Question

biochem help plz.

The balance between the association of actin monomers to form a filament and dissociation of monomers from the actin filament is a Myosin independent b. Myosin dependent c. ATP independent d.ATP dependent e. charge dependent QUESTION 2 Which statement about actin is correct? a Actin is expressed only in muscle b. Actin is expressed at low levels in most cells. GNo known function has been described for actin in nonmuscle cells. d. Nonmuscle cells only contain G actin. eActin is the most abundant cytoplasmic protein in many cell types QUESTION 3 Actin treadmiling describes the equibrium that allows actin monomers to associate and dissociate to produce F-actin filaments of different lengths. After hydrolysis of ATP actin monomers leave the filament through dissociation. How are F-actin polymers formed? a In the ADP bound state the actin subunits have a lower affinity for F actin, allowing G-actin monomers to be added to the () end of the filament. b. Affinity does not change whether in the ADP or ATP bound states and G-actin monomers will be added to the (e) end in either state. C In the ATP bound state the G-actin monomers have a high affinity for F actin, allowing monomers to be added to the () end of the filament d. Affinity of G-actin for F-actin does not change whether in the ADP or ATP bound states and monomers will be added to the () end in either state. e In the ADP bound state the G-actin monomers have a high affinity for F actin, allowing monomers to be added to the () end of the filament. O O

Answer 1

Ans.1) Option D : ATP dependent

Explanation : ATP hydrolysis leads to production of ADP +P_i and also energy is released . This energy is used in diassembly of F-actin, also ATP guides the whole process of F- actin polymerisation from G- actin. This process is called treadmilling.

Ans.2) Option E : Actin is the most abundant cytoplasmic protein in many cell types

Explantion: Actin is found in all eukaryotic cells and are invloved in wide range of cell function like cell division, intracellular transportation, etc.