Bacterial and Viral Genetics
The retroviral genome is composed of...
a) DNA, b) RNA, c) Amino Acids
An operon is regulated by a protein that, when bound, blocks transcription of that gene. Is this negative or positive control? (Brownie points: what is this protein called?)
Negative. (Repressor)
What is one difference between eukaryotic and prokaryotic genomes?
eukaryotic = more complex, bigger, often linear, have introns and exons, not grouped in operons.
A mutation causes a codon that once coded for Tyrosine to instead code for a stop codon. What type of mutation is this?
Nonsense
If a histone is acetylated (acetyl group added), transcription of DNA in that region will (increase/decrease).
Increase
During which cycle does a virus insert its genome into a host cell, integrate the viral genome into the host genome, and have its genome be replicated as the host undergoes mitosis?
lysogenic
When allolactose enters a cell, it binds the Lac repressor, which causes the repressor to detach from the operator, which turns transcription on. Is this an inducible or a repressible operon?
Inducible.
In eukaryotes, regions on DNA where transcriptional regulatory proteins bind are called...
a) operators
b) response elements
c) transposons
d) regulation stations
b) response elements
The deletion of a single base results in a _____ mutation. Is this type of mutation likely to be neutral?
Frameshift, No.
Which image correctly describes the way that a transposon is excised from a DNA strand?
Staggered cut sites.
Passing on genes to progeny is (vertical/horizontal) gene transfer, and transferring genes to a cell that is a member of the same generation and may or may not be the same species is (vertical/horizontal) gene transfer.
Genes to progeny is VGT, genes to same generation is HGT (what would conjugation be an example of?)
When glucose levels are high, cAMP levels are (high/low) and transcription of the Lac operon is (increased/decreased).
cAMP levels are low, transcription is decreased.
Based on this image, which genes can Enhancer A affect? Which can Enhancer B affect?
EA -> Gene 1 only. EB -> Gene 2 only
Wild-Type: 5'...CCGUCA...3'
Mutated: 5'...CCGUCU...3'
What type of mutation is this? Is this likely to result in a gain-of-function, loss-of-function, or neutral mutation? Are all of these possible?
Silent, can only be neutral.
A ___ is first transcribed then reverse-transcribed and added into the genome, increasing the number of copies of the gene (copy-paste). A ___ is removed from the genome then added back in a new location (cut-paste).
Which describes Class I (retrotransposons). Which describes Class II (transposons).
copy-paste: retrotransposons. cut-paste: transposons.
How will an auxotrophic mutant's growth be affected on minimal media?
a)it will grow as normal, auxotroph is a synonyms for wild-type
b)it will grow as normal but have some sort of observable phenotype different from wild-type (ex. color, fluorescence)
c)auxotrophs cannot grow on minimal media.
c) cannot grow on minimal media
The mercury resistance gene is not usually transcribed. When Phenylmercury is present in the system, it binds to a protein called MerR. MerR is then activated and binds to the mercury resistance operon, and transcription of the gene can take place. The mercury resistance gene is an example of what?
Positive Inducible
Name one way that eukaryotic genes can be regulated that prokaryotic genes cannot be? Multiple answers are possible.
Eukaryotic genes can be regulated by chromatin remodeling. Post-transcriptional modifications such as poly-a tail and 5' cap can be affected. Response elements, enhancers, silencers, insulators.
A WT protein has Leucine (Leu) at position 40. The mRNA at that location is ...UUG...
The gene is mutated so the mRNA now reads ...UUC..., which codes for Phenylalanine, and causes a loss-of-function mutation.
The gene is mutated again to be ...CUC..., which is Leucine, and restores the protein to the Wild-type. This is an example of (intergenic/intragenic) suppressor mutation.
intragenic suppressor mutation.
A plant is exposed to radioactivity, which causes a series of single bp mutations which leads to the loss-of-function mutation of a repressor protein, increasing the transcription levels of the associated gene. Is this an example of epigenetic modification?
No! >:(
___: A donor cell forms a pilus with a receptor cell to exchange genetic information.
___: Free DNA floating in the exterior of the cell is picked up by the receptor cell and integrated into the genome.
___: When a viral genome is removed from a host cell, it occasionally will carry portions of the host genome with it, transferring those genes to a new host.
Conjugation: A donor cell forms a pilus with a receptor cell to exchange genetic information
Transformation: Free DNA floating in the exterior of the cell is picked up by the receptor cell and integrated into the genome.
Transduction: When a viral genome is removed from a host cell, it occasionally will carry portions of the host genome with it, transferring those genes to a new host.
The trp gene produces a group of enzymes that together can synthesize tryptophan. When tryptophan levels get high, tryptophan binds to the TrpR protein, and then the TrpR/tryptophan complex binds to the operator and stops transcription. What type of operon is this?
Negative Repressible
Describe one way that siRNA or miRNA can inhibit transcription or translation.
Bind to homologous DNA and recruit methylating proteins. While bound to RISC, bind to homologous mRNA and block translation.