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Foundations of Medicine > Week 3: Microbiology > Flashcards

Week 3: Microbiology Flashcards

1
Q

What are the main differences between prokaryotes and eukaryotes?

A
  • Prokaryotes: single circular chromosome, no nucleus, plasmids, cellular respiration on PM, sex or attachment pili
  • Eukaryotes: paired linear chromosomes, nucleus, cellular respiration in mitochondria, no pili
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2
Q

What is the mesosome in bacteria?

A

where chromosomal DNA attaches to the plasma membrane for bacterial division

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3
Q

What are the 2 subunits in peptidoglycan and which one has variability?

A
  • NAM and NAG

- NAM can have different amino acids attached

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4
Q

What does penicillin inhibit in peptidoglycan?

A

crosslinking between polysaccharide chains

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5
Q

How are the results of gram stain determined?

A 
purple = gram positive
pink = gram negative
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6
Q

What is special about Mycoplasma?

A

smallest free living organism

  • no cell wall (hard to treat with antibiotics)
  • membranes contain sterols
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7
Q

What is special about Mycobacteria?

A
  • acid fast bacteria
  • small amounts of peptidoglycan
  • large amounts glycolipids (mycolic acids make cell wall impermeable)
  • Mostly cause respiratory disease
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8
Q

What is in the core of endospores?

A

calcium dipicolinate

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9
Q

Why to bacteria form spores?

A

resistant to: heat, dessication, chemical damage, dehydration
-allow survival in nutrient limited conditions

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10
Q

What are the basic characteristics viriods?

A
  • very small single stranded circles of DNA

- cause disease in plants

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11
Q 
What is the main component of:
spore wall
spore coat
cortex
core
A
  • spore wall: peptidoglycan
  • spore coat: keratin like proteins
  • cortex: thickest part, peptidoglycan with fewer links
  • core: calcium dipicolinate and nucleic acid for later growth
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12
Q

What species make endospores?

A

-Bacillus and Clostridium

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13
Q

What are basic characteristics of viruses?

A

-viral envelope, nucleocapsid/ capsid (protects nucleic acids), capsomere (subunit of capsid structure). polyhedral/ helical

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14
Q

What are the basic characteristics of prions?

A
  • no nucleic acid
  • resistant to heat
  • inactivated by detergents
  • causative agent is prion protein (PrP ^sc)
  • same sequence as functional protein but folded differently (not degraded)
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15
Q

What are enveloped viruses vs naked capsid viruses?

A

enveloped = acquire membrane from host

naked capsid = nucleic material with coat or capsid

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16
Q

What are the 3 main types of fungi?

A

yeasts (single cell, reproduce by budding), molds (grow as filamentous hyphae, cross walls called septae, masses of hyphae are mycelia), and mushrooms

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17
Q

What is the generation time?

A

the amount of time for number of cells to double

-doubling time

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18
Q

What are the phases in the growth curve?

A
  • lag phase = bacteria adapt to new nutrient rich environment
  • log phase = exponential growth, bacteria double every generation time
  • stationary phase = nutrients are exhausted
  • death phase = not all bacteria have this state, they begin to die
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19
Q

How do you determine the amount of bacteria in liquid sample?

A

dilution x colonies on plate = CFU/mL

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20
Q

What are the differences between fermentation, respiration, and photosynthesis?

A
  • fermentation- form ATP not coupled to electron transport
  • Respiration: formation of ATP by oxidative phosphorylation where ATP is formed during electron transport
  • photosynthesis: ATP formed by reduction of oxidant via light energy
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21
Q

How are fermentation products formed?

A

lactate formed to regenerate NAD+ to be reused in glycolysis

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22
Q

What is a heterotroph?

A

type of nutritional requirement that requires pre-formed organic compounds like sugars, amino acids, and vitamins

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23
Q

How do bacteria take up nutrients (3 ways)?

A
  1. carrier mediated diffusion (facilitated, not energy dependent
  2. Phosphorylation-linked transport, energy dependent
  3. Active transport- energy dependent, protons pumped out causing flux, uses symport
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24
Q

What does positive polarity vs negative polarity mean for virus structure?

A

Single stranded RNA genomes can have same (positive) or complimentary (negative) polarity as viral mRNA.
-positive polarity can be translated right away

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25
Q

What enzyme changes superoxide to hydrogen peroxide?

