#Question id: 799
#Unit 1. Molecules and their Interaction Relevant to Biology
The two cleavage reactions required to generate the miRNA from these primary transcripts are mediated by two distinct RNases. A characteristic of both these enzymes is that they recognize and cleave RNAs on the basis of the structure of their substrates rather than their specific sequence. Which of the following statement is INCORRECT regarding the cleavage reactions that produces a mature RNA?
#Question id: 800
#Unit 1. Molecules and their Interaction Relevant to Biology
Following table lists the two major forms of DNA duplexes, conformation of base attached to the sugar and the nature of major and minor grooves.
|
DNA duplex |
Properties |
|
(A) A
form |
(i) Syn
conformation of the base to sugar |
|
(B) B
form |
(ii) Anti
conformation of the base to sugar |
|
|
(iii) Wide
major groove |
|
|
(iv)
Narrow major groove |
|
|
(v) Wide
minor groove |
|
|
(vi) Narrow
minor groove |
|
|
(vii) C-3’
endo sugar puckering |
|
|
(viii) C-2’
endo sugar puckering |
#Question id: 801
#Unit 1. Molecules and their Interaction Relevant to Biology
Identify the type of DNA from the structures given below and match the correct form with its characteristics described.
#Question id: 802
#Unit 1. Molecules and their Interaction Relevant to Biology
A single-stranded DNA molecule contains 40 nucleotides with equal amounts of A, C, G, and T. This DNA strand can combine with a complementary DNA strand to form a double-stranded DNA molecule. Which is a possible sequence and structure for this DNA molecule?
#Question id: 803
#Unit 1. Molecules and their Interaction Relevant to Biology
A single-stranded DNA molecule contains 40 nucleotides and has the sequence 5’-(GA)20-3’. When this single strand binds to a complementary DNA strand to form a B-DNA structure,
#Question id: 804
#Unit 1. Molecules and their Interaction Relevant to Biology
With respect to microRNAs, which, if any, of the following statements, is false?
a) A microRNA normally works by binding to perfectly complementary sequences within an RNA transcript, usually an mRNA.
b) Like the great majority of mRNAs an miRNA is usually produced as a larger precursor RNA that is capped and has a 3’ poly(A) tail.
c) The precursor miRNA undergoes different types of post-transcriptional cleavage by endoribonucleases that are specific for double-stranded target sequences.
d) A nuclear endoribonuclease called dicer cleaves the miRNA precursor so that it forms a stem-loop RNA.