Biology 2382B Lecture Notes - Lecture 4: Secretion, Differential Centrifugation, Signal Recognition Particle

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aquamarinedonkey701

26 Apr 2013

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Typical mammalian cell: 10,000+ different proteins, must go to the right destination must be localized correctly. Newly made peptides must be directed to the correct destination. Targeting: directing proteins to the right destinations (organelles, during or after synthesis. Sorting: direct proteins to the secretory pathway (er, golgi, lysosomes, more related to proteins involved in the secretory pathway proteins which make it inside the er, golgi and lysosomes (secretory, vesicles, getting rid of stuff) General principles of protein synthesis, targeting and sorting. Many proteins are synthesized just by cytosolic ribosomes: those which remain in the cytosol, those which are targeted to intracellular organelles such as (er), mitochondria, chloroplasts, peroxisomes, and nucleus (they have a specific signal sequence) Most of these targeting sequence happen at the amino terminus: other proteins are synthesized by ribosomes attached to er (the rought er) Those which reside in er and proteins which are sorted to pm,

Related Questions

One effective learning strategy when trying to learn largeamounts of factual information is to group items, or âchunkâ. Youshould include all important structures of the cell (this includescell membrane and membrane adaptations as well as organelles).Examples of general categories could be location, function,morphology, etc. Your categorization groups must tell the viewersomething about the structures. Once your structures are groupedaccording to the characteristics they share, you should include ashort phrase about what differentiates them from each other withinthe group. Citation of your source material must be present.

List of Organelles:

Nucleus, Nuclear envelope/membrane, Nucleolus, Ribosomes,Endoplasmic reticulum, Golgi apparatus, Mitochondria, Plasmamembrane, Cytoskeleton, Transport/secretory vesicles,Phagosomes/endosomes-including sorting & recycling endosomes,Lysosomes, Peroxisomes, Lipid droplets, Glycogen granules

I started this assignment and was going to go withfunction and morphology. Below is what I have so far, but I'mhaving a difficult time coming up with a short phrase for each anddistinguishing between the organelles that can change shape/morphand those that cannot. I am open to changing the categories that Ihave chosen to chunk. I've never used this technique before so it'sa new concept for me.

Function

Protein Synthesis â Nucleus, Nuclear envelope, Nuclear porecomplex, Ribosomes, Rough endoplasmic reticulum, Golgi apparatus,Plasma membrane

Energy Production â Mitochondria, Lipid droplets, Glycogengranules

Transportation â Transport vesicles, Phagosomes,Cytoskeleton

Metabolism â Lysosomes aid in digestion, Peroxisomes oxidizefatty acids

Morphology

Ability to change shape â Mitochondria, Cell membrane, Nuclearenvelope,

Inability to change shape â Nucleus, Nuclear envelope,

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QUESTION 30

The function of centrosome is:

	1.	Microtubule initiation and organization in animal cells
	2.	Organization of thin filaments
	3.	Depolymerization of microtubules
	4.	Organization of intermediate filaments

2.5 points

QUESTION 31

The destinations of proteins synthesized on "free" ribomsomes include:

	1.	Endoplasmic reticulum
	2.	Nucleus
	3.	Mitochondria
	4.	Lysosomes

2.5 points

QUESTION 32

Microtubules can be assembled and disassembled quickly in response to the cellular changes is because:

	1.	Cells synthesize tubulin proteins very fast.
	2.	Cells can turn other cytoskeletal filaments into microtubules
	3.	Microtubules have an instable plus end and microtubules are probably organized by weak non-covalent interactions
	4.	The motor proteins of microtubules can organize the microtubules in response to the cellular changes

2.5 points

QUESTION 33

Both signal recognition particle and a translocon in rough endoplasmic reticulum membrane can recognize and bind to the signal sequence of a secretory protein, so they play the exact same role during protein co-translational translocation.

True

False

2.5 points

QUESTION 34

Rough endoplasmic reticulum is so named is because:

	1.	It has many proteins associated with its surface.
	2.	It has ribosomes associated with its cytosolic surface.
	3.	It is associated with nuclear membrane.
	4.	It has vesicles budding off its surface.

2.5 points

QUESTION 35

The membrane vesicles that transport materials between membrane compartments have a protein coat. The protein coat has similar functions in different vesicles. These functions include:

	1.	Help the enclosed material fold correctly.
	2.	Help degrade the protein in the vesicles
	3.	Maintain the internal pH of the vesicles
	4.	Function as mechanical device to form a vesicle and select the components to be carried by a vesicle.

