questions Flashcards
the final step in cloning a gene is to ensure its correct insertion in the plasmid. what’s the best approach to verify that you cloned the gene into a plasmid, exactly as you have designed?
DNA sequencing
what is an ORF (open reading frame)?
the nucleotides of a gene that make up the codons specifying amino acids
how does a ddNTP terminate DNA synthesis catalyzed by a DNA polymerase?
ddNTP lacks the 3’ hydroxyl on the sugar ring that’s required for phosphodiester bonding
agarose gel electrophoresis is a common technique used to resolve DNA fragments based upon their size. what occurs at pH 7?
DNA fragments migrate toward the positive pole (anode)
what must be taken into account when determining the length of the primers for a PCR reaction?
A:T content of the primers
why is E coli a popular choice to express proteins recombinantly?
E coli grows rapidly and to high density
what is a genomic library?
a collection of recombinant molecules with inserts that contain all of an organism’s genome
what type of sequence is most likely to be recognized by a type II restriction enzyme?
a palindromic sequence
what are the steps of shot gun sequencing in proper order?
create genomic library
sequence DNA
assemble DNA
annotate DNA
why are oncogenes considered transcription factors?
they can directly alter the expression of genes that regulate cell division
why is RNA not stable in alkali solutions?
the 2’ OH is deprotonated and performs a nucleophilic attack on the phosphodiester backbone
what are trans-acting factors that allow transcriptional regulation of bacterial genes
site specific DNA-binding proteins that regulate the recruitment or function of the RNA polymerase holoenzyme
in eukaryotes, a single transcriptional regulatory protein can control multiple genes if…?
all the genes contain a binding site for the transcriptional regulator
what is the most appropriate reason why codons are 3 base pairs in length?
there are 20 amino acids which must be coded for
what does the cloverleaf structure of tRNA result from?
watson crick base pairing between bases
