Module 05: Acellular and Prokaryotic Microbes Flashcards
What are some examples of cellular microbes?
(1) Bacteria
(2) Archaea
(3) Protozoa
(4) Algae
(5) Fungi
What are some examples of non cellular microbes?
(1) Virus
(2) Viroid
(3) Prions
What are some examples of prokaryotic microbes?
(1) Bacteria
(2) Archaea
What are some examples of eukaryotic microbes?
(1) Fungi
(2) Protista
(3) Algae
Viruses viroid and prions are often referred to as what?
Acellular microbes or infectious agents (particles)
These are known as complete virus particles.
Virions
What are the size of viruses?
They range from 10 to 300 nanometers in diameter.
These are known to infect human animals plants fungi protozoa algae and other bacterial cells.
Viruses
These are viruses delineated to cause specific types of cancer.
Oncogenic or oncoviruses
What composes a typical virion?
(1) Genome of either RNA or DNA
(2) Capsid
(3) Capsomeres
This is known as the protein coat surrounding a typical virion.
Capsid
This is known as the protein units constituting a typical virion.
Capsomeres
These viruses have an outer envelope composed of lipids and polysaccharides
Envelope viruses
What are the five (5) properties that distinguish viruses from living cells?
(1) They possess either DNA or RNA, whereas living cells possess both.
(2) They are unable to replicate on their own.
(3) Unlike cells, they do not divide by binary fission, mitosis, or meiosis.
(4) They lack the genes and enzymes necessary for energy production.
(5) They depend on the ribosomes, enzymes, and metabolites of the host cell for protein and nucleic acid production.
What are the classifications under RNA viruses?
(1) Enveloped
(2) Non enveloped
What are the classifications under non enveloped RNA viruses?
(1) Single stranded positive sense
(2) Double stranded
What are some examples of non enveloped Single stranded positive sense - rRNA?
(1) Astroviruses
(2) Caliciviruses
(3) Picornaviruses
What are some examples of non enveloped double stranded - rRNA?
(1) Retroviruses
(2) Rotaviruses
What are the classifications under enveloped rRNA viruses?
(1) Single stranded positive sense
(2) Single stranded negative sense
(3) Retrovirus
What are some examples under single stranded positive sense enveloped rRNA viruses?
(1) Toga viruses
(2) Flaviviruses
(3) Corona viruses
What are the classifications under single stranded negative sense enveloped rRNA viruses?
(1) Linear
(2) Segmented
What are some examples under linear single stranded negative sense enveloped rRNA viruses?
(1) Rhabdoviruses
(2) Paramyxoviruses
What are some examples under segmented single stranded negative sense enveloped rRNA viruses?
(1) Arenaviruses
(2) Bunya viruses
(3) Orthomyxoviruses
What are some examples under retroviruses enveloped rRNA viruses?
(1) Lentiviruses
(2) Oncoviruses
What are the classifications under DNA non enveloped viruses?
(1) Single stranded linear
(2) Double stranded linear
(3) Double stranded circular
What are the some examples under single stranded linear in DNA non enveloped viruses?
Parvoviruses
What are the some examples under double stranded linear in DNA non enveloped viruses?
Adenovirus
What are the some examples under double stranded circular in DNA non enveloped viruses?
(1) Papillomaviruses
(2) Polymaviruses
What are the classifications under DNA enveloped viruses?
(1) Double stranded linear
(2) Double stranded circular
What are the some examples under double stranded linear in DNA enveloped viruses?
(1) Herpes viruses
(2) Pox viruses
What are the some examples under double stranded circular in DNA enveloped viruses?
Hepa Viruses
What are the steps of becoming an enveloped virus?
(1) Virus specific glycoproteins are synthesized and transported to the host cell membrane
(2) The cytoplasmic domains of the membrane proteins bind to the nucleocapsids
(3) The nucleocapsid is enveloped by the host cell membrane
(4) The host cell membrane provided the viral envelope through budding
(5) The enveloped virion is released from the host cell
Viruses are classified based on what?
