The drug vinblastine is used in cancer therapy to stop the runaway division of cancer cells. Vinblastine inhibits the assembly and growth of microtubules. Explain how the action of this drug prevents mitosis (refer to Figure 2.17). Figure 2.17Mitosis is the process of nuclear division in which the chromosomesare distributed to two daughter nuclei. Together with cytokinesis, itproduces two identical daughter cells.InterphaseEarly ProphaseLate ProphaseCentrosomes (each-has 2 centriolos)Early mitoticspindleSpindlepoleNonkinetochore microtubule-PlasmamembraneFragmentsof nuclearenvelopeAsterNucleolus- Chromatin- CentromereChromosomeNuclearenvelopeconsisting of twosister chromatidsKinetochore- KinetochoremicrotubuleInterphaseProphase-first phase of mitosisInterphaseInterphase is the period of a coll's life when itEarly Prophase• The chromatin coils and condenses, formingbarlike chromosomes.Late Prophase• The nuclear envelope breaks up, allowing thespindle to interact with the chromosomes.• Some of the growing spindle microtubulesattach to kinetochores (ki-ne' to-korz), specialprotein structures at each chromosome'scentromere. Such microtubules are calledkinetochore microtubules.carries out its normal metabolic activities andgrows. Interphase is not part of mitosis.• Each duplicated chromosome consists of twoidentical threads, called sister chromatids, heldtogether at the centromere. (Later when thechromatids separate, each will be a newchromosome.)• As the chromosomes appear, the nucleolidisappear, and the two centrosomes separatefrom one another.• During interphase, the DNA-containingmaterial is in the form of chromatin. Thenuclear envelope and one or more nucleoli areintact and visible.• The remaining (unattached) spindlemicrotubules are called nonkinetochoremicrotubules. The microtubules slide pasteach other, forcing the poles apart.• The kinetochore microtubules pull on eachchromosome from both poles in a tug-of-warthat ultimately draws the chromosomes to thecenter, or equator, of the cell.• There are three distinct periods of interphase:G1, S, and G2.• The centrosomes act as focal points forgrowth of a microtubule assembly called themitotic spindle. As the microtubules lengthen,they propel the centrosomes toward oppositeends (poles) of the cell.• Microtubule arrays called asters ("stars")extend from the centrosome matrix.The light micrographs show dividing lung cells froma newt. Fluorescent markers color cell structures.The chromosomes appear blue and themicrotubules green. (The red fibers are intermediatefilaments.) The schematic drawings show details notvisible in the micrographs. For simplicity, only fourchromosomes are drawn. MetaphaseAnaphaseTelophaseCytokinesisNuclear-Nucleolus formingContractileenvelopeformingring atcleavagefurrowSpindleMetaphaseplateDaughterchromosomesMetaphase second phase of mitosisAnaphase-third phase of mitosisTelophase-final phase of mitosis• The two centrosomes aro at opposite poles ofthe cell.• The chromosomes cluster at the midline ofthe cell, with their centromeres preciselyaligned at the spindle equator. This imaginaryplane midway between the poles is called themetaphase plate.• At the end of metaphase, enzymes that willact to separate the chromatids from each otherare triggerod.The shortest phase of mitosis, anaphasebegins abruptly as the centromeres of thechromosomes split simultaneously. Eachchromatid now becomes a chromosome in itsown right.• The kinetochore microtubules, moved alongby motor proteins in the kinetochores,gradually pull each chromosome toward thepole it faces.• At the same time, the nonkinetochoremicrotubules slide past each other, lengthen,and push the two poles of the cell apart.• The moving chromosomes look V shaped.The centromeres lead the way, and thechromosomal "arms" dangle behind them.• Moving and separating the chromosomes ishelped by the fact that the chromosomes areshort, compact bodies. Diffuse threads ofchromatin would trail, tangle, and break,resulting in imprecise "parceling out" to thedaughter cells.TelophaseTelophase begins as soon as chromosomalmovement stops. This final phase is likeprophase in reverse.• The identical sets of chromosomes at theopposite poles of the cell begin to uncoil andresume their threadlike chromatin form.•A new nuclear envelope forms around eachchromatin mass, nucleoli reappear within thenuclei, and the spindle breaks down anddisappears.• Mitosis is now ended. The cell, for just a briefperiod, is binucleate (has two nuclei) and eachnew nucleus is identical to the original mothernucleus.Cytokinesis-division of cytoplasmCytokinesis begins during late anaphase andcontinues through and boyond telophase. Acontractile ring of actin microfilaments formsthe cleavage furrow and pinches the cell apart.

