Eukaryotic Cell Cycle and Division Part 1

-DNA replicates (interphase) and condenses and splits (mitosis) and membrane splits (cytokinesis)
-growth/repair (multicellular), reproduction (single-celled)

-So that they are efficient when they travel across the cell during stages of mitosis

-Cell growth- cell increases in size and proteins and organelles get made

-In interphase - cell grows rapidly, builds new organelles; also performs regular cell functions

-growth and normal cellular functions

-The "synthesis" phase of the cell cycle; the portion of interphase during which DNA is replicated. (doubles each chromosomes)

-synthesis/replication of DNA (longest part of interphase)

-DNA Replication

-Final preparation phase. Cell checks for DNA errors and begins to form centrosomes. (Prepares for Mitosis)

-Preparation for mitosis- organelles and molecules required for cell division are produced

-growth and prep-other organelles (other than nucleus) divide, centrosomes form 2 centrioles

-chromatin condenses into chromosomes made of sister chromatids (exact replicas of each other) attached at centrosomes, nucleolus disappears, centrosomes move to opposite poles of cell and spindles/microtubules form

-1)Chromosomes become visible
2)Centrioles separate on either side of nucleus
3)Chromosomes get attached to spindle fibers and the site of centrioles


-the chromosomes coil up and become visible while the nuclear envelope disappears.
-Sister chromatids are present.
A centriole forms at each pole and spindle fibers made of microtubules grow out of it.
-Short microtubules stick out from the centriole in a star shape known as an aster.

-Prometaphase is the second phase where the microtubules begin to separate from each other, each pair of microtubules attach to the kinetochores and some nonkinetohore microtubules interact with those from the opposite pole of the spindle.

-Metaphase is the third phase where the chromosomes are lined up on the invisible line of the metaphase plate. Anaphase is the fourth phase where the two daughter chromosomes begin to separate from each other to opposite poles. Telophase is the last phase where the two daughter nuclei form creating two identical nuclei.

-Chromosomes line up single file at the middle of the cell
-second stage of mitosis in which motor protons pull sister chromatids to the cell's equator
-Centromeres of duplicated chromosomes are aligned at plate. Fully formed spindle attach to the sister chromatids from opposite poles
-Second phase of mitosis, during which the chromosomes line up across the center of the cell

-chromosomes line up on metaphase plate (spindles still connected to kinetochores on chromatids)

-enzyme cleaves/breaks kinetochores and sister chromatids are separated, microtubules pull chromatids towards each pole so each pole has a complete 2n set of chromosomes, nonkinetochore microtubules lengthen to elongate cell

-In this phase, the paired chromosomes separate and begin moving to opposite poles of the cell

-1)The Centromeres separate, allowing sister chromatids to separate and become individual chromosomes
2)Chromosomes move until they've separated in 2 groups near the pole of the spindle
*This phase ends when the centrioles stop moving

-2 nuclei form, 2 nucleoli reappear, chromosomes uncondense, microtubules break down end of mitosis (splitting of DNA)

-1)Chromosomes decondense
2)Nuclear envelope surrounds each cluster of chromosomes
3)Spindle starts to break apart
4)Nucleolus become visible in each daughter cell

-last stage of mitosis in which nucleoli reappear. Two new nuclear membranes begin to form, but the cell has not yet completely divided.

-animal cell membrane pinches at cleavage furrow, cytoplasm splits, 2 cells formed

-The division of the cytoplasm. When the cell membrane moves down and inward until the cytoplasm is pinched in 2 parts.

-the cytoplasm forms a cleavage furrow at the equator to split the cytoplasm. (in plants a cell plate forms at the equator.)

-In animal cells, the first sign of cytokinesis is the appearance of an indentation around the middle of the cell. The ring contracts like the pulling of a drawstring and pinches the parent cell in two. Because the two new nuclei are forming at the ends of the cell, cytokinesis results in two new cells.In cytokinesis a cell plate forms inside the cell and grows outward. Eventually this new piece of cell wall divides the cell in two. The result is two daughter cells, each bounded by its own continuous membrane and its own cell wall.

-48 (4 pairs or 4n)

-48

-24 (2n) in each new cell

-to conserve energy and to divide at appropriate times; cancer and skin cells not dividing during an injury

-internal and external factors regulate molecules that control events in the cell cycle happening