Question

The neuronal and muscle cells are full of cytoskeletal proteins.

a) The first part of this question is to thoroughly compare and contrast the microfilaments and microtubules.

Include the following in your comparison:

the subunits; how the subunits are activated; their motor proteins (including any directionality differences); the filament/tube structures (at least one similarity and one difference); one protein(s)/complex/factor for each that is required to join the subunits into filaments at the proper location in the cell; their role in cell motility; their role in cell division; their role in intracellular transportation; at least three additional proteins (not mentioned in earlier comparisons) that connect, assist, modulate, or otherwise affect these filaments/tubules; their primary locations in the cell. Point form is perfectly acceptable.

b) Now, compare intermediate filaments to these other two for 4 (only four) of these characteristics listed above. It is your choice as to which four to compare. Include at least one similarity and one difference, but the other two can be your choice (similar or different).

Answer 1

Microfilament-

microfilament are the polymer of actin . which is abundant protein in animal cells. in a vertibrate there are several different gene product of which a actin is found in muscle.

All actin type the monomeric soluble form is called G-actin. actin filament have insert minus end,and a growing plus end to which new monomer are added. G-actin contains ATP and this become hydrolysed to ADP i.e Adenosine diphosphate shortly after addition to filament. As with tubule a rapidly growing filament will bear an ATP cap which stabilised the Plus end . microfilament are often found to undergo treadmilling such that monomer are continuously added to plus end and remove from minus end while leaving the filament at same overall length.

Microfilament are formed When globular actin monomer polymerised in to filamentous actin polymer.the rate of polymerisation is regulated by calcium ATP, camp, and actin bonding protein.All cell contains actin filament through proportion may Vary.

in Cintractile apparatus of straighted muscle myosin head binds with actin filaments.when associated ATp is dephosphorylated ,the myosin heads bend to cause sarcomere shortening and thus muscle contraction.

Microtubule -

microtubule are cellular components that are required for a variety of essential process such as cell motility, mitosis, and intracellular transport.

microtubule are highly dynamic constituent of cytoskeleton.their dynamic property are tightly regulated by cellular MAPs.and modulated in Variety of ways by microtubule targeted drugs. microtubule vary considerably in stability.microtubule in axonemes of eukaryotic cillia and flagella are stable for day to week.cytoplasmic microtubule turn over much more rapidly with in minutes during interphase and tens of seconds in mitotic spindle. these dynamic microtubule randomly undergo period of rapid.