Unit 2 Notes -- Cells, Tissues, and Mitosis

Unit 2 - Cells and Tissues

• Cells
• Cellular Transport
• Mitosis

1. Cells

    

                                      

   1. Differ greatly in size and shape

1. 3 main parts of a cell

                 

    

1.  Plasma membrane - separates cell from tissue fluid

2.  Cytoplasm - found only in living cells

3.  Nucleus - Control center

Organelles - Cell organs

A.  Plasma Membrane

1. Forms outer boundary of cell
2. Made up of two layers of phospholipids (fat molecules containing phosphates)
3. Selectively permeable - Selects which materials are absorbed into and out of the cell

B.  Cytoplasm

1. Area between the plasma membrane and nucleus
2. Contains the organelles

1. Organelles
   1. Act like organs of the body by carrying out specific roles in the cell
      1. Endoplasmic reticulum

         

         • a.  Network of sacs and canals which carry proteins throughout the cytoplasm (miniature circulatory system)                     
           • 1)  Smooth ER - Synthesize fats
           • 2)  Rough ER - Manufacture proteins
             1. *  Smooth or Rough based on presence of ribosomes
      2. Ribosomes

         

         1. a.  Create proteins and enzymnes
         2. b.  Attached to ER or free in cytoplasm
      3. Mitochondria

         

         1. a.  Supply most of power for work
         2. b.  Uses O2 to break down glucose to create energy and heat (byproduct
      4. Lysosomes

         

         1. a.  “Digestive bags” which break down food compounds, old cell parts, and microbes which invade cell.
         2. b.  At times, enzymes break out of sac and destroy own cells (suicide bags)
      5. Golgi Apparatus

         

         1. a.  “Shipping center” of cell
         2. b.  Synthesize carbohydrates, combine it with proteins and transports it out of cell
      6. Centrioles

         

         1. a.  Paired organelles composed of fine tubules present only during cell division (Create spindle fibers in mitosis and meiosis)
         2.  
      7. Cilia (Microvilli)

         

         1. a.  Hair-like extensions of the plasma membrane capable of  wavelike movement
      8. Flagella

         

         1. a.  Single projection of cell surface
         2. b.  Larger than cilia
      9. Nucleus

         

         1. a.  Controls organelles
         2. b.  Responsible for triggering cell division
         3. c.  Nuclear membrane (envelope)
            1. 1)  Surrounds neoplasm (specialized cytoplasm)
            2. 2)  Contains nucleolus and chromatin granules (DNA)
         4. d.  Nucleolus
            1. 1)  Critical in protein production (creates ribosomes which migrate to cytoplasm)
2. Cellular Transport

                                                

   

   1. Passive Transport

       

      1. Movement of materials from high to low concentrations
      2.  Does not require energy
      3. Movement of materials occur until equal proportions are met on each side of membrane
      4. Types of Passive Transport
         1. a.  Diffusion - Substances scatter evenly throughout available space

             

             

             

            1. b.  Osmosis – Diffusion of water
            2. 
            3.  
            4. c.  Dialysis – Diffusion of solute (Things that dissolve in water)
            5. d.  Filtration- Movement of water and solutes by pressure
            6.  
            7. e.  Facilitated Diffusion -- Movement of materials through a membrane protein by passive transport
   2. Active Transport
      1. Movement of materials from areas of low concentration to high concentration
      2. Requires energy (ATP)
      3. Types of Active Transport
         1. a.  Exocytosis – releasing materials from a cell by active transport
            •                                                                                              
         2. b.  Endocytosis – Bringing materials into a cell by Active Transport
            1. 1)  Phagocytosis

               

               1. Used to bring in food and destroy bacteria
               2. Cell membrane engulfs material by forming a pocket around it, brought into cell, destroyed by lysosomes
            2. 2)  Pinocytosis
               1. Used to bring fluids into cell

Mitosis – Cell Division of Autosomes (Non-Sex-Cells)

​

1. Stages of Cell Division
   1. Can only occur after DNA has replicated itself.
   2. Involves the equal division of the cytoplasm, nucleus, and organelles.
   3. Results in “Two Daughter Cells”.
   4. Visible stages are preceded by a “resting phase” called interphase where DNA replicates itself, produces new organelles, and grows.
   5. 4 Main Stages
      1. 1.  Prophase

         

         • a.  Chromosomes in nucleus have formed 2 visible strands called chromatids which are held together by a centromere.
         • b.  Centrioles are moving to opposite poles and create spindle fibers.
         • c.  Spindle fibers used to guide chromosomes to opposite poles.
         • d.  Nucleus, nuclear membrane and nucleolus disappear.
         •  
      2. 2.  Metaphase

         

         1.  
         2. a.  Spindle fibers attach to chromatids.
         3. b.  Chromatids align themselves across middle of cell.
         4.  
      3. 3.  Anaphase

         

         1. a.  Centromeres break apart.
         2. b.  Chromosomes move away from center of cell.
         3. c.  Cleavage furrow forms. (Indentation in center of cell to indicate where cell will divide).
         4.  
      4. 4.  Telophase

             

         1. a.  Two nuclei appear.
         2. b.  Chromosomes become less distinct and appear to have broken up.
         3. c.  Nuclear membrane reforms.
         4. d.  Organelles are divided equally.
         5. e.  Cleavage furrow divides the cell into two.
         6. f.  Two identical daughter cells are formed.
         7.  
   6. Results of Cell Division
      1. 1.  Helps produce cells that have been damaged or destroyed.
      2. 2.  During periods of growth, mitosis allows groups of similar cells to multiply into tissues.
      3. 3.  If the body loses its ability to control mitosis, an abnormal mass of cells (neoplasm) forms resulting in benign or malignant tumors.