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Fall 2022 > Microbio > Flashcards

Microbio Flashcards

1
Q

Structure of prokaryote

A

No nucleus, DNA stored in cytoplasm. Chromosomes are circular (nucleoid), do not contain introns. Reproduction asexual and results in identical daughter cells

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2
Q

Flagella

A

Elongated protein filament cylinders anchored inside cell wall and plasma membrane of predominantly gram negative bacteria. Propels bacteria , can be useful for identification.chemotaxis regulates movement of flagellum to certain chemicals in the environment

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3
Q

Pili

A

Tiny hairs around bacterium, also present in gram positive bacteria and gram negative. Adhesions at the top play important role in allowing bacterial to attach to surfaces or other organisms

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4
Q

Cell envelope

A

Maintains cells shape of bacteria, prevent lysis from osmosis, determines if bacteria is gram positive or negative.

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5
Q

Capsule

A

Gram positive and gram negative bacteria, called glycocalyx or peri cellular matrix. Composed of glycoprotein and glycolipids. Defends against host immune response.
Medically important bacteria with capsules : e.coli, n. Meningitidis, k. Pneumoniae, salmonella

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6
Q

Outer membrane for prokaryotes

A

Formed by glycolipid bilayer, major component is lipopolysaccharide (LPS- endotoxin that can cause septic shock) (glucosamine disaccharide - selective permeability) found exclusively in gram neg. bacteria.

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7
Q

Cell wall of prokaryotes

A

Made of peptidoglycan (glycan chains of NAG and NAM, peptide inter-bridge connecting tetra peptide chain of amino acids) tetrapeptides connect to NAM on the glycan chains
Gram positive has 5 glycine resides that attach to peptidoglycan (also has teichoic acid that stabilizes cell wall)
Gram negative has one glycine reside that attaches to peptidoglycan (smaller layer, but has lipoproteins in periplasm, lipopolysaccharides, outer membrane layer, and porin protein)
exoskeleton to prevent lysis in hypotonic or isotonic solutions.

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8
Q

Cytoplasmic lipid membrane of prokaryotes

A

No sterols

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9
Q

Envelops of gram positive bacteria

A

No outer membrane. Cell walls much thicker than gram negative. Anionicpolymers-teichoic acid and lipotdichoic acid- weave throughout. Surface proteins that replicate the functions of the proteins situated between outer and inner membranes of gram negative bacteria

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10
Q

Obligate anaerobes

A

Lack superoxide dismutase and catalase to protect them from oxygen free radicals.

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11
Q

Facultative anaerobes

A

Can switch between aerobic respiration and anaerobic fermentation

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12
Q

Fastidious bacteria

A

Picky eaters, only grow when certain nutrients are present

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13
Q

Siderophores

A

Fastidious bacteria will produce this chelating compound to bind to iron with great avidity, stealing it from blood and tissue proteins

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14
Q

Bacterial growth

A

Lag phase- bacteria mature and adapt, reproduction rate is slow
Exponential growth phase (log)- rapid growth. Will continue until resources expire
Stationary phase- physiological limitation, lack of nutrients, accumulation of toxic waste. No growth
Death phase - population declines and dies

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15
Q

Gram staining method

A

Differentiate groups of bacteria based on components of cell wall
Violet dye applied to cells, followed to iodide which binds to dye. Decolonizing agent applied (gram neg become colorless), then pink counter stain (safranin)(gram negative becomes red).

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16
Q

Gram staining results

A

Gram positive exhibit deep purple or blue color due to thick peptidoglycan layer
Gram negative remain pink or red

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17
Q

Acid fast staining

A

Differentiates atypical bacteria . Carbol fuchsin dye stains all cells, washed with acid alcohol, acid fast bacteria exhibit bright red color. (Large amounts of my colic acids in cell walls)
Ziehl- Neelsen stain

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18
Q

Endospore staining- Schaefer Fulton method

A

Stained with malachite green which binds to spores, then counter stained with safranin

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19
Q

Capsule staining

A

Stain the background, not the capsules, with India ink or nigrosine. Bacteria are counterstained, show clear halos around them

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20
Q

Bacteria shapes

A

Rods-mildly elongated coccus like a cocktail weenie
Bacillus- more elongated coccobacilli, like hot dog
Coccus- sphere
Vibrio- comma like
Spirillum- wavy
Spirochete- twisted like the threads on a screw

