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107 terms

Microbiology Chapter 4

STUDY
PLAY
What organisms are thought to be the first cells to appear on earth?
Archae
Which component is not found in the cytoplasm of the majority of procaryotes?
Capsule
What term refers to the fine, hairlike bristles that aid in adhesion in procaryotic organisms?
Fimbriae
In a peritrichous arrangement of flagella, how are the flagella distributed over the organism?
Multiple flagella randomly dispersed over the cell surface
Why is the flagellum effective in guiding bacteria through the environment?
The system for chemical detection is linked to the mechanisms that drive the flagellum
In motile bacteria the presence of attractant molecules causes an increase in what?
The length of runs
What type of organisms possesses axial filaments?
Spirochetes
What type of appendage may be responsible for the formation of biofilms?
Fimbria
Pili, elongated tubular structures composed of pilin, are only found on what type of organisms?
Gram negatives
Which of the following is not an example of a biofilm?
A single bacterial cell growing on an agar surface
Why are encapsulated bacteria generally more pathogenic than unencapsulated strains?
Because the capsule helps prevent phagocyte attachment to the organism
Which of the following is incorrect regarding the bacterial cell wall?
It is composed of a repeating framework of lipids
What is the key differentiating step in the Gram stain procedure?
Application of the mordant
The outermost layer of the outer membrane is composed of what?
Lipopolysaccharide
Which statement describes why Gram negative organisms are more sensitive to lysis than Gram positive organisms?
The peptidoglycan layer of the cell while is quite thin
The acid fast stain is used to identify organisms containing what chemical in their cell walls?
Mycolic acid
What is not a function of the bacterial cytoplasmic membrane?
Storage of nutrient reserves
How many chromosomes do bacteria possess?
One
Which of the following is incorrect regarding plasmids?
They are essential for bacterial growth and survival
Under what conditions can endospores form?
When carbon and nitrogen sources become depleted
What is not one of the three general shapes possessed by bacteria?
Pleomorphic
The style of bacterial grouping, or arrangement, is based on what factor?
The number of planes in which the bacteria divide
Identification of bacteria requires a study of all but which of the following?
Quantitative analysis
Current strategies for determining evolutionary relatedness between organisms rely upon what?
rRNA sequence analysis
What type of bacteria naturally lacks a cell wall?
The Mycoplasmas
In spore formation, the stage in which DNA condenses and aligns itself in the center of the cell is called
mother cell
The spore layer containing peptidoglycan is the
cortex
As calcium enters the spore
water is removed from the cell
The protein coat forms outside the exosporangium.
False
Spore formation is initiated when there is a scarcity of nutrients and conditions are adverse.
True
How do bacteria communicate with each other?
Chemical molecules
What is this type of communication known as?
Quorum sensing
When are the genes turned on for chemical expression?
When their population number reaches a critical count
One of the interesting findings about bacteria communication is that
they seem to have a universal language between all bacterial species.
How is using bacterial communication knowledge as a proposed antibiotic method intended to work?
The antibiotic would stop the gene expression or detection of chemical signals.
cells
an individual membrane-bound living entity; the smallest unit capable of an independent existence
cytoplasm
dense fluid encased by the cell membrane; the site of many of the cell's biochemical and synthetic activities
chromosome
tightly coiled bodies in cells that are the primary sites of genes
ribosome
a bilobed macromolecular complex of ribomucleoprotein that coordinates the codons of mRNA with tRNA anticodons and, in doing so, constitutes the peptide assembly site
organelles
a small component of eurocaryotic cells that is bounded by a membrane and specialized in function
metabolism
a general term for the totality of chemical and physical processes occurring in a cell
irritability
capacity of cells to respond to chemical, mechanical, or light stimuli. this helps cells adapt to the environment and obtain nutrients
flagella
a srtucture that is used to propel the organism through a fluid environment
axial filaments
a type of flagellum (called an endoflagellum) that lies in periplasmic space of spirochetes and is responsible for locomotion; also called periplasmic flagellum
fimbriae
a short, numerous surface appendage on some bacteria that provides adhesion but not locomotion
pili
small, still filamentous appendages in gram-negative bacteria that function in DNA exchange during bacterial conjugation
glycocalyx
a filamentous network of carbohydrate-rich molecules that coat cells
peptidoglycan
a network of polysaccharide chains cross-linked by short peptides that form the rigid part of bacterial cell walls. gram-negative bacteria have a small amount of this rigid structure than do gram-positive bacteria
gram stain
a different stain for bacteria useful in identification and taxonomy. Gram-positive organisms appear purple from crystal violet-mordant retention, whereas gram-negative organisms appear red after loss of crystal violet and absorbance of the safranin couterstain
outer membrane
