Test 2 Flashcards
diff btw a nonsense mutation in 3rd codon and missense mutation in 3rd codon
nonsense: translated to 2 AA
missense: create change in 1 AA
what could account for silent mutation?
different 3rd codon encodes the same AA
legs of a phage are disrupted; what stage would that impact?
attachment
picture of plasmid and restriction enzyme; how many pieces are there after the cuts?
3
Ames test
at least twice as much; increase
phage therapy will affect person’s own cell?
no because it will only lyse the cell of the virus, not the person’s own cell
positive sense +ssRNA wants to create more of its genome; what mechanism does it use?
use the host’s ribosome to translate its own RNA dependent RNA polymerase
okazaki fragment: translation
T/F?
F
how does virus get its capsule?
from the cell membrane as it leaves
what does transposon need ?
transposase
can transposon move from one plasmid to the next?
not unless there’s a sex pilus
what is wrong about prion?
it is not a unique virus
DnaG
no initiation due to DNA poly III not being able to attach
IF2
no initiation of translation due to no binding site for initial tRNA on P site
what doesn’t utilize homologous recombination?
F plasmid conjugation
general transduction happens during what replication process?
assembly
spontaneous mutation happens during what phase?
replication
RNA polymerase adds nucleotide at the ___ while DNA poly adds nucleotides before the ___
promotor, origin
how does inosine at the 3rd position save energy?
allows fewer tRNA to be made
riboswitch
change the 2ndary structure of mRNA
a trp operon has trp A, B, C, D, E…..will transcribe a:
polycistronic
auxotroph for arginine can grow on medium that contain:
everything except the answer that says “except arginine”
T4 phage has dsDNA; how does it replicate its genome?
bacterial DNA polymerase
Avery, Macleod, and McCarty confirm DNA by:
testing enzymatic digestions on all 3 compounds
prokaryotic replication
semiconservative and bidirectional
if host cell couldn’t do endocytosis, which would be affected?
naked ssRNA virus
what would affect ability to attach to host cell?
B and D
receptors on host cell altered
enzyme on host cell degrades the attachment on the virus
where does influenza virus gets its classification of respiratory virus?
it specifically attaches to receptors in lung
mosquito species contains a Class IV virus that infect people; suddenly another species of mosquitos starts to infect people with the same virus; what is the molecular mechanism that could explain the change of vector?
mutation of virus leads to new attachment site that enables the virus to attach to the new mosquito species
virus has enveloped particle; explain how this helps them evade host defense mechanism?
the virus will make its protein an when it’s budding out it will take a portion of the host cell membrane with it, creating an envelope; this envelope is recognized as self so the virus will not get attacked
difference between generalized and specialized transduction?
generalized: where a segment of host cell DNA is carried from one bacterial cell to another accidentally by a bacterial virus phage
specialized: where only a few specific genes (near sit of integration) from one bacterial cell are transferred to the 2nd bacterial host by a phage; virus takes part of host chromosome with it but leaves part of the virus prophage behind; so it’s a defective phage that delivers DNA to the new host
F plasmid conjugation
F+ donor has a fertility plasmid
F+ donor produces a sex pilus that connects to F- recipient
F plasmid migrates into F- cell via sex pilus while replication is occurring and at the end of conjugation the recipient cell becomes F+
Hfr conjugation
Hfr sends incomplete F plasmid and part of its DNA (can be all of DNA) to the recipient cell
the longer the cell to cell contact time, the greater the amount of DNA transferred
at the end the recipient cell remains F- but now has a new gene/trait
F’ plasmid conjugation mechanism
F plasmid can de-integrate from the host chromosome and create a F’ plasmid, which has F+ and some other genes; this allows passage of genetic info from chromosome of one cell to another
the de-integration is inaccurate so host cell DNA is taken along with the F plasmid
rolling circle replication is employed
at the end both donor and recipient cell are F’ and capable of conjugation with F- cell
transformation
a cell taking up extracellular DNA directly without cell to cell contact
Class IV replication; how it uses host machinery to replicate and what kind of enzymes it brings with itself
+ssRNA virus
- mRNA (encoded on ssRNA) is translated immediately into the host cell RNA dependent RNA pol
- the pol synthesizes a -ssRNA template, which is used as the template for viral genome replication
- once genome is replicated, proteins are translated
- so once the capsid, packaging proteins, and genome are made, they are assembled in the cytoplasm of host cell
- it only brings its own mRNA and is easily translated into protein by the host mechanism
if there’s a nonsense mutation in the first codon, what happens to the gene?
nonsense mutation in gene 1 will disrupt the entire sequence