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21
Q

Diploid

A

Bacteria that form pairs

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22
Q

Chains

A

Bacteria that form short single file lines

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23
Q

Clusters

A

Bacteria that bunch together like grapes

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24
Q

Hyphae

A

Bacteria that form long thread like filaments

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25
Normal flora
Microorganisms including archaea, fungi, viruses, that inhabit human body or live on its surface. Not harmful, aid immune system in preventing infection , necessary for survival
26
Opportunists
Potentially pathogens that would not normally inhabit the body but take advantage of the opportunity (weakened immune system)
27
Pathobionts
Typically benign endogenous microorganism, potentially pathogenic that may cause disease when overgrowth occurs
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Changes in normal gut flora across lifespan
Actinobacteria- half in gut for infants, decrease with age to 5% Firmicutes- 20% gut bacteria in young children, grows until middle age and begins to decrease again Proteobacteria- starts at 10% in infants, almost disappears in middle age, increases again to 25% in later life
29
Skin flora
S epidermis, staphylococcus aureus, corynebacterium . Prevents pathogenic colonization through resource competition Limits growth of pathogenic cutibacterium acnes and pathobionts S aureus
30
GI tract flora
Stomach Hostile to most microorganisms because of low pH. Lower GI lots of normal flora (clostridium, bacteroides, lactobacilli
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Oral cavity and upper respiratory system normal flora
Many, including streptococcus
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Urogenital normal flora
Urethra contains enterococci, diptheroids, S epidermis. Vagina peptostreptococcus, corynebacterium, streptococcus, staphylococcus
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Sterile sites of body
Not normally in contact with environment; blood, brain, bone marrow, liver, kidneys. Pathogens can enter through medical treatment, trauma , etc.
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Tissue tropism
Pathogens exhibit preference for specific tissue typed
35
Human intestinal microbiota
Responsible for multiple digestive, immune, and metabolic functions. When not properly balanced, dysbiosis occurs caused by overgrowth, too few bacteria, or inappropriate types of bacteria
36
Streptococcus pneumoniae
Bacterial pneumonia
37
Candida albicans
Fungi, infections on interior epithelial surfaces or mucous membranes, causes candidiasis (oral thrush)
38
Viruses
Composed of DNA or RNA surrounded by protein coat, inert outside of other living cells.
39
Fungi
Yeasts single celled, molds multicellular . Have cell wall, considered eukaryotes . Most not pathogenic for humans . Source for many antibiotics, also produce alcohol and carbon dioxide . True nucleus
40
Staph. Aureus causes
Septicemia, toxic shock, food poisoning
41
Group A strept.
Tonsillitis, scarlet fever, sore throat
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E.coli causes
Diarrhea, septicemia, meningitis
43
Coccidioides
Fungi that causes coccidioidomycosis, histoplasmosis, crytpococcosis, candidiasis
44
Toxoplasma gondii
Protozoan parasite that causes toxoplasmosis and cryptosporidiosis
45
Salmonella typhi
Typhoid fever
46
Bacteria
prokaryotes, circular double stranded DNA, haploid DNA Plasmids replicate independently from bacterial genome
47
Bacterial DNA replication
Circular, chromosomal, double stranded DNA first unwound by bacterial helicase (starts at single origin of replication). DNA polymerase 2 replicates the DNA strand, while simultaneously proofreading daughter strand.
48
Transposons
DNA sequences that contain protein coding genes that allow transposition of DNA sequences within a genome. Allow DNA sequences to jump from plasmid to chromosomal dna and vice versa. Must flank both sides of the gene of interest as the enzyme cleaves and ligands the transposon sequence, leaving the gene of interest intact
49
Conjugation
F Plasmid contains dna that encodes for production of sex pilus. Sex pilus on F+ connects to another bacterium or similar so same species that does not have F plasmid (F-). When they connect, mating bridge forms. Single strand of double stranded F plasmid is transferred across bridge to other bacterium. After, both restore the double stranded plasmid
50
High frequency recombination strain
Hfr contains F plasmid in chromosomal dna, usually integrated through site specific recombination (integration of extrachromosomal DNA sequence into bacterial chromosome at specific locations called insertion sites )
51
Transformation
Competent bacteria cell takes up naked dna from environment (usually from lysed cells). Implementation of absorbed bacteria occurs through homologous recombination Strep. Pneumoniae, haemophilus influenzae type b , e. Coli
52
Transduction
Bacteriophage infects susceptible bacterial cell by binding on surface receptors and injecting dna into host bacterial cell. Host dna hydrolysis into pieces, and phage dna proteins made Occasionally a bacterial dna fragment is packaged in phage capsule Transducing phage infect new host cell, where recombination can occur
53
Lytic growth in transduction
