Chapter 3 Microbiology

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The concept of a prokaryote was first fully outlined in 1962 by

Stanier and Van Niel

The genus of bacteria that undergoes cell division in random planes, forming grapelike clusters of round bacteria, are the __________.

staphylococci

Bacteria that do not have a fixed shape are said to be __________.

pleomorphic

A branched network of hyphae formed by the Actinomycetes is called a __________.

mycelium

Actinomycetes form long filaments called ___________.

hyphae

The term used to describe bacteria that are intermediate in shape between spherical and rodshaped is

coccobacilli.

Bacterial cells that are variable in shape are called

pleomorphic.

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

tetrads.

Flexible bacteria with a helical shape are called

spirochetes.

Rigid bacteria with a helical cell shape are called

spirilla.

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

vibrio.

The term used to describe bacteria that are rod shaped is

bacillus.

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

coccus.

Sterol-like molecules called hopanoids are thought to be important for the structural integrity of many bacteria because of their suspected role in membrane stabilization.

TRUE

The cytoplasmic membrane of bacteria

A. retains the cytoplasm and its contents., B. acts as a selectively permeable barrier, allowing some molecules to pass while preventing the movement of others., C. is the major site of ATP synthesis in aerobes.

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

endotoxin.

Which of the following is/are true of capsules?

A. They help bacteria escape phagocytosis by host cells., B. They retain water and help prevent desiccation of the bacteria., C. They prevent entry of many bacterial viruses.

Proteins that are loosely associated with the cytoplasmic membrane are called __________proteins.

peripheral

Proteins that are embedded within the cytoplasmic membrane and not easily extracted are called __________ proteins.

integral

Shrinkage of the plasma membrane away from the cell wall when the bacterium is placed in a hypertonic environment is called

plasmolysis.

Lipids with polar and nonpolar ends are said to be

amphipathic.

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

isotonic

All of the following statements about the periplasmic space are true except:
"It is located between the plasma membrane and outer membrane of gram-negative bacteria."
"It contains hydrolytic enzymes and binding proteins involved in nutrient acquisition."

it is found only in gram-positive bacteria.

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

peptidoglycan

Sortase is a protein enzyme of bacteria that

catalyzes covalent attachment of some surface proteins to peptidoglycan.

The cell membrane is a rigid structure that provides bacteria with their characteristic shapes.

FALSE

Gram-positive bacteria have a thinner layer of peptidoglycan than gram-negative bacteria.

FALSE

Gram-positive bacteria have a structurally and chemically more complex cell wall than gramnegative bacteria.

FALSE

Bacteria growing at lower temperatures have more saturated fatty acids in their membranes.

FALSE

When the cell wall is removed from a Gram-negative bacterium without removing the outer membrane, the resulting form is called a(n) __________.

spheroplast

Enzymes that are secreted out of the cell to aid in the acquisition and digestion of environmental nutrients are called __________.

exoenzymes

Molecules or regions of molecules that readily interact with water are said to be __________, whereas molecules or regions of molecules that are insoluble in water or do not readily interact with water are said to be __________.

hydrophilic, hydrophobic

A __________ layer consists of diffuse unorganized polysaccharide material that lies outside the cell wall and is easily removed.

slime

A __________ is a polysaccharide layer that lies outside the cell wall and is not easily removed.

capsule

A(n) __________ layer is a layer of protein or glycoprotein that exhibits a pattern resembling floor tiles.

S

The most widely accepted current model for membrane structures is called the __________model.

fluid mosaic

The layers of peptidoglycan of the bacterial cell wall can be cross-linked by peptide intrabridges or by direct cross-linking.

FALSE

A feature unique to some archaeal plasma membranes is that they may

consist of a lipid monolayer.

Cell walls of most Archaea and bacteria contain peptidoglycan.

FALSE

_______ is a peptidoglycan-like molecule found in the cell walls of some archaea.

Pseudomurein

The hydrocarbons found in the membranes of archaea are identical to those found in bacteria.

FALSE

Which of the following is not true of bacterial plasmids?

They are required for host growth and/or reproduction.

Some photosynthetic bacteria produce gas vacuoles that regulate their buoyancy but contain no lipid.

TRUE

Intracellular granules of organic or inorganic material that are stockpiled by bacteria for future use are called __________.

inclusions

Bacteria have a region of the cytoplasm known as the __________, which is not bounded by a membrane but contains the chromosome.

nucleoid

Small circular DNA molecules capable of replicating and containing genes that are useful but not necessary to the bacterium are called __________.

plasmids

Some species of aquatic bacteria use inclusion bodies known as ________ to orient themselves in Earth's magnetic field.

magnetosomes

Bacterial and archaeal ribosomes are known as _____ ribosomes, based on their sedimentation coefficient.

70S

_______ are the site of protein synthesis in the cell.

Ribosomes

Sedimentation coefficients are proportional to the molecular weight of a particle and are not affected by the volume and shape of the particle.

FALSE

Bacterial flagella are composed of three parts: the ______ body, which is embedded in the cell, the hook, and the _______, which is the longest part of the flagellum.

basal, filament

The type III bacterial protein secretion machinery:

A. has a needlelike structure through which proteins are secreted., B. includes structural features that may be evolutionarily related to the basal bodies of bacterial flagella., C. is found in gram-negative bacteria.

Export of flagellin subunits is mediated by

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

Proteinacious projections from the surface of a bacterium that are used to mediate conjugation are called sex __________, whereas projections that mediate attachment to surfaces such as host cells are called __________.

pili, fimbriae

During the assembly of the flagellar filament, the flagellin protein monomers assemble at the cell proximal base of the flagellum.

FALSE

Archaeal flagella are superficially similar to bacterial flagella, although archaeal flagella are much thicker than bacterial flagella.

FALSE

Matching: Match the definition with the word. 1) monotrichous, 2) peritrichous, 3) lophotrichous, 4) amphitrichous:
a) a single flagellum,
b) a single flagellum at each pole of an organism,
c) a cluster of flagella at one or both ends of an organism,
d) a relatively even distribution of flagella over the entire surface of the bacterium

1-a, 2-d, 3-c, 4-b

The power used by most flagellar motors is produced by

proton motive force (PMF)

Chemotaxis is a process by which bacteria

move toward an attractant or away from a repellent.

The rotation of bacterial flagella is powered by ATP hydrolysis.

FALSE

The bacterium E. coli swims in a straight line, called a __________, for a few seconds; then it stops, __________, then swims away in a new direction.

run, tumbles

In many spirochetes, multiple flagella combine to form a bundle known as a(n)____________ fibril, which winds around the cell and confers motility on the cell.

axial

Twitching or gliding motility involves

both type IV pili and movement of slime can be involved in twitching or gliding motility.

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

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

__________ is the process through which endospores are formed within a vegetative cell.

Sporulation

__________ is the main part of the process through which a vegetative cell is formed from an endospore.

Germination

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