2.5 points

QUESTION 36

Lysosomes are important for:

	1.	Receptor-mediated endocytosis.
	2.	Breaking down foreign particles brought into the cells by endosomes
	3.	Regulating the process of organelle turnover.
	4.	Protein trafficking between membrane compartments

2.5 points

QUESTION 37

Which of the following is correct about membrane biosynthesis?

	1.	Membranes are synthesized in Golgi Complex.
	2.	Membranes arise from preexisting endoplasmic reticulum membranes.
	3.	Membranes are synthesized on ribosomes.
	4.	Membranes of all organelles have the same composition of proteins and lipids, since they all originate from endoplasmic reticulum.

2.5 points

QUESTION 38

During skeletal muscle contractions, the shortening of the muscle fibers is because of:

		The shortening of the thin and thick myofilaments.
		The shortening of the cytoskeletal filaments.
		The kinesin proteins moving over microtubules.
		The actin and myosin filaments sliding over each other.

2.5 points

QUESTION 39

The assembly and disassembly of microtubules is regulated by rate of growth and shrinkage of the plus end.

True

False

2.5 points

QUESTION 40

The functions of Golgi complex include:

	1.	O-linked oligosaccharides and most of a cellâs complex polysaccharides are assembled in Golgi complex
	2.	Cis Golgi complex sorts proteins
	3.	Trans Golgi complex segregates proteins in different types of vesicles for dilevery.
	4.	N-linked oligosaccharides are further processed in Golgi complex

ochrecoyote721

1. Name two similarities and two differences between thecellular processes of importing

protein into the ER and importing protein to the nucleus.

2. What proteins are directly involved in the transportation ofcargo in a clathrin-coated

vesicle?

a. Dynamin

b. Adaptins

c. Cargo receptors

d. t SNARES

3. Suppose a cell was treated with colchiine, a drug causingmicrotubule disassembly.

What would happen within the cell? Why?

Suppose there were a genetic defect in the genes that code forkinesins and dyneins.

What would happen within the cell? Why?

4. Which of the following are true about microtubules?

a. They are utilized by the disease causing bacteriaLysteria.

b. Instability in the minus-end of the microtubule is caused bythe hydrolization of GTP.

c. Centrosomes contain binding sites for microtubules composed atype of tubulin ring.

d. Cellular concentrations of tubulin are above the criticalconcentration for plus-end

polymerization.

e. Motor proteins can attach organelles to the microtubules.

5. Indicate which of the following statements are false:

a. Membrane fusion is energetically unfavorable and thusrequires ATP or similar high

energy molecule to occur

b. Clathrin is responsible for capturing specific molecules fortransport in coated vesicle

structures.

c. Receptor proteins that are incorporated into an endosome canbe retrieved back to the

membrane domain it originated from; can return to a new domainof the membrane; or

can enter the lysosome for digestion.

d. Transport vesicles occasionally bud from the trans Golginetwork to fuse with the

plasma membrane in a process called constitutive exocytosis.

e. Most components of the endocytic vesicle membrane eventuallyare returned to the

plasma membrane for reuse.

6. Match the following organelles with their function:

Organelle Bank:

a. Mitochondria

b. Endoplasmic reticulum

c. Nucleus

d. Lysosome

e. Endosome

f. Peroxisome

g. Golgi apparatus

_____ quality control of mRNA

_____ location of oxidative phosphorylation

_____ responsible for detoxifying organic molecules (livercells)

_____ houses and protects genetic material

_____ responsible for modification and sorting of proteins andlipids

_____ location of ATP synthesis

_____ responsible for sorting endocytosed materials

_____ site of degradation and digestion

_____ responsible for oxidizing toxic molecules

_____ location of lipid synthesis

_____ location of hormone synthesis (adrenal cells)

B. Which organelle(s) from the above list communicate(s) withother organelle(s)

through the use of vesicular transport? ________________

C. Which organelle(s) from the above list receive proteins madein the

cytosol?___________________

D. Through which organelle(s) must proteins pass to reach theorganelle(s) which do not

receive proteins made exclusively in thecytosol?______________

E. Entrance into which organelle(s) requires that proteinsunfold and snake through the

membrane? _________________

F. How do organelles maintain their position in the cytosol? Bespecific.

G. Give 2 advantages that eukaryotic cells gain by havingorganelles.

7. Which of the following statements are true regardingactin?

a. They are arranged in a

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Biology 2382B Lecture Notes - Lecture 4: Secretion, Differential Centrifugation, Signal Recognition Particle

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