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

1. Cell Behaviors
Biology
Mr. Hildebrandt

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. 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. 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. Cell Movement
Cells 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. 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. 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. 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. 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. 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”