Exam 3-Microbiology

retro viruses

(+) rna reverse transcriptase have DNA that have integrase into the host genome rna virus genome does not come out once its integrated

mature viral particle =

(virion) is capable of exiting a host cell and infecting neighboring host cells

bacterial immunity

-capsules -prevent adsorption, harder for bacteria to get into the genome -CRISPR system used for gene editing therapy=CRISPR is a family of DNA sequences found within the genomes of prokaryotic organisms such as bacteria and archaea. These sequences are derived from DNA fragments of bacteriophages that have previously infected the prokaryote and are used to detect and destroy DNA from similar phages during subsequent infections.

there are more RNA viruses than DNA viruses

DNA-RNA-PROTEIN is the central dogma for eukaryotes and prokaryotes viruses are acellular (no cells)

examples of viral genes getting transcribed

a repressor gene will make rna which will then make that repressor protein an unknown gene will make rna which will then make that unknown protein the excission gene will make rna which will then make an excissiom protein stressors for excission genes are uv light, chemicals, etc knocks repressor protein off; repressor protein is how the cell is lysogenic a repressor protein comes over and binds to excission gene and it blocks transcription and then you cannot build an excission protein

enveloped viruses are

animal viruses only the end result is budding to form an envelope they have a nucleoclapsid surrounded by a membrane then spikes called the viral envelope if something does not have spikes it cannot get into the cell bc it has no way to latch onto the receptor

stressors can make

bacteria phages come out of viruses

retro viruses have

double stranded rna reverse transcriptase; integrase enzymes converts ds rna--(uses reverse transcriptase)--then ds dna-(uses integrase)-then host genome(provirus) HIV is an ex. of a retrovirus bc if left untreated it can lead to AIDS

antigenic shifts are

due to mutation anything capable of triggering an immune response = an antigen which comes in the form of some type of protein pigs are reservoirs for influenza; they can generate 2 diff viruses with endless spikes which will be more vulnerable to a segmented genome flu virus is an rna virus and has segmented genome

serial dillution is always used

for a plaque assay holes that pop up in the agar are called plaques and are indicative of lysis plaques are measured as pfu's = plaque forming units look at notes for examples of this and for how to work it out

DNA viruses

have nucleus are ds dna are ss dna

viral structure:

have to have a genome that can be DNA OR RNA but not both more RNA viruses are in existence than DNA they have to have a protective covering surrounding the genome called a capsid which is a protein coat or shell protein coat is made up of capsomeres which are protein subunits nucleoclapsid is when the genome is inside the shell or coat/ capsid a virus is nucleic acid+protein

virulence is

how great of a disease causing entity something will be more virulence= greater disease

1% of global population are

immune to HIV bc of a mutation to their helper T- cell so it cannot bind to the receptor bc the spike does not fit

prions are

infectious proteins. they do not have DNA or RNA they are already protein they are acellular proteinaceous infectious particles are responsible for causing TSE= Transmissable (spreadable) spongiform (deterioation of brain) ecephalopathy (disease of the head where the brain is) cannot be cooked out bc of strong tertiary enzymes all prion infections cause neurodegenerative diseases of some kind that is rlly what TSE is cannot treat prions PrPC=normal protein PrPsc= abnormal protein

when a virus is outside of a cell

its metabolically inert meaning that it cannot do anything viruses have not metabolism on their own they are only metabolically active when its in an appropriate host cell

DNA viruses

may have double-stranded DNA genome behave much like a cell may also have single stranded DNA genome replicate in nucleus (animals) in eukaryotes the DNA is in the nucleus

virus and cancer

oncovirus= cancer-inducing virus viral transformation= increase likelihood for mutations in host cells two sets of genes in human DNA proto-ocogenes= regulate cell cycle, they are incorporated in our DNA tumor suppressor genes limit mitosis cells are the host of a virus viruses have a host range-range of cells that a virus can infect; it varies

viruses are an obligate intracellular parasite that needs a host

protein can be used to produce a capsid, toxin, enzyme etc. viruses do not have ribosomes so they steal ribosomes of the host cell to make protein for their virus. they just use them while they are in the cell

capsid is

protein shell/ coat that protects DNA double stranded dna is two strands joined together

a naked virus has

receptors called spikes(think of them like keys) so receptors and spikes let viruses into the cell if the receptor and spike fit/ match up a naked virus is non-enveloped. they are more resistant. they are spikes on a capsid the end result with a naked virus is cell lysis aka cell death

