CH. 12
When an aminoacyl-tRNA synthetase charges a tRNA, which molecule is released?
AMP and pyrophosphate
What molecule indirectly provides the energy for translation?
ATP
If a cell's splicesomes were mutated so they no longer functioned normally, what consequences would result?
Introns would remain in the mature mRNA.
Which of the following statements about RNA polymerase in bacteria is INCORRECT?
It catalyzes the addition of nucleotides to the 5′end of a growing RNA strand.
Which of the following statements accurately describes transcription by RNA polymerase?
It is possible for one RNA polymerase to transcribe one strand of DNA in the 5' to 3' direction and another RNA polymerase to transcribe the complimentary strand of DNA in the 5' to 3' direction, producing two different transcripts
When does the small ribosomal subunit bind to the translational complex in eukaryotic cells?
It is the first component to bind to the mRNA
The following mRNA transcript would result in which polypeptide sequence? 5′-ACU UUC ACU AUG UUU UUA UCC UCC ACU CCU UGA-3′ Use the following codons and the amino acids they encode. AUG = Start or Met; UUU, UUC = Phe; UUA, UUG = Leu; UCU, UCC = Ser; CCU, CCC = Pro; ACU, ACC = Thr; UGA = Stop.
Met-Phe-Leu-Ser-Ser-Thr-Pro C
Which of the following statements about the 5′cap and mRNA processing is TRUE?
The addition of a 5′ cap to mRNA occurs while the pre-mRNA is being made.
What basic features of transcription is NOT shared by both prokaryotes and eukaryotes?
The complexity of protein components involved in transcription is similar for both prokaryotes and eukaryotes.
An mRNA sequence is 5′-AUG GGC ACU CAU ACU UAA-3′, where AUG is the start codon and UAA is the stop codon. How many distinct aminoacyl-tRNA synthetases are required to translate the mRNA sequence?
4
If a DNA template strand has a sequence of 3′ TACAATGTAGCC 5′, the RNA produced from it will be which sequence?
5′AUGUUACAUCGG3'
The amino acids of a growing polypeptide chain are held together by what kind of bond during the elongation stage of translation?
peptide
The transcription process in a eukaryotic gene directly produces
pre-mRNA
Transcription begins near a site in the DNA called the ______.
promoter
What is NOT a component of the translation machinery?
protein polymerase
What molecule(s) exhibits self-splicing?
rRNA and tRNA
What factors are utilized by the cell in order to recognize the stop codon and disassemble the translation machinery?
release factors
Which of the following serves as the "translator" or intermediary between an mRNA codon and an amino acid?
tRNA
The process that produces mRNA from DNA is called
transcription. C
What products of nonstructural genes are never translated?
transfer RNA and ribosomal RNA
A defective ribosome would have the MOST detrimental effect on
translation
How many distinct aminoacyl-tRNA synthetases does each cell make?
~20
Which of the following statements about RNA processing in eukaryotes is INCORRECT?
The excision of introns from pre-mRNA is the only modification required to produce a mature mRNA.
What is the function of the poly A tail?
The poly A tail increases mRNA stability in eukaryotes.
Which of the following statements about the mRNA start codon is INCORRECT?
The start codon is usually GGA.
The term N-terminus refers to the presence of a(n) ________ at one of the ends of a polypeptide.
amino group
What enzyme catalyzes the attachment of amino acids to tRNA molecules?
aminoacyl-tRNA synthetase
The most common eukaryotic ribosome carries out its function in the
cytosol.
Because more than one codon can specify the same amino acid, the genetic code is said to be
degenerate.
The processes of transcription and translation are collectively known as
gene expression.
Intervening sequences that are transcribed, but not translated into protein are called
introns.
________ is to transcription as ________ are to translation.
RNA polymerase; ribosomes
Which of the following statements about tRNA is FALSE?
functional tRNAs have been spliced by splicesomes.
An organized unit of DNA sequences that enables a segment of DNA to be transcribed into RNA and ultimately results in the formation of a functional product is called a _______.
gene
Which region of a structural gene contains the information that specifies an amino acid sequence?
transcribed region
What protein influences the ability of RNA polymerase to transcribe genes?
transcription factors
Identify the anticodon sequences for an mRNA sequence that is 5′-AUG GGC ACU CAU-3′.
3′UAC 5' - 3' CCG 5' - 3' UGA 5' - 3' GUA5′
Which sequence of events CORRECTLY describes the initiation and elongation steps of translation in prokaryotic cells? (1) initiator tRNA binds start codon on mRNA (2) small ribosomal subunit binds to mRNA (3) large ribosomal subunit binds (4) tRNA entry and peptidyl transfer reaction (5) translocation of ribosome and release of tRNA
2, 1, 3, 4, 5
How many nucleotides are contained in a single codon?
3
Which of the following statements describe a reason ribosomal genes are useful for comparing evolutionary relationships among organisms?
All organisms possess these genes and they can be compared with each other.
What process enables a single gene to encode two or more polypeptides that are different in their amino acid sequence?
Alternative splicing
If Nirenberg and Leder had the technology, what would be a better substitute to using radiolabeled amino acids?
Amino acids labeled with a fluorescent dye
Which amino acid would Nirenberg and Leder have found when they used the triplet UAG?
None of these
What protein is involved in synthesizing messenger RNA in eukaryotes?
RNA polymerase II
A strain that can grow in minimal medium containing ornithine, citrulline, or arginine, but not in minimal medium alone would have a mutation in the gene that encodes for
enzyme 1.
A strain that can grow in a minimal medium containing arginine, but NOT in minimal media containing citrulline nor in minimal media containing ornithine would have a mutation in the gene that encodes for _____.
enzyme 3.
