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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. Molecules and their Interaction Relevant to Biology

  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: 11032

#Unit 7. System Physiology – Animal

An electrocardiogram (ECG) provides information about ________.
TLS Online TPP Program

#Question id: 11033

#Unit 7. System Physiology – Animal

The velocity of blood flow is the lowest in capillaries because ________.
TLS Online TPP Program

#Question id: 11034

#Unit 7. System Physiology – Animal

An increase in shear stress in a blood vessel results in which of the following changes?
TLS Online TPP Program

#Question id: 11035

#Unit 7. System Physiology – Animal

A 72-year-old man had surgery to remove an abdominal tumor. Pathohistologic studies reveal that the tumor mass contains a large number of blood vessels. An increase in which of the following is the most likely stimulus for the growth of vessels in a solid tumor?
TLS Online TPP Program

#Question id: 11036

#Unit 7. System Physiology – Animal

Under control conditions, flow through a blood vessel is 100 ml/min under a pressure gradient of 50 mm Hg. What would be the approximate flow through the vessel after increasing the vessel diameter to four times normal, assuming that the pressure gradient was maintained at 50 mm Hg?
TLS Online TPP Program

#Question id: 11037

#Unit 7. System Physiology – Animal

A 22-year-old man has a muscle blood flow of 250 ml/min and a hematocrit of 50. He has a mean arterial pressure of 130 mm Hg, a muscle venous pressure of 5 mm Hg, and a heart rate of 80 beats/min. Which of the following is the approximate vascular resistance in the muscle of this man?