Biology 1002B Lecture 5: Lec 5 - Membrane Biology

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sapphirebear815

21 Jan 2016

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The er and golgi make the secretory pathway. Proteins that are destined to be secreted, proteins are sent outside of the cell. Proteins that sit on the plasma membrane go through secretory pathway, they just don"t leave the cell, they stay on the membrane: proteins are synthesized on ribosomes that attach themselves to the. Er as opposed to free ribosomes that never attach themselves to the. What determines if a protein is synthesized in the cytosol, on free ribosomes, or on ribosomes that associate with the er is determined by protein targeting. Protein targeting: how you get proteins to specific compartments/organelles. Protein targeting to the er how proteins get to secretory pathway. Mrna with the signal peptide binds to ribosomes that are initially free, the signal peptide is recognized by the signal recognition particle, this directs the ribosome to the er: signal recognition particle and translocation complex interact.

Related Questions

29 Most proteins destined to enter the endoplasmic reticulum _________.

(a) are transported across the membrane after their synthesis is complete.

(b) are synthesized on free ribosomes in the cytosol.

(d) are keep binding to Signal recognition particle (SRP) while they are translated.

30 Which of the following choices reflects the appropriate order of locations through which a protein destined for the plasma membrane travels?

(a) lysosome â endosome â plasma membrane

(b) ER â lysosome â plasma membrane

(d) ER â Golgi â plasma membrane

31 Which of the following statements about vesicle budding from the Golgi is false?

(a) COPII can initiate vesicle budding on Golgi membrane.

(b) Some vesicles budded from Golgi membranes move towards ER.

(d) Clathrin molecules act at the cytosolic surface of the Golgi membrane.

32 Which of the following statements is false?

(a) The signal sequences on mitochondrial proteins are first bound to translocator on outer membrane after translation.

(b) Most mitochondrial proteins are not imported from the cytosol but are synthesized inside the mitochondria.

(c) Chaperone proteins in the mitochondria facilitate the movement of proteins across the outer and inner mitochondrial membranes.

(d) Mitochondrial proteins cross the membrane in their unfolded state.

orangeplatypus673

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

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

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Biology 1002B Lecture 5: Lec 5 - Membrane Biology

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