Mitosis

my toes sis

Mitosis

a type of cellular reproduction where a cell will produce an *identical copy* of itself with the same number and patterns of genes and chromosomes.

Why do cells go under mitosis

* Repair damages


* Regenerate lost parts
* Grow in size
* Reproduce asexually
* Produces body cells (biggest difference between mitosis and meiosis)

**Interphase**

cells metabolic activity is very high and keeps growing and copying it DNA and organelles so it can divide

What are the stages of Interphase?

* Gap 1 (G1)
* Synthesis (S Phase)
* Gap 2 (G2)

**Mitotic phase**

the splitting of the nucleus

**Prophase**

* Spindles form from 2 centrosomes
* They start to travel to opposite ends (poles of the cell)
* Nuclear membrane starts to break apart

**Prometaphase**

* Nucleoli and nuclear membrane disappears
* Spindle is almost ready to provide a scaffold for the chromosomes to travel
* Chromosomes attached to the spindle of their kinetochores-- a protein structure at the centromere region of the sister chromatids

**Metaphase**

* Spindle is completely formed
* Chromosomes align on the Metaphase plate (middle)

**Anaphase**

Sister chromatids separate from each other from the centromere and are pulled to the 2 poles by the spindle fibers (opposite ends)

**Telophase**

* Cell elongation continues
* Nuclear envelope reappears
* Nucleolus reappears

**Cytokinesis**

the splitting of the cello

**Cell Cycle Control System**

chemical signals that must be checked before mitosis can start

What cells do not get a signal to proceed in mitosis?

Nerve and muscle cells

**G0 Phase**

a phase where cells get stuck due to their non-dividing properties

**Stem cells**

create new cells that are not stuck in the G0 phase

**Embryonic stem cells (pluripotent)**

found in the blastocysts of developing embryos, embryonic stem cells and can turn into any type of cell

**Adult stem cells (multipotent)**

acts as a repair system by maintaining the turnover of regenerative organs, such as blood, skin or intestinal tissue

**Contact inhibition**

cells grows and reproduce until they touch each other and then the cell cycle control system signals them to stop

What happens if contact inhibition does not work?

the cells (cancer) turns into masses called tumors which are non-responsive to the cell cycle control system

Cytokinesis in animal cells

forms a contractile ring

rings for a cleavage ;) furrow and splits the cytoplasm into two

Cytokinesis in plant cells

vesicles containing the materials of the cell wall collect in the center of the cell to fuse together creating a **cell plate**

order of mitosis

prophase → prometaphase → metaphase → anaphase → telophase

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*note these phases are NOT considered a part of mitosis:*

* **interphase**: occurs BEFORE mitosis
* **cytokinesis**: occurs AFTER mitosis