RNA viruses

replicate in cytoplasm can have a couple of forms of single stranded RNA in a + configuration= correct configuration for translation ready; can also do double stranded RNA single stranded RNA in a - configuration = not ready for translation bacteria phages are typically double DNA genomes animal viruses are typically single stranded DNA genomes and replication occurs in the nucleus DNA--(transcription occurs here)-RNA--(translation occur here)--protein everything not in the nucleus is in the cytoplasm zoonotic= can go from animals to humans ex. rabbies

animal viruses

still need adsorption, membrane fusion/ endocytosis -- which is most likely the mechanism of entry if dealing w/ naked viruses which is one thats not enveloped ---will happen in nucleus if its a DNA virus, or will happen in the cytoplasm if its an RNA virus uncoating which is the releasing of genome either into the cytoplasm or nucleus its a special feature assoc. w/ animal viruses

bacteria phages are

strictly a virus that affects bacteria propahge= once its integrated in the virus is called a cell the dna is integrated in lysogen= bacterial cell lysogenic phages= confer to the host

host ranges

tells a virus what it can infect ex FIV feline immunodeficiency virus what dictates host range is tissue tropism Tissue tropism is the cells and tissues of a host that support growth of a particular virus or bacterium. Some bacteria and viruses have a broad tissue tropism and can infect many types of cells and tissues. Other viruses may infect primarily a single tissue.

lysogeny is

the integration of viral dna into bacterial dna

viral taxonomy

viridae= describes a viral family ex. poxviridae virus= genus ex. poxvirus name of disease= species ex. poliovirus -typically use name of disease w/ virus attached to the end of it HIV (1) & HIV(2) numbers tell the strand which are viral subtypes cannot have enveloped complex virus combination

viruses

within cells all viruses are obligate intracellular parasites they need a host in the form of a cell they are ultramicroscopic in size (very small) (10nm to 800nm) 800 nm is really large and rare tobacco mosaic virus was the first virus ever identified

in dna genome

A binds to T G binds to C and they are complimentary look at notes

rna viruses

1. ss rna (+) is ready for translation and (+) has to be copied into RNA (-) involving replicases (terrible proff readers) 2. ss rna (-) need replicase to convert to (+) strand then to protein 3. ds RNA is rare

3 types of horizontal gene transfer

1. Transformation=transformation is the genetic alteration of a cell resulting from the direct uptake and incorporation of exogenous genetic material from its surroundings through the cell membrane(s). 2. Conjugation=Bacterial conjugation is the transfer of genetic material between bacterial cells by direct cell-to-cell contact or by a bridge-like connection between two cells 3. Transduction= viral mediated genetic transfer cannot happen wo/ a bacteria phage Transduction, a process of genetic recombination in bacteria in which genes from a host cell (a bacterium) are incorporated into the genome of a bacterial virus (bacteriophage) and then carried to another host cell when the bacteriophage initiates another cycle of infection.

lysogenic phages

1. attachment 2. genome entry 3. [recombination]= integration, can stay like this for a while until there is a stressor this does not happen in lytic phages 4. synthesis 5. assembly 6. release (lysis)

lytic phages = 5 stages

1. attachment; also known as adsorption; means to latch onto gotta be able to attach to a bacterial cell 2. genome entry; DNA-RNA-PROTEIN-viral protein 3. synthesis 4. assembly 5. release; virions= mature viruses lysogenic phages will eventually kill the host cell lytic phages the end result is lysis of the host cell backwards y is the abbreviation for lambda which is the most well studied lysogenic stage

3 ways to study animal viruses

1. cell (tissue) cultures ( primary way we want to study viruses) viral induced damage-cythopathic effect=presence of inclusion bodies (sites of viral replication) viral infection= multinucleated cells there is not much diversity of media for animal cells animal cells divide rapidly HIV like to infect helper T cells which are white blood cells they prefer using cell (tissue) cultures if you can but you cannot always do that bird embryos method- bc of shell outer covering keeps internal covering completely sterile pandemic=mass- worldwide outbreak

there are two types of transduction

1. generalized transduction which occurs because of a packaging error and its where there are picking up of the genes at random 2. specialized transduction= picking up of specific genes that are adjacent to the viral dna and adjacent to bacterial dna this happens bc of an excission mistake/ error Double stranded rna is only seen in viruses

capsid shapes:

1. icosahedral capsid (triangular in shape) (has 20 flat triangles) 2. helical capsid= rod shaped (not bacillus morphology) they vary in lenght 3. complex- bacteriopahges (viruses that infect bacteria)legs are tail fibers they have lysosomes an organelle in the cytoplasm of eukaryotic cells containing degradative enzymes enclosed in a membrane. adsorption= when spikes latch to a receptor / meaning to latch on

bacteria phages come in 2 forms

1. lytic phages= infect a cell and trigger lysis (lyse host cells) 2. Lysogenic phages= cause silent infections

a virus is made up of either

DNA OR RNA NOT BOTH either has one or the other as its genome not both all cellular life forms are susceptible to viral infections viruses have to follow a host range