Cell Cycle: Mitosis How you got from one to trillions!!

Cell Cycle Interphase Longest phase (94%) G1: Cell growth S: Replication of DNA G2: Growth for division of cell Mitosis Division of nucleus and chromosomes Cytokinesis Division of cytoplasm and organelles into two daughter cells.

Mitosis Cell Basics Somatic (body) cells. Diploid (2n): one chromosome from each parent. (n=23) Duplicated chromosomes have 2 sister chromatids. Attached at centromere in the middle. Both are called chromosomes!!

Mitosis Responsible for: Growth and replacement Repair Asexual Reproduction

Interphase Resting period. Nerve and muscle cells rarely or don’t divide. Cancer cells continually divide. Most important: DNA replication while chromatin. S phase.

Interphase

Prophase 1st stage of mitosis Preparation Chromosomes condense. Nuclear membrane and nucleolus disappear. Spindle forms: spindle fibers from centrioles.

Prophase

Metaphase 2nd stage of mitosis Meet in the Middle. All chromosomes are lined up at the middle, also called the equator. Spindle fibers are attached to the centromeres, one from each centriole. Equal pulling from opposite sides.

Metaphase

Anaphase 3rd stage of mitosis Moving away Centromeres split. Sister chromatids are pulled to opposite poles by spindle fibers. Each is now considered a chromosome. Two diploid cells are forming.

Anaphase

Telophase 4th stage of mitosis Two nuclei. Chromosomes change to chromatin. Nuclear membrane reforms. New nucleoli form. Cytokinesis is usually happening at the same time as telophase.

Telophase

Cytokinesis Cell membrane and cytoplasm division. Plant cells have a cell plate that forms between the new nuclei. Animal cells have a cleavage furrow. Two new diploid daughter cells.

Video Quiz Let’s see how well you know your mitosis!!

Cell cycle s ignals Cell cycle controls  Cyclins  regulatory proteins  levels cycle in the cell  Cdks  cyclin-dependent kinases  phosphorylates cellular proteins activates or inactivates proteins  Cdk-Cyclin complex  triggers passage through different stages of cell cycle activated Cdk inactivated Cdk

Cyclins & Cdks Interaction of Cdk’s & different cyclins triggers the stages of the cell cycle Leland H. Hartwell checkpoints Tim Hunt Cdks Sir Paul Nurse cyclins 1970s-80s | 2001

Cdk / G 1 cyclin Cdk / G 2 cyclin (MPF) G2G2 S G1G1 C M G 2 / M checkpoint G 1 / S checkpoint APC Active Inactive Active Inactive Active mitosis cytokinesis MPF = Mitosis Promoting Factor APC = Anaphase Promoting Complex Replication completed DNA integrity Chromosomes attached at metaphase plate Spindle checkpoint Growth factors Nutritional state of cell Size of cell