Tay-Sachs disease belongs to the family of lysosomal storage diseases; it is an autosomal recessive neurodegenerative disorder caused by deficiency of the lysosomal enzyme hexosaminidase. The inability to degrade sphingolipids results in the deposition of these lipids in the cells that causes severe mental retardation and death in childhood. The most common mutation in Tay-Sachs disease patients is a 4-base pair insertion in exon 11 of the 14 exons of the hexosaminidase gene. What could be the most likely consequence of this mutation?

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: 13124

#Unit 10. Ecological Principles

A recent study of ecological footprints concluded that

TLS Online TPP Program

#Question id: 13125

#Unit 10. Ecological Principles

Which of the following statements is consistent with the principle of competitive exclusion?