________.
peptidoglycan
6. In the final step of spore formation, a ________ coat forms around the cortex.
protein
3. When ethanol is applied correctly, gram-positive cells appear ________ and gram-negative cells appear ________.
purple; colorless
Spirillum is a genus of spiral-shaped bacteria that move by flagella.
tRUE
3. The developing spore is surrounded by ________.
the membrane of the mother cell
Rods that are slightly curved are called ________.
vibrio
