Biolab 3

• Cell division can be viewed as a cycle, which canbe arbitrarily, categorized into two stages namelyinterphase and mitosis
• The interphase, wherein the cell undergoes growth and prepares for cell division, comprises as much as 90% of the cycle
• Interphase: The genetic materials inside the nucleus appear as thin, thread-like structures appropriately called chromatin fibers. Within the nucleus can be found 1 to 2 nucleoli, which are dense, darkly stained bodies formed by several chromosomal materials that code for certain RNAs.
• Near the nucleus is the centrosome, which contains centrioles.
• Prophase: The chromatin fibers start to appear as coiled,thickened, condensed structure forming chromosomes that are visible under the light microscope. Centrioles are seen in the opposite poles. Locate ray-like microtubule bodies called asters radiating around each centrioles and mitotic spindles forming between centrioles. The nucleoli disappear at this stage
• Metaphase: The cell at this stage can readily be identified from the rest of the stages of mitosis in that the chromosomes are aligned at the equatorial region of the nucleus. At this stage, the replicated chromosomes, which are much shorter and more condensed, are known as sister chromatids. They are joined together at their central region called centromere. Closely associated with centromeres are kinetochores, protein complexes to which the spindle fibers are attached to.
• Anaphase: At this stage, look for a cell where the sister chromatids are separated and pulled apart toward the opposite poles. This stage is differentiated into early and late stages depending on the distance travelled by the chromatids. Once the sister chromatids separate, these are considered as daughter chromosomes reaching the opposite poles.
• Telophase: Look for a cell where a cleavage furrow, a constriction of the plasma membrane at the region of the equatorial plate, starts to appear. This is the start of early telophase. At this stage the nuclear membrane and the nucleolus start to reappear. The chromosomes begin to uncoil and assume a threadlike appearance. The asters and mitotic spindles disappear. At late telophase, the cleavage furrow becomes more constricted leading to the formation of 2 daughter cells
• Cytokinesis, which is the division of the cytoplasm, usually occurs along with telophase. Completely separated daughter cells are formed soon after mitosis
• Cell division - the process by which a single cell divides into two or more daughter cells, each with the potential to grow, develop, and carry out specific functions
• Cell division - it is a fundamental process in biology that is essential for the growth, repair, and reproduction of living organism
• Interphase GAP 1 - microscopic aspect, little change is visible, cell grows physically larger
• Interphase GAP 1 - biochemical aspect, more active, makes the molecular building blocks for later
• Interphase - the genetic materials inside the nucleus appear as thin, thread-like structures appropriately called chromatin fibers. The centrioles may not readily be seen.
• Interphase Synthesis Phase - DNA replication, formation of identical pairs of chromatin forming sister chromatids connected via centromere. Centrosome is duplicated (microtubule-organizing structure, help separate DNA during M phase)
• Interphase GAP 2 - cells grow more, make proteins and organelles, double checks the chromosomes for errors, begins to reorganize its contents in preparation for mitosis
• Prophase - the chromatin fibers start to appear as coiled, thickened, condensed structures of chromosomes, centrosomes migrates to opposite poles, nucleolus and nuclear membrane dissapear, asters radiate around each centriole
• Prophase - mitotic spindles form, capture chromosomes via the kinetochore
• Metaphase - spindle has captured all the chromosomes and lined them up at the middle of the cell, ready to divide
• Spindle Checkpoint - all the chromosomes are at the metaphase plate with their kinetochores correctly attached to microtubules, which helps ensure that the sister chromatids will split evenly between the two daughter cells
• Anaphase - the sister chromatids are separated and pulled apart toward the opposite poles
• Telophase - cleave furrow, a constriction of the plasma membrane at the region of the equatorial plate, starts to appear, nuclear membrane and the nucleolus start to reappear
• Telophase - the chromosomes begin to uncoil and assume a threadlike appearance, the asters nad mitotic spindles disappear, establish its normal structures
• Cytokinesis - division of the cytoplasm, occurs along with telophase, completely separated daughter cells are formed soon after mitosis