1. 1
Biology lessons - subject cytology
Summary:
Presentation of the optical microscope,
study of animal and vegetal cells using the microscope,
generalization about the structure of animal and vegetal cells.
Brief presentation of procaryotic cells.
Structure of the cell membrane,
different transportation mechnisms across this membrane.

2. 2
Lesson Course:
Lesson 1
A. the light microscopeor optical microscope
Presentation of the different parts and their use
eyepiece and objective lenses: magnification
Nosepiece: choice of objective
Base and neck: manipulation, fixation of different parts
Light source: illumination
Focus: vertical movements of sample
Iris diaphragm: controls how much light passes through the sample. Partially closing the
diaphragm may increase contrast
Condensor lens: concentrates light from the illumination source
Stage and stage clips: serves to deposit and fix the sample
Stage control: horizontal movements of sample
( Simple exercise with ready sample, no notes):
Raise stage, choose smallest objective, center sample, lower stage until you see
something, verify whether it is part of the sample by using the stage controls. If it is, focus,
switch to next objective, focus, center, switch to 40x objective. )

3. 3
B. Structure of cells
Homework given here so the students may already take notes : compare animal and
vegetal cells
1. animal cells
* observation of liver cells
No notes: how to prepare a sample: use a microscope slide, touch the slide with a piece of
liver, add water, add cover glass
- observe and sketch
As a conclusion:
* structure of the animal cell
Annotated sketch
***
Lesson 2
* roles of different cell organites
cell membrane: maintains integrity of the cell, partially controls incoming ant outgoing
substances (see cell membranes), reacts with certain chemicals that attach to receptors in
the cell membrane
cell plasma: cell metabolism takes place here
nucleus: contains genetic material, controls cell metabolism
2. structure of vegetal cells
* Observation of onion cells
Red onion cells: observe and sketch
No notes, prepare slide and a drop of water, cut onion into pieces, locate slightly brilliant
skin on the surfacel, cut small squares, take one out with pincers, put it into the drop of
water, apply cover glass
- observe and sketch
For the quick students only:
b. observation of waterweed cells (Elodea canadensis)
no notes: put a tender young leaf into a drop of water…
As a conclusion:
* structure of the vegetal cell
Annotated sketch
* roles of different cell organites
Nucleus, membrane, plasma: see animal cell
cell wall: cell form, resistance to osmotic pressure (cf later in this chapter), deposit of
waste products
vacuole: contains reserve stock of certain substances, most importantly water, waste
products

4. 4
tonoplast: delimitation of vacuole, controls transportation
chloroplasts: photosynthesis = transformation of atmospheric CO to organic substances in
the presence of light
***
Lesson 3
Correction of homework
Demonstration using the three potato pieces needed under C.2.c is started
3. procaryotic cells
Bacterial cells do not contain a nucleus. Such cells are called procaryotic (before (the
evolution of) a nucleus) cells. Cells containing a nucleus are called eukaryotic (cells with a
real nucleus) cells.
Show pictures
Annotated sketch
***
Lesson 4
C. Transportation through cell membranes
1. diffusion
Demonstration: a few ink drops in a container of water will spread through the entire
volume in less than an hour, even without stirring. At the end, the concentration of ink
molecules is the same in the entire volume of water.
This may be explained by the random brownian movement of the molecules in a fluid (=
liquid or gaz)
(Robert Brown, Scottish botanist discovered these movements in 1827 in observing
moving particules inside dead pollen grains). He noticed the same kind of movements in
all kind of finely ground substances in a fluid)
Illustration of the phenomenon by computer animation
2. passive transportation of molecules through biological membranes
N. B.: passive transportation
- is based on diffusion
- allows mvts according to the concentration gradient
- has no energy cost
a. structure of the biological membrane

