Allosteric effectors:

82. Allosteric effectors:

a)      block transcription by RNA polymerases through the binding of DNA regulatory regions

b)     are enzymes that regulate gene expression through the degradation of activators and repressors.

c)      enhance translation by exporting mature mRNA from the nucleus

d)     cause changes in the conformation of activators and repressors that influence their DNA binding affinity.

e)      regulate gene expression by preventing the translation of activators and repressors.

83. The expression of the Lac operon in an E. coli cell missing the gene that encodes for the lac repressor will:

a)      increase when lactose is present.

b)     decrease when lactose is present.

c)      decrease when glucose is present.

d)     increase when glucose is present.

e)      always be reduced, independent of the sugars present

89) .  Which of the following is not a feature of miRNAs?

a)      Pri-miRNAs have internal complementary sequences capable of forming hairpin structures.

b)     Pre-miRNAs are trimmed to a length of —20 nucleotides by Dicer

c)      miRNAs are exported from the nucleus in their single-stranded form.

d)     In animals, miRNAs typically guide RISC to the 3' UTR of mRNAs through complementary base pairing

e)      A high degree of complementarity between mRNA and miRNA leads to mRNA degradation

90.  microRNA-27 binds the 3'-UTR of the mRNA for the receptor IGF-I. microRNA-27 also has a high degree of complementarity with a segment of the long non-coding RNA, IncRNA133.

Based on this information, you expect that an increase in microRNA-27 would cause the level of [GF-I protein to and an increase in IncRNA-133 would cause the level of IGF-I protein to

a)      Increase, increase

b)     decrease, decrease

c)      Increase, decrease

d)     decrease, increase

e)      decrease, remain unchanged