Viruses

Describe two different ways that animal viruses exit from their host cell.

1. Lysis of host: causing the host cell to lyse 2. Budding, which are only done by enveloped viruses, involves the virus pushing out from the inside of the cell and taking a piece of the membrane of its host cell after it's out. This is how enveloped viruses acquire their envelope.

Describe the process of generalized transduction

1. Lytic phage infects a target cell and causes DNA to fragment 2. lytic phage incorporates bacterial chromosomal DNA into its phage head 3. this phage can infect another bacteria 4. the DNA it carried can be incorporated into the host chromosome via homologous recombination

To be considered a virus, a virus MUST...

1. Only replicate in the host cytoplasm 2. Contain enzymes

lytic cycle steps

1. Virus attaches to host cell and inserts genetic material into cell 2. Viral genetic material takes over host cell 3. Host cell replicates immediately and is expressed to produce viral parts and assembles them to make viruses. 4. Host cell burst and releases viruses and the cycle continues with other cells.

lysogenic cycle steps

1. Virus attaches to host cell and inserts genetic material into cell. 2. Genetic material is copied into the host cell's own chromosome. 3. Every time the cell divides the viral genes divide too 4. A trigger from the environment could causes the viral genes to begin a different cycle

Generalized transduction process

1. phage infects the bacterial cell, 2. host DNA is hydrolyzed into pieces and phage DNA and proteins are replicated, 3. phage assembles and sometimes packages piece of host cell chromosome, 4. transducing phage injects (double-strand?) DNA into new recipient, transduced DNA is recombined into the chromosome of the recipient cell

size of viruses

10-100 nm smaller than a bacteria

Lysogen

A bacterium that carries phage DNA (a prophage) integrated into its genome

Which components would you find in all viruses?

A capsid and nucleic acid

What's a lytic bacteriophage?

A lytic bacteriophage exits the host at the end of the infection cycle by lysing the host cell. They result in the production of new virus particles called productive infections.

What's a prophage?

A phage genome as it exists during a lysogenic infection. Prophages are formed when temperate bacteriophages integrate their DNA into the bacterial chromosome during the lysogenic cycle of the phage infection to bacteria

Temperate phage

A phage that is capable of reproducing by either the lytic or lysogenic cycle. Makes lysogen immune to superbugs (infection by the same phage)

Describe the basic structure of a virus.

Nucleic acid with a protein coat called capsid.

To be considered a virus, a virus must..

Only replicate inside of a host's cytoplasm

Capsid

Outer protein coat of a virus

What are two structures that are found in some, but not all, viruses?

Some viruses have a matrix protein, which is external to the capsid protein and also an envelope found external to the matrix protein that is made primarily of phospholipids. A nucleocapsid with an envelope always has a matrix protein in between them. Without these two structures, the virus is called a naked virus. However, enveloped viruses are more susceptible to disinfectants because the chemicals damage the envelope which makes the viruses non-infectious

Suppose a bacteriophage infected a mutant E. coli cell that is unable to perform homologous recombination

Transducing phage has some of the bacterial DNA that is mistakenly encapsulated. So yes it could form for generalized. No for specialized because specialized has to do with homologous recombination

What's a temperate phage?

bacteriophages that can choose between the lytic and the lysogenic pathways of development. The lytic pathway is similar to that of virulent phages. In the lysogenic pathway, the virus remains dormant until induction. Upon infection, a temperate phage must choose between reductive (lysogenic) and productive infections.