Question

The drug vinblastine is used in cancer therapy to stop the runaway division of cancer cells. Vinblastine inhibits the assembly and growth of microtubules. Explain how the action of this drug prevents mitosis (refer to Figure 2.17). Figure 2.17Mitosis is the process of nuclear division in which the chromosomesare distributed to two daughter nuclei. Together with cytokinesis, itproduces two identical daughter cells.InterphaseEarly ProphaseLate ProphaseCentrosomes (each-has 2 centriolos)Early mitoticspindleSpindlepoleNonkinetochore microtubule-PlasmamembraneFragmentsof nuclearenvelopeAsterNucleolus- Chromatin- CentromereChromosomeNuclearenvelopeconsisting of twosister chromatidsKinetochore- KinetochoremicrotubuleInterphaseProphase-first phase of mitosisInterphaseInterphase is the period of a coll's life when itEarly Prophase• The chromatin coils and condenses, formingbarlike chromosomes.Late Prophase• The nuclear envelope breaks up, allowing thespindle to interact with the chromosomes.• Some of the growing spindle microtubulesattach to kinetochores (ki-ne' to-korz), specialprotein structures at each chromosome'scentromere. Such microtubules are calledkinetochore microtubules.carries out its normal metabolic activities andgrows. Interphase is not part of mitosis.• Each duplicated chromosome consists of twoidentical threads, called sister chromatids, heldtogether at the centromere. (Later when thechromatids separate, each will be a newchromosome.)• As the chromosomes appear, the nucleolidisappear, and the two centrosomes separatefrom one another.• During interphase, the DNA-containingmaterial is in the form of chromatin. Thenuclear envelope and one or more nucleoli areintact and visible.• The remaining (unattached) spindlemicrotubules are called nonkinetochoremicrotubules. The microtubules slide pasteach other, forcing the poles apart.• The kinetochore microtubules pull on eachchromosome from both poles in a tug-of-warthat ultimately draws the chromosomes to thecenter, or equator, of the cell.• There are three distinct periods of interphase:G1, S, and G2.• The centrosomes act as focal points forgrowth of a microtubule assembly called themitotic spindle. As the microtubules lengthen,they propel the centrosomes toward oppositeends (poles) of the cell.• Microtubule arrays called asters (&#34;stars&#34;)extend from the centrosome matrix.The light micrographs show dividing lung cells froma newt. Fluorescent markers color cell structures.The chromosomes appear blue and themicrotubules green. (The red fibers are intermediatefilaments.) The schematic drawings show details notvisible in the micrographs. For simplicity, only fourchromosomes are drawn. MetaphaseAnaphaseTelophaseCytokinesisNuclear-Nucleolus formingContractileenvelopeformingring atcleavagefurrowSpindleMetaphaseplateDaughterchromosomesMetaphase second phase of mitosisAnaphase-third phase of mitosisTelophase-final phase of mitosis• The two centrosomes aro at opposite poles ofthe cell.• The chromosomes cluster at the midline ofthe cell, with their centromeres preciselyaligned at the spindle equator. This imaginaryplane midway between the poles is called themetaphase plate.• At the end of metaphase, enzymes that willact to separate the chromatids from each otherare triggerod.The shortest phase of mitosis, anaphasebegins abruptly as the centromeres of thechromosomes split simultaneously. Eachchromatid now becomes a chromosome in itsown right.• The kinetochore microtubules, moved alongby motor proteins in the kinetochores,gradually pull each chromosome toward thepole it faces.• At the same time, the nonkinetochoremicrotubules slide past each other, lengthen,and push the two poles of the cell apart.• The moving chromosomes look V shaped.The centromeres lead the way, and thechromosomal &#34;arms&#34; dangle behind them.• Moving and separating the chromosomes ishelped by the fact that the chromosomes areshort, compact bodies. Diffuse threads ofchromatin would trail, tangle, and break,resulting in imprecise &#34;parceling out&#34; to thedaughter cells.TelophaseTelophase begins as soon as chromosomalmovement stops. This final phase is likeprophase in reverse.• The identical sets of chromosomes at theopposite poles of the cell begin to uncoil andresume their threadlike chromatin form.•A new nuclear envelope forms around eachchromatin mass, nucleoli reappear within thenuclei, and the spindle breaks down anddisappears.• Mitosis is now ended. The cell, for just a briefperiod, is binucleate (has two nuclei) and eachnew nucleus is identical to the original mothernucleus.Cytokinesis-division of cytoplasmCytokinesis begins during late anaphase andcontinues through and boyond telophase. Acontractile ring of actin microfilaments formsthe cleavage furrow and pinches the cell apart.

Accepted Answer

Mitosis is a process of cell duplication, in which one cell gives rise to two genetically identical…