Question

Which enzyme or complex shortens the length of BOTH siRNA and miRNA?
a) Dicer
b) Slicer/Argonaute
c) RISC
d) RNase III
e) both a and b

siRNA introduced into a cell is amplified by the action of _____.
a) Dicer
b) Drosha
c) a DNA-dependent DNA polymerase
d) an RNA-dependent DNA polymerase
e) an RNA-dependent RNA polymerase

What is the correct order of steps in generation of a functional miRNA?
a) RISC binding RNA, processing in the nucleus, processing in the cytosol.
b) RISC binding RNA, processing in the cytosol, processing in the nucleus.
c) Processing in the nucleus, processing in the cytosol, incorporation into RISC.
d) Processing in the cytosol, processing in the nucleus, incorporation into RISC.
e) Processing in the nucleus, incorporation into RICS binding, processing in the cytosol.

Answer 1

Question 1 Which enzyme or complex shortens the length of BOTH siRNA and miRNA?

Both siRNA and miRNA are involved in post transcriptional gene silencing

siRNA k/n as small interfering RNA is exogenous double stranded RNA having 21- 23 Nucleotide.It is cis acting and form RISC complex which bind with specific mRNA and silenced them

MiRNA also k/n as micro RNA is endogenous double stranded RNA having 23-25 Nucleotide which RNA silencing by degradation of mRNA or translation inhibition

Now lets go to option one by one

Option 1 Dicer

Yes it is correct answer as DIcer is ribonuclease is an enzyme which act on pre miRNA in cytoplasm and slice it into small pieces of double stranded RNA

It also act on exogenously incorporated double stranded RNA and slice into small siRNA which leads to RNA interference

Hence it shorten the lengthe of siRNA and miRNA

Option b Argonaute is a protein which bind with siRNA or miRNA and form RISC complex(RNA inducing silencing complex) causing translational inhibition

Hence option b is incorrect

Option c RISC is RNA inducing silencing complex which is formed when Argonaute protein bind siRNA or miRNA and causes mRNA degradation or translation inhibition

Hence option c is incorrect

Option d RNAse 3

Found mostly in bacteria are endoribonuclease enzyme which cleave double stranded RNA at specific site and form mature RNA

Hence option d is incorrect as it cleave at specific means make cut at specific location hence does not shorten the length

Hence correct answer is option a

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