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Microbiology Final last third > Microbiology Lect 25 > Flashcards

Microbiology Lect 25 Flashcards

1
Q

What virus causes Covid-19?

A

-SARS-CoV-2
-In the Coronavirus family, known for colds to more severe but rare respiratory diseases

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2
Q

How do Covid-19 mRNA vaccines work

A

-Pfizer and Moderna
-mRNA that codes for the covid-19 spike protein are encapsulated into “lipid nanoparticles”
-After injection, these nano particles fuse with human cell membranes releaseing the mRNA into our cells, where it is translated into spike proteins
-The spike proteins are then displyed on our cells causeing an immune response
-Summary: mRNA enters our cells via membrane nano particles, where it is translated to make spike proteins, resulting in the adaptive immune response and protection against infection

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3
Q

Viral Vector Vaccines

A

-J&J
-A DNA copy of the genes that encode the spike protein are incorporated into the genome of a harmless Adenovirus
-After injection, the Adenovirus delivers the viral DNA to the nuclei of our cells where it is transcribed into mRNA
-The mRNA is then translated into spike proteins that are displayed on our cells causing and immune response

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4
Q

Virus definition and basics

A

-Non-cellular particle capable of infecting a host cell where it reproduces
-Consists of DNA or RNA enclosed in a coat of protein (and sometimes a membrane envelope
-Unable to reproduce outside of living cells
-Bacteriophage: infects bacteria

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5
Q

Viral Nuclei Acid genome sizes

A

-5000-250,000 bp
-linear or circular

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6
Q

Virus size

A

0.02-0.2 um

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7
Q

Naked virus

A

Lacks an envelope

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8
Q

Enveloped virus

A

Envelope from host plasma membrane, often with spikes

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9
Q

Helical symmetry

A

-Only one promoter
-474/6000 nucleotides
-Self-assembly
-Helical sheath can be found on bacteriophage

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10
Q

Baltimore Virus Classification

A

-David Baltimore proposed that the primary distinctions among classes as viruses be
-The genome composition (RNA or DNA)
-The route used to express messenger RNA (mRNA)

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11
Q

Animal viruses

A

-Most are enveloped, but some are naked (capsid only)
-Complex virions of smallpox virus

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12
Q

Host ranges of phage

A

Many phage are specific to the species they infect- they attach to specific receptors on the outer layers of the bacterium- e.g. some phage of E. coli attach specifically to the proteins of the flagellum, but some phage are non-specific and infect different hosts

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13
Q

Phage can undergo lytic or lysogenic cycles, or both

A

-Lytic: Genetic info is inserted and the bacterium makes lots of copies before lysing
-Lysogenic: Genetic info is incorporated into host DNA, where the host multiplies over and over

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14
Q

Advantages of being lysogenic

A

-Host dormancy results in long term survival
-Reproduced along with host chromosome
-Lytic cycle kills hosts, thus host may go extinct if the virus is too efficient at killing hosts

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15
Q

Bacteriophage basics

A

-Always are naked viruses (no membrane)
-Important for
-Genetic transfer (transduction)
-Control of Bacteria in Nature, think 10^7 phage per mL of sea water
-Transduction can cause bacteria to become pathogens

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16
Q

Lysogenic conversion (via transduction):

A

-Phenotype of host cell changed by presence of temperate phage
-Can confer pathogenic properties
-Ex: cholera not pathogenic until phage

17
Q

Prophage

A

The lysogenic phage incorporated into the bacterial chromosome

18
Q

T4 Bacteriophage

A

-dsDNA, lytic life cycle, infects E. coli
-Chromosome is digested into small pieces- some of which can end up being packaged in virus particles

19
Q

Importance of Viruses in Nature

A

-Controlling microbial populations
-Ex: as populations get too high, the virus kills a lot of them off
-Recycling nutrients

20
Q

ATV (Acidianus Two-tailed Virus)

A

-Infects the hyperthermophile/acidophile Acidianus convivator
-Lemon shaped virus when first released
-Then they grow appendages at each end
-Also the only known virus that keeps developing outside the host cell
-Budding, extrusion of virons

21
Q

Viroids

A

-RNA molecules that infect plants
-No protein capsid or membrane
-Are replicated by host RNA polymerase
-Some have catalytic ability (ribozyme)
-Smallest known pathogens, <400 nucleotides
-Seem to interfere with regulatory RNAs

22
Q

Potato Spindle Tuber Viroid (PSTV)

A

-First viroid discovered in 1971
-Serious disease of potatoes and can be spread by contaminated tools or pollen, and seeds can infect eggplants, tomatoes, and potatoes

23
Q

Prions basics

A

-Prions are proteins that infect animals
-No nucleic acid component
-Have abnormal structure that alters the confomation of normal proteins
-Cause brain disease in sheep (scrapie), cows (mad cow), humans (Kuru), and elk/deer (Chronic Wasting DIsease)
-These are Transmissbible Spongioform Encephalopathies (TSEs)
-Long latency (incubation period before symptoms)

24
Q

Transmissible Spongioform Encephalopathies (TSEs)

A

-Result of prion diseases: holes in brain tissue, sponge-like appearance
-Some caused by exposure to brains
-Kuru was figured out by Gajdusek

25
Q

Kuru

A

-Disease limited the Fore people in New Guinea
-2500 Fore died 1957-1975 out of a total population of 30,000
-Fore people exposed relatives’ brains during mourning rituals, and developed Kuru many years later

26
Q

Kuru symptoms and where it comes from

A

-Lack of coordination
-Coma
-Death within 6-12 months of first symptoms
-Originally thought to be genetic
Gajdusek injected Kuru brain matter into the brains of monkeys, and monkeys developed Kuru
-Convinced the Fore to change the ritual, Kuru is now extinct

27
Q

How do prions cause disease and replicate without nucleic acids

A

-Recruit proteins to themselves in the membranes of brain cells
-Prions line up next to similar proteins that line brain cells
-Cause a shift in their tertiary structure
-Causes the outer lining of brain cells to become rigid and cavity forming, resulting in death to brain cells and holes

28
Q

Mad Cow Disease/BSE

A

-First described in 1984-86 in Britain, 180,000 confirmed (cow) cases by 2000
-Traced to feed supplements, meat and bone meal (including brains) were fed to cows as a protein supplement
-Latent period of up to 5 years in cows, so may infected cattle were ground up and fed to humans
-1996 British gov admitted that human cases of BSE (variant Creutzfeldt-Jacob Disease/vCJD) were probably caused by consuming hamburgers
-Prions are not destroyed by cooking, burial in soil, disinfectants, more durable than endospores

29
Q

Other problems in US and Canada

A

-Chronic Wasting Disease in Deer and Elk in Front range of CO
-Transmissible prions found in Elk Antler Velvet

Microbiology Final last third (10 decks)

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