Bio Exam 2- RNAi 2024/2025 with 100% correct answers
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Course
Bio E2- RNAi
Institution
Bio E2- RNAi
RNA can fold into an
__________: Double helical RNA with Watson-Crick base-pairing and GU wobble (weak) pairs
__________: Observed for alternating rCrG sequences under extreme salt concentrations (like 6M NaClO4)
The __________ (typical DNA form) has never been observed in RNA correct answersA-...
__________: Double helical RNA with Watson-Crick base-pairing and GU wobble (weak) pairs
__________: Observed for alternating rCrG sequences under extreme salt concentrations (like 6M
NaClO4)
The __________ (typical DNA form) has never been observed in RNA correct answersA-form, Z-form, B-
form
DNA is mostly found in helical forms. In general, RNAs (like proteins) adopt more diverse and complex
____________________. This structural diversity correlates with the wide variety of RNA __________.
correct answersthree-dimensional structure, functions
The primary structure of RNA is its __________________. It's secondary structure consists of
_____________, _____________, and is ____________________ Its tertiary structure is its
__________________ correct answersnucleotide sequence, loops, helices, single and double stranded,
3-D folding
A cell's noncoding RNAs consist of (besides siRNA and miRNA): correct answersrRNAs, tRNAs, snRNAs
(small nuclear RNAs, function in nuclear processes like splicing pre-mRNA), snoRNAs (small nucleolar
RNAs, chemically modify rRNA), piRNAs (piwi-interacting RNAs, bind to piwi proteins and protect
germline cells from transposable elements), and lncRNAs (long noncoding RNAs, serve as scaffolds and
regulate cell processes such as X-chromosome inactivation)
siRNAs (noncoding RNA) correct answerssmall interfering RNAs, turn off gene expression by directing the
degradation of selective mRNAs and the establishment of compact chromatin structures
miRNAs correct answersmicroRNAs, regulate gene expression by blocking translation of specific mRNAs
and causing their degradation
Early hypothesis for how anti-sense RNA interferes with gene expressiom correct answersThe sense
strand is the strand of DNA or RNA that has the same sequence as the mRNA. The anti-sense strand is
, that DNA or RNA strand's complementary pair, which is used as a template for mRNA synthesis (hence
why mRNA has same sequence as sense strand).
It has hypothesized that anti-sense RNA (RNA formed with the sense strand as a template) would base
pair with mRNA and block the ribosomes from accessing it, thus disrupting translation. This interference
should be STRAND SPECIFIC (only antisense RNA should be able to disrupt sense mRNA translation if
injected into a cell), and interference should be DOSAGE DEPENDENT (the more antisenseRNA injected,
the more mRNA interference)
Surprisingly, in a study that used anti-sense RNA to study the functioning of the par-1 gene in C. elegans,
it was found that in-vitro synthesized __________ worked equally as well as anti-sense RNA in interfering
with par-1 function and induced the ________________ of embryonic lethality- wtf?? correct
answersSense RNA, same percent
Another surprise: potent and specific genetic interference by double-stranded RNA in C. elegans correct
answersWhy: RNA interference was proposed to result from an antisense mechanism that depends on
hybridization between interfering RNA and endogenous mRNA. The study wanted to examine what form
of RNA was required for RNA interference
How: scientists injected different forms of RNA (sense, antisense, and dsRNA) into C. elegans and
observed their effects on gene expression
What: 1) dsRNA was substantially more effective at producing interference than either strand was
individually. 2) only a few molecules of dsRNA were required per affected cell. 3) The interference was
evident in both the affected animals and their progeny
So what: A simple antisense mechanism is not likely, there could be a catalytic or amplification
component in the RNAi process, and RNA interference is inheritable
The puzzle: worm study #2 found that dsRNA is _______________________ than anti-sense RNA in
interfering with mRNA! Embryos from parent injected with anti-sense RNA of mex-3 gene showed
reduced levels of mex-3 mRNA, which indicated ________________. Embryos injected with dsRNA of
mex-3 showed no mex-3 mRNA, which indicated ________________________. correct answersMore
potent, some interference, strong interference
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