Exam 2 Review Flashcards
when is the lac operon optimally expressed
in presence of lactose and absence of glucose
how many different secondary structures(hairpins) may be formed by the Trp leader mRNA
3
what regulatory sequence may be located tens of thousands of nucleotides away from the genes they regulate
enhancers
(any trans regulators)
what is the role of DNA methylation in eukaryotes
aid in silencing transcription
increased acetylation of histones is typically associated with what
gene activation and euchromatin formation
which enzyme acts as template for telomere repeat DNA sequence
telomerase
the process by which pneumococcus transfers DNA between RII and heat killed SIII is known as what
transformation
which direction of DNA will be the lagging strand
side where point of origin moves towards 3’ end
what is one difference between DNA replication in bacteria vs eukaryotes
eukaryotic chromosomes have many origins of replication while bacteria only have one
if single stranded binding protein is not present during DNA replication what would you expect to see
SSB prevents reannealing, so strands would quickly reanneal and DNA replication could not proceed
why are leading strand primers removed rather than joined like okazaki fragments
they contain nucleotides with 2’OH groups, and are targeted for excision by DNA polymerase
a plant cell exhibits in transcription of tRNA genes, which polymerase is mutated
RNA plymerase III
what region of gene would need to be mutated to prevent access of RNA polymerase to the gene
promoter sequence
why does rho dependent transcriptional termination in bacteria require the rho protein
RNA polymerase stalls on termination stem-loop and rho is needed to displace it
what defines end of eukaryotic gene
presence of polyadenylation signal sequence leads to cleavage of pre-mRNA
what is the purpose of alternative splicing in eukaryotic cells
produce multiple polypeptide sequences from a single primary transcript
role of promoter region
recruit transcription factors that form initiation complex
what is the shine-dalgarno sequence in bacteria
purine-rich sequence found in 5’ UTR of mRNA
how does eukaryotic ribosomal small subunit recognize start codon on mRNA
binds met-tRNA to first AUG codon after kozak sequence
what would you expect to find bound to stop codon at A site
translation release factor
how would a single base insertion into second codon of sequence affect AA sequence
AA sequence would be changed
difference between NER and BER
NER detects ribosomes in double helix, BER removes damaged bases
which class of point mutation almost always results in mutant phenotype
frameshift
2 mutagens classified as base analogs
5-bromouracil
2-aminopurine
2 forms of double stranded break repair
NHEJ
SDSA
how is DNA replication in both prokaryotes and eukaryotes described
bidirectional and semiconservative
which protein is responsible for initiation of oriC in E. coli
DnaA
sequence of steps in PCR
denaturation, primer annealing, primer extension
where does sigma subunit of bacterial RNA pol bind
bacterial gene’s promoter
what is a characteristic of short tandem repeats in genetic analysis
STRs segregate independently
A mutation of the O region of the lac operon would most likely result in what?
constitutive expression of lac operon, whether or not lactose was present, as the repressor cannot bind
in griffins experiment did mice die
live IIIS and live IIR with dead IIIS
which protein removes RNA primer from nascent DNA in E. coli
DNA polymerase I
properties of holoenzyme but not core enzyme
promoter recognition and binding
property of core enzyme but not holoenzyme
5’ to 3’ synthesis
necessary component of intrinsic but not rho dependent terminators in E. coli
string of U’s in RNA
during transcription in E. coli when does sigma subunit fall off
after first 8-10 RNA nucleotides
role of general transcription factors
GFT binds to core promoter and allow transcriptional initiation
function of shine dalgerno sequence
specification of authentic start codon in bacterial RNA
what will never be found in A-site of ribosome
initiator tRNA(that will be in P-site)
in bacterial translation initiation, the mRNA…
is oriented on small subunit by shine dalgarno sequence through base pairing with an rRNA
last component incorporated in process of translation initiation
large ribosomal subunit
what complex(es) binds to open A site in process of translational elongation
charged tRNA
elongation factor
GTP
what class of mutation generally creates decreased amount of gene product
promoter mutations
strand slippage during DNA replication generally results in what type of mutation?
expansion of trinucleotide repeat sequence
spontaneous nucleotide changes
depurination and deamination
alkylating agents generally result in what type of mutations?
base substitutions
what repair mechanism is used most to repair thymine dimers
photoactivation repair
presence of what combination of molecules could prevent transcription of a repressible operon
repressor and corepressor
binding of which complex increases ability of RNA polymerase to transcribe the lac operon
cap-cAMP operon
what complex transports regulatory RNAs to RNAs targeted for degradation or inhibition of translation
RISC
what is most efficient at changing gene expression through RNA interference
DS RNA that includes gene sequence you want to silence
what is primarily responsible for genomic imprinting
methylation of cytosine in DNA
