Cell Division 1 6 Cell Division Process were

Cell Division 1. 6

Cell Division �Process were one cell nucleus divides into two genetically identical nuclei.

Cell Cycle �Series of steps cells go through. �Includes G 1, S, G 2, & M. �G 1, S, G 2 make up interphase. �If a cell does not divide, it is in G 0.

THE THREE PARTS OF INTERPHASE G 1 – CELL GROWS AND FUNCTIONS NORMALLY (PROTEIN SYNTHESIS / MITOCHONDRIA REPLICATION ETC. ) 2. S – DNA IS COPIED. At this point the mass of DNA in the cell has doubled. 3. G 2 – CELL CHECKS ITSELF AND PREPARES TO ENTER MITOSIS 1.

Chromosomes �Formed by DNA in the nucleus supercoiling around histones (proteins) with enzyme help. �Have a centeromere and telomeres.

Mitosis �M phase of mitosis. �Cell divides into two new cells over 4 distinct phases.

Prophase � 1 st stage. �Chromosomes are visible for the first time in structures called sister chromatids. �Nuclear membrane breaks down.

Centrioles - the main microtubule organizing center Mitotic Spindle microtubules – cytoskeleton that pulls apart chromosomes

Metaphase �SPINDLE MICROTUBLES – LINE UP THE SISTER CHROMATIDS AT THE EQUATOR

Anaphase �Sister chromatids split at centromeres, and individual chromosomes move to opposite poles of the cell.

Telophase �Chromosomes reach the poles, nuclei start to form at opposite poles. Chromosomes relax into chromatin fiber.

Cytokinesis �Happens after mitosis. �Division of cytoplasm. �Differs in plants and animals.

Animal Cytokinesis �Cytokinesis occurs by the cytoplasm pinching inwards forming a cleavage furrow.

Plant Cytokinesis �Vesicles move towards the center of cell and fuse to form plasma membrane. �More vesicle move pectin out (exocytosis) of the membrane forming middle lamella. �Both cells deposit cellulose reforming the cell wall.

Purposes of Mitosis Growth: multicellular organisms increase their size This growth involves increasing the number of cells through mitosis. These cells will differentiate and specialize their function. Embryonic Development Tissue Repair: As tissues are damaged they can recover through replacing damaged or dead cells. Asexual Reproduction: the production of offspring from a single parent using mitosis. offspring are genetically identical to each other and to their “parent”

Cyclins �Family of proteins that help regulate the cell cycle. �Bind to proteins called cyclin dependent kinases. �Kinases bind phosphates to other proteins, making them carry out processes for each specific phase.

Tumors �Abnormal group of cells. �Benign tumors= tumors that stick together. �Malignant tumors= tumors who can spread. �Diseases caused by malignant tumors are called cancers.

Cancer �Involves a change in genes. �Oncogenes control cell division, mutation of these leads to uncontrolled cell growth. �Chemicals, viruses, and radiation that can cause cancer are carcinogens.

�If one tumor moves and forms secondary tumors, this is called metastasis.