bis_104_pq_27_ans_ss_i_2009 - (1 presence of microsomes...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
BIS 104 PQ 27 ANS SS I 2009 27. a. Provide a one or two sentence description of the signal peptide hypothesis. Secretory proteins contain a signal sequence at their NH2-terminus that directs the emerging polypeptide and ribsomes to the ER membrane. The polypeptide is then moved into the cisternal space of the ER through a protein lined aqueous channel in the ER membrane. Polypeptides lacking this specific signal sequence do not follow this pathway for translation. b. Describe the results you would expect to observe if you added mRNA coding for alpha globin to a cell-free translation system in (1) the presence, or (2) in the absence of added microsomes.
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Background image of page 2
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: (1) presence of microsomes: Since the mRNA has no signal sequence code, the translation system would synthesize native size alpha globin protein, not associated with the microsomes. Therefore, a single protein band on SDS gel, that would be digestible by protease. (2) absence of microsomes: Same as above; only native alpha globin protein is made. c. Why is the procedure described in (b) above an important control for the in vitro experiments described by Lingappa? It demonstates that native alpha globin protein, in the absence of a signal sequence, does not associate non-specifically with an in vitro preparation of microsomes....
View Full Document

{[ snackBarMessage ]}

Page1 / 2

bis_104_pq_27_ans_ss_i_2009 - (1 presence of microsomes...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online