bio chap 19 Flashcards
True or false: It is likely that over half of human proteins have their synthesis regulated by miRNAs.
true
True or false: The nucleosome is a complex of eight histone subunits wrapped by a short DNA strand approximately 10 base pairs long.
false
True or false: The miRNA-RISC-mRNA complex enhances the translation efficiency of the mRNA transcript.
false
True or false: Histone modification occurs only during early development.
false
Analysis of the primary transcript for an insulin receptor protein reveals that exon 11 has been removed from the mRNA in skeletal muscle, but not in liver. How does this affect the proteins synthesized in these two types of cells?
The insulin receptor in skeletal muscle has a higher affinity for insulin than the receptor in the liver
Which of the following is not an accurate description of events leading to the lysogenic pathway following viral infection in a bacterium?
Reduction in the concentration of cI protein is the most important contributor to lysogeny
True or false: RNA splicing joins together the coding regions of messenger RNA in their original linear order after the removal of introns.
true
Which one of the following is not a result of RNA editing?
the recruitment of RNA polymerase following the binding of general transcription factors
Which of the following statements about protein modifications is incorrect?
Proteins can be modified following the addition of a polyadenylated tail
True or false: Amino acid sequences that are rich in lysine and protrude from the histone proteins in the nucleosome are called “tails”.
true
A virus that infects bacteria is called a ___________
bacteriophage
In female humans and other mammals, dosage compensation is achieved by the inactivation of one of the two X chromosomes in each cell. Which one of the following does not occur in the X-inactivation mechanism of female mammals?
Xist RNA is attracted to and associates with a protein called the X-chromosome inactivation center (XIC), which becomes entirely coated with Xist.
True or false: The primary transcript is transported directly to the cytoplasm and prepared for translation.
false
True or false: Small interfering RNAs (siRNAs) are a type of small regulatory RNA that, like microRNAs, are incorporated into the RISC complex.
true
Which one of the following is not a characteristic shared by miRNA and mRNA?
They both fold upon themselves, forming stems and hairpin loops that are stabilized by hydrogen bonding.
Which one of the following statements about regulation of translation is incorrect?
Regulation of translation does not depend on sequences in the 3’UTR or the poly(A) tail.
Which one of the following statements about gene regulation is incorrect?
gene regulation occurs only in prokartyotes
The alternative pathways for viral infection—lytic and lysogenic—are determined by positive and negative regulatory effects of proteins produced by the virus following infection.
true
Which one of the following statements about mutations in the lactose operon is not correct?
In cells containing one mutant and one normal copy of lacO, lacZ and lacY are expressed only in the absence of lactose.
All CpG sites located near the promoter region of protein coding genes are methylated.
false
Which of the following is not an accurate description of events leading to the lysogenic pathway following viral infection in a bacterium?
Reduction in the concentration of cI protein is the most important contributor to lysogeny.
Primary RNA transcripts are always spliced in the same fashion in order to maintain continuity.
false
Which of the following statements about transcription in prokaryotes is incorrect?
In prokaryotes, the RNA polymerase complex will bind at the promoter in the presence or absence of an activator protein and transcription will proceed.
When a group of functionally related genes located next to one another along the bacterial DNA is transcribed together as a single molecule of mRNA, that mRNA is called a _________________ RNA.
polycistronic
Untranslated regions of the mRNA transcript may interact with motor proteins to enhance transport of the mRNA to a distinct region of the cell; or these regions may interact with proteins that repress the translation of the mRNA.
true
Which of the following does not occur during RNA processing?
the removal of all exons during RNA splicing
