Chapter 2 - Cells

Cell – smallest unit capable of carrying on

                          life’s functions                                                                        

                        Cell size and shape relates to its function:

                                    Ex.  Nerve cell – extensions for

                                                sending/receiving impulses

                                                Plant cell – long and hollow for

                                                transporting food and water

Cell Theory

1. All living things are composed of one or

             more cells.

      2. Cells are the basic unit of structure and function in an organism.

      3.  Cells come from pre-existing cells

Discovery of the Cell

1. Discovery of cells was made possible by the development of the microscope

2. Robert Hooke – English scientist who first observed thin slices of cork using

            a microscope; coined the term “cell”

      3.  Anton van Leeuwenhoek- Dutch microscope maker who was the

           first to observe living cells  (in pond water) using a microscope.

Two Cell Groups

1. Procaryotic – lacks membrane bound  structures                                                                                  
2. Eukaryotic – contains membrane-bound  structures

Cell Organization

1. Cell wall – grows, changes shape, and  

                    protects the cell

            Ex. Plants, algae, fungi, bacteria                                                                                   

2. Cell membrane –protective layer around the

            cell; allows materials (food, water, wastes, oxygen, etc.) to move in and out of the                    

            cell. 

3. Cytoplasm – gelatin-like substance in cell; many important chemical

            reactions occur here

            -contains the cytoskeleton which  helps the cell maintain its shape and

             move

            -organelles - membrane-bound structures that carry out various cell

              functions in the eukaryotic cell                                                

       4.   Nucleus – directs all of the cell’s activities

             a. genetic information – DNA

             b. chromomsomes – rod-shaped structures of DNA

             c. nucleolus – produces ribosomes                                                      

       5. Chloroplast – organelle that uses sunlight to produce sugar from H2O and CO2

            -contains the green pigment chlorophyll that captures sunlight to make sugar                                                                              

6. Mitochondria – produces the cell’s energy;  the “powerhouse”          

7. Ribosome – produces proteins; sometimes attached to the endoplasmic reticulum (ER)                                                                     

8. Endoplasmic reticulum (ER)- series of folded membranes used for storing, packaging,

    and transporting materials                 

            a. smooth ER – no ribosomes

            b. rough ER – contains ribosomes                                            

9. Golgi body- stacked, flattened membranes that sort and package

    proteins in vesicles

10. Lysosome – organelle containing chemicals used for digesting food and wastes

11.  Vacuole – storage compartment for food and water

       -in plants the vacuole holds large amounts of water

Levels of Organization

    1.  tissue – groups of cells carrying out a specific function

    2.  organ – groups of tissues (lung) carrying out a specific function

    3.  organ system – group of organs working together to carry out a

         specific function (respiratory system)