Some bacteriophages are packaged with host bacterial dna rather than viral dna. (Transducing phages). Does not result in lysis, instead is expression of donor bacterial dna
54
Specialized transduction
Temperate bacteriophage infects bacterium and transfers viral dna that incorporated into host dna forming a pro phage . Viral dna becomes dormant and is passed to daughter cells Bacterial cell has prophage integrated between genes A and B Occasionally prophage dna exits incorrectly, taking adjoining bacterial dna with it Phage particles carry bacterial dna along with phage dna Transducing phage infect new host cell, recombination can occur
55
Lysogenic growth in transduction
Prophage dna is imprecisely excised. Bacteriophage formed from this inject a new recipient with the hybrid dna, recipient bacterium genome will include its own dna, bacteriophage dna, and dna from host
56
Virulence factors
Protein A Immunoglobulin (Ig) A protease M protein
57
Protein A
Produced on bacteria cell wall that binds to Fc portion of human IgG, prevents subsequent immune response Impairs phagocytosis and opsonizatiln
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IgA protease
Protein that binds and degrades IgA antibodies
59
M protein
Prevents phagocytosis by preventing opsonization by binding to fibrinogen, forming dense fibrillar barrier bacterial surface interfering with C3b deposition
60
HIV life cycle
Virus binds and fuses with host cell It releases numerous viral proteins, including reverse transcriptase and integrase Reverse transcriptase converts viral rna to dna Inside cells nucleus, new viral dna integrated into host dna with integrase Newly integrated viral dna transcribed by host cell machinery to make new hiv rna, some of which is translated into immature hiv proteins HIV rna and proteins more to cell surface, assembled into new immature hiv viruses Immature hiv viruses exit cell and release protease, cleaves immature proteins to yield mature hiv viruses
61
HIV info
Primarily infects CD4 lymphocytes, used by the virus to replicate First infected no symptoms. Acute illness after 2-4 weeks with symptoms like mononucleosis ELISA screens for hiv. Can detect antibodies. Often confirmation test is required Patients with this and TB are at increased risk for developing serious life threatening form of TB
62
A. T. Still and microbiology connection
3 of his children died if became risk meningitis
63
Pure culture
Isolation and cultivation of etiologic agents of disease (first done with bacteria) Pasteur most famous for his work in developing an effective rabies vaccine
64
Koch’s postulate
1. Organism / pathogen must always be found in the diseased animal but not in the healthy ones 2. Organism must be isolated from diseased animals and grown in pure culture away from the animal 3. Organism located in pure culture must initiate and reproduce the disease when reinoculated into susceptible animals 4. Organism should be reisolated from experimentally infected animal Linked particular pathogen with matching infection or disease Using anthrax bacteria, he showed pure cultures could cause diseased when re inoculated info healthy animals
65
Sulfonamide
Sulfa dedicate of metabolite p-aminobenzoic acid Prontonsil (1935)
66
Penicillin
Florey and chain developed Fleming original discovery of this into a practical means by producing and administering the antibiotic (1940s)
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Immunity
1880s- metchnikoff developed cellular theory of immunity
68
Antimicrobials
Early 1900s, Paul erhlich developed concept of magic bullets : forerunners of antitoxins (anti sera) and antibiotics for treating infections. Formulated salvarsan which he used to treat syphilis before penicillin
69
Smallpox
Cowpox and milkmaids led to immunity to smallpox, due to similarity between some of antigens present in these 2 viruses
70
Formalinization
Permitted production of safe killed vaccines
71
Epidemiology
Study of determinants and distribution of health and disease in human populations (infectious and noninfectious )
72
Non communicable infection
Not transmitted by person to person or animal to person contact. Caused by patients normal flora like peritonitis (ruptured appendix) and endocarditis (from stept. Bacteria disseminating from oropharnynx into blood)
73
Other types of infections
Caused by organisms common in nature (clostridial gas gangrene, certain fungi) Ingestion of preformed toxins (botulism- clostidial food poisoning) (staphylococcal food positioning) (can’t be transmitted)
74
Communicable infections
Can be spread Require organisms able to multiply in or on the body and leave body in a form directly infection to others or indirectly infections after development in living insect vector West Nile disease: requires presence of a biting infected mosquito
75
Endemic
Disease present at low but fairly constant level in population (common cold) Histoplasmosis in US
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Epidemic
Level of infection above usually found in population. Patient develops severe, life threatening water diarrhea with Cholera
77
Pandemic
Widespread disease in region or worldwide, with high attack rates
78
Infection
Multiplication of organisms in or on the host
79
Disease
Clinically apparent response of the host to infection characterized by typical (or atypical) disease manifestations. Less common than infection
80
Subclinical infections and the carrier state
