1. A View of the Cell Unit #2

2. The History of the Cell Theory Light microscopes Light microscopes Anton van Leeuwenhoek created and used first simple light microscope Anton van Leeuwenhoek created and used first simple light microscope Compound light microscope uses a series of lenses to magnify objects Compound light microscope uses a series of lenses to magnify objects

3. The History of the Cell Theory (cont) Robert Hooke – used a compound light microscope to study cork; looked like empty boxes or rooms so he called them cells after a monk’s room Robert Hooke – used a compound light microscope to study cork; looked like empty boxes or rooms so he called them cells after a monk’s room

4. The History of the Cell Theory (cont) Matthias Schleiden observed plants; concluded that all plants are composed of cells Matthias Schleiden observed plants; concluded that all plants are composed of cells Theodor Schwann observed different animal tissues; concluded that all animals are made of cells Theodor Schwann observed different animal tissues; concluded that all animals are made of cells

5. The Cell Theory of Modern Biology All organisms are made up of one or more cells. All organisms are made up of one or more cells. The cell is the basic unit of structure, organization, and function in an organism. The cell is the basic unit of structure, organization, and function in an organism. All cells come from preexisting cells. (refers to life comes from life) All cells come from preexisting cells. (refers to life comes from life)

6. Electron microscopes uses a beam of electrons instead of light to magnify structures uses a beam of electrons instead of light to magnify structures specimens must be examined in a vacuum because electrons will collide/react with other atoms in the air specimens must be examined in a vacuum because electrons will collide/react with other atoms in the air

7. Electron microscopes Scanning Electron Microscope (SEM) used for 3D images of outside structures Scanning Electron Microscope (SEM) used for 3D images of outside structures Transmission Electron microscope (TEM) used for images of inside structures in the cell Transmission Electron microscope (TEM) used for images of inside structures in the cell

8. Two Basic Cell Types Cells can be divided into two broad groups based on whether or not they contain organelles. Cells can be divided into two broad groups based on whether or not they contain organelles. Organelles are specialized, membrane- bound structures within the cell Organelles are specialized, membrane- bound structures within the cell

9. Two Basic Cell Types Prokaryotic cells (prokaryotes) do not have organelles Prokaryotic cells (prokaryotes) do not have organelles Eukaryotic cells (eukaryotes) do have organelles Eukaryotic cells (eukaryotes) do have organelles

10. The Plasma Membrane Homeostasis – maintaining stable conditions regardless of external or internal factors Homeostasis – maintaining stable conditions regardless of external or internal factors Plasma membrane is a flexible, selectively permeable boundary between the cell and its external environment Plasma membrane is a flexible, selectively permeable boundary between the cell and its external environment Selective permeability – allowing some materials to pass while keeping others out Selective permeability – allowing some materials to pass while keeping others out

11. Structure of the Plasma Membrane Phospholipid bilayer Phospholipid bilayer Other components of the plasma membrane are Other components of the plasma membrane are

12. Phospholipid bilayer Lipids, triglycerides, are composed of 3 fatty acid “tails” attached to Phospholipids Lipids, triglycerides, are composed of 3 fatty acid “tails” attached to Phospholipids

13. Phospholipid bilayer Phospholipid divided into two areas: the backbone or head is polar and “likes water”, the fatty acids are nonpolar and are hydrophobic (fear water) Phospholipid divided into two areas: the backbone or head is polar and “likes water”, the fatty acids are nonpolar and are hydrophobic (fear water) Polar ends face the outside and inside of the membrane Polar ends face the outside and inside of the membrane Nonpolar tails face in like a sandwich Nonpolar tails face in like a sandwich

14. Fluid Mosaic Model the membrane is fluid because the phospholipids can move within the membrane just as water moves with the current the membrane is fluid because the phospholipids can move within the membrane just as water moves with the current protein components are also embedded in the membrane and move, creating a pattern or mosaic protein components are also embedded in the membrane and move, creating a pattern or mosaic

15. Other components of the plasma membrane Cholesterol – steroid – stabilizes membrane by keeping the fatty acids from sticking together Cholesterol – steroid – stabilizes membrane by keeping the fatty acids from sticking together Transport proteins or membrane-spanning proteins – span entire membrane and create channels or carrier molecules for certain substances to enter and leave the cell Transport proteins or membrane-spanning proteins – span entire membrane and create channels or carrier molecules for certain substances to enter and leave the cell Integral proteins – are embedded in either the inside layer or the outside layer; they play a role in cell identification and attaching structures to the cell membrane Integral proteins – are embedded in either the inside layer or the outside layer; they play a role in cell identification and attaching structures to the cell membrane

16. Plasma Membrane