(1) Type of genetic material (either DNA or RNA)
(2) Shape and size of capsid
(3) Number of capsomeres
(4) Presence or absence of an envelope
(5) Type of host it infects
(6) Disease it produces
(7) Target cell(s)
(8) Immunologic/antigenic properties
What are the four (4) categories of viruses based on the type of nucleic acid that they possess?
(1) Double-stranded DNA viruses
(2) Single-stranded RNA viruses
(3) Single-stranded DNA viruses
(4) Double-stranded RNA viruses
What are the most viral genomes?
Most viral genomes are circular molecules, but some are linear.
What are the steps of multiplication of animal viruses?
(1) Attachment
(2) Penetration
(3) Uncoating
(4) Biosynthesis
(5) Assembly
Animal viruses escape from their host cells either by ___________.
lysis of the cell or by budding.
Viruses that escape by budding become ___________.
enveloped viruses.
Explain the penetration of a host cell by a nonenveloped virus via endocytosis.
(1) Binding of a virus
(2) Invagination of the membrane
(3) Formation of an endocytotic vesicle
(4) Release of virion in the cytoplasm
Explain the penetration of a host cell by an enveloped virus.
(1) Binding of the virus to a host cell membrane receptor
(2) Fusion of viral envelope with the host membrane
(3) Nucleocapsid enters the cell
Viral infections in which the virus is able to hide from a host’s immune system _____________
By entering cells and remaining dormant (Latent)
Examples of Latent virus infections.
Once acquired, herpes virus infections (e.g., those that cause cold sores, genital herpes, and chickenpox/shingles) never completely go away; for example, chickenpox may be followed, years later, by shingles—both are the result of the same virus.
These viruses cause cancer.
Oncogenic viruses or oncoviruses
What are some examples of Oncogenic viruses or oncoviruses?
(1) Epstein–Barr virus,
(2) Human papillomaviruses, and
(3) Human T-lymphotrophic virus
type 1 (HTLV-1)
This virus causes acquired immunodeficiency syndrome (AIDS).
Human immunodeficiency virus (HIV)
How do you characterized Human immunodeficiency virus (HIV)?
It is an enveloped, single-stranded RNA virus
What are the target cells of HIV?
The primary targets for HIV are CD4+ cells—those having CD4 receptors on their surface.
These are drugs that are used to treat viral infections.
Antiviral drugs (Antibiotics are not effective against viral infections)
These agents interfere with virus-specific enzymes and virus production by disrupting critical phases in viral multiplication or inhibiting synthesis of viral DNA, RNA, or proteins
Antiviral drugs
These are viruses that infect bacteria.
Bacteriophages or simply phages
What are the two categories of bacteriophages?
(1) Virulent bacteriophages
(2) Temperate bacteriophages
They are always the cause to what is known as the lytic cycle, which ends with the destruction of the bacterial cell.
Virulent bacteriophages
What is the five (5) steps of the lytic cycle?
(1) attachment,
(2) penetration,
(3) biosynthesis,
(4) assembly, and
(5) release
Explain the lytic cycle
(1) Attachment of the phage to cell surface receptor
(2) Injection of the phage DNA into the cell
(3) Synthesis of phage DNA and phage proteins
(4) Assembly of new phage particles
(5) Lysis of the cell and release of progeny phage
These are smaller and less complex infectious particles than viruses
Viroid and prions
These are short, naked fragments of singles stranded RNA, which can interfere with the metabolism of plant cells.
Viroid (Can be transmitted in plants the same way viruses can)
Examples of viroid
(1) Potato spindle tuber
(2) Citrus exocortis
These are small infectious proteins that cause fatal neurologic diseases in animals and humans called transmissible spongiform encephalopathies
Prions
Prions are small infectious proteins that cause fatal neurologic diseases in animals and humans called _____________
Transmissible spongiform encephalopathies
Examples of Prions
Scrapie, bovine spongiform encephalopathy [mad cow disease], and Creutzfeldt–Jacob disease
Prions are resistant to what?
Disinfectants
How do prions cause disease?
Prions are thought to convert normal protein molecules into nonfunctional ones by causing the normal molecules to change their shape.
What are the three (3) major phenotypic categories of bacteria?
(1) Those that are Gram-negative and have a cell wall
(2) Those that are Gram-positive and have a cell wall
(3) Those that lack a cell wall (Mycoplasma spp.)