In apparent infections- subclinical Carrier state applies to situations where infectious agent establishes itself as part of a patients indigenous micro-flora or causes low grade chronic disease after occurring as an acute recoverable infection Ex: staph. Aureus, salmonella typhi (chronic fall bladder colonizations infection following attack of typhoid fever originating in GI tract. Leads to periodic fecal excretion of organisms for years by human carrier)
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Routes of transmission
Reservoirs - refers to only mammalian carriers of infectious agents such as Humans : principal living reservoir of human disease, clinical and sub clinical Animals: both wild and domestic, Zoonoses: diseases that occur primarily in animals and can be transmitted to humans
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Infectivity
Frequency with which infection is transited when there in contact between agent and susceptible individuals
83
Pathogenicity
Number of persons who develop disease divided by total number infected
84
Virulence
Number of fatal or severe cases divided by total number of cases
85
Incidence
Number of new cases of a disease within specified period and also the number of new cases divided by size of population
86
Prevalence
Total number of cases existing in given population at risk at a given point in time or during defined period
87
Botulism
Number of people consuming food contaminated with performed toxin : no secondary spread
88
Control of epidemics
Surveillance, and identify cause and route of spread, notifying and reporting to appropriate authorities Local, state department of health, CDC WHO- includes cotuntires with limited reporting capabilities White House Covid 19 response team
89
Plague
Black Death Pathogen: yersinia pestis- gram negative bacillus Route: mostly urban rat to flea to human
90
Measles
Paramyxovirus-single stranded rna with lipid envelope Route: human to human through respiratory route One of the most highly communicable viruses infections. Largely controlled with vaccine, only 95% effective
91
Influenza
Orthomyxovirus, causes flu, has segmented rna genome with lipid envelope Neuraminidase (N1-9) and hemagglutinin( H1-6) key identifying components Route: airborne spread through respiratory route. Led to several epidemics. Vaccines available annually
92
Lyme disease
Borrelia burgdorferi, spirochetal bacterium Route: by hard shelled ticks of lxodes species mostly in nymphal stage of life cycle. Disease prevalent (hyper endemic) in northeast US and Europe
93
AIDS
Human immunodeficiency virus, retrovirus Route: sexual contact, intravenous route, and congenital infection.
94
MERS
Middle East respiratory syndrome (2014), one of the corona viruses like SARS-CoV-2
95
Staphylococcus under microscope
Gram positive and clusters
96
Streptococcus under microscope
Gram pos chains
97
Niceria under microscope
Gram negative diploid
98
Bacillus
Gram positive rod bacilli chains
99
Lipopolysaccharide
In gram neg cell walls O-antigen, oligosaccharidic core (with outer and inner core), and Lipid A (endotoxin)
100
Lipid A
Part of lipopolysaccharide part of gram neg Can cause fever, hypertension, hypotension, histamine release, neutrophil chemotaxis, DIC endotoxin
101
Gram nomenclature exceptions
Mycobacteria (gram positive, mycolic acid in wall) Mycoplasma (don’t have peptidoglycan, not gram positive or negative) Treponema (syphillis) Legionella, rickettsia, chlamydia, bartonella, ehrlichia, anaplasma
102
Auramine-rhodamine fluorochrome staining
New acid fast stain Less time Less experience Lower magnification (x400) Needs fluorescent microscope
103
Endospores characteristics
Viable Metabolically dormant Highly resistant
104
Endospore structure
From exterior to interior: exosporium(jelly like layer on outside), protein cost, outer membrane, cortex, spore wall (peptidoglycan layer), inner membrane, core (DNA)
105
Types of Endospore shapes
Terminal (circle on end of pole) Central (circle in middle of pole) Sub terminal (circle almost at end of pole)
106
Endospore growth
Stationary phase (growth doesn’t change, where sporulation will take place, lack of nutrients) Vegetative phase (exponential growth) Autoclave (only way to kill Endospore)
107
Endospore resistance properties
Spore wall/cortex/coat/ exosporium - protects from chemicals SASPs- small acid soluble proteins. Bind to dna, change P conformation to A, enzyme repair during germination Ca++/Dipicolinic acid (DPA)- controls damage to Endospore
108
Medically significant Endospore so
Bacillus (B. Anthracis, B. Cereus ) gram positive rods , soil growing organism Clostridia (botulinum(botulism from canned foods), tetani (tetanus, locked musculoskeletal system) perfringens (gangrene), difficile (diarrhea)), soil growing organism , anaerobes
109
Binary fission in prokaryotes
Replication of circular chromosome begins at origin of replicated and continues in both directions Cell begins to elongate. FtsZ protein migrate towards midpoint of cell Duplicate chromosomes separate and move away toward opposite ends of cell. FtsZ form ring around periphery of midpoint between chromosomes FtsZ ring direct formation of septum that divides cell. Plasma membrane and cell wall materials accumulate After septum complete, cell pinches into two, forming two daughter cells. FtsZ dispersed throughout cytoplasm of new cells
110
Aerotolerant anaerobes
Fermenters
111
Growth requirements pH
Bacteria - slight alkaline Fungi - slight acid

Fall 2022 (15 decks)

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