5. 5
Source: http://www.tulane.edu/~biochem/faculty/facfigs/fluid_mosaic.htm
Fluid mosaic model by Singer and Nicolson (1972)
Annotations: phosphate, fatty acid chain, phospholipid, double bilayer, membrane proteins
Hydrophile layer (x2), hydrophobe layer
b. consequences for molecule transportation
→ Only small fat soluble (non-charged) molecules can cross the biological membrane by
diffusion
→ big or polar molecules can cross membranes by using specialized membrane proteins
called channel or transporter proteins. These are specific for the transported substance
Different forms of passive transportation mechanisms: see picture
Examples: O2 or CO2,
Channel for sodium ions
Transporter for glucose
Source:
http://susankannasjackiegunderson.wi
kispaces.com/03+Cell+Physiology

6. 6
Observation of the potato pieces
Lesson 5
c. passive transportation of water molecules- osmosis
* observation on a macroscopic level
demonstration : using an apple corer, cut 3 pieces out of a potato, each the same size
put one piece into distilled water, one into physiological serum, one into a 1M saline
solution
the potato piece in the distilled water increased in size: influx of water
The potato in the physiological serum maintains its size: no water movement or equal
movement in an out of the piece
The piece in the salt solution decreased in size . efflux of water

7. 7
* observation on a microscopic level
Observation of beef blood under the microscope
- once in a drop of distilled water,
- once in a drop of physiological serum,
- once in a drop of 1M saccharose solution
Observe, sketch, explain:
Correction: sketches and cf potato, but replace piece of potato with cell
***
Lesson 6
* events on a submicroscopic level
Sketch of a biological membrane containing aquaporins separating two fluids, one
containing little free water, the other containing more free water. Important movement from
hypotonic to hypertonic solution, small movement in the other direction, net resultant.
Remarks:
- application of mechanical presure on hypertonic side: reduction or even inversion of
osmotic flux. At equilibrium (incoming flux = outgoing flux), this pressure is called osmotic
pressure. In plant cells, when ‘the box is filled’, the mechanical pressure of the cell wall
prevents the cell from expanding further or even blowing up.
- technical applications of osmosis are dialysis and water desalination. Both use artificial
membranes permeable to water and small molecules, but impermeable to bigger solutes.
In hemodialysis, blood is channeled through tubes immersed in hypertonic salt solution:
water and small molecules transit, while bigger molecules (e.g. glucose) and blood cells
are retained.
In dessalination, pressure superior to the osmotic pressure is applied on the hypertonic
side, thus inversing the sense of the osmotic flow.
Homework: cf annexed sheet

8. 8
Lesson 7
3. active transportation of substances through biological membranes
N. B. Active transportation uses up energy, but allows the cell to transport substances
opposing their concentration gradient.
Active transportation uses specific membrane proteins called transporters.
Source:
http://g11-bioa-2011-
12.wikispaces.com/(d)+Active+transport
Remark : the activity of both channels
and transporters can be influenced by
hormones and other substances
D. Transportation of voluminous material
Text to be distributed
Voluminous materials (cells, viral particules, macromolecules) are enclosed in an
invagination of the cytoplasmic membrane, which closes up on itself and forms a ‘bubble’
called an endocytic vacuole containing the ingested matter. The phenomenon is called
endocytosis.
If the substance ingested is formed of solid matter (cells, pieces of cells, viral particles), it
is called phagocytosis (phagocytic vacuoles or phagosomes are relatively big, with a
diameter often bigger than 1 um)
If the substance ingested is formed of liquid drops, it is called pinocytosis (pinocytic
vesicles are small, about a 11nm in diameter)
In the same way, material can be expulsed from the cell by a phenomenon called
exocytosis.
* phagocytosis
Cf annexed sketch

9. 9
Lesson 8
Evaluation: will follow in a separate folder (I haven’t written it yet)
Requirements:
- Time: 8 lessons ( in my case two double lessons, 1 single lesson, 2 double lessons and
another single lesson)
- Material:
Lesson 1: Opitcal microscopes, liver cells, slides, pincers, cover glasses
Lesson 2: Opitcal microscopes, onions, waterweed, knives, scalpels, slides, pincers,
cover glasses
Lesson 3: pictures of different kind of bacteriae
Lesson 4: container, ink, computer with internet access, handouts
Lesson 5: Apple corers, potatoes, distilled water, physiological serum, concentrated salt or
sugar solution, containers, rulers, microscopes, slides, cover glasses, pipettes, beef blood
Lesson 6: handouts
Lesson 7: handouts
Lesson 8: handouts
Teaching methods
Lesson 1: didactic teaching, the students practice taking notes; guided practical work
Lesson 2: guided practical work
Lesson 3: didactic teaching
Lesson 4: problem solving, didactic teaching
Lesson 5: practical work, problem solving, didactic teaching
Lesson 6: didactic teaching
Lesson 7: didactic teaching
Lesson 8: Evaluation

