Remember…. Cell Theory- 1.All living things are composed of one or more cells. 2.The cells is the basic unit of structure. 3.All cells come from preexisting cells.

Cell Theory #2 In Detail ORGANIZATION of LT –Cells -> Tissues –Tissues organize into organs –Multiple organs work together to for an organ system –All systems work together for survival of the organism

Why does a cell need to divide? IN GENERAL- All organisms grow and change Worn-out tissues are repaired or are replaced by newly produced cells.

Why does a cell need to divide? SPECIFICALLY: Cell Size Limitations 1.Diffusion: short distances = efficient; long distances = inefficient Think running 1/4mi vs. running 24 mi. 2.DNA: must be copied and made into protein to make necessities…can only be done so fast. Think about copying homework for 1 class in 5 minutes vs. 7 classes in 5 minutes

3.Surface Area-to-Volume ratio : volume will become to much for the PM’s surface area to handle. Think about a city growing, but no one builds new roads or bridges etc.= traffic jam

A Cell’s Life – Describe the cell cycle The Cell Cycle 1.Interphase – Longest Part of Cycle –“Growing Stage” - cell grows (G1, S, G2) –carries on metabolism, spends most of its time here. (G1, S, G2) –DNA is copied (S only)

A Cell’s Life – Describe the cell Cycle 2.Mitotic Phase a.) Mitosis : chromosomes divide b.) Cytokinesis: cytoplasm divides into 2

HONORS Chromatin - long strands of DNA wrapped around histones. Must copy DNA Supercoil to form chromosomes composed of two halves called sister chromatids: exact copies of each other held together by centromeres micro.magnet.fsu.edu/ cells/nucleus/images/chr...

How do cells reproduce/divide? a.) Mitosis- I. Prophase – –longest phase – Sister chromatids join –Nucleus (envelope and nucleolus) disintegrate mg.sparknotes.com/

8.2 Cell Growth and Reproduction Mitosis cont’ II. Metaphase – –Chromosomes pulled to the equator (middle) mg.sparknotes.com/

8.2 Cell Growth and Reproduction Mitosis cont’ III. Anaphase- –Chromosomes split and sister chromatids are pulled apart to opposite poles of the cell mg.sparknotes.com/

8.2 Cell Growth and Reproduction IV. Telophase - –Chromatids reach the opposite poles (ends),

What is Cytokinesis? b.). Cytokinesis - cytoplasm divides, cells separate into two daughter cells. mg.sparknotes.com/

Honors: What is cytokinesis? Animal cells: plasma membrane pinches in along the equator Plant cells: a cell plate is laid down across the cell ’ s equator and a cell membrane forms around each cell. New cell walls form on each side of the cell plate until separation is complete

What is the end result of Mitosis? Two identical cells that are identical to the original parent cell. –will carry out the same cellular processes and functions as those of the parent cell –will grow and divide too Specifically - Unicellular organisms = doubled number of organisms. Called asexual reproduction Multicellular organisms = growth = more tissue.

Can you find all the stages?