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Cell Behaviors


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This slideshow is designed for students in Mr. Hildebrandt's biology classes.

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Cell Behaviors

  1. 1. Cell Behaviors Biology Mr. Hildebrandt
  2. 2. Early Microscopy  Robert Hooke developed first documented microscope  He discovered cell walls of cork and coined the name “cells.”  His was a simple light microscope.
  3. 3. Electron Microscopes  Use expensive technology to “bounce” electrons off the specimen to produce very highly magnified images.  The specimens are killed in the process.  Computers are used to enhance color (like this dust mite)
  4. 4. Light Microscopes  Light Microscopes use a light source to view specimen  Multiple “objectives” are used to produce a variety of magnifications  Total magnification = Eyepiece power X Objective power
  5. 5. Cell MovementCells have structures to help them move: Cilia – short hair-like extensions that occur in large numbers Flagella – long, whip- like extensions that occur singly or in pairs.
  6. 6. What limits cell size?  DNA Overload – each cell has a limited amount of material. More “stuff” creates too much demand.  Difficulty exchanging materials –each cell is limited by the surface area to volume ratio.
  7. 7. Movement through the membrane Diffusion – particles move from areas of greater concentration to areas of lesser concentration. Continues until equilibrium is reached No energy required by the cell
  8. 8. Movement through the membrane  Osmosis – the movement of water through a selectively permeable membrane.  Continues until both solutions are isotonic  No energy required by cell  Osmotic pressure: 1. Hypotonic: below strength 2. Hypertonic: above strength
  9. 9. Movement through the membrane Facilitated diffusion - small protein channels in the membrane allow specific molecules to flow through No energy required by the cell
  10. 10. Movements that require Energy  Active Transport uses protein channels to move specific molecules against the gradient  Endocytosis – engulfs “big stuff”  Exocytosis – expelling pockets of “big wastes”