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CELL DIVISION
*Cell Life Cycle: Series of changes a cell goes through from time it is formed until it divides
-Cycle has three major phases:
1. Interphase: Cell grows and carries on normal metabolic functions; longest phase; majority of cell’s life
spent here
2. Mitosis: Cell reproduces itself; get two daughter cells
3. Cytokinesis: Cell’s cytoplasm divides, creating a new cell
-Prior to cell division, must always have a duplication of genetic material  DNA Replication
Chromosome: Structure that contains genetic material passed from generation to generation
Chromatin: Relaxed form of DNA in cell’s nucleus
*Interphase: Has 3 stages
-G1: protein synthesis occurs; carrying out normal cell functions
-S: chromosomes replicated (DNA Replication)
-G2: chromosomes shorten and coil; protein synthesis in high gear
*Phases of Mitosis
-Cells undergo mitosis as they approach the maximum cell size at which the nucleus can provide blueprints
for proteins and the plasma membrane can efficiently transport nutrients out of the cell
*1. Prophase: Long, stringy chromatin coils up into visible chromosomes
-Each duplicated structure is made up of two halves
Sister Chromatids: Two halves of the double structure
-Held together by Centromere: Plays a role in chromosome movement during mitosis
-Near late prophase nucleus and nucleolus disappear
Centriole: Small, dark cylindrical structures made of microtubules located just outside the nucleus
Spindle: A football-shaped, cage-like structure consisting of thin fibers made of microtubules
*2. Metaphase: Short phase
Chromosomes are pulled and line up at middle of spindle (“Think middle”)
*3. Anaphase: Chromatid pairs from each chromosome move away from each other; get separation
of sister chromatids (“Think away”)
-Centromeres split apart
*4. Telophase: Two distinct daughter cells are formed; final stage of mitosis
-Nucleus and nucleolus reappear
-Chromosomes uncoil
-Still need separation of cytoplasm to finish division  Cytokinesis