Microbiology Ch 3 & 4 Study Guide
Flagellated bacteria can detect and move in response to chemical signals- chemotaxis; positve chemotacis is movement of a cell in the direction of a favorable chemical stimule; negative chemotaxis is movement away from a repellent compound
Define chemotaxis and state its significance for bacteria with flagella
Conjugation pili are utilized in a "mating" process between conjugation cells- which involves partial transfer of DNA from one cell to another; a conjucation pilus from the donor cell untied with a recipient cell, thereby providing a cytoplasmic connection for making the transfer
Describe conjugation involving pili
Timed, sequential applications of crystal violet (primary dye), Grams iodine (the mordant) and alcohol rinse (decolorizer) and a contrasting counterstain; bacteria that stain purple are gram + and those that stain red are gram -; due to thickness of a petidoglycan layer in the cell membrane cell walls dyes certain colors; gram + have thick layer and gram - have thin
Describe how a Gram stain works and the outcomes for gram- negative and gram- positive bacteria
primary function is to confer motility
Describe the function of flagella
provide some type of adhesion but not locomotion
Describe the functions of fimbriae and pili
contribute to cell shape
Describe the main function of the cytoskeleton in bacteria
similar in construction to cytoplasmic membrane, contains specialized types of polysaccharides and proteins; uppermost layer contains lipopolysaccharide- extend off surfeace function as signaling molecules and recepts; lipid portion of LPS endotoxin because it stimulates fever and shock reactions in most gram - infections such as meningitis and typhoid fever
Describe the major components of the outer membranes of Gram negative bacteria and their medical significance
Gram -: can be decolourized to accept counterstain, thin peptidoglycan layer, does not contain teichoic acids, has outer membrane, high lipopolysaccharide content gram +: retain crystal violet dye and stain dark violet or purple, thick layer of peptidoglycan, teichoic acid, doesnt have outer membrane; no lipopolysaccharide content
Describe the similarities and differences between Gram positive and Gram negative cell envelopes; know the major components
thin ( 5- 10 nm), flexible sheet molded around cytoplasm; general composition lipid bilayer with proteins embedded to varying degrees; bacterial cytoplasmic membranes have typical structure containing primarily phospholipids and proteins; provides site for functions such as energy reactions, nutrient processing, and synthesis; major action is to regulate transport- passage of nutrients and discharge of waste
Describe the structure of cytoplasmic membranes and their major function
show an unusual, wriggly mode of locomotion caused by two or more long, coiled threads, the periplasmic flagella or axial filaments
Describe the unique motion of spirochetes
a species is a distinct type of organism that can produce viable offspring only when it mates with others of its own kind; microbiologists use terms like subspecies, strain or type to designate bacteria of the same species that have differing characteristics
Describe what is meant by species versus strain, subtype or type
they "love" extreme conditions in the enviorment; they live in the remaining habitats on the eath that have ancient conditions- most extreme habitats in nature
Describe why some archaens are called extremophiles
slime layer- loose shield that protects them from loss of water and nutrients capsule- bound more tightly to the cell than a slime layer is and it is denser and thicker; often visible in negatively stained preps and produce sticky character to colonies on agar
Difference between slime layers and capsules
withstand hostile conditions and facilitating survival; medically relevant ones are all gram +; hardiest of all life forms, capable of withstanding extremes in heat, drying, freezing, radiation, and chemicals that would readily kill vegetative cells
Discuss the advantages of endorpore formation for bacteria
often called "the armor" of a bacterial cell; protects the cell and in some cases helps it adhere to its enviorment
Discuss the function of glycocalyces
some aspects of diseases pathogens cause are related to the persistence and resistance of their spores; when the tissue, they can germinate, grow, and release potent toxins
Discuss the medical significance of bacterial endospores
gram negative bacteria are more resistant to antibiotices; have doubt layered for their cells boundary
Discuss why Gram- negative bacteria are often harder to kill than Gram- positive bacteria
bacteria can store nutrients through inclusion bodies to respond to periods of low food availability; can pack gas into vesicles to provide buoyancy in an aquatic environment; can store crystals of iron oxide with magnetic properties in inclusion bodies; use granules to orient themselves in polar and gravitational fields to bring them to environments with the proper oxygen content
Functions of inclusion bodies or inclusion granules
mycobacterium species; thick waxy nature imparted to the cell wall by these lipids is responsible for high degree of resistance to certain chemicals and dyes
State the type of organisms identified by an acid- fast stain
spirochetes
a coiled, spiral shaped bacterium that has endoflagella and flexes as it moves
slime layer
a diffuse, unorganized layer of polysaccharides and/or proteins on the outside of some bacteria
glycocalyx
a filamentous network of carbohydrate- rich molecules that coats cells
cytoplasm
a gelatinous solution encased by the cytoplasmic membrane; major component is water which serves as a solvent for the cell pool, a complex mixture of nutrients including sugars, amino acids, and salts
filament
a helical structure composed of proteins that is part of bacterial flagella
