Cell Division & Mitosis (Science 7) PDF

The Cell Cycle & Mitosis Ms. Amilicia Science 7 What is a Cell? Cells are the basic building blocks of life. Every living organism is made up of one or more cells. Cells are made up of many individual organelles working together to perform a specific funct...

The Cell Cycle & Mitosis Ms. Amilicia Science 7 What is a Cell? Cells are the basic building blocks of life. Every living organism is made up of one or more cells. Cells are made up of many individual organelles working together to perform a specific function. They are found in every part of an organism. The Cell The Basic Unit of Life Cell Division Why is it important? growth replace worn out or dead cells reproduce themselves The Cell Cycle Living organism life cycle begins with… * organism’s formation * growth and development * Death Length of Cycle NOT THE SAME IN ALL CELLS EX: bean plants= 19 h to complete embryos= less than 20 min. some human cells= 16 h * Skin cells and bone cells constantly repeat the cycle for repair, growth, or replacement Stages of Cell Cycle TWO main stages Interphase and Mitosis Interphase MOST of a cell’s life is spent in this stage * period of growth and development Interphase 3 phases * G1 (Gap phase) * S (synthesis) * G2 (second gap phase) G 1 (Gap phase) Cell grows larger (double in size) cell functions organelles duplicate S phase (synthesis) DNA in nucleus is copied ( chromosomes duplicated) ****Chromosomes contain hereditary information of cell**** G 2 phase (second gap) Cell grows more prepares for CELL DIVISION (MITOSIS) CELL CYCLE Mitosis ♦ Process in which the cell divides to produce two identical cells ♦ two cells are called daughter cells Chromosomes ***VERY IMPORTANT*** contain the genetic material that is passed on to the daughter cells Chromosomes are found in the nucleus During INTERPHASE, each chromosome duplicates  Chromosome --> Chromatid each duplicate chromosome coils tightly into two thickened identical strands called chromatids two strands of identical DNA stands are held together by centromere Steps of Mitosis Prophase Metaphase Anaphase Telophase  Prophase The pairs of chromosomes are visible Two small structures called centrioles move to opposite ends of the cell A thread like spindle fiber forms between the centrioles and stretches across the cell  Metaphase pairs of chromatids line up across MIDDLE of cell (center) centromere of each pair becomes attached to two spindle fibers (one for each side of cell)  COWBOY CENTRIOLES (metaphase) COWBOY uses a rope to lasso something CENTRIOLE uses spindle fibers to lasso the chromatids around their centromere (middle section)  Anaphase centromere divides spindle fibers shorten chromatids separate & move to OPPOSITE ENDS of the cell Give me an A for Anaphase! chromatids are shaped like an A on its side Ex: < > Telophase Spindle fibers start to disappear chromosomes uncoil new nucleus forms Cytokinesis separation of cytoplasm TWO DAUGHTER CELLS formed Daughter cells begin cycle Amoeba Sisters