BIO130H1 Chapter : Pg.1010-1022.docx

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BIO130H1 Full Course Notes

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Motor proteins: bind to cytoskeleton filament and move along actin/microtubule. They carry cargo and differ in the direction that they are moving. Motor proteins can carry membrane enclosed organelles such as mitochondrion, vesicles and golgi stacks. The motor proteins interact with filaments using their heads and hydrolyzes. Actin-based motor proteins are members of the myosin superfamily. Myosin ii: two heavy chains and two light chains; long amino acid sequence. Each myosin head binds and hydrolyzes atp. Many different types of myosin were discovered. All myosin move to the plus end of the actin filament except myosin vi. There are two types of microtubules motor protein: kinesin and dyneins. Kinesin: motor protein that moves along microtubules. Identified first in the axon of a squid. Has two heavy chains and two light chains. Most walk towards the plus end of the microtubule. Dynesin: minus end directed proteins of microtubules. 2 or 3 chains that vary in combination of light and dark chains.

Related Questions

Materials traffic through the endomembrane system of eukaryotic cells via vesicles. There are two coat proteins COP I and COP II that assemble vesicles for transport along microtubules. COP I coated vesicles undergo retrograde transport, for example, to move materials from the Golgi back to the ER. COP II coated vesicles undergo anterograde transport to move materials from the ER outward.

(1 pt) Which motor protein (myosin, kinesin or dynein) interacts with COP I vesicles? ______________

(1 pt) Which motor protein interacts with COP II vesicles? ______________

(1 pt) Some proteins that traffic in this system contain a KDEL amino acid signal sequence for retention in the ER that interacts with a KDEL receptor protein. Would you expect the KDEL receptor protein to be found associated with COP I or COP II coated vesicles? _________

sangriahedgehog950

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

1. Kinesin motors are highly processive, moving long distances on microtubule tracks without dissociating. In contrast, myosin motors in skeletal muscle cannot move processively, and take only a single step before letting go of the actin microfilament. Using complete sentences, describe the structural features of these two proteins that dictates the processive/non-processive movement cycles of these proteins. Then discuss the consequences if kinesin exhibited non-processive movement and myosin moved processively.

2. AMPPNP can be used to study microtubule (MT) motors as well as myosins. What effect would you predict on a sperm flagellum to which AMPPNP was added? In your explanation, please be specific about what moleculeâs function would be inhibited and what the effect on overall flagellar function would be.

sapphireherring638

BIO130H1 Chapter : Pg.1010-1022.docx

BIO130H1 Full Course Notes

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