BIOL 3530 Lecture Notes - Lecture 8: Phalloidin, Chromosome, Microfilament

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plumcamel14

29 Aug 2020

School

University of Windsor

Department

Biological Sciences

Course

BIOL 3530

Professor

Andrew Hubberstey

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Document Summary

Microtubules: it is really important to note the similarities and differences between actin and microtubules. And they only exist as monomer when the cell is being done initially. And they always exist as heterodimers other than that. These are the largest cytoskeleton elements in the cell and they are hollow tubes. In the same way that actin has polarity microtubules also have the same thing. Barbed end is the + end and the slow growing end. The + ends sticks out toward the far end of the cell. The end are inside a special complex call the mtoc, also found in centrosome. Microtubules form a spindle and attach to centromere to pull the chromosomes apart and this is the major function of them. This motc are found in the centrioles in the cytoplasm. And some microtubules (special type) are found in cilia, motcs begin the process of polymerization of all the tubules.

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

1. Kinesin-1 motors can move long distances on microtubule tracks without dissociating. By contrast, myosin II motors in skeletal muscle take only one or a few steps before letting go. What is most likely the difference between these two motors that allow two different types of movement?

A. Differences in length of the stalk of each respective motor allow for differences in step size

B. Differences in ATP versus GTP hydrolysis alter the motor head movement along filaments

C. Actin filaments are smaller in diameter and have less space for movement

D. Binding affinity of the Kinesin-1 motor head to microtubules is high, whereas binding affinity of the myosin II motor head to actin filaments is low

E. Microtubules are larger in diameter and have more space for movement

2. Dynamic instability causes microtubules either to grow or to shrink rapidly. What is the most likely reason for a microtubule to undergo rapid growth?

A. GTP hydrolysis exceeds the rate of heterodimer addition

B. GTP hydrolysis of alpha tubulin causes an outward bend in the heterodimer conformation

C. A low concentration of tubulin heterodimers are in solution

D. Heterodimer addition exceeds the rate of GTP hydrolysis

E. Increased trafficking of microtubule motor proteins favors stability

3. There are no known motor proteins that move on intermediate filaments (IFs). What property of intermediate filaments would most likely explain the lack of motor proteins?

A. Tissue specific expression of IFs prevent a single type of motor protein to evolve over time

B. Lateral bundling of IFs prevent motor movement

C. IFs are less dynamic than microtubules and actin filaments

D. IFs are unpolarized

E. IFs do not bind a nucleotide

4. You discover a mutation that results in less rapid hydrolysis of GTP by the beta-tubulin subunit. What would most likely occur?

A. There would be no change in filament assembly

B. There would be enhanced instability of the microtubule

C. There would be enhanced stability of the microtubule

D. Microtubules would not form

E. There would be enhanced treadmilling

5. Which of the following statements describes common features of cadherins and integrins?

A. They can link to microtubules using specific adapter proteins

B. They mediate heterophillic interactions

C. They achieve high binding affinity through clustering

D. They are responsible for interactions of a cell with the extracellular matrix

E. They are found in the apical plasma membrane of an epithelial cell

6. Intermediate filaments are uniquely non-polar and built by lateral bundling in five steps: 1) synthesis of an alpha-helical monomer, 2) formation of a coiled-coil dimer, 3) formation of a staggered tetramer of two coiled-coil dimers, 4) lateral association of 8 tetramers, and 5) addition of 8 tetramers to a growing filament. At what step is polarity lost?

A. Step 1

B. Step 2

C. Step 3

D. Step 4

E. Step 5

7. Collagenase is an enzyme that breaks peptide bonds in collagen to help destroy extracellular structures. What would be the most likely reason to use collagenase in a cell biology laboratory?

A. Disrupt cadherin interaction with the extracellular matrix

B. Disrupt cell-cell contacts to passage cells in cell culture

C. Dissociate epithelial cells from the underlying basement membrane to separate tissues

D. All of the answers are likely uses for collagenase

E. Lyse cells to expose intracellular proteins and organelles

yellowherring775

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

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BIOL 3530 Lecture Notes - Lecture 8: Phalloidin, Chromosome, Microfilament

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