BIOL 150 Lecture Notes - Lecture 13: Signal Recognition Particle, Chloroplast Dna, Cell Membrane

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bronzefly406

15 Mar 2018

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Biol 150 principles of molecular & cellular biology. We took one last look at cell export, by examining how a protein just beginning be synthesized can cause a ribosome to bind to the er membrane for translation directly into the. A short signal sequence near the n-terminus (first amino acid) in the protein is bound by the signal recognition particle, which binds the ribosome to the membrane. The signal plus rest of the protein then is fed into the er lumen as translation continues. If the protein has other hydrophobic regions besides the signal, the protein will end up being embedded into the er membrane, and will eventually become a plasma membrane protein. Cells bring stuff into the cytoplasm, including water and food (proteins, polysaccharides), and also recycle proteins in the plasma membrane. Vesicles bud into the membrane carrying these materials, and sometimes fuse with each other to form endosomes.

Related Questions

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

1- What is the role of a rER translocon?

a- Bind with a ribosome for peptide synthesis in the rER lumen.

b- Flip proteins into the cytosol.

c- Bind a signal recognition particle.

d- Proofread newly assembled proteins.

e- Terminate translation.

2- Select all of the following categories of proteins which are made (synthesized by the Rough ER).

a- Secreted Proteins (like hormones, neutotransmitters)

b- Proteins integrated into a cellâs own plasma membrane

c-Proteins integrated into a cellâs own intracellular membranes (such as the Gogli, vesicles)

d-Proteins that are dissolved in a cellâs own cytosol

tealmouse499

1.Bacteriorhodopsin is a protein that has 7 alpha helices embedded in the cell membrane. As such, how many start-transfer and stop-transfer sequences would it need?

7 start transfer sequences, 6 stop transfer sequences

7 of each, in alternating fashion

4 start transfer sequences and 3 stop transfer sequences

7 start transfer sequences

2. The role of GTP hydrolysis by the Signal Recognition Particle during cotranslational translocation to the ER is

to release the SRP after docking to the translocon so translation can resume.

to open the gate/pore of the translocon into the ER.

to arrest translation so that synthesis does not finish before the peptide is delivered to the translocon.

to allow binding to the ribosome.

3. The cisternal maturation model is just one model that describes how objects might move through the Golgi. Some of the statements below describing the cisternal maturation model are correct and some are incorrect. Select all the incorrect descriptions.

There's no need for retrograde movement

Vesicles bud off from the Trans Golgi Network toward the plasma membrane

Vesicular tubules move materials from the cis to medial Golgi networks.

There are no vesicles moving in the anterograde direction

4. Select all statements that are correct concerning electron transport and ATP synthesis during photosynthesis in chloroplasts.

Each photosystem (I and II) pump protons.

Protons are pumped into the lumen of the thylakoid.

The bulb of the synthase projects into the stroma

Photosystem I is reduced directly by Photosystem II

5. Select all that are true about ATP synthesis with an F_oF₁ synthase complex.

Each ADP+Pi is transferred from one beta subunit in Open conformation to a second beta subunit in Loose conformation and finally to the 3rd beta subunit in the T conformation

As the gamma subunit rotates to each beta subunit, it forces them to the open state.

As the gamma subunit rotates to a particular beta subunit, the unit before it changes conformation to Tight and the one ahead of it changes to Loose

As the gamma subunit rotates to a particular beta subunit, the unit before it changes conformation to Loose and the one ahead of it changes to Tight

All 3 beta subunits are always in a different conformation (open, loose, or tight)

6. The number of ATPs per NADH generated by the electron transport system is higher than the number generated per FADH2 because __________.

		electrons from FADH₂ are not oxidized all the way to water
		NADH is converted to NAD⁺, which increases the charge gradient for ATP synthesis
		FADH₂ has a lower (less negative) redox potential than NADH does
		FADH₂ has a higher (more negative) redox potential than NADH does

BIOL 150 Lecture Notes - Lecture 13: Signal Recognition Particle, Chloroplast Dna, Cell Membrane

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