Which components would you find in envelope viruses

capsid, protein spikes, matrix protein, phospholipase bilayer, nucleic acid

-ssRNA viruses

carry an RNA-dependent RNA transcriptase for transcribing mRNA from the -RNA genome so that protein can then be translated . Transcription of RNA from RNA is not found in cells.

acute infection

comes on rapidly, with severe but short-lived effects

chronic infection

continuous production of low levels of virus particles Carriers may lack symptoms, but still transmit virus. (persistant)

Which viral type has a genome that can be directly translated?

ds DNA ss (+) DNA ss (-) DNA ss (+) RNA

Shapes of viruses

icosahedral, helical, complex

Super infection

infection by the same phage. Lysogens are immune to super infection.

latent infection

infection in which the infectious agent is present but not causing symptoms. Inactive

Why are Hfr cells able to cause a "high frequency of recombination" in the recipient cell

they have the F plasmid incorporated into their own genome which causes them during rolling circle replication, the plasmid will get transferred and so will part of the main chromosome, the main chromosome will very likely be similar or identical on the corresponding DNA in the recipient. So since it is similar it will have a high frequency of homologous recombination since they are the same/similar. Increased genetic exchange.

productive infection

viral infection in which more viral particles are produced. Active

Latent infection

viral infection in which the viral genome is present but not active, so viral particles are not being produced, can reactivate to cause productive infection

Transformation

(genetics) modification of a cell or bacterium by the uptake and incorporation of naked DNA. a process in which one strain of bacteria is changed by gene or genes from another strain of bacteria

What's the difference between a productive viral infection and a latent viral infection?

A productive viral infection are bacteriophage that, when they infect a host cell, cause the production of new, complete viruses that end up leaving the cell eventually to infect other cells. A latent viral infection is when the virus end up replicating the viral nucleic acid without causing the production of complete viruses.

Would you expect a transducing phage to reproduce in a host? Why or why not?

A transducing phage would not reproduce in a host because the virus is injecting bacterial DNA into the cell, not viral DNA. Bacterial DNA does not have the genetic information that encodes for viral replication so it would not happen. Instead, the bacterial cell uses homologous recombination to insert the DNA into its genome. The daughter cells will have this new DNA, and will not produce viruses.

lytic cycle

A type of viral (phage) replication cycle resulting in the release of new phages by lysis (and death) of the host cell. Replicate host genome and kills the host

What is a viral receptor and why is this a poor term?

A viral receptor is a protein receptor on the cell's membrane that the viral proteins can bind to and then allow it to enter the cell. It is a poor term because it makes it seem as though the receptor is there specifically for the virus. However, the membrane receptors can be channels, pores, pumps, or ligand binding proteins.

Enveloped virus

A virus enclosed within a phospholipid membrane derived from its host cell.

Describe two different ways that bacteriophage can cause a latent infection.

Although latent infections don't cause the production of new viruses, they cause the viral genetic material to be replicated. One way for a bacteriophage to cause a latent infection is the virus injects their genetic material into the host cell and then the capsid gets degraded. The viral genetic material becomes circularized and basically becomes a piece of plasmid DNA inside the bacterial cell (plasmid DNAs can replicate independently of the host cell's chromosomal DNA). In other words, the phage DNA circularizes to become plasmid DNA which gets passed along as the host cell divides. So every time the host cell replicates its chromosomal DNA and split in the middle via binary fission, the viral genetic material gets passed on to the daughter cells that are being produced. So the viral genetic material becomes a plasmid DNA that's replicated along with the host cell. Another way bacteriophage can cause a latent infection is that the virus inserts their genetic material into the chromosome of the host cell. So every time the host cell replicates and does binary fission, the piece of viral DNA goes along with the daughter cells produced. In other words, the phage DNA integrates into the host cell's chromosome and gets passed along as the host cell divides.

Explain why the transfer of DNA in Hfr conjugation is often incomplete.

An Hfr cell is one where the plasmid recombines into the main chromosome. When this cell attempts to do conjugation it often is incomplete because the cell does not have enough time to fully transfer its whole genome. This is because this is a very fragile process and the cells can get knocked around from each other. What results is the recipient cell having some of the donor's DNA, and it is integrated into the cell's chromosome by homologous recombination

What's the function of restriction enzymes (in relation to infection with bacteriophage)?

Bacterial cells have a gene that encodes for restriction enzymes which help protect the bacterial cell against viral infection. They recognize specific sequences that tend to be found in viral DNA and cause the viral DNA to get cut at those spots. This prevents the viral DNA from using the host cell to make more viruses.

