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TLS Online TPP Program

#Question id: 2888

Repressive complexes have been discovered that are composed of multiple repressing proteins bound to RNAs many kilobases in length that do not contain long open reading frames and are consequently called long noncoding RNAs or lncRNAs. Which of the following statements is correct regarding the regulation of these lncRNAs?

#Unit 2. Cellular Organization

  1. X inactivation is controlled by a roughly 100-kb domain on the X chromosome called the X-inactivation center that encodes a lncRNA known as XIST that is responsible for inactivation of the maternally derived chromosome.

  2. Depletion of a 2.2-kb noncoding RNA expressed from the HOXC locus by siRNA unexpectedly led to derepression of the HOXD locus, a roughly 40-kb region on another chromosome encoding several Hox proteins and multiple other noncoding RNAs, in these cells.

  3. HOTTIP lncRNA, which is transcribed from the 5’end of the HOXA locus, is proposed to coordinate the activation of HOXA genes by binding to a histone H3 lysine 9 methylase represents the cis activation by lnc-RNAs.

  4. In humans, but not in mice, a lncRNA called XACT has been discovered to associate with multiple sites along the full length of the active X chromosome and is postulated to contribute to repression of gene activity on that chromosome.

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TLS Online TPP Program

#Question id: 11827

#Unit 6. System Physiology – Plant

Which of the following enzyme is involved in the rate-limiting step in ethylene biosynthesis?
TLS Online TPP Program

#Question id: 11828

#Unit 6. System Physiology – Plant

Given some enzymes of ethylene biosynthetic pathway and its character;

A) ACC synthase                                                               i) It is an unstable, cytosolic enzyme. Its level is regulated by environmental and internal factors, such as wounding, drought stress, flooding, and auxin

B) ACC oxidase                                                                  ii) It catalyzes the last step in ethylene biosynthesis, the conversion of ACC to ethylene

                                                                                                iii) Its activity can be the rate-limiting step in ethylene biosynthesis

                                                                                                iv) That is encoded by a multigene family that is differentially regulated

                                                                                                v) It is present in such low amounts in plant tissues and is very unstable and also difficult to purify the enzyme  for biochemical analysis

                                                                                                vi) These enzymes belong to the Fe2+/ascorbate oxidase superfamily

Find out the correct combination from the given enzymes and its character?
TLS Online TPP Program

#Question id: 11829

#Unit 6. System Physiology – Plant

The certain cyclic olefin compounds, have been shown to block ethylene breakdown without inhibiting ethylene action?
TLS Online TPP Program

#Question id: 11830

#Unit 6. System Physiology – Plant

Not all the ACC found in the tissue is converted to ethylene, ACC can also be converted to a conjugated form, which does not appear to break down and accumulates in the tissue?
TLS Online TPP Program

#Question id: 11831

#Unit 6. System Physiology – Plant

A volatile compound is a strong competitive inhibitor of ethylene binding______
TLS Online TPP Program

#Question id: 11832

#Unit 6. System Physiology – Plant

Ethylene production and action can be inhibited by various types of inhibitors, some statements about  the inhibitor is given below, which one of the following is incorrect?