Correct statement about two striking structural changes are seen in the enzyme upon isomerization from the closed to the open complex;

A. First, the pincers at the front of the enzyme clamp down tightly on the downstream DNA.

B. Second, there is a major shift in the position of the amino-terminal region of s. When not bound to DNA, s region 3.2 lies within the active center cleft of the holoenzyme, blocking the path that, in the open complex, is followed by the template DNA strand.

C. In the open complex, region 1.1 shifts some 50 A˚ and is now found on the outside of the enzyme, allowing the DNA access to the cleft.

D. Region 1.1 of s is highly negatively charged ( just like DNA).

TLS Online TPP Program

#Question id: 4718

#Unit 2. Cellular Organization

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

TLS Online TPP Program

#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?

TLS Online TPP Program

#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?

TLS Online TPP Program

#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?

TLS Online TPP Program

#Question id: 12185

#Unit 2. Cellular Organization

Mitotic CDKs affect nuclear envelope components by specific mechanism. Which of the following statement is not related to this mechanism?

TLS Online TPP Program

#Question id: 12186

#Unit 2. Cellular Organization

In 2001, the Nobel Prize in Physiology or Medicine was awarded to three cell cycle scientists. Paul Nurse was recognized for his studies with the fission yeast S. pombe, in particular for the discovery and characterization of the wee1+ gene. What did the characterization of the wee1+ gene tell us about cell cycle control?