BIMM 100 questions well answered
rated A+
Poly(A) polymerase adds G's instead of As - correct answer ✔✔ Poly(A) binding proteins would
not be able to bind -> decreased gene expression (low protein levels)
anticodon of a tRNA^Tyr is changed from 5'-GUA-3' to 5'-CUA-3' - correct answer ✔✔ 5'-UAG-3'
= stop codon
continue to translate beyond what was intended
- protein might not be functional: changed polypeptides ability to fold and bind
The aminoacyl-tRNA synthetase specific for Phe is also able to bind Tyr - correct answer ✔✔
incorporation of Tyr in Phe positions, affect actual sequence
Loss of the methyltransferase that adds a methyl group to the N-7 position on the 5'cap
structure - correct answer ✔✔ some degradation of mRNA prevent export, decrease expression
mutation of the first 10 nucleotides of U1 snRNA - correct answer ✔✔ U1 associates at the 5'
splice site, U1 might not be able to base pair -> less splicing of mRNA
name the 4 sequence elements required for pre-mRNA splicing and describe the effect a
mutation of each element would have on splicing - correct answer ✔✔ *5' splice site*: U1 can't
bind, no spliceosome complex
*branch point*: U2 can't bind, no spliceosome complex
, *polypyrimidine tract*: U2 does associate, but the spliceosome complex is not able to form ->
disrupts splicing
*3' splice site*: U2 associates, cannot do second transesterification to ligate exon 1 and exon 2
To study the expression of this gene in different cell types, you run a Northern blot using RNA
isolated from kidney, liver, and intestine cells. You design probes to analyze 3 different regions of
this gene in each cell type. Briefly describe how you would perform this northern blot, including
how you would design your probe to detect exon 1, exon 2, and the region between the STOP
and position 500. - correct answer ✔✔ 1) isolate RNA
2) denature (heat)
3) run on gel
4) transfer and fix to better membrane
5) add probe (complementary and detectable)
6) run northern blot
7) re-probe
How is it possible to have different patterns of splicing of the same mRNA in different tissue
types? - correct answer ✔✔ different cells have different expression levels of splicing factors
Deletion of the amino acid in CPEB that gets phosphorylated in response to progesterone in
early embryo development - correct answer ✔✔ CPEB would not be able to release maskin ->
decreased expression
mutation of the IRE-BP so that it can no longer bind to iron - correct answer ✔✔ always bound
to ferritin -> cant sense iron levels -> inhibit initiating complex -> high transferrin
treatment of tumor cells with a drug that inhibits TOR kinase activity - correct answer ✔✔ TOR
kinase upregulates transcription -> inhibition will result in reduced transcription
rated A+
Poly(A) polymerase adds G's instead of As - correct answer ✔✔ Poly(A) binding proteins would
not be able to bind -> decreased gene expression (low protein levels)
anticodon of a tRNA^Tyr is changed from 5'-GUA-3' to 5'-CUA-3' - correct answer ✔✔ 5'-UAG-3'
= stop codon
continue to translate beyond what was intended
- protein might not be functional: changed polypeptides ability to fold and bind
The aminoacyl-tRNA synthetase specific for Phe is also able to bind Tyr - correct answer ✔✔
incorporation of Tyr in Phe positions, affect actual sequence
Loss of the methyltransferase that adds a methyl group to the N-7 position on the 5'cap
structure - correct answer ✔✔ some degradation of mRNA prevent export, decrease expression
mutation of the first 10 nucleotides of U1 snRNA - correct answer ✔✔ U1 associates at the 5'
splice site, U1 might not be able to base pair -> less splicing of mRNA
name the 4 sequence elements required for pre-mRNA splicing and describe the effect a
mutation of each element would have on splicing - correct answer ✔✔ *5' splice site*: U1 can't
bind, no spliceosome complex
*branch point*: U2 can't bind, no spliceosome complex
, *polypyrimidine tract*: U2 does associate, but the spliceosome complex is not able to form ->
disrupts splicing
*3' splice site*: U2 associates, cannot do second transesterification to ligate exon 1 and exon 2
To study the expression of this gene in different cell types, you run a Northern blot using RNA
isolated from kidney, liver, and intestine cells. You design probes to analyze 3 different regions of
this gene in each cell type. Briefly describe how you would perform this northern blot, including
how you would design your probe to detect exon 1, exon 2, and the region between the STOP
and position 500. - correct answer ✔✔ 1) isolate RNA
2) denature (heat)
3) run on gel
4) transfer and fix to better membrane
5) add probe (complementary and detectable)
6) run northern blot
7) re-probe
How is it possible to have different patterns of splicing of the same mRNA in different tissue
types? - correct answer ✔✔ different cells have different expression levels of splicing factors
Deletion of the amino acid in CPEB that gets phosphorylated in response to progesterone in
early embryo development - correct answer ✔✔ CPEB would not be able to release maskin ->
decreased expression
mutation of the IRE-BP so that it can no longer bind to iron - correct answer ✔✔ always bound
to ferritin -> cant sense iron levels -> inhibit initiating complex -> high transferrin
treatment of tumor cells with a drug that inhibits TOR kinase activity - correct answer ✔✔ TOR
kinase upregulates transcription -> inhibition will result in reduced transcription
