B1 TEST 1 Flashcards
How many chromosomes do prokaryotes have and how do they replicate?
1 DNA chromosome, no histones, replicate through binary fission.
What provides protection from outside world for almost all prokaryotes?
Cell wall AND plasma membrane
Protozoa and helminths are both types of what?
Parasites
What are Koch’s Postulates/Germ Theory (4 points)
1) If pathogen is cause of disease it must be able to be found in EVERY scenario disease is involved 2) If pathogen is cause of disease, you should be able to culture it from an infected patient (GROWN IN VITRO) 3) If pathogen is cause of disease, you should be able to infect a new host using the pathogen that you have cultured.. 4) If pathogen is cause of disease, you should be able to recover original pathogen from new infected host.
Fill in the blanks
Define core microbiome
commonly shared microbioal species among individuals at specific bodily sites
Define secondary microbiome
Microbial species that uniquely contribute to the diversity of individuals at specific body sites.
What type of environment (within humans) do gram negative bacteria prefer?
The type of bacteria prefer wet/moist conditions.
(hint: you’re upset to get wet)
These four types of tissue are usually considered sterile. List them.
1) Deep muscle
2) sinovial fluid
3) cerebrospinal fluid
4) blood
What is immune stimulation?
Exposure to low concentrations of anti-normal flora help provide protection against other bacterial pathogens, which allows response for foreign blood types, deep infections, etc.
What are some ways that normal flora prevent foreign invasion? What are some nutritional and metabolic benefits?
1) maintaining specific pH (low pH in vaginal tract)
2) physical occupancy (no room for invaders!)
3) secreting antibiotics and bacteriocins (proteins that can act against other bacteria)
Benefits
1) vitamin K synthesis
2) biotin synthesis
What is dysbiosis?
Disruption of the normal microbiota is called this.
What are the 3 common shapes of bacteria. Give both names for each type.
1) Cocci (spheres)
- clusters
- chains
- diplococci
2) Bacilli (rods)
3) Spirochetes (spirals)
Describe the unique features of gram + bacteria. What color does it turn in response to staining sequence?
1) THICK peptidoglycan (PTG) layer
2) Teichoic acid (major surface antigen and support structure. Found inside PTG.
3) Lipoteichoic acid
both (2) and (3) have some SLIGHT endotoxic properties associated with them
Describe the unique features of gram - bacteria. (6) What color does it turn in response to staining sequence?
1) THIN peptidoglycan layer
2) periplasmic space (between outer membrane and cytoplasmic membrane, hydrolytic ezymes found here)
3) Lipoproteins (such as beta-lactamase), located inside that periplasmic space
4) LPS or lipopolysaccharide
5) Endotoxin (lipid A)
6) Porin proteins ( allow entry of essential substances AND anitmicrobial drugs)
WILL TURN PINK
What is the backbone of peptidoglycan composed of? What component has the cross link/peptide interbridges attached?
alternating glycan chain of
1) (NAG) N-acetylglucosamine
2) (NAM) N-acetylmuramic acid
NAM has the cross-link/peptide interbridge attached
The cross-link reaction in the formation of peptidoglycan is catalyzed by these two enzymes? What class of enzymes do these belong to?
1) transpeptidase (responsible for cross-linking the tetrapeptides)
2) carboxypeptidases (turns 5-polypeptide into tetrapeptide and uses that energy to form peptide cross-link)
BOTH of these enzymes belong to the penicillin binding protein (PBP) class
List the two Penicillin binding proteins and the types of antibiotics that they are susceptible to.
1) Transpeptidase
2) Carboxypeptidase
Both susceptible to Beta-lactam (penicillin) and vancomycin antibiotics
What holds together the outermembrane in gram (-) bacteria? What can disrupt this?
Divalent Cations (Mg2+, Ca2+) hold this together through linkages b/w phosphates of lipopolysaccharides (LPS)
EDTA (Ethylenediaminetetraacetic acid) will destroy this outermembrane of gram - bacteria
Define antigenic.
something that causes a strong innate immune response. can induce fever and cause shock
(think LPS and endotoxin/lipid A)
What are the (4) steps of Gram Staining? What does each step do to both gram (+) and (-)?
1) Crystal Violet (dye tissue)
2) Gram Iodine (fix tissue to hold color)
3) Decolorizer/Alcohol/Acetone (disrupts lipids, washes off excess CV dye)
4) Safranin Red (dyes exposes tissue, counterstain)
commonly shared microbioal species among individuals at specific bodily sites
Define core microbiome
Microbial species that uniquely contribute to the diversity of individuals at specific body sites.
Define secondary microbiome
Exposure to low concentrations of anti-normal flora help provide protection against other bacterial pathogens, which allows response for foreign blood types, deep infections, etc.
What is immune stimulation?
Disruption of the normal microbiota is called this.
What is dysbiosis?
What is the compostion and function of bacteria’s external structure?
1) Capsule?
2) Glycocalyx?
3) Pili (fimbriae)?
4) Flagella?
