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TLS Online TPP Program

#Question id: 799

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?

#Unit 1. Structure and Function of Biomolecules

  1. Drosha resides in the cell’s nucleus, and the Drosha-catalyzed cleavage event occurs in that cellular compartment that generates a pre-miRNA which is ~65–70 nucleotides long.

  2. The pre-miRNA liberated by Drosha is exported to the cytoplasm, where the second RNA cleavage reaction, performed by Dicer, takes place which cleaves pre-miRNA 22 nucleotides from its ends.

  3. For processing by Drosha, ssRNA lacking significant secondary structure, is needed flanking each side (5’ and 3’) of the stem-loop. It is the ssRNA–dsRNA junctions that are in responsible for determining the cleavage specificity of Drosha.

  4. The RNase II family enzymes are specific for dsRNA and cleave it in a manner that leaves a 2-nucleotide overhang on the 3’ ends of the dsRNA product. This 3’ overhang is important for recognition of that RNA molecule by the next enzyme in the pathway, Dicer.

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TLS Online TPP Program

#Question id: 12495

#Unit 8. Inheritance Biology

Haemophilia A is a severe coagulation disorder that shows X-linked recessive inheritance. Red-green colour blindness also shows X-linked recessive inheritance. A man with both haemophilia A and colour blindness is referred for genetic counseling. Assume that his partner is not a carrier of either of these conditions. Which of the following is correct?
TLS Online TPP Program

#Question id: 12496

#Unit 8. Inheritance Biology

A woman who has two brothers and a maternal uncle (her mother's brother) with non-specific X-linked mental retardation is referred for genetic counselling. There are no diagnostic tests available to help determine whether or not she is a carrier. Which of the following is correct?
TLS Online TPP Program

#Question id: 12497

#Unit 8. Inheritance Biology

In this pedigree A and B represent alleles at a marker locus closely linked to the disease locus. Affected individuals are shown as shaded. The disease status in III 1 is unknown. Which of the following is correct?
TLS Online TPP Program

#Question id: 12498

#Unit 8. Inheritance Biology

In this pedigree II 1 is affected with an autosomal recessive disorder. The disease status for II 2 and II 3 is unknown. A and B represent alleles at a locus which is tightly linked to the disease locus with recombination fraction of 0. On the basis of the linked marker genotypes II 2 can be told that: 
TLS Online TPP Program

#Question id: 12499

#Unit 8. Inheritance Biology

On the basis of the linked marker genotypes II 3 can be told that:
TLS Online TPP Program

#Question id: 12500

#Unit 8. Inheritance Biology

In this pedigree II 1 is affected with an autosomal recessive disorder. The disease status for II 2, II 3 and II 4 is unknown. A and B represent alleles at a locus which is tightly linked to the disease locus with recombination fraction of 0. On the basis of the linked markers II 2 can be told that: