Chapter 13

RNA or DNA can be + or - stranded, what is that

+ stranded directly acts as mRNA and is tranlated to proteins by pssing transcription - stranded makes + strand from negative then translated to proeins

Function of capsid dealing with binding

The capsid/envelope is used in binding/attachement by providing a site to attach to the cell so penetration can occur.

termperate bacteriophages carry out two types of cycles.

The lytic and the lysogenic

types of transduction

generalized -any gene can be transfered by a virrulent or temperate phage specialized - only temperate phages can transfer specific bacterial genes

Function of the capsid with protection

in the host cell there is a protective enzyme/protein to stop the virus. Normally viruses will have spikes/other things to neutralize the effcts of the cell.

lysogenic state

reproduction of bacteria with prophage

Latent cell

silent phage, quiet, not active, non expensing, ex chickenpox

capsomerers

subunits that make up the coat

transduction

the DNA from chromosome of one cell is transferred to another cell via a replicating virus.

traits of bacterial cells

-either DNA or RNA, Double stranded or single stranded -Nucleic acid surrounded by a protein coat called a capid forming the nucleocapsid -Virus's are very specific to the host the attachk because of there attachment sites -multiply inside of host cell

life cycle of animal cells

1 - attachment - outside hte cell there are surface proteins on nucleocapsids, spikes can attach to cell membrane. Virus attachemnt is very specific and a speicific host is required 2 - entery/ penetration - virons enter cells in on of two ways. either endocytosis or fusion. when the viron enters its DNA is uncoated 3 a portion of viral DNA is trasncribed producing mRNA that ecodes early viral proteins 4 biosynthesis occurs where viral DNA is replicated and some viral proeins are made 5 - late translation occurs and capsid proteins are synthesised 6 - Maturation - virons mature by capsid proteins migtating into nucleus and assembly occurs 7 - viruses are released by budding or exocytoisis. In bindding

bacteriophage lytic cycle.

1 - the phage attached to host cell cell in attachment 2 - the phage injects the host cell and injects its DNA during the penetration stage 3 - the phage causes the host DNA to break into pieces and the phage then uses the host machinery to synthesize new copies of its DNA.this is biosynthesis. biosynthesis also involves production of viral proteins. 4 the phage components are assembled into virons during the maturation or assembly state 5 - in the release state the cell lyses and the phage irons are releaesd

temperate lysogenic cycle

1 - the phage attaches to the host cell during the attachhment stage 2 - the phage injects its DNA intothe host cell during penetration stage 3 - the phage DNA forms a circle which integrates within the bacterial chromosome by recombination. The inserted phage DNA is called a prophage. Most phage proteins are repressed by two repressor proteins that are produts of phage genes 4 - whenever the bacterium reproduces the prophage is also copied 5- evenutally the prophage is excited from the host choromosome in a process called induction. Induction can occur spontaneously through recombination or other genetic events or through UV light or certain chemicals. 6 - when induction occurs the phage may enter the lytic cycle

temperate lytic cycle

1 - the phage attaches to the host cell during the attachhment stage 2 - the phage injects its DNA intothe host cell during penetration stage 3 - the phage DNA forms a circle which is replicated and transcribed to produce phage components and continue on in the lytic cycle or can proceed into the lysogenic cycle 4 the phage DNA directs the host cell to synthesize viral components in biosynthesis stage 5 - the phage components are assembled into viron during the maturation/ assembly stage 6 - in the release stage the cell lyses and the released phage goes on to infect other cells

Viron

A complete fully developed viral particle

Types of animal virus

DNA virus (nucleus) Virus with DNA as genetic material and needs nucleus to help transcribe. IT enters inot nucleus where transcription occurs then moves to the cytoplasm for transduction RNA virus (cytoplasm) virus where RNA is genetic material and doesnt need nucleus so it stays in the cytoplasm for replication/translation.

provirus

Viral DNA that integrates into animal DNA

Bacteriophage (phage

Virus that infects bacterial cells

function of the capsid in stimulating the immune response

a infected host's iimmune system is stimulated to produce antibodies that react with surface proteins of the virus. Host antibodies react with viral proteins and try to inactivate the virus

Virus

a non living agentain containg specific genetic elements

Lysogeny

a state in which phage DNA is incorporated into host without lysis

Phage

a virus that infects bacteria (aka as bacteriophage)

Coat/capid

can be helical or polyhedral made of subunits called capsomeres.

Obligatory intracellular paracite

cant function on there own, need a host cell to multiply

virulent bacteria/ productive cycle

causes distruction of the cell

lytic cycle

causes distruction of the cell, ends with lysis and death of the cell

Enveloped vs non enveloped structure

enveloped virus have a layer of host cells plasma membrane with spikes/proteins on it that are determined by the virus nucleic acid. Non enveloped viruses only have the capsid

three typres of viral structures

enveloped-usually spherical nonenveloped- helical or polyhedral complex virus- capsid with additional structures. Ex: bacteriophage

specialized transduction

initiated durin the lysogenic cycle of temperate bacteriophages. 1 - Phage DNA becomes incorporated into the bacterial chromosome and the phage DNA is now called a prophage and can be transferred throughout generations of cells during each replication. 2 - during induction when the prophage is excised from the host chromosome it occasionally takes with it some of the bacterial chromosomal genes. This phage DNA, with the attached bacterial genes begins the lytic cycle where it is replicated and becomes packaged into new bacteriophages. 3 - the cell bursts releasing the bacteriophages containing the prophage 4 - one of the bacteriophages attaches to a bacterial cell releasing its DNA into the recipeint and it becomes incorporated into the recipients chromosome. Now the recipient cell has a prophage plus new bacterial genes from the donor cell. This recipient cell is a recombinant cell because it recived DNA from another bacterium. The donor bacterial cell has a resistance gene

generalized transduction

initiated during the lytic cycle of cirulent bacteria. The donor DNA can be any fragment of bacterial chromosome 1 - bacteriophage attaches to a bacterial cell wall and inserts its DNA 2 -the phage commandeers the bacteria cellular machinery to synthesize new phage DNA and produce phage proteins 3 - in order to conver the bacterium inot an effecient virus producing factory some of the phage proteins break the bacterial DNA into small pieces. phage DNA is coated with phage proetins to form new virus particles but sometimes pieces of bacterial DNA are mistakenly packaged into phage proteins. these now carry bacterial DNA rather then phage DNA and are called tranducing phages 4- when a tranducing phage composed of phage proteins and bacterial DNA infects a new host the phage injects the bacterial DNA into the new bacterial host. The infected bacterium sometimes incorporates this DNA Into its own chromosome thorugh recombination resulting in the transfer of genes from hte donor bacterium to the recipeint bacterium

prophage

inserted phage DNA

Temperate phages

phages capable of lysogeny (a state where a phage DNA is incorportaed into host without lysis), goes through the lytic cycle

What are exceptions to the two types of animal viruses

pox- carries all enzymes for maltiplication to occur so it replicates in the cytoplasm hepadnavirus - a dna virus that transcribes RNA then uses reverse transcripate to make DNA molecules retrovirus - RNA virus that uses reverse transcriptase to make DNA which is intergrated as provirus into the host chromosomes. To treat must target provirus