A View Of The Cell

 Simple light microscope – one lens ◦ Anton van Leeuwenhoek: 1600’s  Compound light microscope – multiple lenses ◦ Maximum Magnification: 2000x  Total magnification = eyepiece X objective ◦ E.g. Eyepiece (10X) X Objective (40X) = 400X

 Electron Microscope – uses a beam of electrons to magnify structures up to 10,000,000x

 Robert Hooke was the first person to view cells under a microscope ◦ Cork cells

 1. All organisms are composed of one or more cells  2. The cell is the basic unit of life  3. All cells come from preexisting cells

 All cells have tiny specialized structures called ORGANELLES ◦ Some are surrounded by double membranes  PROKARYOTIC cells do NOT contain membrane- bound organelles ◦ Bacteria; no nucleus; small and very simple (primitive)  EUKARYOTIC cells DO contain membrane-bound organelles ◦ All organisms except bacteria (animals, plants, fungi, protists); do have nucleus; larger and much more complex

 1. Nucleus – controls the cell; contains the DNA ◦ “Brain” of the cell ◦ Found in the middle of the cell; surrounded by nuclear membrane ◦ ONLY EUKARYOTES HAVE A NUCLEUS!!!  Plants, Animals, Fungus, Protists  DNA – hereditary molecule that contains coded instructions for how to build all the proteins and enzymes in a cell.

DNA

 2. Ribosomes – assemble proteins and enzymes by reading instructions delivered from the DNA ◦ Do NOT have membrane surrounding them ◦ Found in BOTH eukaryotic and prokaryotic cells  Proteins are an essential part of all living cells

 3. Nucleolus – makes ribosomes ◦ Dark spot INSIDE the nucleus

 4. Mitochondria – breaks down food for energy (ATP) ◦ “Powerhouse” of the cell ◦ Site of cellular respiration  The use of OXYGEN improves efficiency ◦ Membrane folds allow for more surface area and more enzyme catalyzed reactions

More surface area means more enzymes/reactions for increased efficiency

 5. Endoplasmic Reticulum (ER) – carries out various chemical reactions and transports materials within the cell ◦ Rough ER – has ribosomes attached; aids in the assembly of proteins and enzymes ◦ Smooth ER – no ribosomes attached; aids in metabolism and detoxification  Abundant in liver cells

 6. Cell Wall – inflexible barrier for support and structure ◦ ONLY IN PLANT CELLS*!!! ◦ Made of cellulose  Humans cannot digest ◦ Gives cell “square” shape ◦ Porous; allows molecules to freely enter and exit

 7. Cytoplasm – clear gelatinous fluid that suspends the organelles ◦ Cytosol – the watery substance that makes up the majority of cytoplasm  70% water

 8. Golgi Apparatus – sorts, packages, and modifies proteins to be sent elsewhere in the cell or excreted out of the cell via vesicles ◦ “Post office” of the cell ◦ Stack of membrane bound VESICLES  Vesicles are small enclosed membranes that contain and transport cell materials ◦ Also called Golgi Complex or Golgi Body

Transport Vesicle

 9. Vacuole – temporary storage of materials ◦ “Locker” ◦ Plant cells have LARGE CENTRAL vacuole  Water storage ◦ Vacuoles are much smaller in animal cells

 10. Lysosomes –contains enzymes which digest waste materials ◦ “Garbage disposal”

 11. Chloroplast – PHOTOSYNTHESIS in plants ◦ Green; ONLY IN PLANTS ◦ Contains the pigment chlorophyll ◦ Stacked discs called THYLAKOID DISCS

 12. Cytoskeleton – internal support structure ◦ Like the skeleton that supports your body ◦ Made of protein fibers called microtubules and microfilaments

 13. Centrioles – help with cell division ◦ ONLY IN ANIMAL CELLS!!! ◦ Made of microtubules (protein fibers) ◦ A pair of CENTRIOLES is called a CENTROSOME

Centrioles

 14. Plasma Membrane – controls what enters and exits the cell; made of phospholipids ◦ aka CELL membrane  “Bouncer”  Selectively Permeable ◦ Lets in some stuff but not everything

 15. Flagella – whip-like structure ◦ “Tail”  16. Cilia – short numerous hair-like projections that move back and forth ◦ “Oars on a rowboat”