A

superoxide dismutase

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26
Q

What is the viral attachment protein (VAP)?

A

-on capsid of naked virus, interacts with the cell

enveloped viruses have specific glycoproteins that act as VAPs

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27
Q

What is the difference between differential and selective media?

A
  • differential media: supplies nutrients and indicators for visual determination of which organisms are present
  • selective media: selects AGAINST growth of particular bacteria by addition of dyes, acid/base, salts, or antibiotics
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28
Q

What are the 3 temperature classifications?

A
  • psychrophiles- low temps
  • mesophiles- most, medium temps
  • thermophiles- high temps
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29
Q

What are the 3 classification categories for human viral pathogens?

A
  • virion structure
  • nucleic acid characteristics
  • replication strategy
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30
Q

What are the 2 possible types of capsids?

A
  • cylindrical (helical form)

- cubic shape (icosahedron form)

31
Q

What 3 things are part of the viral envelope?

A

lipids, proteins, and glycoproteins

32
Q

Which are more hardy, enveloped or naked viruses?

A

naked viruses, enveloped viruses are disrupted by non-moist environments

33
Q

What 3 factors influence host range?

A

virus ability to 1) enter a cell, 2) find appropriate cellular machinery, and 3) exit the cell

34
Q

What determines productive vs nonproductive viral infection?

A 
production = infection yields new infectious viruses
non-productive = infection occurs when viral genetic material persists in cell (latent state) but no infectious viruses formed
35
Q

What are the 6 phases of viral multiplication?

A

1) attachment
2) penetration
3) uncoating
4) virus component synthesis
5) assembly
6) release

36
Q

What are cytopathic effects (CPE)?

A

morphological changes to host cell from synthesizing viral proteins
ex) cell rounding, cell fusion, etc

37
Q

What are viroporins?

A
  • small, hydrophobic virus encoded proteins that oligomerize at host cell membranes
  • involved in envelope virus budding and non enveloped virus cellular lysis
  • cytopathogenic effects: formation of hydrophilic pores and alterations of calcium and H+ gradients
38
Q

What are the parts in the one step growth cycle?

A
  • eclipse period- time between infection and increase in total virions per cell
  • latent period- time between infection and released virions accumulating (2nd increase on graph)
  • early protein is for replication of AAs then shut off
  • late proteins are structural proteins of virus
39
Q

Where do most RNA viruses replicate? exceptions?

A

in cytoplasm (except orthomyxoviruses like influenza and retro viruses)

40
Q

Which DNA virus remains in the cytoplasm and how?

A

poxviruses (have enzymes with them)

41
Q

Which DNA viruses (3 families) have doubles stranded DNA genome?

A
  • adenoviruses
  • herpesviruses
  • papovaviruses
42
Q

What type of DNA and replication does hepadnaviruses (Hepatits B) undergo?

A
  • partially double stranded DNA genome
  • replicate DNA in nucleus via RNA intermediate
  • involves RND- dep DNA polymerase (reverse transcriptase)
  • can transform cells
43
Q

What kinds of DNA viruses have a single strand of DNA as genome?

A

parvoviruses (some strains need helper virus to replicate)

44
Q

How do cytoplasmic DNA viruses replicate?

A

Poxviruses, have double stranded DNA genome

  • provide their own mRNA and DNA
  • synthesize own envelope
45
Q

What cancer does the virus family papovavirdae, virus HPV cause?

A 
Genital tumors (cervical, vulvar, penile)
squamous cell carcinoma
46
Q

What cancer does virus family Herpesviridae, virus EBV Virus cause?

A

Nasopharyngeal carcinoma, African Burkitt’s lymphoma, B-cell lymphoma

47
Q

What cancer does virus family Herpesviridae, virus Herpes simplex type 2 cause?

A

cervical carcinoma

48
Q

What cancer does virus family Hepadnaviridae, virus Hepatitis B virus cause?

A

Hepatocellular carcinoma

49
Q

What cancer does virus family retroviridae, cancer HTL virus cause?

A

Adult T cell leukemia

50
Q

What 2 genes can be targeted to cause cancers?

A

p53 (turns on p21 which phosphorylates the master break)

pRB (when complexed with inactive transcription factors, acts as master break)

51
Q

What are the 6 general classes of cellular oncogenes?

