Biology 2382B Lecture Notes - Thymosin, Myosin, Polymerization

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beigereindeer807

12 Mar 2014

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Actin filaments microfilaments: cortical function, cell shape and movement. Tubulin is the thickest cytoskeletal component, microfilaments actin are the thinnest. Tubulin forms long tubes that are unbranched and straight. Actin is different in that it can form branches. Actin vs. microtubules: actin can form networks and bundles, mts can somewhat form bundles (e. g. , in nerve axons, maps), but they usually do not, actin bundles are quite common (e. g. , microvilli, actin can branch out into networks. Actin always has a on one side, cleft on the other side when these molecules polymerize, cleft is always in the same position. Polymerized actin is a double helix (goes from monomer to filament) and has polarity (-) end where the cleft is present, (+) end where the cleft is not present. Polarity allows for independent regulation of actin assembly or disassembly ( decorated with myosin s1) Adding s1 myosin can bind to and give it a distinct, arrowhead pattern ( decoration )

Related Questions

7 questions could use some help on for Molecular Biology. Pleasehelp. Just answers will do (I'll figure out), but wouldn't mindexplanations. If answered correctly 5 star guarantee & goodattempt definite 'best answer'. Thanks!

Question1

Which of the following cytoskeletal components is thelargest?

Microtubules
Microfilaments (actin)
Intermediate filaments

Question2

During mitosis, all microtubules emanate from the centrosome.Therefore, the centrosome is an example of:

a microtubule organizing center (MTOC)
A +TIP protein
A catastrophin
A monomer sequestering protein

Question3

Tubulin is a G-protein. It can stabilize microtubules when boundto which of the following?

GDP
GTP
Either GTP or GDP
Neither GTP nor GDP

Question4

In the formation of microtubules, dimers are built when analpha-tubulin protein binds to a beta-tubulin protein. This is anexample of what level of protein structure?

Primary structure
Secondary structure
Tertiary structure
Quartenary structure

Question5

Different tissues in the body express slightly differentversions of alpha tubulin. Which of the following could lead toslightly different alpha-tubulin molecules with a modified proteinsequence?

One tissue has more DNA methylation upstream of thealpha-tubulin gene.
One tissue has more miRNAs produced than the other.
One tissue uses different splice sites than the other.
One tissue has different trans-elements than the other.

Question6

How is confocal microscopy different from traditionalfluorescent microscopy?
The molecules are labelled red instead of green.
The molecules are observed over time.
The molecules are observed in many thin planes, which are thenstacked together to create a crisper image.
The confocal microscope has higher objective power than regularfluorescent microscopes.

Question7

Taxol is a chemotherapy drug that permanently stabilizesmicrotubules and prevents their degradation. Describe howmicrotubules are typically destroyed and why permanentstabilization would kill dividing cells. Note: you may need toreview the basics of cell mitosis from a previous course.

ultramarinepig913

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

Biology 2382B Lecture Notes - Thymosin, Myosin, Polymerization

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