a structure made of lipids in the outer layer of the cell wall of a gram-negative bacteria
nucleoid
the basophilic nuclear region or nuclear body that contains the bacterial chromosome
plasmids
extrachromosomal genetic units characterized by several features. A plasmid is a double-stranded DNA that is smaller than and replicated independently of the cell chromosome; it bears genes that are not essential for cell growth; it can bear the genes that code for adaptive traits; and it is transmissible to other bacteria
inclusions
a relatively inert body in the cytoplasm such as storage granules glucogen, fat, or some other aggregater metabolic product
cytoskeleton
a fine intracellular network of fibers, filaments, and other strands that function in support and shape of cells
bacterial actin
fine protein fibers within cells that contribute to structure and support
endospore
a small, dormant, resistant derivative of a bacterial cell that germinates under favorable growth conditions into a vegetative cell
cocci
a spherical-shaped bacterial cell
bacilli
bacterial shape that is cylindrical
spirilla
a type of bacterial cell with a rigid spiral shape and external flagella
spirochetes
a coiled, spiral-shaped bacterium that has endoflagella and flexes as it moves
pleomorphic
normal variability of cell shapes in a single species
coccobacilli
an elongated coccus; a short, thick oval-shaped bacterial rod
vibrios
a curved, rod-shaped bacterial cell
diplococci
spherical or oval shaped bacterial cells, typically found in pairs
tetrads
groups of four
sarcina
a cubical packet of 8, 16, or more cells
palisades
the characteristic arrangement of Corynebacterium (italics) cells resembling a row of fence posts and created by snapping
strains
in microbiology, a set of descendents cloned from a common ancestor that retains the original characteristics. Any deviation from the original is a different strain.
rickettsias
edically important family of bacterial, commonly carried by ticks, lice, and fleas. Significant cause of important emerging diseases
obligate
without alternative, restricted to a particular characteristic
Bacterial cells could have any of the following appendages except
cilia
The short, numerous appendages used by some bacterial cells for adhering to surfaces are called
fimbriae.
The transfer of genes during bacterial conjugation involves rigid, tubular appendages called
sex pili.
All bacterial cells have
a chromosome.
The term that refers to the presence of flagella all over the cell surface is
peritrichous.
The outcome of the Gram stain is based on differences in the cell's
cell wall.
A bacterial cell exhibiting chemotaxis probably has
flagella.
If bacteria living in salty seawater were displaced to a freshwater environment, the cell structure that would prevent the cells from rupturing is
cell wall.
Peptidoglycan is a unique macromolecule found in bacterial
cell walls.
A procaryotic cell wall that has primarily peptidoglycan with small amounts of teichoic acid and lipoteichoic acid is
gram positive.
A bacterial genus that has waxy mycolic acid in the cell walls is
Mycobacterium.
Lipopolysaccharide is an important cell wall component of
gram negative bacteria.
The site/s for most ATP synthesis in procaryotic cells is/are the
cell membrane.
The bacterial chromosome
is part of the nucleoid.
The function of bacterial endospores is
protection of genetic material during harsh conditions.
Bacterial endospores are not produced by
Staphylococcus
When a rod shaped bacteria is short and plump, it is called a
coccobacillus
What is the correct sequence for a Gram stain?
crystal violet, Gram's iodine, alcohol, safranin
Bacteria with small bunches of flagella emerging from the same site are said to be
lophotrichous
Lysozyme, an enzyme found in tears, provides a natural defense against bacteria by
hydrolyzing peptidoglycan in cell walls.
In the Gram stain, the mordant is
iodine
Archaea do not have the typical peptidoglycan structure found in bacterial cell walls.
True
Bacteria in the genus Mycoplasma and bacteria called L-forms lack cell walls.
True
Gram negative bacteria do not have peptidoglycan in their cell walls.
False
The procaryotic cell membrane is a site for many enzymes and metabolic reactions.
True
The procaryotic cell membrane is a site for many enzymes and metabolic reactions.
True
If during the gram stain procedure, the bacterial cells were viewed immediately after crystal violet was applied, gram positive cells would be purple but gram negative cells would be colorless.
False
Endospores of certain bacterial species can enter tissues in the human body, germinate, and cause an infectious disease.
True
Iodine is the decolorizer in the Gram stain.
False
The _____ stain is used to stain and differentiate Mycobacterium and Nocardia from other bacteria.
Acid-fast
The procaryotic flagellum has three parts: the _____, the hook, and the basal body.
Filament
Movement of a cell toward a chemical stimulus is termed _____.
Chemotaxis
The cell _____ is composed of three layers: the glycocalyx, the cell wall, and the cell membrane.
Envelope
During the Gram stain, gram _____ cells decolorize when the alcohol is applied.
Negative
The enzyme _____, that is found in tears and saliva, can hydrolyze the bonds in the glycan chains of certain bacterial cell walls.
Lysozyme
Cells form a _____ arrangement when cells in a chain snap back upon each other forming a row of cells oriented side by side.
Palisade
_____ Manual of Systematic Bacteriology is a manual of bacterial descriptions and classifications.
Bergey's