vegetative state or form
a metabolically active and growing entity thata can be induced by enviormental conditions to undego endospore formation or sporulation
peptidoglycan (PG)
a network of polysaccharride chains cross- linked by short peptides that forms the rigid part of bacterial cell walls; gram- negative bacteria have a smaller amount of this rigid structure than do gram positive bacteria
cell wall
a semirigid casing that provides structural support and shape for the cell
fimbria
a short, numerous surface appendage on some bacteria that provided adhesion but not locomotion
endospore
a small, dormant, resistant derivative of a bacterial cell that germinated under favorab,e growth conditions into a vegetative cell; bacterial genera bacillus and clostridium are typical endospore formers
acid- fast stain
a solution containing carbol fuchsin, which, when bound to lipids in the envelopes of mycobacterium species, cannot be removed with an acid wash
flagellum
a structure that is used to propel the organism through a fluid enviorment
cell (cytoplasmic membrane)
a thin sheet of lipid and protein that surrounds the cytoplasm and controls the flow of materials into and out of the cell pool
appendages
accessory structures that sprout from the surface of bacteria; they can be divided into two major groups; those that provide motility and those that enable adhesion
porin
act as a pore through which molecules can diffuse
outer membrane
an additional membrane possessed by gram- negative bacteria; a lipid bilayer containing specialized proteins and polysaccharides; it lies outside of the cell wall
pilus
an appendage used for drawing another bacterium close in order to transfer DNA to it
heterotrophic
an organism that relies upon organic compounds for its carbon and energy needs
teichoic acid
anionic polymers containing glycerol that appear in the walls of gram positive bacteria
lipoteichoic acid
anionic polymers containing glycerol that are anchored in the cytoplasmic membranes of gram- positive bactera
inclusion bodies
bacteria manufacture to respond to their environmental conditions; they can store nutrients in this way to respond to periods of low food availability; they can pack gas into vesicles to provide buoyancy in an aquatic enviorment; can store crystals of iron oxide with magnetic properties in inclusion bodies
mycoplasms
bacteria that naturally lack a cell wall; cytoplasmic membrane is stabilized by sterols and is resistant to lysis
spirillum
bacterium having a slightly curled or spiral shaped cylinder; rigid helix twisted twice or more along its axis
gram negative
category of bacterial cells that describes bacter with an outer membrane, a cytoplasmic membrane and a thin cell wall
streptobacillus
chain of bacilli cells
tetrads
cocci in packets of four
staphylococcus
cocci that appear in clusters
diplococcus
cocci that appear in pairs
bacterial chromosome or nucleoid
composed of condensed DNA molecules. DNA driects all genetics and heredity of the cell and codes for all proteins
sarcina
cubical packet of 8, 16, or more cells; the cellular arrangement of the genus ___ in the family micrococcaceae
site of protein synthesis
describe the basic functions of ribosomes
the hereditary material of most bacteria exist in the form of a single circular strand of DNA designated as the bacterial chromosome
describe the molecules that contain the hereditary information of bacteria
evidence indicates that the first eukaryotic cell appeared on the earth approx 2-3 billion years ago; now believe that bacteria, archaea, and eukaryotes evolved from a different kind of cell called the last common ancestor- neither prokaryotic or eukaryotic; irst probably single celled and independent but over time some cells began to aggregate forming colonies; further evolution some became specialized or adapted specific function
discuss current thinking about how the first eukaryotic cell formed and when this likely occurred
endospore
dormant body formed within some bacteria that allos for their survival in adverse conditions
plasmid
double- stranded DNA circle containing extra genes
outer membrane
extra membrane similar to cytoplasmic memvrane but also containing lipopolysaccharide; controls flow of materials and portions of it are toxic to mammals when released
branching filaments
few bacteria produce multiple branches off of a basic rod structure
fimbriae
fine, hairlike bristles extending from the cell surfact that help in adhesion to other cells and surfaces
mycosis
fungal infections: vary in the way the pathogen enters the body and the degree of tissue involvement they display
cell wall
in bacteria, a rigid structure made of petidoglycan that lies just outside the cytoplasmic membrane; eukaryotes also have a cell wall but may be composed of a varitety of materials
conjugation
in bacteria, the contact between donor and recipient cells associated with the transfer of genetic material such as plasmids; can involve special (sex) pili; also a form of sexual recombination in ciliated protozoa
capsule
in bacteria, the loose, gel- like covering or slime made chiefly of polysaccharies; this layer is protective and can be associated with virulence
dimorphic fungi
in mycology, the tendency of some pathogens to alter their growth form from mold to yeast in response to rising temperature
cytoplasmic membrane
lipid bilayer that encloses the cytoplasm of bacterial cells
cytoskeleton
long fibers of proteins that encircle the cell just inside the cytoplasmic membrane and contribute to the shape of the cell
hyphae
long, threadlike cells found in the bodies of filamentous fungi, or molds
pili
long, tubular structures made of pilin protein produced by gram - bacteria and used for conjugation
S layer
monolayer of protein used for protection and/or attachment
lipopolysaccharide
