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.

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#Question id: 12184

#Unit 2. Cellular Organization

Following graph represent Control of S phase onset in S. cerevisiae by regulated proteolysis of the S phase inhibitor Sic1. 

Which of the following is correct according to graph?

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#Question id: 12183

#Unit 2. Cellular Organization

Following statements are regarding to regulation of S phase and mitotic cyclin levels in budding yeast.

A. In late anaphase, the anaphase-promoting complex (APC/C) ubiquitinylates S phase and mitotic cyclins.

B. In late anaphase, the anaphase-promoting complex (APC/C) phosphorylates S phase and mitotic cyclins.

C. During exit from mitosis and G1, Cdh1 is dephosphorylated and active; during S phase and mitosis, Cdh1 is phosphorylated and dissociates from APC/C, and APC/C becomes inactive.

D. During exit from mitosis and G1, Cdh1 is phosphorylated and active; during S phase and mitosis, Cdh1 is dephosphorylated and dissociates from APC/C, and APC/C becomes inactive.

E. The G1/S phase CDKs, which themselves are not APC/CCdh1 substrates, phosphorylate Cdh1 at the G1–S phase transition.

F. The G1/S phase CDKs, which themselves are not APC/CCdh1 substrates, ubiquitinylates Cdh1 at the G1–S phase transition.

Which of the following combination is correct?

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#Question id: 12182

#Unit 2. Cellular Organization

The cell cycle is controlled by protein kinases that comprise a catalytic subunit and a regulatory subunit. Which of the following statement is correct regarding to these subunits?

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#Question id: 4718

#Unit 2. Cellular Organization

All the following statements about destruction of cyclins are true, except:

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#Question id: 2994

#Unit 2. Cellular Organization

If a cell has completed meiosis I and the first cytokinesis, and is just beginning meiosis II, which of the following is an appropriate description of its genetic contents?

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#Question id: 2993

#Unit 2. Cellular Organization

During meiosis, a defect occurs in a cell that results in the failure of spindle microtubules binding at the kinetochores. Which of the following statements describes the most likely result of such a defect?