Objectives List and describe three main stages of
Objectives • List and describe three main stages of cell division • List and describe the four steps of mitosis • Explain the end result of cell division: two cells identical to the parent cell
Cell Division Overview Three Main Phases to Cell Division Interphase Mitosis Cytokinesis
Cell Reproduction • Cells spend the majority of time in what is called INTERPHASE • Interphase is a period of growth • Interphase can be broken into 3 parts: o. G 1 o. S o. G 2
Interphase • G 1 (Gap 1) o. Cell growth o. About 90% of a cell’s life • S (Synthesis) o. DNA is copied o 2 full sets of DNA • G 2 (Gap 2) o. Preparation for division
Cell Division Overview • Interphase: G 1, S, G 2 DNA duplicates, cell gets ready to divide • Mitosis • Cytokinesis
Mitosis • Mitosis is the process of cell division in which 1 cell divides into 2 cells… • Both cells are exactly like each other • Both cells are exactly like the original • Each having the same number of chromosomes as the original cell
Basics of DNA • CHROMATIN: DNA, uncondensed, • during Interphase CHROMOSOME: DNA condensed in Mitosis o Contains both copies (new and old) • CHROMATIDS: Each chromosome is made up of two sister chromatids o Each chromatid is one copy of the DNA o Two chromatids joined by a CENTROMERE
Basics of DNA • In Interphase the DNA is copied • During Interphase, you cannot • • distinguish individual DNA strands In Prophase the DNA condenses into this recognizable shape After condensing, you can see the DNA is this shape under a microscope
Steps of Mitosis • Interphase • Mitosis o. PROPHASE o. METAPHASE o. ANAPHASE o. TELOPHASE • Cytokinesis P. M. A. T.
Prophase • When a cell is in interphase, the DNA is • loose and not condensed (not coiled up) During mitosis, the DNA must be condensed so that it is not damaged during cell division
Prophase • 1. Prophase is when the DNA begins to • • condense 2. The nuclear envelope begins to dissolve 3. Spindle fibers start to form
Metaphase • The condensed and duplicated DNA moves to the center of the cell and lines up at the “equator” o “M” = middle
Metaphase • Spindle fibers attach to the DNA to the opposite poles of the cell • Spindle fibers are attached to the centromere of the DNA and the centriole o Organelle used during cell division • Getting ready to separate the two duplicate copies of the DNA
Anaphase • The spindle fibers that are attached to the duplicate copies of DNA, shrink up and pull the two copies of DNA to opposite sides of the cell o Separates the two sister chromatids
Anaphase • Now, this one cell has two complete copies of DNA • One is now at one end of the cell • The other copy at the other end of the cell
Telophase 1. A new nuclear envelope forms around each of the two sets of DNA 2. The spindle fibers dissolve 3. End of mitosis Opposite of Prophase
Cell Division Overview • Interphase: G 1, S, G 2 DNA duplicates, cell gets ready to divide • Mitosis: PMAT Duplicated DNA is split into two equal cells • Cytokinesis
Cytokinesis • Cytokinesis: cytoplasm divides and the two new cells separate • After DNA is separated into two equal nuclei, the DNA unwinds • The cell divides in half • End result is two identical cells
Cell Division Overview • Interphase: G 1, S, G 2 DNA duplicates, cell gets ready to divide • Mitosis: PMAT Duplicated DNA is split into two equal cells • Cytokinesis Physical splitting of 1 cell into 2
Mitosis Video
Cell Cycle & Mitosis Video
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