polysaccharide chains that extend off of uppermost layer of the OM that unction as signaling molecules and receptors; lipid portion referred to as endotoxin because it stimulates fever and shock reactions in gram - infections
bacterial microcompartments
protein coated packets used to localize enzymes and other proteins in the cytoplasm
motility
self- propulsion
vibrio
singly occuring rods that are gently curved
flagellum
specialized appendage attached to the cell by a basal body that holds a long, rotating filament; the movement pushes the cell forward and provides motility
coccus
spherical or ball- shaped bacterium; can be perfect sphered but they can exist as oval, bean shaped or even pointed variants
spirochete
spiral cell containing periplasmic flagella; more flexible form that resembles a spring
gram stain
staining technique used for identification of bacteria in which violet dye is applied followed by a decolorizing agent and then a red dye; the cell walls of certain bacteria retain first dye while those that lost it appear red
inclusion/ granule
stored nutrients such as fat, phosphate, or glycogen deposited in dense crystals or particles that can be tapped into when needed
lysis
the physical rupture or deterioration of acell
chemotaxis
the tendency of organisms to move in response to a chemical gradient (toward an attractant or to avoid adverse stimuli)
ribosomes
tiny particles composed of protein and RNA that are the sites for protein synthesis
plasmids
tiny strands that exist as separate double stranded circles of DNA, although at times they can be duplicated and passed on to related nearby bacteria; not essential to bacterial growth and metabolism, often confer protective traits such as resisting drugs and producing toxins and enzymes
streptococcuus
variable number of cocci in chains
mycolic acid
very long cahin fatty acid aka cord factor that contributes to the pathogenicity of nontypical cell walls
cytoplasm
water- based solution filling the entire cell
have unique sequences in their rRNA; exibit novel method of DNA compaction, and contain unique membrane lipids, cell wall components and pilin proteins; most primitve of all life forms; some thrive in extremley high temps; no nucleus and membrane bound organelles; lack peptidoglycan in cell wall
Key features of archae (single cell or unicellular; prokaryotic or eukaryotic)
Clostridium; C. tetani (tetanus), C. perfringens (gas gangrene), C. botulinum (botulism), C. diff (GI disease)
Name the example endospore forming bacteria discussed and the diseases they can cause
cocci, spirilla, and bacilli
Name the three major cell shapes of bacteria
mycolic acid, or cord factor, contributes to the pathogenicity of this group: mucobacterium and nocardia; thick waxy nature is resposnibel for high degree of resistance to certain chemicals and dyes
State the significance of mycolic acid cell walls for the organisms that have them
Gram + bacteria have a thick layer of peptidoglycan in their cell walls, also contains teichoic acid and lipoteichoic acid; gram - bacteria have single/ thin sheet of peptidoglycan; thinness gives it a greater flexibility and sensitivity to lysis
Relate Gram Stain results to cell envelope structure
Capsules are formed by many pathogenic bacteria; encapsulated bacterial cells generally have greater pathogenicity because capsules protect the bacteria against white blood cells called phagocytes; helps them escape phagocytosis
Understand how capsules can enhance the ability of bacteria to cause disease
Some pathogens can colonize and infect host tissue because of a tight adhesion between their fimbriae and epithelial cells
Understand how fimbriae can contribute to the ability of a bacterial organism to cause disease
glycocalyces from multiple microbes merge to form them; protective shield for the micrones; strongly adherent; used for single celled microorganims- microorganisms attach to surface cells stick
What are biofilms
helps determine the shape of a bacterium and provides the kind of strong structural support necessary to keep a bacterium from bursting or collapsing because of changes in osmotic pressure; peptidoglycan is a compound composed of a repeating framework of glycan (sugar) chains cross- linked by short peptide (protein) fragments to provide a strong but flexible support framework
What are the key functions of a bacterial cell wall and describe the peptidoglycan from which it is built
purple- gram + red- gram -
What are the results of this Gram Stain
cell (cytosplasmic) membrane, bacterial chromosome or nucleoid, ribosomes, and cytoplasm
What bacterial cell parts do all bacteria have in common?
S layer, fimbriae, outer membrane, cell wall, cytoskeleton, pilus, glycocalyx, inclusion/granule, bacterial microcomponents, plasmid, flagellum, endospore, intracellular membrane
What bacterial cell parts do some but not all bacterial have in common
1) vegetative cell begins to be depleted of nutrients 2) chromosome is duplicated and separated 3) cell is septated into a sporanglum and forespore 4) sporangium engulfs forespore for further development 5) sporangium begins to actively synthesize spore layers around forespore 6) cortex and outer coat layers are deposited 7) mature endospore 8) free endospore is released with the loss of sporangium 9) germination: endospore swells and releases vegetative cell
What is the sporulation cycle of bacteria that can form endospores
gram postive
a category of bacterial cells that describe bacteria with a thick cell wall made of peptidoglycan and no outer membrane
rod/ bacillus
a cell that is cylindrical; also a genus that has same name; quite varied in actual form depending on species
bacterial chromosome
a circular body in bacteria that contains the primary genetic material; also called nucleoid
glycocalyx ( tan coating_
a coating or layer of mlecules external to the cell wall; serves protective, adhesive, and receptor functions; may fit tightly (capsule) or be very loose and diffuse (slime layer)