Answer:
A. True. If the delivery of prospective lysosomal proteins
from the trans Golgi network to the late endosomes
were blocked, lysosomal proteins would be
secreted by the constitutive secretion pathway.
B. False. Lysosomes digest only substances that have been
taken up by cells by endocytosis.
C. False. N-linked sugar chains are found on glycoproteins
that face the cell surface, as well as on
glycoproteins that face the lumen of the ER, trans
Golgi network, and mitochondria.
Explanation:
A. Lysosomal proteins are carried through the indirect constitutive secretion pathway that transports lysosomal proteins from the TGN to plasma membrane and delivers to the late endosomes and the lysosomes.
B. Lysomes digest cellular components and materials by both endocytosis and autolysis.
- Autolysis is a self-destructive pathway by the action of enzymes in the lysosomes.
- Endocytosis is a receptor-mediated pathway and lysosomes digests substances that have been taken up or attached by specific receptors.
- Phagocytosis, an endocytosis pathway, involves ingestion of macromolecules, degraded cellular material, cellular debris, and decayed microbial cells
.
C. N-linked sugar chains are not present on the lumen of the mitochondria because mitochondria does not involve in vesicular transport.
N-linked glycosylation occurs by the action of the enzymes are present in the lumen of ER and golgi cisternae of the TGN and the sugars get attached to the glycoproteins on their lumen.