What is the name of a biochemical reaction in which antibodies bind to the bacterial capsule for specific type of bacteria. This antibody reaction allows these species to be visualized under a microscope. If the reaction is positive, the capsule becomes slimy or mucoid appearance of a bacterial colony is usually evidence of capsule production
Quellung reaction
What is the benefit of a flagella?
Chemotaxis and motility
How can you tell whether a strain of bacteria has flagella?
Motility test in soft auger.
Stick inoculated need inside auger.
If bacteria spread across entire tube (looks cloudy) then they have flagella.
What external structure found on bacteria promotes adherence?
Pili (fimbriae)
What is the name for a bacterial tube that can transfer large segements of bacterials chromosomes between bacteria?
F pili (sex pili)
(hint: f*** pili)
How do many bacteria overcome the lack of environmental iron?
By secreting siderophores (small, high-affinity iron chelating compounds secreted by microorganisms such as bacteria, fungi and grasses. Siderophores are amongst the strongest soluble Fe binding agents known)
What are the starting and ending products of anaerobic bacteria metabolism?
Pyruvate–> ATP + NADH (fermenation)
What are the starting and ending products of aerobic bacteria metabolism?
Pyruvate–> ATP (Electron transport chain)
What enzyme must all aerobic bacteria contain but NO obligate anaerobes contain? What is the function of this enzyme?
superoxide dismutase!
this enzyme converts 02 –> H2O2
Which specific aspect of the bacteria growth curves always for identification of many types of bacteria?
The Lag period: how long it takes bacteria to adapt to new environment and start growing exponentially
What type of bacteria can use sporogenesis to resist being killed?
ONLY gram + bacteria, usually bacili
What is the name of the preservation mode that some bacteria can enter to survive harsh conditions? What is the trigger for entering this phase? How do bacteria exit this phase?
Sporogenesis (only employeed by gram + bacteria)
-thick coat protects DNA and only spore mRNA is transcribed; make it resistant to chemicals (antibiotics) and heat
Sporogenesis is triggered by depletion of nutrients
Sporogenesis is exited by disruption of the outer coat (mechanical stress, pH, boiling a potato)
What are examples of cytoplasmic DNA for both eukaryotes and prokaryotes?
Eukaryotes: mitochondrial DNA
Prokaryotes: plasmids, bacteriophage (usually this is non-essential DNA, or BONUS DNA)
What helps maintain the supercoiled DNA structure inside bacteria?
Polyamines and DNA Gyrase (topo II)
What are some of the benefits of bacterial plasmids?
Can confer antibiotic resistance, bacteriocins, toxins, virulence determinants.
Replicates completely independently of the main bacterial chromosome
Describe the bacteriophage lytic cycle? 5 steps!
1) ATTACHMENT Bacteriophage lands on specific type of bacteria
2) PENTRATION- bacteriophage inserts DNA into host cell
3) Biosynthesis- bacteriophage DNA uses host cell machinary to replicate DNA and bacteriophage proteins
4) Maturation- newly synthesis proteins and DNA are assembled to form lots of new Bacteriophages
5) Lysis- rupture of cell and bacteriophages spread to find new hosts
What is a prophage?
bacteriophage DNA that has been integrated into the host chromosome and DNA. Can remain dormant for long periods of time
A bacteriophage actively undergoing the lytic cycle is considered to be a ______ phage.
virulent
A bacteriophage that has inserted its DNA into the host chromosome and DNA and is not actively undergoing replication is considered to be a _________ phage.
temperate
Describe the lysogenic cycle?
A bacteriophage enter the host cell and inserts its DNA into the bacterial DNA. Integrated bacteriophage DNA is called prophage.
The host cell survives and continues normal activity, but sometime this phage DNA will confer additional properties like antibiotic resistance.
The prophage can change its phenotype to LYTIC cycle at any time.
The acquisition of properties by the bacteria due to the presence of a prophage is called _________.
lysogenic conversion
the genome of an organism that is responsible for its capacity to cause disease (its pathogenicity). The virulence of the organism is modulated by genes harbored on this portion of DNA.
pathogenicity island
“island of evil”
Topoisomerases are susceptible to this type of antibiotic
quinolones (end in -floxacin)
Do bacterial have multiple different types of RNA? If not, what takes its place?
Bacterial only have one type of RNA: DNA dependent RNA polymerase
DNA dependent RNA Polymerase is composed of a sigma enzyme (responsible for transcribing “SOS genes”) and a core enzyme.
__________ are groups of one or more structurally or functionally related genes under the control of one promoter.
Operons
Define and contrast:
Endogenous vs. exogenous infections
Endogenous infection are caused by flora that are normally part of your body/surrounding that are opportunistic.
Exogenous infections are infections that are ACQUIRED from a new source (pre-school etc)
There can be some overlap
Define and contrast
Community acquired (CAI) vs. healthcare -associated (HAI) Infections
Community acquired: anywhere that is not healthcare related
Heathcare: anywhere that is healthcare related
nosocomial infection: hospital
latrogenic infection: intervention by a physician (think latex)
What are 4 examples of newly emerging infectious diseases?
1) West Nile Virus
2) SARS (severe acture respiratory syndrome, severe form of pneumonia)
3) Zika VIrus
4) Middle East Respiratory Syndrome
Describe the common anatomical portals and modes of microbial transmission in infections.
