1) The Flow of genetic information from
DNA to RNA
A fly carries a loss of function mutation in an enzyme, which is responsible for adding the
7-methylguanosine residue to the hnRNA. Suggest at least three potential ramifications to
the presence of this mutation - ANS-- subsequent processing in nucleus affected
- 5' end of molecule not protected from nuclease attack
- won't transport mature mRNA across nuclear membrane into cytoplasm and initiation of
translation of mRNA into protein won't happen
\A hypothetical bacterial strain has a mutated version of the sigma subunit. The mutated
subunit can bind to the RNA polymerase core enzyme, but it cannot bind to the DNA. Would
such a strain be able to transcribe RNA? Explain. - ANS-No, this strain would not be able to
transcribe DNA, because the sigma subunit wouldn't be able to bind and recognize the
promoter region of the DNA
\A mutation in the -10 (Pribnow) consensus sequence would have what affect? - ANS-The
rate of transcription would be DRASTICALLY reduced, if not stopped.
\Apply what you are learning: "piRNAs are small RNA molecules (26-31 nucleotides) that
form RNA-protein complexes through interactions with piwi proteins. These complexes are
important in regulation of gene transcription." Would you classify piRNA as a functional
RNA? Why? - ANS-Yes piRNA is a functional RNA because even though it is not translated
into protein, it plays an important role in the gene regulation of other proteins/genes.
\At which end of the hnRNA is the cap being added to? - ANS-at the 5' end of the hnRNA, a
7-methylguanosine (7-mG) cap is added
\Briefly list other functional RNAs that do not make proteins. - ANS-telomerase RNA -
involved in DNA replication at the ends of chromosomes
small nuclear RNA (snRNA) - participates in processing mRNAs
antisense RNA, microRNA (miRNA), short interfering RNA (siRNA) - involved in gene
regulation
\Collectively a pool of pre-RNAs in the nucleus is called: ____________________. -
ANS-heterogeneous nuclear RNA (hnRNA)
\Contrast eukaryotic information flow from prokaryotic on these characteristics:
a) In prokaryotes, translation can occur while transcription is still completing. True in
eukayotes? Explain.
b) In prokaryotes, DNA is not packaged compactly around histones. How is this a challenge
in eukaryotes?
c) In prokaryotes we have the promoter and the RN holoenzyme. In eukaryotes things will
get more complicated because of:
DNA to RNA
A fly carries a loss of function mutation in an enzyme, which is responsible for adding the
7-methylguanosine residue to the hnRNA. Suggest at least three potential ramifications to
the presence of this mutation - ANS-- subsequent processing in nucleus affected
- 5' end of molecule not protected from nuclease attack
- won't transport mature mRNA across nuclear membrane into cytoplasm and initiation of
translation of mRNA into protein won't happen
\A hypothetical bacterial strain has a mutated version of the sigma subunit. The mutated
subunit can bind to the RNA polymerase core enzyme, but it cannot bind to the DNA. Would
such a strain be able to transcribe RNA? Explain. - ANS-No, this strain would not be able to
transcribe DNA, because the sigma subunit wouldn't be able to bind and recognize the
promoter region of the DNA
\A mutation in the -10 (Pribnow) consensus sequence would have what affect? - ANS-The
rate of transcription would be DRASTICALLY reduced, if not stopped.
\Apply what you are learning: "piRNAs are small RNA molecules (26-31 nucleotides) that
form RNA-protein complexes through interactions with piwi proteins. These complexes are
important in regulation of gene transcription." Would you classify piRNA as a functional
RNA? Why? - ANS-Yes piRNA is a functional RNA because even though it is not translated
into protein, it plays an important role in the gene regulation of other proteins/genes.
\At which end of the hnRNA is the cap being added to? - ANS-at the 5' end of the hnRNA, a
7-methylguanosine (7-mG) cap is added
\Briefly list other functional RNAs that do not make proteins. - ANS-telomerase RNA -
involved in DNA replication at the ends of chromosomes
small nuclear RNA (snRNA) - participates in processing mRNAs
antisense RNA, microRNA (miRNA), short interfering RNA (siRNA) - involved in gene
regulation
\Collectively a pool of pre-RNAs in the nucleus is called: ____________________. -
ANS-heterogeneous nuclear RNA (hnRNA)
\Contrast eukaryotic information flow from prokaryotic on these characteristics:
a) In prokaryotes, translation can occur while transcription is still completing. True in
eukayotes? Explain.
b) In prokaryotes, DNA is not packaged compactly around histones. How is this a challenge
in eukaryotes?
c) In prokaryotes we have the promoter and the RN holoenzyme. In eukaryotes things will
get more complicated because of:
