Chapter 7 Flashcards
Which of the following molecules of RNA would you predict to be the most likely to fold into a
specific structure as a result of intramolecular base-pairing?
5′-CCCUAAAAAAAAAAAAAAAAUUUUUUUUUUUUUUUUAGGG-3′
-More complementarity will lead to greater likelihood for the formation of a specific structure
You have a piece of DNA that includes DNA sequence below. Which RNA molecule could be
transcribed from this piece of DNA?
5′-ATAGGCATTCGATCCGGATAGCAT-3′
3′-TATCCGTAAGCTAGGCCTATCGTA-5′
5′-AUAGGCAUUCGAUCCGGAUAGCAU-3′
-RNA molecules synthesized 5’-3’
The sigma subunit of bacterial RNA polymerase
recognizes promoter sites in the DNA.
Which of the following might decrease the transcription of only one specific gene in a
bacterial cell?
a mutation that introduced extensive sequence changes into the DNA that precedes the
gene’s transcription start site
Total nucleic acids are extracted from a culture of yeast cells and are then mixed with resin
beads to which the polynucleotide 5′-TTTTTTTTTTTTTTTTTTTTTTTTT-3′ has been
covalently attached. After a short incubation, the beads are then extracted from the mixture.
When you analyze the cellular nucleic acids that have stuck to the beads, which of the
following is most abundant?
mRNA
-mRNA only type of RNA that is polydenylated and its poly-A-tail would be able to pair w/ the poly-T
snRNAs __________________
can bind to specific sequences at intron–exon boundaries through complementary base-
pairing
rRNA contains the catalytic activity that joins amino acids together
True
A poison added to an in vitro translation mixture containing mRNA molecules with the
sequence 5′-AUGAAAAAAAAAAAAUAA-3′ has the following effect: the only product made is
a Met-Lys dipeptide that remains attached to the ribosome. What is the most likely way in
which the poison acts to inhibit protein synthesis?
It inhibits movement of the small subunit relative to the large subunit
Which of the following methods are used by cells to regulate the amount of a protein in the cell?
-Genes can be transcribed into mRNA with different efficiencies.
-Many ribosomes can bind to a single mRNA molecule
-Proteins can be tagged with ubiquitin, marking them for degradation
Introns need to be removed carefully since leaving in an extra one/two nucleotides would shift the reading frame of the mRNA molecule & change the protein it encodes
True
The length of a particular gene in human DNA, measured from the start site for transcription
to the end of the protein-coding region, is 10,000 nucleotides, whereas the length of the mRNA produced from this gene is 4000 nucleotides. What is the most likely reason for this difference?
The gene contains one or more introns
How do RNA polymerase molecules move? Why are RNA transcripts so much shorter than DNA segments that encode them?
-Move left to right, indicated by gradual lengthening of the RNA transcripts
-Transcripts aren’t fully extended b/c begin to fold up and interact w/ proteins as they are synthesized
In eukaryotes, which parts of a gene are transcribed into RNA
Introns and exons
Role of aminoacyl-tRNA during normal translation of genetic code
Performed by synthetase enzymes that correctly match tRNAs and amino acids
The bonds that form between the anticodon of a tRNA molecule and the three nucleotides of a codon in mRNA are _____.”
-hydrogen bonds that form when the tRNA is at the A site
-broken by the translocation of the ribosome along the mRNA
