BCMB 412 Final Exam Questions With
Accurate Answers
Why is regulation important at level of translation? - ANSWER Rapid change in
level of proteins
What step of translation regulation has the greatest benefits? - ANSWER
Regulation at Initiation increases efficiency and prevents formation of
incomplete proteins
What is an example of something controlling initiation of translation with mRNA?
- ANSWER siRNA degrades mRNA or microRNA represses mRNA to be
translated
What is the primary target during regulation of bacterial translation initiation? -
ANSWER 30S subunit binding using RNA-binding proteins that bind close to
mRNA RBS
Why don't RNA-binding proteins bind directly at the RBS? - ANSWER Would
prevent all ribosomal biding not just targeted to a family of mRNAs
What secondary structure in mRNA can prevent ribosomal binding? - ANSWER
base pairing within mRNA
How do ribosomal proteins repress their own translation? - ANSWER mRNA
increase but translation is not increased. There is always a autorepressor which
controls translation
How do autoregulators work in operons for ribosomal proteins? - ANSWER
When there is no free rRNA the ribosomal binding proteins bind to their own
mRNA preventing translation
Two ways of regulating Initiation of translation in eukaryotes: Global. - ANSWER
Global: 1. phosphorylation of elF2 reduces levels of elF2-GTP which results in
reduced levels of translation initiation
2. eIF4E interacts with 5' cap to initiate translation. 4E-BP can interact with
elF4E and prevent translation of growth factors. mTOR kinase can
phosphorylate 4E-BP which inactivates its ability to bind to eIF4E
, Cancer biology with over expression of elF4E - ANSWER over expression leads
to cancer
mTOR inhibitors (rapamycin) used as cancer drugs
Controlling translation of specific mRNA (oskar) in eukaryotes - ANSWER oskar
mRNA has elements which bind to Bruno a protein which binds which binds a
4E-BP domain (cup).
When cup binds to bruno, it interacts with eIF4E, which inhibits translation of
mRNA.
Controlling translation of specific mRNA (Ferrittin) - ANSWER Ferrittin stores
iron and releases it when needed
mRNA for ferrittin has element called Iron regulatory element which binds a Iron
regulatory protein (IRP). When there is little iron in the cell it can bind the IRE of
ferrittin mRNA and prevent translation.
When there is iron, iron binds to the IRP and prevents its binding which allows
for translation
What happens to broken mRNA in prokaryotes? - ANSWER tmRNA can help a
stalled ribosome and creates a finished protein that is tagged for degradation
Why do some protein stay attached to mRNA? - ANSWER most are exon junction
complexes,
What is the nonsense mediated mRNA decay pathway? - ANSWER Ribosome
encounters a premature stop codon, activates Upf proteins in exon junction
complex, which triggers activation of decapping and deadenylating enzyme
which degrades the 5' and 3' ends, which frees the mRNA to be degraded by
exonucleases and exosomes
Non-stop vs non-go mRNA decay - ANSWER Non-stop: no stop codon, Dom34
and Hbs1 bind to ribosome and recruits Rli1 which helps ribosome disassembly,
tail of mRNA targets it for degradation
Non-go: ribosome is prevented from moving, same mechanim as non-stop but
the protein is not degraded it is just unstable
How does DNA polymerase discriminate against incorrectly paired bases? -
ANSWER DNA polymerase has structural characteristics which prevent
incorrectly paired bases 1 in 10000 chance of incorrect alignment
How does DNA polymerase discriminate against rNTPs? - ANSWER
discriminator of amino acids in pocket of DNA pol, if correct structure is not
formed then discriminator of amino acids does not allow incorporation (steric
exclusion). 1 in 1000 error
Accurate Answers
Why is regulation important at level of translation? - ANSWER Rapid change in
level of proteins
What step of translation regulation has the greatest benefits? - ANSWER
Regulation at Initiation increases efficiency and prevents formation of
incomplete proteins
What is an example of something controlling initiation of translation with mRNA?
- ANSWER siRNA degrades mRNA or microRNA represses mRNA to be
translated
What is the primary target during regulation of bacterial translation initiation? -
ANSWER 30S subunit binding using RNA-binding proteins that bind close to
mRNA RBS
Why don't RNA-binding proteins bind directly at the RBS? - ANSWER Would
prevent all ribosomal biding not just targeted to a family of mRNAs
What secondary structure in mRNA can prevent ribosomal binding? - ANSWER
base pairing within mRNA
How do ribosomal proteins repress their own translation? - ANSWER mRNA
increase but translation is not increased. There is always a autorepressor which
controls translation
How do autoregulators work in operons for ribosomal proteins? - ANSWER
When there is no free rRNA the ribosomal binding proteins bind to their own
mRNA preventing translation
Two ways of regulating Initiation of translation in eukaryotes: Global. - ANSWER
Global: 1. phosphorylation of elF2 reduces levels of elF2-GTP which results in
reduced levels of translation initiation
2. eIF4E interacts with 5' cap to initiate translation. 4E-BP can interact with
elF4E and prevent translation of growth factors. mTOR kinase can
phosphorylate 4E-BP which inactivates its ability to bind to eIF4E
, Cancer biology with over expression of elF4E - ANSWER over expression leads
to cancer
mTOR inhibitors (rapamycin) used as cancer drugs
Controlling translation of specific mRNA (oskar) in eukaryotes - ANSWER oskar
mRNA has elements which bind to Bruno a protein which binds which binds a
4E-BP domain (cup).
When cup binds to bruno, it interacts with eIF4E, which inhibits translation of
mRNA.
Controlling translation of specific mRNA (Ferrittin) - ANSWER Ferrittin stores
iron and releases it when needed
mRNA for ferrittin has element called Iron regulatory element which binds a Iron
regulatory protein (IRP). When there is little iron in the cell it can bind the IRE of
ferrittin mRNA and prevent translation.
When there is iron, iron binds to the IRP and prevents its binding which allows
for translation
What happens to broken mRNA in prokaryotes? - ANSWER tmRNA can help a
stalled ribosome and creates a finished protein that is tagged for degradation
Why do some protein stay attached to mRNA? - ANSWER most are exon junction
complexes,
What is the nonsense mediated mRNA decay pathway? - ANSWER Ribosome
encounters a premature stop codon, activates Upf proteins in exon junction
complex, which triggers activation of decapping and deadenylating enzyme
which degrades the 5' and 3' ends, which frees the mRNA to be degraded by
exonucleases and exosomes
Non-stop vs non-go mRNA decay - ANSWER Non-stop: no stop codon, Dom34
and Hbs1 bind to ribosome and recruits Rli1 which helps ribosome disassembly,
tail of mRNA targets it for degradation
Non-go: ribosome is prevented from moving, same mechanim as non-stop but
the protein is not degraded it is just unstable
How does DNA polymerase discriminate against incorrectly paired bases? -
ANSWER DNA polymerase has structural characteristics which prevent
incorrectly paired bases 1 in 10000 chance of incorrect alignment
How does DNA polymerase discriminate against rNTPs? - ANSWER
discriminator of amino acids in pocket of DNA pol, if correct structure is not
formed then discriminator of amino acids does not allow incorporation (steric
exclusion). 1 in 1000 error
