In the Meselson-Stahl DNA replication experiment, if the cells were first grown for many generations in 15N containing media, and then switched to 14N containing media, what percent of the DNA had 1 light strand and 1 heavy strand after 2 generations of growth in 15N growth media?

TLS Online TPP Program

#Question id: 13119

#Unit 2. Cellular Organization

Ions, small metabolites, and globular proteins up to about ---------- can diffuse passively through the central aqueous region of the nuclear pore complex.

TLS Online TPP Program

#Question id: 13120

#Unit 2. Cellular Organization

Match the correct one?

Target organelle	Location of sequence within protein	Removal of sequence	Nature of sequence
1- ER	i- N- terminal	a- yes	P- Core of 6-12 hydrophobic aa often preceded by one or more basic ammo acids (Arg, Lys)
2-Mtochrondria matrix	ii- N- terminal	b- yes	Q- Multiple different kinds;  rich in Lys and Arg residues
3-Chloroplast stroma	iii- N- terminal	c- no	R- Lys and arg one side and other side hydrophobic aa
4-Nucleus	iv-varies	d- yes	S- Generally rich in ser and thr, poor in glu and asp

TLS Online TPP Program

#Question id: 13121

#Unit 2. Cellular Organization

--------- act as a nuclear export factor and directs the associated mRNP to the central channel of the NPC by transiently interacting with FG- nucleoporins.

TLS Online TPP Program

#Question id: 13122

#Unit 2. Cellular Organization

Choose the incorrect?

1- COPI vesicles transport proteins from the rough ER to the cis -Golgi; COPII vesicles transport proteins in the reverse s Direction.

2- The KDEL receptor binds more tightly to its ligand ar low pH, and it is thought that the receptor is able to bind KDEL peptides in the cis-Golgi but to release these peptides in the ER because the pH of the Golgi is slightly lower than that of the ER.

3- The KDEL sorting signal is recognized and bound by the KDEL receptor, a transmembrane protein found primarily on small transport vesicles shuttling between the ER and the cis -Golgi and on the cis-Golgi reticulum.

TLS Online TPP Program

#Question id: 13123

#Unit 2. Cellular Organization

Match the correct one?

A- COPI                           i- vesicles transport proteins from the ER to the Golgi.

B- COPII                          ii- vesicles mainly transport proteins in the retrograde direction between Golgi cisternae and from the cis -Golgi back to the ER.

C- Clathrin                      iii- vesicles transport proteins from the plasma membrane (cell  surface) and the trans-Golgi network to late endosomes.

TLS Online TPP Program

#Question id: 13154

#Unit 2. Cellular Organization

In starving cells, however, such degradation would deplete essential enzymes and regulatory proteins. Lysosomes therefore also have a selective pathway, which is activated only after a prolonged fast, that imports and degrades cytosolic proteins containing the pentapeptide  , the sequence is