Bio1330 Unit 4 Quizzes Mastering Biology – Flashcards
Unlock all answers in this set
Unlock answersquestion
A promoter is ______.
answer
a sequence in DNA that brings RNA polymerase near the site for transcription
question
What is responsible for termination of transcription in eukaryotic protein-coding genes?
answer
a polyadenylation signal or poly(A)
question
If RNA polymerase is missing in E coli _____, then transcription initiation would not occur at the appropriate initiation sites.
answer
sigma
question
How is a mutation in a bacterial cell that deletes three base pairs 10 base pairs upstream from the +1 site likely to affect transcription and why?
answer
Initiation will be inhibited because sigma cannot bind to the promoter.
question
Death cap mushrooms produce a substance called alpha-amanitin. Alpha-amanitin efficiently blocks synthesis of mRNA, but not of tRNA or rRNA in eukaryotic organisms. This is possible because alpha-amanitin efficiently interferes with _____.
answer
the action of RNA polymerase II, but not RNA polymerase I or III
question
Which statement is most accurate concerning the function(s) of the 5' cap and the 3' poly(A) tail of eukaryotic mRNAs?
answer
Both structures are important for initiating translation and extending the lifespan of the mRNA.
question
During mRNA splicing ______.
answer
snRNPs that make up the spliceosome recognize and remove introns
question
Refer to the figure above. The mRNA is smaller than the length of the DNA that codes for it because _____.
answer
post-transcriptional modification removes the introns
question
A particular triplet of bases in the coding sequence of DNA is AAA. The anticodon on the tRNA that binds the mRNA codon is _____.
answer
UUU
question
What is recognized by an aminoacyl tRNA synthetase?
answer
one amino acid and the set of tRNAs that are coupled to that amino acid
question
The wobble hypothesis explains ______.
answer
the ability of some tRNAs to read more than one codon
question
During the elongation phase of translation, individual tRNAs move through the three sites of the ribosome in the following sequence _____.
answer
A—>P—>E
question
Just prior to the formation of a new peptide bond, the tRNA attached to the polypeptide chain occupies the _______ site of the ribosome.
answer
P
question
How does termination of translation take place?
answer
A stop codon is reached.
question
Which of the following is the first event to take place in translation in eukaryotes?
answer
the small subunit of the ribosome recognizes and attaches to the 5' cap of mRNA
question
Alternative RNA splicing _____.
answer
can allow the production of proteins of different sizes and functions from a single mRNA
question
What is the most likely way that humans can produce at least 50,000 different proteins (with different amino acid sequences) from around 20,000 genes?
answer
Alternative splicing
question
Which of the following statements about the DNA in one of your brain cells is true?
answer
It is the same as the DNA in one of your heart cells.
question
In eukaryotes, the first step in the control of gene expression is ______.
answer
chromatin remodeling
question
Are histone deacetylases (HDACs) associated with negative or positive control of gene expression? Why?
answer
Negative control, because they make DNA less accessible for transcription
question
Which answer best explains how certain patterns of histone acetylation or DNA methylation could influence whether a cell became a muscle cell or a brain cell?
answer
They could affect which sets of genes are transcribed in different cell types.
question
The addition of acetyl groups to histones is associated with ______.
answer
chromatin decondensation and higher levels of gene expression
question
A mechanism of inheritance that does not depend on differences in DNA sequence is ______.
answer
epigenetic inheritance
question
Differential gene expression is the result of different cells containing different ______.
answer
regulatory proteins
question
Regulatory transcription factors _____.
answer
influence the assembly of the basal transcription complex
question
If cells of an individual contain the same set of genes, how do these cells become different from each other during development?
answer
Differences in extracellular signals received by each cell lead to differences in the types of regulatory proteins present in each cell.
question
Alternative RNA splicing allows for the number of different _________ to exceed the number of different __________.
answer
proteins; genes
question
MicroRNAs work to ______.
answer
destroy mRNA or block its translation
question
Why are loss-of-function mutations in p53 observed in over half of all human cancers?
answer
p53 normally functions as a tumor suppressor to stop the cell cycle after DNA damage occurs.
