AP BIOLOGY CHAPTER 17 - PART 2
Which of the following is the first event to take place in translation in eukaryotes?
the small subunit of the ribosome recognizes and attaches to the 5' cap of mRNA
In the structural organization of many eukaryotic genes, individual exons may be related to which of the following?
the various domains of the polypeptide product
Use the following model of a eukaryotic transcript to answer the next few questions. 5' UTR E₁ I₁ E₂ I₂ E₃ I₃ E₄ UTR 3' 24) Which components of the previous molecule will also be found in mRNA in the cytosol?
5' UTR E₁ E₂ E₃ E₄ UTR 3'
What is the function of GTP in translation?
GTP energizes the formation of the initiation complex, using initiation factors
Use the following model of a eukaryotic transcript to answer the next few questions. 5' UTR E₁ I₁ E₂ I₂ E₃ I₃ E₄ UTR 3' 26) Which of the following is a useful feature of introns for this model?
Introns allow exon shuffling.
What is the function of the release factor (RF)?
It binds to the stop codon in the A site in place of a tRNA
Use the following model of a eukaryotic transcript to answer the next few questions. 5' UTR E₁ I₁ E₂ I₂ E₃ I₃ E₄ UTR 3' 28) Suppose that an induced mutation removes most of the 5' end of the 5' UTR. What might result?
Removal of the 5' UTR also removes the 5' cap and the mRNA will quickly degrade
An experimenter has altered the 3' end of the tRNA corresponding to the amino acid methionine in such a way as to remove the 3' AC. Which of the following hypotheses describes the most likely result?
The amino acid methionine will not bind
In an experimental situation, a student researcher inserts an mRNA molecule into a eukaryotic cell after he has removed its 5' cap and poly-A tail. Which of the following would you expect him to find?
The molecule is digested by exonucleases since it is no longer protected at the 5' end.
When translating secretory or membrane proteins, ribosomes are directed to the ER membrane by
a signal-recognition particle that brings ribosomes to a receptor protein in the ER membrane.
When the ribosome reaches a stop codon on the mRNA, no corresponding tRNA enters the A site. If the translation reaction were to be experimentally stopped at this point, which of the following would you be able to isolate?
an assembled ribosome with a polypeptide attached to the tRNA in the P site
Accuracy in the translation of mRNA into the primary structure of a polypeptide depends on specificity in the
bonding of the anticodon to the codon and the attachment of amino acids to tRNAs.
Alternative RNA splicing
can allow the production of proteins of different sizes from a single mRNA
Use the following model of a eukaryotic transcript to answer the next few questions. 5' UTR E₁ I₁ E₂ I₂ E₃ I₃ E₄ UTR 3' 27) Suppose that exposure to a chemical mutagen results in a change in the sequence that alters the 5' end of intron 1 (I₁). What might occur?
inclusion of I₁ in the mRNA
The process of translation, whether in prokaryotes or eukaryotes, requires tRNAs, amino acids, ribosomal subunits, and which of the following?
polypeptide factors plus GTP
A mutant bacterial cell has a defective aminoacyl synthetase that attaches a lysine to tRNAs with the anticodon AAA instead of the normal phenylalanine. The consequence of this for the cell will be that
proteins in the cell will include lysine instead of phenylalanine at amino acid positions specified by the codon UUU.
There are 61 mRNA codons that specify an amino acid, but only 45 tRNAs. This is best explained by the fact that
the rules for base pairing between the third base of a codon and tRNA are flexible.
Use the following model of a eukaryotic transcript to answer the next few questions. 5' UTR E₁ I₁ E₂ I₂ E₃ I₃ E₄ UTR 3' 25) When the spliceosome binds to elements of this structure, where can it attach?
to the end of an intron
Which of the following is a function of a signal peptide?
to translocate polypeptides across the ER membrane
A particular triplet of bases in the coding sequence of DNA is AAA. The anticodon on the tRNA that binds the mRNA codon is
uuu