Describe two different ways that animal viruses gain entry into their host cell.

Animal viruses - Productive infection: The animal virus has to have molecules on its surface that can bind to molecules on the surface of the cell it's going to infect. It then gains entry into the host cell. The entire animal virus can enter into the host cell via two different ways. One way is via endocytosis by tricking the host cell into thinking that the virus is valuable and then the virus ends up endocytosing it. The viral particle becomes enveloped by the membrane of the host cell until the membrane pinches off around the viral particle which results in the virus being inside of the host cell. The other way is via fusion which is only done by viruses that have an envelope. The virus binds to a receptor on the host cell and then the membrane of the host cell joins together with the envelope of the virus that is infecting it (fused together). So, the animal virus can gain entry into the hosts cell through endocytosis or fusion between the host cell membrane and the viral envelope. Once the virus is in the host cell, it sheds its protein coat which is a process called uncoating. Then, the viral nucleic acid is released so it can direct the host cell to produce more viruses by making and assembling the viral nucleic acids and viral proteins. The new viruses leave the host cell to infect other cells either by lysis of the host cell or budding (which is how some viruses acquire their envelope). Animal viruses - Latent infection: One way is that the virus remains in the host cell's cytoplasm without replicating (e.g. herpes virus in the nerve cells). Another way is that the animal virus integrates the viral DNA or viral genetic material into the DNA of the host cell (e.g. HIV). HIV has a nucleic acid that's made of anti-sense RNA and after it gets into the host cell, it uncoats and the viral RNA goes into the nucleus of the host cell and is then read to make a complementary piece of nucleic acid, a DNA strand, then the complement of the DNA is produced to create a normal-looking double-stranded piece of DNA. So, now there is a DNA version of the original viral genome. This process is called reverse transcription so the virus is called a retrovirus because the virus does transcription backwards. Reverse transcription is what happens as a result of what retroviruses do. HIV is an example of an animal virus that causes latent infections by converting RNA into DNA so the viral DNA can be integrated into the host cell's DNA. Once the HIV genetic material becomes part of the host cell's DNA, it's possible for the viral DNA to do nothing and that makes it a latent infection. So, viral nucleic acid integrates into the host cell's DNA and it's viral gene expression is repressed so it cannot makes more viruses (which makes it latent). *The herpes virus can cause fever blisters or cold sores and can cause both productive infections (when herpes virus infects epithelial cells and makes complete viruses) and latent infections (the virus does not completely go away because the herpes virus hides in the nerve cells and the virus just hangs out in the cytoplasm of the nerve cell; sunburn, stress, and menstruation can trigger the viruses to leave the nerve cell via budding because the herpes virus is an enveloped virus; the enveloped cell can travel to an epithelial cell and enter via fusion). The virus can sense if the host is stressed so it buds out of the nerve cell and then the enveloped virus enters the epithelial cell via fusion to create more viruses because if the host is stressed, there is a chance that the host is about to die so instead of dying along with the host if it remains in the cytoplasm of the host's nerve cells, the new viruses can leave so they can infect a healthier host.

Entry exit of animal viruses

Animal viruses may enter a host cell by either receptor-mediated endocytosis or by changing shape and entering the cell through the cell membrane. They leave their host cell by either budding or lysis. Budding, is when the virus pushes out from the inside of the host cell and takes a piece of the membrane of its host cell after it's out which creates its surrounding envelope.

Anti-sense DNA can be used to make what?

Anti-sense DNA is the complement of sense (+) RNA so anti-sense DNA can be transcribed to find its complement sense (+) RNA.

What's the relationship between sense RNA and anti-sense RNA?

Anti-sense RNA is the complement of sense RNA. Anti-sense RNA can use a polymerase to read the strand and make a complement of it and then that can make the proteins.

Viral spikes

Attach specifically to host cell receptors

Describe the steps of a productive infection, as caused by a bacteriophage.