A
  • nonreceptor protein tyrosine kinases
  • receptor protein tyrosine kinases
  • serine/threonine protein kinases
  • growth factors
  • membrane associated G proteins
  • nuclear transcription factors
52
Q

What are 2 tumor suppressor genes?

A

retinoblastoma (RB)

p53 gene

53
Q

What are the main characteristics of Adenoviruses?

A
  • vary in oncogenic potential
  • transform rodent cells (no human tumors)
  • E1a binds p110^Rb (represses cell proliferation)
  • E1b binds p53 (represses cell proliferation)
54
Q

What are the main characteristics of Papillomaviruses?

A
  • majority of cervical, penile, and vulvar cancers contain HPV DNA
  • E6 binds p53
  • E7 binds p110^Rb
55
Q

What are the main characteristics of Herpesviruses?

A
  • EBV (estine bar virus)
  • viral genome is episomes (ouside chromosomes)
  • need 3 genes for transformation (LMP 1 and LMP 2a and b)
  • large virus, 16 cellular genes
56
Q

What are the main characteristics of Hepadnaviruses?

A
  • 75-85% primary human hepatocellular carcinoma cells have hep B (HBV) genes
  • X protein interacts with p53
  • has reverse transcriptase
57
Q

What are the 3 transformation mechanisms for viruses?

A
  • introduction of oncogenes
  • insertional activation or promoter insertion
  • transcriptional activation
58
Q

What are characteristics of Retroviridae?

A
  • helical nucleoprotein complex inside icosahedral capsid which is enveloped
  • reverse transcription
  • as DNA genome integrates into host genome
  • cause tumors
  • HIV-1 causes AIDS
59
Q

What are the 3 subfamilies of retroviruses?

A
  • Lentiviruses (HIV)
  • Spuma viruses
  • onco viruses (types B,C, and D
60
Q

What type of retrovirus is naturally occurring in humans?

A

Endogenous type C viruses

-viral information is a constant part of genetic constitution

61
Q

How many viruses or bacteria do you need to be sick?

A
  • viruses need a lot in body to cause disease

- bacteria can have toxins, so may not need many

62
Q

What are the 3 mechanisms that bacteria cause disease?

A
  • direct
  • indirect (natural immune response)
  • indirect via adaptive immune response (hypersensitivity)
63
Q

What is virulence?

A

quantitative measure of pathogenicities measured by number of bacteria required to cause disease

64
Q

What are virulence factors?

A

properties of a bacteria which assist in causing disease (pili, capsules, toxins, etc)

65
Q

What are the 6 bacterial virulence factors?

A
  • pili
  • capsules (stop phagocytosis)
  • glycocalyx
  • endotoxin
  • biofilms
  • bacterial secretion systems
66
Q

What are the 4 main portals of entry?

A

respiratory tract (most common), GI tract, skin, genital tract

67
Q

what does complement do in bacteria?

A

necessary for cell to be lysed

68
Q

What are exotoxins?

A

polypeptides secreted by bacteria

  • toxoids (when treated with formaldehyde or heat for protective vaccines)
  • AB subunits (B binds and A is toxic)
  • genetically coded in bacterial chromosome
69
Q

What is endotoxin?

A
  • part of gram negative cell wall (lipid A of LPS) is toxic when being broken down by body
  • causes fever and shock
70
Q

What is the difference between innate and acquired immunity?

A
  • innate: macrophages endocytose and complement causes lysis

- acquired: antibodies form to specific antigens, and cytotoxic T cells kill what antibody binds to

71
Q

What is active vs passive immunity?

A
  • active: given specific antigens to stimulate development of immunity to protect from disease (ex: MMR, HPV, rubella, Varicella)
  • passive: give antigen to protect from disease (ex: Hep A, polio, rabies, cholera)
72
Q

How do bacteria avoid innate immune response?

A
  • avoid contact with phagocytes
  • inhibition of engulfment (capsid and biofilm)
  • survival within phagocyte (escape, adapt, or modify phagosomal compartment)
73
Q

How do bacteria avoid acquired immune response?

A
  • antigenic variation

- immunological disguise (bind antibodies to hide)

Foundations of Medicine (7 decks)

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