M Phase of the Cell Cycle

in this lesson we'll be exploring the m phase of the cell cycle including mitosis and cytokinesis let's do a quick review of the cell cycle to see where they fit in the g1 s and g2 phases make up interphase and the m phase represents cell division cell division includes division of the nucleus called mitosis and division of the cytoplasm called cytokinesis mitosis is further broken down into four phases prophase metaphase anaphase and telophase prophase is the longest phase of mitosis prophase is when chromatin begins to condense into the shape of chromosomes and the nucleolus disappears the previously replicated dna coils tightly into sister chromatids for the first time you see individual chromosomes in the center of each chromosome a centromere attaches the sister chromatids together meanwhile in the cytoplasm microtubules known as spindle fibers begin to fan out from two sets of paired structures called centrioles the spindle fibers elongate as the centrioles begin moving to opposite sides or poles of the cell while this is happening the nuclear membrane surrounding the nucleus disappears now that chromosomes are no longer separated from the cytoplasm the opposite ends of the spindle fibers can attach to the centromeres next the cell enters metaphase the centrioles complete their movement to the poles of the cell while the spindle fibers line up the chromosomes along the equator of the cell the end-to-end alignment of chromosomes results in a sister chromatid on either side of the equator anaphase follows metaphase during anaphase spindle fibers separate the sister chromatids at their centromere once separated from each other each chromatid is called a chromosome the single-stranded chromosomes form a v-shape as the spindle fibers shorten and drag them through the gel-like cytoplasm the chromosomes move to opposite poles of the cell toward their centrioles it's common to confuse centrioles with centromeres which connect chromatids remember centrioles are at the poles telophase is the final stage of mitosis in telophase a nuclear membrane reforms around each set of chromosomes then the chromosomes spread out into chromatin and the nucleolus becomes visible once again mitosis the division of the nucleus is now complete the final step of the m phase is cytokinesis the division of the cytoplasm in animal cells cytokinesis occurs through the inward movement of the cell membrane this progressively pinches the cytoplasm until two identical daughter cells form in contrast plant cells can't pinch into because they have a rigid cell wall surrounding their cell membrane instead cell wall material assembles along the equator forming a structure called the cell plate the cell plate grows until it joins with the existing cell membrane separating the two halves of the cell into daughter cells over time new cell walls form between the two daughter cells here are the key points to remember the m phase is the fourth and final phase of the cell cycle during the m phase cell division occurs through two processes mitosis when the nucleus divides and cytokinesis when the cytoplasm divides mitosis has four phases during prophase chromatin condenses into chromosomes spindle fibers form and the nucleolus and nuclear membrane disappear during metaphase spindle fibers align the chromosomes along the cell equator in anaphase the spindle fibers separate sister chromatids into two separate groups of chromosomes pulling them toward the poles and in telophase the nucleolus and nuclear membrane reform the chromosomes disperse into chromatin cytokinesis is division of the cytoplasm the m phase is complete after cytokinesis occurs the m phase of the cell cycle always results in two daughter cells both of these daughter cells are identical to each other and identical to the original cell that underwent mitosis [Music] foreign

Channel: Nucleus Biology

Views: 884,622

Keywords: science, education, biology, video, high school, cell, nucleus, DNA, nucleolus, chromosomes, genetic, daughter cells, somatic cells, gametes, sex cells, chromatid, centromere, chromatin, deoxyribonucleic acid, division, reproduce, reproduction, M phase, mitosis, cytoplasm, cytokinesis, replication, prophase, metaphase, anaphase, telophase, centrioles, spindle fibers, cell membrane, cell plate, cell wall

Id: 5bq1To_RKEo

Length: 6min 6sec (366 seconds)

Published: Fri Nov 05 2021