BIOLOGY 2B03 Lecture 10: Bio 2B03 Module 4 Lecture 3

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19 Oct 2016

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The membrane of the rer is continuous with the nucleus. The black dots on the rer represent membrane-associated ribosomes which are translating secretory proteins (travel through the golgi apparatus and in vesicles to reach outside of the cell). The bound ribosomes are on cytosolic side of the rer and these ribosomes are the same as free ribosomes, they are simply cycling between on and off of the er membrane. Microsomes: mimic the rer by disrupting the er membranes though homogenization which spontaneously creates a spherical structure with the same membrane-bound proteins (such as ribosomes) as the rer. If so, then transport will not be able to occur after translation is complete. In the control, proteins were synthesized in vitro in presence of microsomes and mature proteins were found. But free proteins synthesized in absence of microsomes and then placed in a solution with microsomes had no incorporation into the microsome.

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1A. Which of the following statements about the endomembrane system is/are correct? (select all that apply)

A.	Secreted proteins are inserted into the ER as they are being made by ribosomes.
B.	the nucleus is surrounded by two phospholipid bilayers.
C.	"Free" ribosomes attach to the endoplasmic reticulum.
D.	Secreted proteins are moved from the ER to the Golgi by ribosomes

1B. Place these components of the endomembrane system into the correct order in respect to when they first function in the production of a secreted protein.

	Endoplasmic Recticulum (ER)
	Riibosome
	Nucleus
	Transport Vesicle
	Cell Membrane
	Golgi Apparatus

lilacgnat89

Which of the following statements about secreted proteins is/are correct? Choose all that apply. Which of the following statements about secreted proteins is/are correct? Choose all that apply.

Secreted proteins travel directly from the rough endoplasmic reticulum into the trans face of the Golgi apparatus.

Secreted proteins are likely to have received N-linked glycosylation in the rough ER.

Secreted proteins are the only proteins that receive sugar modifications in the Golgi.

Secreted proteins that are constitutively expressed are exported as they are prepared, as opposed to being released as a response to a signal.

Secreted proteins are synthesized on membrane-bound ribosomes, not free cytosolic ribosomes.

sangriacat694

1. The histones that form the core of the nucleosome get into the nucleus by which of the following?

a) Passive diffusion through nuclear pores

b) Selective and facilitated active transport through nuclear pores

c) Ribosomes located in the nucleus synthetize histones in the nucleus

d) Histones are made at the ER membrane and then diffuse to the nucleus

2. Membrane proteins that belong to the golgi, lysosome, or plasma membrane first pass through which organelle before reaching their final subcellular destination?

a) The golgi apparatus

b) The smooth ER

c) The nucleus

d) The ER membrane

e) The ER lumen

3. Where in the cell would a ribosomal protein be located if it has had its nuclear export signal inactivated (non-functional or non-existent).

a) The protein would be found in the ER lumen

b) The protein would remain in the nucleus

c) The protein would be secreted

d) The protein would remain in the cytoplasm

e) The protein would be in the ER membrane

4. Where would be the final destination of a protein if it contained a NLS anywhere in the protein sequence (and which is exposed to the cytoplasm after protein folding) but also contained an ER signal sequence at the carboxy terminus?

a) The ER lumen

b) The nucleus

c) The cytoplasm

d) The inner nuclear membrane

e) The ER membrane

5. The sequence K-D-E-L serves as a retention/retrieval signal for ER proteins.

a) True

b) False

6. The following are true for both cell membrane proteins and secretory proteins EXCEPT?

a) Precursors of the mature proteins contain signal sequence.

b) Both types of proteins contain stop-transfer sequences

c) Both types of proteins enter the ER while being synthetized

d) Both types of proteins pas through the golgi apparatus

e) Both are carried by clatherin-coated vesicles

7. If you isolate a regulated secreted protein from a secretory/storage vesicle and inject it into the cytosol, is will?

a) Be secreted through channels in the plasma membrane

b) Be taken up into secretory vesicle and secreted

c) Remain in the cytosol until it is degraded

d) Be taken up into the rough ER and follow the secretory pathway

goldmanatee250

BIOLOGY 2B03 Lecture 10: Bio 2B03 Module 4 Lecture 3

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