Attachment: in liquid, phage particles collide to host cells. Bacteriophage binds to the host cell by attaching its tail to a receptor made of molecules on the cell surface. Penetration/Genome Entry: The bacteriophage then injects genetic material into the host cell, through the cell wall and membrane and into the interior of the cell. Biosynthesis/Synthesis of Phage Proteins and Genome: The bacteriophage ends up disengaging from the host and degrades while the viral genome is transcribed and translated. The host cell begins to make the viral proteins using the host ribosomes. Some genes on the viral nucleic acid are needed immediately after infection, such as nuclease that encodes for the nuclease enzyme, to make protein out of the genetic information. The enzyme nuclease degrades the host's chromosomal DNA so that the DNA can no longer be read in order to make mRNAs and protein. This provides the virus all of the cell's machinery to itself. The genes on the viral genome encodes for nuclease, capsid protein, polymerease, lysozyme and other extra parts like for the tail structure of a virus. The genes that encode for the structural components of the virus are expressed later while the nuclease and polymerase genes are early viral genes. Assembly (maturation): All of the viral parts are put together to make complete viruses. Release: The newly made viruses are released by lysozyme lysing open the host cell or extrusion from the host cell (which assembles all of the viral parts within the phospholipid bilayer then the viral parts gets pushed out via extrusion which does not kill the host cell).

Animal virus replication (enveloped virus)

Attachment: spikes of a vision attach to specific host cell receptors Membrane Fusion: envelope of vision fuses with cytoplasm Nucleocapsid release: nucleocapsid is released into the cytoplasm, viral envelope remains part of the cytoplasmic membrane Uncoating: nucleic acid separates from capsid Synthesis: nucleic acids and proteins

How are bacteria and viruses similar to one another?

Bacteria and viruses are similar in which that they are so small that you would have to use a microscope in order to see the individual bacterial cell or virus. They both contain genetic information.

How are bacteria and viruses different from one another?

Bacteria are a type of living organism (cell) whereas viruses lack a lot of the things that all cells have, and are just a type of nucleic acid wrapped inside a protein coating without any free-floating amino acids and nucleotides and so they are really small. They are incapable of metabolism, replication, or motility unless they find a host cell, then they are able to replicate its genetic material through the host. There are different kinds of viruses that infect different organisms such as a bacteriophage (virus that infects bacteria), animal virus and plant virus. Bacteria are often referred to by their genus and species but viruses are only commonly called by its species name.

Types of viruses

Naked and Enveloped

Describe two different ways that newly constructed bacteriophage can leave their host cell. How are these two ways different from one another?

Bacteriophage can either leave by lysing its host cell open (which kills the host cell), or via extrusion. During extrusion, the viral parts are assembled within the membrane of the host cell. Once assembled, the complete virus is then "pushed" (extruded) out without causing the host cell to die.

Describe the basic structural differences between bacteriophage and animal viruses.

Bacteriophages have a nucleic acid, protein coat, and a tail structure. However, animal viruses have a nucleic acid and protein coat. It doesn't have the tail structure. Some animal viruses can have a matrix protein and an envelope. Animal viruses infect their host cell by having the whole virus structure enter the host cell.

What's the purpose of the modification gene in bacteria?

Because the restriction enzymes look for specific sequences normally found in viral DNA, bacterial cells also have a modification gene that helps prevent its own DNA from being chopped up. The modification gene encodes for modification enzymes that add methyl groups (CH3) to the bacterium's DNA. The methyl groups on the DNA prevents the restriction enzymes from acting upon the bacterial cell's DNA.

How does generalized transduction differ from the lytic cycle?

Differs because as the viruses are coming together, some will envelope broken pieces of cellular DNA that will be incorporated into the capsid which creates a transdusing particle

Viral nucleic acids include which of the following A. Double stranded DNA B. Single stranded DNA C. Double stranded RNA D. Single stranded RNA E. All of the choices are correct

E

What is meant by a viral "early gene"? What are two examples of early genes in bacteriophage?

Early viral genes are those that are expressed immediately after entering the host cell. These are the ones that encode for nuclease which chops up the host cell's DNA and polymerase which makes copies of the viral nucleic acid.