What are the three (3) basic categories of bacteria based on shape?
(1) Cocci
(2) Bacilli
(3) Curved and spiral shaped bacteria
This is the round shaped bacteria.
Cocci
This is the rod shaped bacteria
Bacilli
What is the size of an average coccus?
1 micrometer in diameter
This is known as the cocci in pairs.
Diplococci (Neisseria gonorrhoeae - gonorrhea)
This is known as the cocci in chains.
Streptococci (Streptococcus pyrogenes - strep throat)
This is known as the cocci in clusters.
Staphylococci (Staphylococcus aureus - boils)
This is known as the packet of 4 cocci.
Tetrad (Micrococcus luteus)
This is known as the packet of 8 cocci.
Octad (Sarcina ventriculi)
They are often referred to as rods; they may be short or long, thick or thin, and pointed or with curved or blunt ends.
Bacilli
What is the average sized bacillus?
1 x 3 micrometers
What are some examples of medically important bacilli?
(1) Escherichia,
(2) Klebsiella,
(3) Proteus,
(4) Pseudomonas,
(5) Haemophilus, and
(6) Bacillus spp.
What are some examples of curved bacteria?
(1) Vibrio spp.
(2) Campylobacter spp.
(3) Helicobacter spp.
What are some examples of spiral bacteria?
(1) Treponema spp.
(2) Borrelia spp.
The cause of relapsing fever, in a stained blood smear
Borrelia hermsii
What are the three (3) staining procedures.
(1) Simple staining
(2) Structural staining
(3) Differential staining
What are the different types of structural staining procedures?
(1) Capsule staining
(2) Spore staining
(3) Flagella staining
What are the different types of differential staining procedures?
(1) Gram staining
(2) Acid fast staining
What should be done prior to staining?
Bacterial smears must be fixed.
This serves to kill organisms, preserve their morphology, and anchor the smear to the slide.
Fixation
This fixation is not a standardized technique; excess heat will distort bacterial morphology
Heat fixation
This type of fixation is the standardized technique; the preferred method
Methanol fixation
Explain the procedure of simple bacterial staining?
(1) Smear loopful of microbes onto slide
(2) Air dry
(3) Drip methanol onto the specimen to fix
(4) Flood slide with stain
(5) Rinse with water and blot dry
(6) Observe with 100x objective
What are the two major groups of bacteria?
(1) Gram positive
(2) Gram negative
This bacteria end up being blue to purple
Gram positive
This bacteria end up being pink to red
Gram-negative
The final Gram reaction (positive or negative) depends on what?
Cell wall structure.
Compare the difference between the cell wall structure of the gram positive and gram negative bacteria?
(1) The cell walls of Gram-positive bacteria have a thick layer of peptidoglycan, making it difficult to remove the crystal violet–iodine complex.
(2) Gram-negative organisms have a thin layer of peptidoglycan, making it easier to remove the crystal violet; the cells are subsequently stained with safranin.
Teichoic acid and lipoteichoic acids are present in the cell walls of
Gram positive
Lipopolysaccharide are present in the cell walls of?
Gram negative
These bacteria are known to neither consistently be purple nor pink after gram staining.
Gram variable bacteria - Gardenalia vaginalis
These are often identified using the acid-fast stain
Mycobacterium
This is the red dye that is driven through the bacterial cell wall using heat.
Carbol Fuschin
This is used to soften the waxes in the cell wall.
Heat
Why are mycobacteria acid fast?
Because mycobacteria are not decolorized by the acid–alcohol mixture, they are said to be acid fast
If a bacterium is able to “swim,” it is said to be _________.
motile
Bacterial motility is most often associated with _____________.
flagella and less often with axial filaments.
Which bacteria are motile?
Most spiral-shaped bacteria and about 50% of bacilli are motile; cocci are generally nonmotile.
How can motility be demonstrated?
(1) stabbing the bacteria into a tube of semisolid medium
(2) by using the hanging drop technique
This contains millions of organisms
Bacterial colony
This is known as the appearance of the colony which varies from one species to another. This includes size, color, overall shape, elevation, and the appearance of the edge or margin of the colony. This is also important “clue” for identification (speciation) of bacteria.
