ch. 5 Flashcards
what are viruses and what is important to note
they are obligate intracellular parasites that relies on host cell machinery to reproduce. IT IS NOT ALiVE
what is the structure of a virus
they have nucleic acid genome surrounded by a protein shell called capsid. they have a collar under the capsid with a sheath acting as its body. tail fibers for mobility and a base plate under the sheath.
what kind of genetic info can a virus have?
single/double stranded DNA or RNA
a virus that infects bacteria is called a
bacteriophage
what is an effect from the virus using host machinery to replicate
VIRUS GENOME CANNOT GET BIGGER BUT new offspring can include host dna from using their stuff
how does virus inject genome into host cell
it uses atp to contract and inject the host with its genome through its base plate
what do animal viruses and plant virus not have in common? hint: a structure
animal viruses have envelopes that surrounds the virus made up of the hosts cells membrane so it doesnt get attacked by immune system, plant viruses and bacteria viruses are NAKED
how is the envelope acquired
through budding: coming out of the host cell from the inside
bacteriophages have two life cycles but have the same start: describe the first few common steps and state the two different cycles
the first step: virus binds to outside of host cell through attachment
second step: injects its viral genome through penetration/eclipse
-after this, the virus will either go through lytic or lysogenic cycle
lytic cycle of bacteriophages
the host cell machinery starts to transcribe/translate viral genome with a early gene that creates hydrolase: an enzyme that degrades host genome. the new viral dna gets encapsulated with capsid and a late gene creates lysozyme that breaks down cell wall and virus babies burst out host cell KILLING it
lysogenic cycle of bacteriophages
once genome is inside host cell, the virus is called prophage and the host is called lysogen. the prophage stays silent while the genome gets replicated and new viruses are release while the host cell does its own thing. once prophage gets activated, it excises itself from host genome and enters lytic cycle
lytic vs lysogenic
lytic immediately kills host cell while lysogenic allows the cell to live while it creates more viruses until the prophage gets activated to then go into the lytic cycle
transduction
when host DNA thats with viral genome codes for a new trait not found in previous host cell
how do animal viruses choose and enter cells?
they choose cells with their specific receptors and then endocytose itself into the cell and release genome
animal viruses can go through what cycles?
they can do the lytic, lysogenic, or productive cycle: similar to lytic cycle but doesnt kill host and leaves by budding
dormant form of viral genome in host cell is called
provirus
rna + viruses
they must encode for RNA dependent RNA POL (AND DONT NEED TO CARRY IT ITSELF). they are single stranded that act just like mRNA and it creates -RNA strand to complement it.
rna - viruses
they must carry and encode RNA dependent RNA pol therefore they dont need hosts cell machinery. the - rna strand is used as a temp for mRNA and the RNA pol will make the + strand
retroviruses
they are + RNA that go through lysogeny and integrate as provirus. they must encode reverse transcriptase to make DNA from RNA using the RNA pol thats encoded in its own genome
doublestranded DNA viruses characteristics
often encode enzymes required for dntp synthesis and DNA replication. these viruses have big genomes and need their own enzymes for make their dntp if host cell doesnt have it readily available.
subviral particles
infectious agents that are smaller and more simple
prions
misfolded versions of a protein that already exists and they cause good proteins to misfold as well.
prions are responsible for? how do you get them?
transmissible spongiform encephalopathies that degrade the NS and are ALWAYS fatal. very resistant to chemicals and temp. you can get them by eating them or them being genetically linked
viroids
viral like things that consist of a circular short piece of RNA
cell theory by hooke
- all living organisms are made up of one or more cells and their products
- cells are the monomer for organisms
- new cells come from preexisting cells
prokaryotes include what type of organisms
bacteria , archea, and blue green algae
living organisms are classified through what? whats the biggest division of this system? what three ____ exist?
they are classified through taxonomy and domain is the biggest and it divides into bacteria, archae, and eukarya
each eukarya breaks into what sections
animalia, plantae, and fungi
bacteria have what inside their cytoplasm
they have no membrane bound organelles, they have ribosomes but they are not membrane bound where they translate mRNA into a polyribosome
bacteria have what other thing made up of genome besides its own DNA
plasmid: circular piece of ds-DNA that is much smaller than main DNA, they are extra chromosomal genetic material
what can bacteria do with plasmid
they can go through conjugation where two bacteria swap genetic info (plasmid) to each other