Which of the following statements are correct? Explain your answers.

A. Ribosomes are cytoplasmic structures that, during protein synthesis, become linked by an mRNA molecule to form polyribosomes.

B. The amino acid sequence Leu-His-Arg-Leu-Asp-Ala-Gln-Ser-Lys-Leu-Ser-Ser is a signal sequence that directs proteins to the ER.

C. All transport vesicles in the cell must have a v-SNARE protein in their membrane.

D. Transport vesicles deliver proteins and lipids to the cell surface.

E. 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 pathways shown in Figure 15−30.F. Lysosomes digest only substances that have been taken up by cells by endocytosis.

G. 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.

H. Ribosomes bound to the outer nuclear membrane make proteins that are translocated co-translationally into the membrane.

Figure 15−30

Transcribed Image Text:

newly synthesized soluble proteins for constitutive secretion Golgi apparatus newly synthesized plasma membrane lipids transport vesicle trans Golgi network unregulated exocytosis newly synthesized plasma membrane protein signal transduction secretory vesicle storing concentrated secretory proteins regulated exocytosis CYTOSOL CONSTITUTIVE SECRETION plasma membrane extracellular signal such as hormone or neurotransmitter REGULATED SECRETION EXTRACELLULAR SPACE