Colony morphology
Colony morphology can also include what?
Colony morphology can also include the results of enzymatic activity on various types of media.
Size of colonies is determined by the organism’s _________ and is another important characteristic of a particular bacterial species.
generation time
0 hr - 1
4 hr - 256
8 hr - 65,000
12 hr - 17,000.000
Bacteria can be classified based on their _______________, including their relationship with oxygen and carbon dioxide.
Atmospheric requirements
With respect to O2, bacterial isolates can be classified as
(1) Obligate aerobes
(2) Microaerophilic aerobes
(3) Facultative anaerobes
(5) Aerotolerant anaerobes
(6) Obligate anaerobes
They grow best in the presence of increased concentrations of CO2 (usually 5%–10%)
Capnophilic organisms
What are some nutritional requirements of bacteria?
(1) Carbon
(2) Oxygen
(3) Sulfur
(4) Phosphorus
(5) Hydrogen
(7) Calcium, iron or zinc (special elements)
Organisms with especially demanding nutritional requirements are said to be ________________.
fastidious (“fussy”).
Under biochemical and metabolic activities, as bacteria grow they produce many ______________.
Waste products, secretions (enzymes)
This of many bacteria, such as staphylococci and streptococci, can be tentatively identified by the enzymes they secrete
Pathogenic secretions
In particular environments, some bacteria produce gases such as ________.
carbon dioxide or hydrogen sulfide
Under biochemical and metabolic activities, to identify bacteria in the laboratory they are?
To identify bacteria in the laboratory, they are inoculated into various substrates (i.e., carbohydrates and amino acids) to determine whether they possess the enzymes necessary to break down those substrates.
How do pathogens cause disease?
because they possess capsules, fimbriae, or endotoxins, or because they secrete exotoxins and exoenzymes that damage
cells and tissues.
Frequently, pathogenicity is tested by __________.
injecting the organism into mice or cell cultures.
Laboratory identification of bacteria is moving toward analyzing the organism’s DNA or RNA—techniques collectively referred to as _____________.
molecular diagnostic procedures.
These make it possible to identify an isolate without relying on phenotypic characteristics.
DNA probes
In this, the degree of relatedness between two different bacteria can be determined.
16S rRNA sequencing
These are type of bacteria that do not possess all the attributes of typical bacterial cells.
(1) Rickettsia’s
(2) Chlamydia’s
(3) Mycoplasmas
How do you characterized Rickettsia and Chlamydia?
They have a Gram-negative type of cell wall and are obligate intracellular pathogens (i.e., they must live within a host cell; they cannot grow on artificial culture media).
They have “leaky membranes.”
Rickettsias
They are “energy parasites,” meaning they prefer to use ATP molecules produced by their host cell.
Chlamydia’s
They are the smallest of the cellular microbes. They lack a cell wall and therefore assume many shapes
Mycoplasmas - pleomorphic
In humans, pathogenic mycoplasmas cause:
(1) Primary atypical pneumonia
(2) Atypical genitourinary infections
Mycoplasmas are resistant to what?
Because they have no cell wall, they are resistant to drugs like penicillin that attack cell walls
Mycoplasmas produce what?
They produce tiny “fried egg” colonies on artificial media.
Photosynthetic bacteria include?
(1) Purple bacteria - do not produce oxygen
(2) green bacteria - do not produce oxygen
(3) Cyano bacteria
These bacteria use light as an energy source
Photosynthetic bacteria
Photosynthesis that produces oxygen is called
________.
oxygenic photosynthesis.
Photosynthesis that does not produce oxygen is
called ________________.
anoxygenic photosynthesis.
When are archaea discovered?
Archaea (meaning “ancient”) were discovered in 1977; they are prokaryotic organisms.
They vary widely in shape; some live in extreme environments, such as extremely acidic, extremely hot, or extremely salty environments.
Archaea
Describe the archaea cell wall.
Archaea possess cell walls, but their cell walls do not
contain peptidoglycan (in contrast, all bacterial cell walls contain peptidoglycan).
Archaea are genetically closer to
Genetically, archaea are more closely related to eukaryotes than they are to bacteria
