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http://www.haines.com.au/index.php/vce-microscope-with-light.html
http://www.rkm.com.au/cell/plant/plant-cell.html
The Big Picture
 Cells are the basic unit of
life.
 They are able to perform all
of the life processes.
 They have the machinery
(organelles) and are able to
maintain their environment
(using the cell membrane).
http://api.ning.com/files/RS902N06*Fsot6dEtvdAUDfQajqc68oT*kdh4bqE9
cv3rIrFEyUDasIVfRbSUufHci0jNgAlNKa7VUAbFFZ1Am5Qrk6q*u9/Parameciumdiagramlabeled.gif
Regulation
 There are many chemical reactions required for
sustaining life.
 The cell must be able to regulate its own
composition to be able to maintain
HOMEOSTASIS
Homeostasis: the
maintenance of a
balanced state of
constant conditions
within a cell
The cell is able to do this by permitting some materials to enter or
leave the cell passively [without using energy], or by actively
moving certain materials in or out [by using energy].
https://chem.colorado.edu/palmergroup/images/research/Intrac
ellular_zinc_distribution_2_copy_1.png
Permeability
 How is all of this accomplished? It is dependent on
the permeability of the membrane.
**Molecules may be
restricted by size, charge
or solubility.
http://bioserv.fiu.edu/~walterm/fallspring/cell_components/cell_talk_files/image008.jpg
 If the membrane does not allow a substance to move
from one side to the other, it is IMPERMEABLE to that
substance.
 If the membrane allows free movement of a substance
from one side to the other it is PERMEABLE to that
substance.
If the membrane allows
only certain types of
molecules to move across it,
it is SELECTIVELY
PERMEABLE or
SEMIPERMEABLE.
http://chadchemistry.weebly.com/uploads/4/8/6/1/4861692/8734716.jpg?530
 Each type of membrane will be selectively permeable to different
substances: eg. cell membrane, nuclear membrane,
mitochondrion, vacuole, chloroplast, E.R.
 It is these differences that allow the cell to control it’s own
composition
http://image.slidesharecdn.com/diffusionosmosisactivetransport2010voice-100519123734phpapp02/95/diffusion-osmosis-active-transport-2010-voice-4-728.jpg?cb=1274290740
Methods for Moving Substances across
Membranes
Passive Transport: requires no energy
 Diffusion: the movement of
a substance from an area of
high concentration to low
concentration.
 The greater the
concentration gradient
(the difference in
concentration), the faster
the rate of diffusion.
 Diffusion cannot move
molecules rapidly over
long distances.
 Osmosis: the diffusion of
water across a semipermeable membrane.
 Active Transport: the cell uses energy to
move materials [energy is in the form of
ATP]
•Pinocytosis: the inpocketing or outpocketing of the cell
membrane to surround
and move a small particle
suspended in a liquid
droplet.
•Phagocytosis: the
engulfing of a large
particle of matter into the
cell.
Types of Solutions
 In the liquid environment surrounding the cell (the
extracellular fluid), water is the SOLVENT; the substance in
which other substances dissolve.
 The other substances are called SOLUTES; the substances
that dissolve in the solvent.
 All body cells are bathed by extracellular fluid and must be
able to maintain homeostasis when subjected to different
types of conditions.
 Often if a membrane is selectively permeable, water (the solvent) is able to
move across the membrane by osmosis, but the solutes are unable to move
across the membrane.
Equilibrium
Balance based on the constant movement of all
particles to establish a uniform concentration
throughout
REMEMBER:
•Tonic refers to the tone of something
•Iso means “the same”
•Hyper means “higher or more”
•Hypo means “lower or less”
a. Isotonic Solution
Equal movement of water in and out of the cell (equilibrium) because the solute
concentration on one side of the membrane is the SAME AS the concentration on
the other side of the membrane
b. Hypotonic Solution
If the extracellular fluid (ECF) has a lower concentration of solutes than the
cytoplasm, the cell will move water molecules into the cell (causing it to expand)
c. Hypertonic Solution
If the ECF has a higher concentration of solutes than the cytoplasm, the cell will
move water molecules out of the cell (causing it to shrink)
http://adapaonline.org/images/biobook_images/A000142_animal_cell.gif
http://2.bp.blogspot.com/_10M5kCPMTYM/S-1kTAlmmrI/AAAAAAAAABc/Duc-LSzYgyU/s1600/Bio+hypotonic,+Isotonic,+Hypertonic.gif
Red Blood Cells in Solution
http://internalandexternalenvironments2012.wikispaces.com/Hypertonic,+hypotonic+and+isotonic+effects+on+plants+and+animal+cells.
What Controls the movement of
material into and out of the Cell?
The Cell Membrane
HO – The Cell Membrane
 Use the overhead diagram to label the cell
membrane
Functions of Cell Membrane Proteins:
• Transport
• Cell surface identity markers
• Hormone receptor sites
• Enzyme receptor sites
• Cell adhesion (stickyness to build tissues)
Microscopes
Light
SEM
 Types of
microscopes can
be found on
pages 8 and 9 of
your textbook –
please read
and make a
brief study
note
http://www.cas.miamioh.edu/mbi-ws/microscopes/images/LightDiagram.GIF
http://www.purdue.edu/rem/rs/graphics/sem2.gif
 SEM picture of the lower
surface of a walnut leaf [right]
and a marine worm [below]
A Comparison of SEM & light
microscopes
Cost
Magnification
(max)
Resolution
Training
Illuminated by
Lenses
Specimen
SEM
Millions
200 000x
Light
Thousands (max)
400-2000x
Very high (3D)
2 year tech
Electrons
Magnets
Dead
Limited
1 class (today)
Light
Glass
Dead/alive
Stomata on a leaf
Light
SEM
http://www.plantscafe.net/media/files/enex03_MG_Experiments_M3_Stomata_LM_of_Rhoeo.jpg
http://www.psmicrographs.co.uk/_assets/uploads/lavender-leaf-stomata-80200158-l.jpg
The Optics of Microscopes
 Depth of field decreases and becomes darker as magnification
increases (objects are harder to see – light source essential)
 Diameter of field of view decreases as magnification increases
Activities:
 Microscope Lab – observing banana cells [stained with iodine to
make the starch in the leucoplasts visible]; paramecia and
amoeba, and your choice of an insect slide (multicellular)
 Microviewer Activity – Body Cells