BIO315H5 Lecture Notes - Lecture 4: Phagocytosis, Cell Membrane, Hydrolase

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grayimpala213

23 Oct 2017

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Use figure 13. 3 to explain how proteins are transported from the tgn to endosomes. The proteins are tagged with m6p added in the cgn (shown in figure 13. 44). The golgi recognizes hydrolases for tagging through amino acid signals. Memorize figure 13. 44 the structure of mannose 6 phosphate on a lysosomal hydrolase. M6p receptors are retrieved into vesicles from endosomes to tgn for reuse (seen in figure. Some m6p receptors take a detour to the plasma membrane. It recaptures escaped lysosomal hydrolases through the default path and returns them by receptor-medicated endocytosis. Explain figure 13. 45: the transport of newly synthesized lysosomal hydrolases to endosomes. Give an overview of the lysosome: it is membrane enclosed, it has an acidic interior environment i) due to h+ atpases. It uses atp energy to pump h+ to maintain acidity. This also provides energy for transporting small molecules across the membrane.

Related Questions

5 A) Which of the following statements about apical and basolateral protein sorting is FALSE?

Transcytosis is a mechanism for the movement of basolaterally secreted proteins to the apical membrane.

Infection of epithelial cells with specific viral proteins has helped elucidate the mechanisms of polarized protein secretion.

GPI-linked proteins are sorted specifically to the apical membrane of most polarized epithelial cells.

Vesicles that bud from the trans-Golgi network travel specifically to the apical membrane.

5 B) How does lysosomal pH contribute to lysosomal protein sorting?

Lysosomal proteins only properly fold at the acidic pH found in the lysosome.

Acidic pH is required for fusion of clathrin-coated vesicles with the lysosomal membrane.

Clathrin/AP1 vesicles that travel to the lysosome have a high affinity for lysosomal membranes due to their low pH.

The mannose-6-phosphate receptor has altered affinity for M6P under acidic pH conditions.

sapphireeagle929

The vesicles that transport materials from donor membranes to acceptor membranes include:

	1.	COP-II coated vesicles
	2.	COP-III coated vesicles
	3.	COP-I coated vesicles
	4.	Clathrin coated vesicles

2.5 points

QUESTION 11

During skeletal muscle contraction, the roles of ATP include:

	1.	ATP is not required for forming the crossbridges between myosin and actin filaments.
	2.	ATP is utilized as a structural linker to mediate the interaction between myosin and actin filaments
	3.	Hydrolysis of ATP provides energy for myosin head to move along actin filaments and the binding of ATP to myosin head allows the detachment of myosin fromactin filaments.
	4.	ATP binds to actin filaments to drive the power stroke of myosin head.

2.5 points

QUESTION 12

One of the functions of smooth endoplasmic reticulum is

	1.	Synthesizing steroid hormone in the endocrine cells of the gonad and adrenal cortex
	2.	Serves as the starting point of the biosynthetic pathway
	3.	Synthesizing secretory proteins
	4.	Degrading cell debris

2.5 points

QUESTION 13

The function of COP-II coated vesicles is mainly:

	1.	Transporting materials from endosomes to Golgi complex
	2.	Moving materials from the ER to the ERGIC and Golgi complex.
	3.	Transporting materials from Golgi complex back to endoplasmic reticulum.
	4.	Involved in receptor-mediated endocytosis.

2.5 points

QUESTION 14

Which of the following processes is completed in rough endoplasmic reticulum?

	1.	Chaperones help misfolded proteins fold correctly.
	2.	Proteins that target to nucleus are synthesized in rough endoplasmic reticulum.
	3.	O-linked glycosylation occurs in rough endoplasmic reticulum.
	4.	Misfolded proteins are destructed in rough endoplamic reticulum.

2.5 points

QUESTION 15

Kinesin is the motor protein that coorporates with microtubules. It has the following functions:

	1.	It uses GTP as energy source.
	2.	It can hydrolyze ATP and use the energy to drive cargo along microtubules from minus end to plus end.
	3.	It has a globular head that can act as GTPase
	4.	The tail of kinesin is more diverse and binds to cargo

2.5 points

QUESTION 16

For correct segregation and trafficking, lysosomal proteins are tagged in the cis-Golgi with phosphorylated mannose residues, and then the tagged lysosomal enzymes are recruited to clathrin coated vesicles by mannose 6-phosphate receptors.

True

False

2.5 points

QUESTION 17

The process that specialized cells, such macrophages, engulf relatively large particles is:

	1.	Called pinocytosis
	2.	Called phagocytosis
	3.	Mediated by COP-II coated vesicles
	4.	Called autophagy

2.5 points

QUESTION 18

Proteins synthesized on rough endoplasmic reticulum and smooth endoplasmic reticulum are imported co-translationally to their destinations

True

False

2.5 points

QUESTION 19

Treatment of cells with a drug that promotes microtubule disassembly disperses Golgi complex into separate stacks of membrane compartments, suggesting that:

	1.	Golgi complex is made of microtubules.
	2.	Microtubules are important for the organization of Golgi complex.
	3.	Microtubules are transported into Golgi complex
	4.	Golgi complex is composed of tubulin proteins

2.5 points

QUESTION 20

Which of the following is correct about signal sequence of a secretory protein?

	1.	It is an âaddress codesâ for protein trafficking pathways
	2.	It is usually located at the C-terminus.
	3.	It targets the ribosome and the protein that is being synthesized to endoplasmic reticulum.
	4.	It is removed in Golgi complex.

apricotgrasshopper117

BIO315H5 Lecture Notes - Lecture 4: Phagocytosis, Cell Membrane, Hydrolase

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