Study Question Sets for Exam 2 Study Question Set 9 -- Gene Expression
A humorous TV ad last fall for the St. Louis Zoo says "The human genome
and the chimp genome are 98% identical. What are we doing with the
other 2%?" Comment on whether this question realistically reflects
the total information content of our genome.
What is "transcription"? Is
the process aptly named?
Why is "translation" an appropriate term for the biological process
it describes?
Describe the relationships among "codon, "anticodon", mRNA, nascent protein,
and tRNA.
What types of genes are transcribed by RNA polymerase II?
In general, what are "transcription factors?"
Defend or refute the following satement. Be
thorough.
"The exon content of a mature mRNA molecule produced from a specific gene
is invariant".
Distinguish among the A site, P site, and E site in a ribosome.
Describe the steps in insertion of an amino acid group into a growing polypeptide chain.
What is the " exit tunnel" of a ribosome?
Where is it located relative to the site where the mRNA is "read"?
When does a newly synthesized cytosolic protein begin to fold? Explain.
Describe the role of hsp 70 chaperones during the synthesis of new
proteins.
Distinguish between hsp70 chaperones and ribosome-associated chaperones in terms of (a) how they encouter nascent or newly formed proteins; and (b) which, if either, can be responsible for maintaining fully formed proteins in an unfolded state under certain circumstances.
What are chaperonins? What is their role in cells?
Describe the general structure of GroEL.
Distinguish between GroEL and TriC. Why do we find genes for both
in the nucleus of, for example, a mammalian liver cell?
Why is proteasome activity high during protein synthesis?
What is ubiquitin? Describe its role in protein degradation by proteasomes.
Describe the complementary roles played by hsp 70 molecular chaperones (and/or
ribosome associated chaperones), hsp 60 chaperones, and proteosomes in protein
quality control in cells.
What is a "polysome"?
Does one find in the cell cytoplasm intact ribosomes that are not engaged
in protein translation? Explain.
Compare the rRNAs found in eukaryotic ribosomes to those present in
the ribosomes of bacteria, paying attention to evolutionary relationships.
The human genome contains approximately 35,000 genes that code for protein
sequences. This number is not significantly greater than the number of protein
coding sequences in the genome of the weed Arabidopsis or in the yeast
genome. How is it that mammalian systems are able to produce a much greater
variety of tissue-specific or development-specific protein sequences than
the simpler Arabidopsis or yeast systems without having a substantially
greater number of protein-coding genes? What is the evolutionary significance
of this phenomenon?