What's the function of the nuclease gene that's found in the genome of bacteriophage?

Encodes for the nuclease enzyme which degrades the host cell's DNA so that it cannot be read in order to make mRNAs and protein which is a benefit for the viral genome because it can use the cell's machinery without any disruptions from the host cell's DNA processes.

What's the function of the polymerase gene found in the genome of bacteriophage?

Encodes for the polymerase enzyme. Polymerases read the viral nucleic acid and make the complement. This is one of the firsts steps to make more viruses, to make lots of viral nucleic acids. The viral nucleic acids are used to make viral proteins and the viruses themselves.

Enveloped viruses enter their host cell via ___, and exit their host cell via ____.

Enveloped viruses enter their host cell via fusion, and exit their host cell via budding.

Herpes virus causes productive infection in what type of cells?

Epithelial cells

Synthesis

Expressin of viral genes to produce viral structural and catalytic genes like capsid proteins and enzymes required for replication

generalized vs specialized transduction

Generalized transduction results from an error in DNA packaging. In generalized transduction, the transducing phage carries a random DNA segment from a donor host cell's chromosome or plasmids to a recipient host cell. Generalized transduction is initiated during lytic cycle of a virulent bacteriophage Specialized transduction results from an error in DNA excision of a prophage. A highly specific part of the host genome is regularly incorporated into the virus. Specialized transduction is initiated during the lysogenic cycle of a temperate bacteriophage.

Viral matrix proteins

Give the virus its shape, only present in enveloped viruses

How is generalized transduction similar to a normal lytic replication cycle?

It begins the same with a virus inserting its DNA into a host cell, destroying the host cell's genome, and then creating more viruses.

When HIV is latent, describe what it's doing inside its host cell.

It integrates its viral genetic material into the host's DNA by uncoating, entering the nucleus of the host cell, and then gets read to make a complementary piece of nucleic acid that is a DNA strand. Then that DNA produces its complement DNA to form a normal looking double stranded piece of DNA (reverse transcription: retroviruses that converts RNA into DNA). The viral DNA can then be integrated into the host cell's DNA and stay there

lysogenic vs lytic

LYSOGENIC 1. phage DNA inserts itself as a prophage into bacterial chromosome 2. phage is replicated along with the bacterial DNA prior to binary fission 3. binary fission complete; each cell has the phage DNA incorporated LYTIC 1. phage absorbed to receptor site on bacterial cell wall, penetrates, and inserts its DNA 2. phage DNA directs cell's metabolism to produce viral components - proteins and copies of phage DNA 3. heads are packed with DNA 4. collars, sheaths, and base plates attached to heads, tail fibers added last 5. release: bacterial cell lyses, releasing completed infective phages

What's a lysogen?

Lysogen: Bacterial cells that are infected with temperate phage and contains an un-induced prophage. Lysogens are immune to superinfection.

How is methylation protective against restriction endonucleases?

Methylation makes the restriction sites unrecognizable for the restriction enzymes. Bacteria prevent their own DNA from being chop down by restriction enzyme through methylation of the restriction sites

What is specialized transduction?

Part of the bacterial DNA adjacent to the incorporated viral DNA becomes part of the virus that will take it to another bacterial cell. It's called specialized because it's always typically the same part of the DNA. Some of the viral DNA is also left within the host cell's genome. This makes every phage produced inside this cell ineffective, and no other phages will be produced by these phages when they infect a host cell.

HIV is considered a retrovirus because it does what with its genome?

Performs reverse transcription (makes DNA from RNA)

Lytic phage

Phage attaches to specific receptors on the cell wall, tail contracts and phage DNA is injected into the bacterial cell leaving the phage coat outside. Phage genome is transcribed and phage proteins are synthesized. Phage DNA is replicated and host DNA is destroyed. Phage components are assembled and then the cell lyses and phages are released

viruses

Pieces of genetic material surrounded by a protein coat

How do bacteria protect against phages

Prevent attachment of phage to specific receptors on the cell surface. Some bacteria produce proteins that cover phage receptors, biofilms or capsules also cover phage receptors. Via restriction enzymes(endonuclease) •Restriction-Modification Systems(methylation of its own DNA) CRISPR system

Capsids are made of what type of molecule?

