Question

QUESTION 25

1. The concentration of mitotic cyclin ____________________.

	A.	is highest in G1 phase
	B.	decreases at the end of M phase as a result of ubiquitylation and degradation
	C.	decreases at the prophase
	D.	is controlled by phosphorylation

QUESTION 26

1. Which of the following statements about the ubiquitin-proteasome pathway is false?

	A.	Proteases, which reside in the central cylinder of a proteasome, degrade the ubiquitin-modified protein.
	B.	Ubiquitin is a small protein that is non-covalently attached to proteins to mark them for delivery to the proteasome.
	C.	The ubiquitin enzymes (E1, E2, and E3) covalently attached ubiquitin to the short-lived and misfolded proteins.
	D.	Misfolded proteins are first modified by poly-ubiquitin chain and then degraded by the proteasome.

QUESTION 27

1. Which of the following statements about S-phase is false?

	A.	DNA synthesis can only begin after pre-replicative complexes assemble on the ORCs.
	B.	The phosphorylation and degradation of Cdc6 help to ensure that DNA is replicated only once in a cell cycle.
	C.	DNA synthesis begins at the origins of replication.
	D.	The loading of the origin recognition complexes (ORCs) is triggered by S-Cdk.

QUESTION 28

1. Which one of the followings is the main reason that a typical eucaryotic gene is able to respond to a far greater variety of regulatory signals than a typical procaryotic gene or operon?

	A.	Eucaryotes have three types of RNA polymerase.
	B.	The transcription of a eucaryotic gene can be influenced by multiple proteins that bind far from the promoter.
	C.	Eucaryotic RNA polymerases require many general transcription factors.
	D.	Procaryotic genes are packaged into nucleosomes.

QUESTION 29

1. Which of the following statements about procaryotic mRNA molecules is false?

	A.	Ribosomes must bind to the 5′ cap before initiating translation.
	B.	Ribosomes can start translating an mRNA molecule before transcription is complete.
	C.	mRNAs are not polyadenylated.
	D.	A single procaryotic mRNA molecule can be translated into several proteins.

Answer 1

Answer

25. Option B is the right answer as The concentration of mitotic cyclin decreases at the end of M phase as a result of ubiquitylation and degradation.

26. Option B is the right answer as ubiquitin attached to the target protein via covalent interaction rather than non-covalent interaction