Chapter 17 Mastering Biology
Where does translation take place?
ribosome
If the sequence in the coding strand of DNA for a particular amino acid is 5'AGT3', then the anticodon on the corresponding tRNA would be ________.
5'ACU3'
At which site do new aminoacyl tRNAs enter the ribosome during elongation?
A-site
The tRNA anticodon, GAC, is complementary to the mRNA codon with the sequence _____.
CUG
Which of the following processes is an example of a post-translational modification?
Phosphorylation
The enzyme complex associated with a holoenzyme
RNA polymerase
Which of the following statements is true about protein synthesis in prokaryotes?
Translation can begin while transcription is still in progress.
You want to engineer a eukaryotic gene into bacterial colony and have it expressed. What must be included in addition to the coding exons of the gene?
a bacterial promoter sequence
Which of the following mutations is most likely to cause a phenotypic change?
a single nucleotide deletion in an exon coding for an active site
The anticodon of a particular tRNA molecule is _____.
complementary to the corresponding mRNA codon
Translation occurs in the _____.
cytoplasm
The RNA segments joined to one another by spliceosomes are _____.
exons
True or false. A tRNA with an anticodon complementary to the stop codon catalyzes the reaction by which translation is terminated.
false
Which nucleic acid is translated to make a protein?
mRNA
Translation requires _____.
mRNA, tRNA, rRNA
During RNA processing a(n) _____ is added to the 5' end of the RNA.
modified guanine nucleotide
What molecules in the spliceosome catalyze the intron removal reactions?
ribozymes
In eukaryotic cells, transcription cannot begin until _____.
several transcription factors have bound to the promote
Spliceosomes are composed of _____.
small RNAs and proteins
What ensures that the correct amino acid is added during translation?
the anticodon of a properly formed aminoacyl tRNA
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
During transcription, in which direction is (1) RNA synthesized and in which direction is (2) the DNA template "read"?
(1) 5'—>3' (2) 3'—>5'
Life as we know it depends on the genetic code: a set of codons, each made up of three bases in a DNA sequence and corresponding mRNA sequence, that specifies which of the 20 amino acids will be added to the protein during translation. Imagine that a prokaryote-like organism has been discovered in the polar ice on Mars. Interestingly, these Martian organisms use the same DNA → RNA → protein system as life on Earth, except that there are only 2 bases (A and T) in the Martian DNA, and there are only 17 amino acids found in Martian proteins. Based on this information, what is the minimum size of a codon for these hypothetical Martian life-forms?
5 bases
How does the arrival of a termination codon at the A site trigger the end of protein synthesis?
A protein release factor binds in the A site and releases the polypeptide from the final tRNA to which it is bound.
During elongation, which site in the ribosome represents the location where a codon is being read?
A site
Assume a promoter sequence is rotated 180 degrees. How will this rotation affect what is considered upstream and downstream DNA? Also, which strand will now be template and which will be nontemplate?
Both upstream and downstream DNA and the template and nontemplate strands will be reversed if the promoter sequence is rotated 180Ëš.
The initiator tRNA attaches at the ribosome's _____ site.
E
Which one of the following statements about RNA processing is true?
Ribozymes may function in RNA splicing
Which of the following steps occurs last in the initiation phase of translation?
The large ribosomal subunit joins the complex.
In an experimental situation, a student researcher inserts an mRNA molecule into a eukaryotic cell after she has removed its 5' cap and poly-A tail. Which of the following would you expect her to find?
The molecule is digested by enzymes because it is not protected at the 5' end.
What is meant by translocation?
The ribosome slides one codon down the mRNA.
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
During RNA processing a(n) _____ is added to the 3' end of the RNA.
a long string of adenine nucleotides
What enzyme catalyzes the attachment of an amino acid to tRNA?
aminoacyl-tRNA synthetase
David Pribnow studied the base sequences of promoters in bacteria and bacterial viruses. He found two conserved regions in these promoters (the -10 box and the -35 box). These two regions of the promoter _____.
bind the sigma subunit that is associated with RNA polymerase
Which of the following processes is central to the initiation of transcription in bacteria?
binding of sigma to the promoter region
Accuracy in the translation of mRNA into the primary structure of a polypeptide depends on specificity in the _____.
binding of the anticodon to the codon and the attachment of amino acids to tRNAs
In comparing DNA replication with RNA transcription in the same eukaryotic cell, only DNA replication _____.
incorporates the entire template molecule in the product
Translation directly involves _____.
mRNA, tRNA, ribosomes, and GTP
In E. coli, if RNA polymerase is missing ________, then transcription initiation would not occur at the appropriate initiation sites.
sigma
In eukaryotes, the size of the primary transcript is generally ________ the gene in the template DNA strand.
the same length as
Some viruses can be crystallized and their structures analyzed. One such virus is yellow mottle virus, which infects beans. This virus has a single-stranded RNA genome containing about 6300 nucleotides. Its capsid is 25-30 nm in diameter and contains 180 identical capsomeres.If the yellow mottle virus begins its infection of a cell by using its genome as mRNA, which of the following would you expect to be able to measure?
translation rate
