Chapter 13: The Genetic Code and Transcription
Both the codons UUU and UUC specify the amino acid phenylalanine. What is the term for this phenomenon?
Which of the following experiments or discoveries did not help to identify the "triplet nature" of the DNA code?
Universality of the genetic code
How many different codons code for an amino acid?
all except 3 stop codons
The wobble hypothesis involves
Both mRNA and rRNA
Both mRNA and tRNA
DNA and RNA
In prokaryotes, the initial amino acid in a polypeptide chain is the modified form of methionine, N-formylmethionine, or f-met. Which term describes the codon for f-met?
RNA synthesis from a DNA template is called
Which subunit of RNA polymerase establishes template binding to a promoter in prokaryotes?
Where does transcription in prokaryotes end?
A gene's stop codon
A gene's stop anticodon
A region beyond the end of one or more tandem genes
A region called the TATA box
A region at the head of every gene
prokaryotes may contain polycistronic mRNA
Which RNA polymerase transcribes protein-coding genes into mRNA in eukaryotes?
RNA polymerase I
RNA polymerase II
RNA polymerase III
RNA polymerase IV
RNA polymerase V
Which of the following statements about the effects of enhancers and transcription factors (TFs) on gene expression is true?
Both are cis-acting.
Both are trans-acting.
Enhancers are trans-acting, TFs are cis-acting.
Enhancers are cis-acting, TFs are trans-acting.
What are the two main types of posttranscriptional modifications that take place in the mRNA of eukaryotes?
The addition of a poly-T sequence at the 5' end of the gene and the addition of a poly-U tail at the 3' end.
The addition of a 7-mG cap at the 5' end of the transcript and the addition of a poly-A sequence at the 3' end of the message.
The addition of a poly-A sequence at the 5' end and the addition of a 7-mG cap at the 3' end of the RNA transcript.
The excision of the introns and the addition of a 7-mG cap to the 3' end.
Which of the following does not involve introns?
Which mRNA sequence is transcribed from the DNA template strand TACGGGATT?
Which amino acids would be incorporated in a repeating copolymer assay involving A and U?
Isoleucine (ile) would be incorporated into the protein.
Phenylalanine (phe) would be incorporated into the protein.
Isoleucine and tyrosine would both be incorporated into the protein.
Leucine (leu) would be incorporated into the protein.
No amino acids are incorporated, since only stop codons are present.
The codons UGU and UGC both code for cysteine. The anticodon for UGU is ACA. What is the anticodon for UGC?
3'-AUC-5' or CUA
3'-GAA-5' or AAG
3'-AGG-5' or GGA
3'-ACG-5' or GCA
What is the consequence of a mutational event that inserts the codon UGA into a gene?
A partial polypeptide chain would be synthesized because the mutation would cause premature release of the polypeptide from the ribosome.
It would start the translation of another gene.
The rate of transcription would decrease.
The rate of transcription would increase.
Which term describes sequences that are similar (homologous) in different genes of the same organism or in one or more genes of related organisms?
What is the function of transcription factors?
To serve as sequences where RNA polymerase binds
To direct mRNA from the nucleus to the cytoplasm
To recognize sequences within the enhancer and promoter and activate transcription
To initiate binding at the Shine-Dalgarno sequence
To inactivate repressors
this occurs in eukaryotic RNA polymerases
Which of the following events does not happen during hnRNA processing?
A 7-methylguanosine cap is added to the 5' end of the RNA.
Introns are spliced out.
Exons are spliced together.
Ribosomes bind and begin translation.
A DNA sequence produces a mutant protein in which several amino acids in the middle of the protein differ from the normal protein. What kind of mutation could have occurred?
An addition or deletion mutation
A nonsense mutation
An addition and a deletion mutation
A silent mutation
Which of the following statements about eukaryotic transcription is false?
A polycistronic mRNA may be transcribed if the gene products are used in the same pathway or needed at the same time.
The transcripts produced contain both exons and introns.
Eukaryotic promoter regions contain a TATA box and a CAAT box.
Transcription initiation occurs when RNA polymerase blinds to a complex of transcription factors at the TATA box.