URAM infections into host!
Urogenital (body fluid)
Respiratory (inhalation)
Alimentary (eating, drinking)
Mucousal (kissing, open wound)
• Define inoculum size and explain its significances in causing a symptomatic infection (disease state).
Inoculum size is the number of pathogens enter into the host during transmission. SIZE MATTERS. Higher number of pathogens= better chance of establishment in host
Most infections DO NOT lead to symptomatic disease, must pass a theshold number to reach symptomatic diseased state
• Define and give examples/explanation for: fomites, reproduction number and total attack rate in the spread of infectious diseases.
fomites: objects that are used to carry/spread infection (clothes, doorknobs, pencils, computers)
total attack rate: the percentage of a population that will become infected with disease over the course of an outbreak
reproduction number (Ro): the number of people 1 infected person will spread the disease to during the infectious phase of disease life cycle
• Identify host and microbial factors that can influence microbial colonization in/on a host.
Virulent/microbial factors that influence colonizationL
1) slimy capside
2) long/strong pili for adhence
3) nutrients from host cell
Host efforts to prevent infection:
1) phagocytes
2) sweeping pathogens aways (UTI)
3) strave microbes
• Describe the basic mechanism and the significances of microbial adhesion.
direct lateral adhesion using pili/slimy capsid/disguizing yourself- usually must have adhesins that bind to host receptors. If you have huge numbers of pathogens this is not as important
dissemination: spreading to distant sites using host systems (circulatory, neuronal, lymphatic, respiratory, etc)
• Explain the determinants and significances of microbial invasiveness and tissue tropism in microbial pathogenesis.
tissue tropism is the specific type of environment/host cells that a pathogen like to encounter to increase their ability to spread. factors to be considered include
1) temperature
2) pH
3) cell receptor type
• Explain the possible clinical outcomes from an infection.
1) asymptomatic- infection is flushed or destroyed (can occur during colonization phase OR after infection phase)
2) latent infection- no harm to host, infection becomes part of normal flora or integrates into host cells
3) pathogenicity
infection crosses the theshold number of organism and starts becoming symptomatic
• Explain the roles of innate and adapted host immune responses in clearing an infection, and give examples of microbial strategies in evading immune defense.
innate: pH, flushing, shedding, temperature, skin
adapted: phagocytes, immune system (haha)
• Explain the biological processes responsible for tissue damage in an infection. (3)
microbe pathogenic activity
1) secrete toxins or invasins
2) lysing cells
3) stop cell growth
Chlamydiae (list 2 species)
Chlamydiae trachomatis- an obligate intracellular bacteria that is the most common cause of STD.
Chlamydiae pneumoniae- an obligate intracellular bacteria that causes atypical pneumonia
Mycoplasmas
- causes atypical (walking pneumonia) and is transmitted by aerosols
- is resistant to penicillin and other cell wall antibiotics
- requires sterols to live
- do not have cell walls
Rickettsiae
an obligate intracellular bacteria that causues EPIDEMIC TYPHIS (lice)and ROCKY MOUNTAIN SPOTTED FEVER (tick)
(uses arthropod vector)
Treponema pallidum
(syphilis)
an type of spirochete bacteria that is an STD
FLEXIBLE CELL WALL
Borrelia burgdorferi
Lyme disease
a type of spirochete bacteria that is tick transmitted
FLEXIBLE CELL WALL
Leptospira so (leptospirosis)
a spirochete bacteria with a flexible cell wall
also zoonotic
mycobacterium
mycobacterium tuberculosis
- stain red by acid-fast stain
- a filamentous bacteria
example of a gram (+) aerobic bacteria
nocardia
an example of a gram (+) strict anaerobe
actinomyces
streptococcus
gram (+) cocci; subdivided into groups based of hemolysis pattern
examples: pharyngitis, pneumonia, soft tissue infections
staphylococcus
a gram (+) cocci that is salt resistant
causes soft tissue infections and TOXIC shocks
Neisseria. Gives two species examples.
a gram (-) diplococci
- include normal flori of moth and pharynx
1) neisseria gonorrhoeae -std
2) neisseria meningiditis- meningitis
corynebacterium (2 speicies)
non spore forming gram (+) rods
corynebacterium diphtheria
corynebacterium listeria
bacillus
aerobic,spore-forming, gram (+) rods
clostridium
strict anaerobes, spore forming, gram (+) rods
E coli
gram (-) rods
ENTERIC BACTERIA
enterobacteriaceae family
causes diarrhea and sepsis
vibrio
cholera
gram (-) rods
ENTERIC BACTERIA
non-enterobacteriaceae family
pseudomonas
gram (-) rods
NON-ENTERIC
found in aqueous environment, opportunistic infections
haemophilus
gram (-) rods
non-enteric
(sp?) cocobacilli, fastidious, meningitis
neutrophils
granulocytes
multiple lobes (3-4)
stain dark purple and lilac
involved in acute inflammation and bacterial infections
first to be recruited to scene
make up 60% of WBC
phagocytic activity, specifically target bacteria