Protein

Non-enveloped viruses COULD have

Protein spikes double or single-stranded DNA Single or double-stranded RNA

Enveloped viruses COULD have ...

Protein spikes, matrix proteins, single or double-stranded DNA or RNA, phospholipid bilayer

Entry and exit of bacteriophages

Proteins in the "tail" of the phage bind to a specific receptor (in this case, a sugar transporter) on the surface of the bacterial cell. Entry: The phage injects its double-stranded DNA genome into the cytoplasm of the bacterium. Bacteriophages inject their genetic materials into the cytoplasm of the host cell, leaving an empty viral capsid shell on the host cell surface. They lyse the cell and kill it in order to exit the cell.

Which components would you find in ALL viruses? ...

RNA or DNA, Capsid , proteins

lysogenic cycle

Replicate host genome without killing the host.A phage replication cycle in which the viral genome becomes incorporated into the bacterial host chromosome as a prophage and does not kill the host. The viral DNA is added to the host cell's DNA and is copied along with the host cell's DNA

What's the difference between sense (+) RNA and anti-sense (-) RNA?

Sense (+) RNA can be translated to make protein [similar to mRNA which can be directly translated to make proteins] with a start codon (AUG) and a ribosome binding site (AGGAGG) so the ribosome can bind to the RNA and start translating it (appropriate codon encodse for appropriate amino acid). The anti-sense (-) RNA is complementary to the sense (+) RNA and is not translatable. It does not have a start codon or a ribosome binding site.

If you are analyzing the DNA sequence of a non-pathogenic E. coli bacterium and notice that it has a gene that is most similar to another pathogenic strain of E. coli. Upon further analysis, there are no other flanking genetic sequences that have been transferred... just the gene. Which of the following modes of HGT could explain this result? Explain your reasoning.

Specialized transduction Generalized Transduction Transformation Conjugation between HFR and F- For specialized and conjugation, it could happen if only the bacterial chromosomal DNA was incorporated and not the viral genes or the F plasmid genes

+ssRNA viruses

The (+) strand is already mRNA (can be directly translated into viral proteins), the (+) strand is copied into (-) template, the template is used to make more (+) strands

Which stage of the viral replication cycle (attachment, uncoating, entry, synthesis) best explains why bacteriophage do not infect human cells?

The attachment phase best describes why the bacteriophage can only infect bacteria. Viruses can only infect cells that have very specific proteins on their membrane. If the cell doesn't have the proteins that the virus can bind to then the virus will not bind to the cell. Human cells do not have the same membrane proteins as bacteria do, which explains why bacteriophages can't infect human cells.

What's the function of a viral capsid?

The capsid protects the viral nucleic acid whenever the virus is outside of the host cell (such as enzymes and toxic chemicals in the environment) and helps to deliver the viral nucleic acid to new host cells.

Which type of bacteriophage is most similar to a chicken pox virus: T4 or lambda? Explain your reasoning in terms of their respective life cycles.

The chicken pox virus has a latent phase within the human body where it does not show any symptoms. This means that it is most similar to the lambda life cycle since lambda will have a latent phase, while T4 will go immediately to the lysing phase of the cell.

Which component of an enveloped virus is directly involved with attachment to a host cell?

The envelope

Bacteriophage vs eukaryotic phage

The genome, but not the protein coat, enters the cell

What's the function of the lysozyme gene that's found in the genome of bacteriophage?

The lysozyme genes encodes for the enzyme lysozyme which lyses the host cell by degrading the peptidoglycan so the newly formed viruses can leave the cell to infect other cells.

How does the size of bacteria compare to that of the mitochondria found in eukaryotic cells?

