Module 1 Chapter 2.3 and 3.2-3.9

How do spheroplasts and protosplasts differ?

Spheroplasts retain their outer membrane but protoplasts do not.

A strain of Neisseria gonorrhoeae has undergone a mutation and is no longer able to make pili. Predict the most likely outcome.

The bacteria will become less virulent and will not be able to readily establish infection.

Which of the following statements is FALSE when comparing bacterial and eukaryotic cytoskeletal proteins?

The cytoskeletal proteins found in bacterial cells are structurally and functionally unrelated to those found in eukaryotic cells.

A pathogenic bacterial species has mutated and is no longer able to synthesize a capsule. Which outcome would you predict?

The mutated bacteria will not be able to cause disease as readily

The cytoplasmic membrane of bacteria

all are correct

Match the description of the slime layer

diffuse, easily removed, facilitates motility

The lipopolysaccharide (LPS) that is found in the outer membrane of Gram-negative bacteria is also known as

endotoxin

In the Gram-staining procedure, the counterstain is __________.

safranin

What are the steps of endospore formation?

1. axial filament formation 2. septum formation 3. engulfment of forespore 4. cortex formation 5. coat synthesis 6. coat completion 7. lysis and spore liberation

Which of the following is considered to be a differential staining procedure?

Both Gram stain and Acid-fast stain

If you forgot to apply the safranin counterstain while performing a Gram stain, which outcome would you expect?

Gram-negative bacteria would be unstained

If you forgot the decolorization step while performing a Gram stain, which outcome would you expect?

Gram-negative bacteria would stain purple

Although penicillin inhibits peptidoglycan synthesis, bacterial cells will continue to grow normally in the presence of penicillin in a(n) __________ environment.

Isotonic

Square planar arrangement of cells that forms when round bacteria remain attached to each other during reproduction are called _________.

Tetrads

If you forgot to heat fix a smear before doing a Gram stain, which of the following might occur?

The smear may not adhere to the slide

A fellow student carries out the Gram stain on a mixed culture containing Gram-negative rods and Gram-positive cocci. On completion he finds purple cocci and clear (no color) rods when viewing the prepared slide with a microscope. From the following, choose the best reason for these results.

The student forgot to add the counterstain.

Predict the change in surface area and volume of a spherical cell if the diameter of the cell doubles.

The surface area will increase by a factor of 4, while the volume will increase by a factor of 8.

Which of the following is not true of bacterial plasmids?

They are required for host growth and/or reproduction.

Which of the following is/are true of capsules?

all are correct

Export of flagellin subunits is mediated by

an apparatus in the basal body of the flagellum that is related to the type III secretion

Prior to staining, smears of microorganisms must be heat-fixed in order to __________.

attach them firmly to the slide

The term used to describe bacteria that are rod-shaped is _________.

bacillus

Which of the following structures is NOT found in an endospore?

capsule

The term used to describe bacteria that are intermediate in shape between spherical and rod-shaped is _________.

coccobacilli

The term used to describe bacteria that have a spherical shape is _________.

coccus

In the Gram-staining procedure, the primary stain is

crystal violet

Endospores represent a challenge to the fields of industrial and medical microbiology because _________.

endospores are resistant to harsh environments, thus allowing survival of endospore-forming organisms under conditions in which non-endospore-forming cells would not survive, and endospore-forming organisms are often dangerous pathogens

Germination is one process by which bacterial cells can reproduce

false

Which of the following bacterial structures are most directly linked to swimming motility in chemotaxis?

flagella

Bacteria and archaea are typically fixed to slides by ________ while eukaryotes with subcellular structure, such as protists, are typically fixed by _________.

heat, chemicals

In the Gram-staining procedure, the mordant is __________.

iodine

All of the following statements about the periplasmic space are true except __________.

it is found only in Gram-positive bacteria

Acid-fast organisms such as Mycobacterium tuberculosis contain __________ constructed from mycolic acids in their cell walls.

lipids

Chemotaxis is a process by which bacteria _________.

move toward an attractant or away from a repellent

Basic dyes such as methylene blue bind to cellular molecules that are

negatively charged

In addition, there is an __________ external to the Gram-negative bacterial peptidoglycan layer.

outer membrane

In the Gram-positive bacterial cell wall, the tetrapeptides that extend from the peptidoglycan layers are linked by

peptide interbridges

This structure contains only a thin layer of

peptidoglycan

Which of the following protects bacteria from lysis in dilute solutions and helps to determine their cellular morphology or shape?

peptidoglycan

The two layer cell wall of Gram-negative bacteria is separated from the plasma membrane by the

periplasmic space

flagella spread over the entire surface of the bacterium

peritrichous

The addition of alcohol during the Gram-staining procedure causes decolorization of Gram-negative bacteria and the addition of safranin results in ___ cells

pink

If the decolorizer is left on too long in the Gram-staining procedure, Gram-positive organisms will be stained __________ and Gram-negative organisms will be stained __________.

pink; pink

The cell wall of Gram-negative bacterial cells is external to the

plasma membrane

Bacterial cells that are variable in shape are called

pleomorphic

one flagellum at one end of the bacterium

polar

Nearly all bacteria contain peptidoglycan. Review the structure of peptidoglycan by selecting the correct characteristics listed below.

polymer of alternating N-acetylglucosamine(NAG) and N-acetylmuramic acid and contains D amino acids not found in proteins

The power used by most bacterial flagellar motors is produced by __________

proton motive force (PMF)

After the decolorizer has been added, Gram-positive organisms are stained __________ and Gram-negative organisms are stained _______

purple, colorless

After the primary stain has been added but before the decolorizer has been used, Gram-positive organisms are stained __________ and Gram-negative organisms are stained _________

purple, purple

After the mordant has been added, Gram-positive organisms are stained __________ and Gram-negative organisms are stained __________.

purple; purple

Rigid bacteria with a helical cell shape are called _________.

spirilla

Flexible bacteria with a helical shape are called

spirochetes

After conducting the Gram stain on a mixed culture containing Gram-positive rods and Gram-negative cocci, all the cells were purple in color. This was most likely because

the cells were not decolorized enough with alcohol or acetone

Structural differences between Gram-positive and Gram-negative bacteria are observed following the Gram-staining procedure since __________.

the thick layer of peptidoglycan in Gram-positive bacteria is dehydrated during the alcohol step, thus acting as an impermeability barrier retaining the crystal violet/iodine complex

The term used to describe bacteria that are shaped like curved rods is _________.

vibrio

Match the description of the capsule

well organized, not easily removed, helps against phagocyotisis