MB Ch 17 & 18 (exam 3)
Which of the following is true of the cytoplasm of an unfertilized egg?
It is an unevenly distributed mixture of mRNA, proteins, organelles, and other substances.
Which of the following statements about the function of RNA polymerase is correct?
It unwinds the double helix and adds nucleotides to a growing strand of RNA.
Given a DNA molecule with the sequence of bases 5'-ATTGCA-3', what would be the sequence of the complementary strand? (It will be helpful to draw the DNA molecule when answering the question.)
3'-TAACGT-5'
Identify a 5′→3′ sequence of nucleotides in the DNA template strand for an mRNA coding for the polypeptide sequence Phe-Pro-Lys.
5′-CTTCGGGAA-3′
Which of these indicates an enhancer region?
A
Transcription begins at a promoter. What is a promoter?
A site in DNA that recruits the RNA Polymerase
_____ bind(s) to DNA enhancer regions.
Activators
Which of these directly bind(s) to the promoter?
C and D
Which of the following shows the flow of genetic information?
DNA to RNA to protein
Which of the following is true of RNA processing?
Exons are cut out before mRNA leaves the nucleus.
The operon model of the regulation of gene expression in bacteria was proposed by _____.
Jacob and Monod
DNA does not store the information to synthesize which of the following?
Organelles
What is the process called that converts the genetic information stored in DNA to an RNA copy?
Transcription
What does a mutagen cause?
a change in the sequence of DNA
Which of the following mutations would be most likely to have a harmful effect on an organism?
a single nucleotide insertion downstream of, and close to, the start of the coding sequence
What enzyme catalyzes the attachment of an amino acid to tRNA?
aminoacyl-tRNA synthetase
miRNAs can control gene expression by what action?
binding to mRNAs and degrading them or blocking their translation
The anticodon of a particular tRNA molecule is
complementary to the corresponding mRNA codon.
Muscle cells differ from nerve cells mainly because they
express different genes.
The flow of information in a cell proceeds in what sequence?
from DNA to RNA to protein Submit
The initiator tRNA attaches at the ribosome's _____ site.
P
Which of the following are required for the process of transcription?
RNA polymerase and the promoter
Which component is directly involved in translation?
ribosome
In eukaryotic cells, transcription cannot begin until
several transcription factors have bound to the promoter.
It is possible for a cell to make proteins that last for months, hemoglobin in red blood cells is a good example. However, many proteins are not this long-lasting; they may be degraded in days, hours, or even minutes. What is the advantage of short-lived proteins?
short-lived proteins enable the cells to control their activities precisely and efficiently
What does the DNA methylation mechanism used by eukaryotes do?
inactivate genes
What is the name of the process shown in the diagram?
initiation (of translation)
What process is shown in the diagram below?
initiation of translation
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?
introns, exons
Where does RNA polymerase begin transcribing a gene into mRNA?
it starts after a certain nucleotide sequence called a promoter
Within a cell, the amount of protein made using a given mRNA molecule depends partly on
the rate at which the mRNA is degraded.
Which of the following is an example of post-transcriptional control of gene expression?
the removal of introns and alternative splicing of exons
A codon consists of __________ bases and specifies which __________ will be inserted into the polypeptide chain.
three, amino acid
The functioning of enhancers is an example of
transcriptional control of gene expression.
Why is the lac operon said to be an inducible operon?
when allolactose is present, it induces the inactivation of the lac repressor Submit
Which of the following clues would tell you if a cell is prokaryotic or eukaryotic?
whether or not the cell is compartmentalized by internal membranes
Which of the following statements best describes the promoter of a protein-coding gene?
The promoter is a nontranscribed region of a gene.
Which statement(s) about inducible operons is/are correct?
- In an inducible operon, an inducer inactivates the repressor. - In an inducible operon, the repressor is synthesized in an active form.
Which statement(s) about repressible operons is/are correct?
- Repressible operons usually contain genes that code for anabolic enzymes. - A repressible operon is on unless a corepressor is present.
How is translation initiated?
- the tRNA bearing methionine binds to the start codon - the start codon signals the start of translation - the small ribosomal subunit binds to the mRNA - the large ribosomal subunit binds to the small one
Which of these is a tRNA?
B
What determines which base is to be added to an RNA strand during transcription?
Base pairing between the DNA template strand and the RNA nucleotides
How is euchromatin different from heterochromatin?
Both consist of the 10-nm fiber, which during interphase is more densely arranged in heterochromatin, and more loosely arranged in euchromatin.
The tRNA anticodon, GAC, is complementary to the mRNA codon with the sequence _____.
CUG
Which of the following terms best describes the relationship between the newly synthesized RNA molecule and the DNA template strand?
Complementary
Which of these is a regulatory gene?
D
Which of the following is true of a codon?
It can be either in DNA or in RNA
What happens to RNA polymerase II after it has completed transcription of a gene?
It is free to bind to another promoter and begin transcription.
Would the coupling of the processes shown below be found in a eukaryotic cell? Explain why or why not.
No, in bacterial cells, the translation of mRNAmRNA can begin as soon as the 5′5′ end of it peels away from the DNADNA template. In eukaryotic cells, however, transcription and translation are separated in space and time as a result of the eukaryotic cell's nuclear membrane.
Which one of the following statements is true of tRNAs? -There are four types of tRNA. -Each tRNA binds a particular codon. -tRNAs are double-stranded. -tRNAs carry special sequences known as codons.
None of the listed answers are correct.
Your body contains tens of thousands of different proteins, each with a specific structure and function. The unique three-dimensional shape of each of these diverse proteins is based on several superimposed levels of structure. Which of the following is an accurate statement about proteins?
The primary structure of a protein is the order of amino acids in a polypeptide, as coded for by the DNA of a gene.
What is a ribozyme?
a biological catalyst made of RNA
In the presence of a regulatory protein the lac operon is _____.
not transcribed
Which of these is NOT a component of the lac operon?
regulatory gene only
Regulatory proteins bind to _____.
the operator