The size of bacteria is about the same size of a mitochondria in a eukaryotic cell because the endosymbiotic theory says that in the past, mitochondria were free living bacteria.

What's the function of the tail structure in bacteriophage?

The tail is used to inject the viral nucleic acid into the host cell that it infects.

Prophage

The viral DNA that is embedded in the host cell's DNA

When herpes virus is latent, describe what it's doing inside its host cell.

The virus does not completely go away because it hides in the cytoplasm of the nerve cells, where the host cell's immune system can't reach it.

How does the size of bacteria compare to that of typical eukaryotic cells?

They are about 10 to 100 times smaller than a typical eukaryotic cell.

Exit of enveloped viruses

They exit through budding and that is how they get their envelope. In this way the cell can still be alive after the virus has left it

Exit of bacteriophages

They lyse the cell and kill it in order to exit the cell.

Which of the following mechanisms is most likely the explanation of how N. gonorrhoeae acquired human DNA? A. Transformation B. Conjugation C. Transduction

Transformation: this is because conjugation can only occur between two bacterial cells, not between a eukaryotic cell and a bacterial cell. Transduction is not an option because viruses can't infect both a eukaryotic cell and a bacterial cell. They are too specific to infect both types of cells so it would be impossible to have gene transfer this way. The most likely is transformation because gonorrhoeae kills human cells they likely picked up naked human DNA from the environment

Lysogenic infection

Type of infection in which a virus embeds its DNA into the DNA of the host cell and is replicated along with the host cell's DNA. It is silent and does not produce any affects while this is occurring. Can return to a phage and continue the lytic cycle. This will occur when the cell has damage to its DNA

How does the size of viruses compare to that of bacteria?

Viruses are typically 100 to 1,000 times smaller than a bacterial cell. There is also a variety in the sizes of viruses depending what type of virus they are. The measles virus is bigger than animal viruses. A rhino virus (causes the common cold) is about the same size as a ribosome, so that's part of why viruses don't have ribosomes.

Different viruses have different types of nucleic acids. Describe all the ways that viral nucleic acids may differ.

Viruses either contain: RNA (ribonucleic acid) or DNA (deoxyribonucleic acid) the genome can either be circular or liner ss (single stranded) or ds (double stranded) There can be ss RNA, ds RNA, ss DNA, ds DNA. Each virus has a unique type of nucleic acid inside of it. non-segmented (one continuous piece) or segmented (genetic material is split up into different parts) sense (+) which gets translated or anti-sense (-) which is untranslatable

Lysogenic conversion

When a bacterium acquires a new trait from its temperate phage

What is uncoating?

When the animal virus enters the host cell and sheds its protein coat. This releases the viral nucleic acid so it can direct the host cell to produce more viruses

How do enveloped viruses acquire their envelope?

When the virus exits the host cell, it uses the process of budding, which is when the virus pushes out from the inside of the host cell and takes a piece of the membrane of its host cell after it's out which creates its surrounding envelope.

persistant infection

a disease process that occurs gradually over a long period; years or life time.

Specialized transduction

a highly specific part of the host genome is regularly incorporated into the virus

What are viruses?

acellular, non-living particles

Conjugation

process in which paramecia and some prokaryotes exchange genetic information

Non-enveloped viruses COULD have

protein spikes Single stranded DNA Single stranded RNA Double stranded DNA

Enveloped viruses COULD have .... (check all that apply)

protein spikes matrix protein Single stranded DNA Single stranded RNA Double stranded DNA A phospholipid bilayer

virulent phages

reproduce strictly through the lytic cycle and always kill their host cells. . Those phages that kill the bacterial cells after every cycle are termed as virulent

generalized transduction

results from error in DNA packaging. lytic cycle accidentally places host DNA into a phage, which is brought to another cell

ssDNA

single-stranded DNA; in DNA replication, the DNA after it is separated to serve as the template for replication

A virus that has which type of genome must carry replicase within the viral particle?

ss (-) RNA

Which of the following characterizes bacteriophage but NOT eukaryotic viruses

the genome, but not the protein coat, enters the cell