mastering ch 17
The flow of information in a cell proceeds in what sequence?
from DNA to RNA to protein
A codon consists of _____ bases and specifies which _____ will be inserted into the polypeptide chain.
three... amino acid
A particular triplet of bases in the template strand of DNA is 5' AGT 3'. The corresponding codon for the mRNA transcribed is
3' UCA 5'
The genetic code is essentially the same for all organisms. From this, one can logically assume which of the following?
A gene from an organism can theoretically be expressed by any other organism
What is the function of RNA polymerase?
It unwinds the double helix and adds nucleotides to a growing strand on RNA
Which of the following statements best describes the termination of transcription in prokaryotes?
RNA polymerase transcribes through the terminator sequence, causing the polymerase to seperate from DNA and release the transcript
Transcription in eukaryotes requires which of the following in addition to RNA polymerase?
Several transcription factors (TFs)
After an RNA molecule is transcribed from a eukaryotic gene, what are removed and what are spliced together to produce an mRNA molecule with a continuous coding sequence?
What is a ribozyme?
a bioogical catalyst made of RNA
In order for a eukaryotic gene to be engineered into a bacterial colony to be expressed, what must be included in addition to the coding exons of the gene?
a bacterial promoter sequence
Which one of the following is true of tRNAs?
Each tRNA binds a particular amino acid
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 attatchment of amino acids to tRNAs
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
Which of the following is a function of a signal peptide?
to translocate polypeptides across the ER membrane
Which of the following types of mutation, resulting in an error in the mRNA just after the AUG start of translation, is likely to have the most serious effect on the polypeptide product?
a deletion of two nucleotides
A frameshift mutation could result from
either an insertion or deletion of a base
The most commonly occurring mutation in people with cystic fibrosis is a deletion of a single codon. This results in
a plypeptide missing an amino acid
Which of the following statements is true about protein synthesis in prokaryotes?
Translation can begin while transcription is still in progress
In comparing DNA replication with RNA transcription in the same cell, which of the following is true only of replication?
The entire template molecule is represented in the product