Biology, Eighth Edition (Raven)

Chapter 16: Control of Gene Expression

Pre Test

Why is most regulation of gene expression controlled by inhibiting transcription? (p. 304)
A)By not making a transcript that won't be needed, the cell saves a lot of energy.
B)Transcription of a gene leads to many different polypeptides in a particular cell, so many proteins can be regulated simultaneously.
C)Ribosomes can be freed up to perform their work on other genes.
D)RNA polymerase is inefficient, and by not transcribing a molecule that's not needed, it's preserved for other genetic pathways.
E)Once a transcript is made, there are few, if any, other ways to prevent it from being interpreted into a polypeptide.
A DNA-binding motif is (p. 306)
A)a part of RNA polymerase that recognizes a promoter.
B)a catalytic region of an enzyme which can identify specific parts of a gene and promote chemical reactions which lead to gene expression.
C)a particularly-shaped portion of a polypeptide which fits into the major groove of DNA so that it can interact with a specific sequence of nucleotides.
D)part of the ribosome large subunit.
E)part of the ribosome small subunit.
In an operon, the region termed an "operator" has the job of (p. 307)
A)attracting RNA polymerase to increase transcription.
B)binding to an effector to demonstrate the presence of a metabolite.
C)attracting a repressor protein when transcription of the operon would not be beneficial.
D)inducing transcription of the genes which follow.
E)preventing ribosome association with an mRNA molecule.
True or false: General transcription factors are required for the majority of eukaryotic transcription events. (p. 312)
Which of the following is (are) associated with inactivation of eukaryotic genes? (p. 316)
A)Deacetylation of histones
B)Methylation of bases in the genes to be deactivated
C)Binding of proteins which are attracted to clusters of 5-methylcytosine
D)Chromatin remodeling
E)All of the above can inactivate eukaryotic genes.
Which of the following can trigger the dicer enzyme to initiate cleavage of an mRNA? (p. 318)
A)Editing of mRNA to change the bases.
B)Mutation of the gene into an oncogene.
C)Formation of snRNPs in the nucleus.
D)Production of hairpin loops from genes located in "non-coding" regions of the DNA.
E)Accumulation of miRNA in the nucleoplasm.
Cyclin levels accumulate in a cell to indicate how much time has passed since the last cell division. When they reach a threshold concentration, they stimulate a new round of cell division. What would it mean if a large number of cyclin proteins was analyzed and found to be polyubiquitinated? (p. 322)
A)That the threshold concentration of cyclin was exceeded and division was triggered, so the "count down" needs to be re-set.
B)That ribosomes will be attracted to ubiquitin, thereby becoming activated so they can create more proteasomes.
C)Ubiquitin ligase needs to be created in order to deal with the extra amount of its substrate.
D)The ubiquitin will protect the cyclin from degradation, allowing the cell to more precisely determine where it is in the cell cycle.
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