10. 10
Homework lesson 6
1. How many concentration gradients can you identify? Draw an arrow from high
concentration to low for each solute.
5 mM K+
142 mM Na+
100 mM Cl-
4 mM PO4-
2. Explain what a concentration gradient is using the figure as an illustration for your
points.
3. Describe what is meant by a semi-permeable membrane.
Source: Peer-Led Team Learning: Anatomy and Physiology, Module 7: Cell Membranes and Transport,
Page 1 – Nichole McDaniel -- Progressions, V.7, No. 3, Spring 2006 – www.pltl.org Volume 7, Issue 3 Spring
2006 The Workshop Project Newsletter
nucleus
140 mM K+
10 mM Na+
4 mM Cl-
75 mM PO4-

11. 11
___active transport A. Movement of molecules down the concentration gradient
___phospholipid B.When placed in such a solution the cell swells and bursts
___fluid mosaic model C. Movement of water molecules towards salt across a
semipermeable membrane.
___passive transport D. When placed in such a solution the cell remains stable
___pinocytosis E. When placed in such a solution the cell shrivels
___osmosis F. A secretory vesicle uses this method to expel its contents outside the cell
___phagocytosis G. It has a hydrophilic head and a hydrophobic tail.
___ facilitated diffusion H. A process by which the cell engulfs water (liquid)
___ simple diffusion I. A process by which the cell engulfs solid objects such as a
pathogen
___ endocytosis J. The molecular arrangement of the cell membrane is described in this
way.
___ exocytosis K. This type of transport requires a protein but not ATP
___ hypertonic L. This type of transport requires both a protein pump and ATP.
___ hypotonic M. Any type of transport that does not require ATP
___ isotonic N. Cholesterol is picked up by liver cells using this method.
Peer-Led Team Learning: Anatomy and Physiology, Module 7: Cell Membranes and
Transport, Page 1 – Nichole McDaniel -- Progressions, V.7, No. 3, Spring 2006 –
www.pltl.org Volume 7, Issue 3 Spring 2006 The Workshop Project Newsletter
QCM
Use the diagram to answer questions 3 and 4.
3. What happens with the water molecules?
a. The water molecules will enter the cell.
b. The water molecules will move out of the cell.
c. The water molecules will remain where they are.
4. What happens with the sugar molecules?
a. The sugar molecules will enter the cell.
b. The sugar molecules will move out of the cell.
c. The sugar molecules will remain where they are.
5. Through which process do sugar molecules enter or exit a cell?
a. diffusion c. facilitated diffusion
b. osmosis d. none of the above
6. Which process ALWAYS involves movement of materials from inside the cell to outside
the cell?
a. osmosis c. exocytosis
b. diffusion d. endocytosis
7. A substance that moves across a cell membrane without using the cell’s energy tends to
move
a. toward the area where it is more concentrated.
b. away from the area where it is less concentrated.
c. away from the area where it is more concentrated.
8. If a solution outside a cell is more concentrated so that the cell loses water to its
environment, which of the following describes the external solution?
a. isotonic c. hypertonic
b. hypotonic d. in equilibrium
Cell
Membrane
Outside Cell
Inside Cell
= Sugar

12. 12
9. Which mechanism requires energy?
a. osmosis c. active transport
b. diffusion d. facilitated diffusion
10. Certain types of lymphocytes (white blood cells) in the lymph nodes ingest bacteria
and
debris. This function most likely occurs by
a. exocytosis d. passive transport
b. pinocytosis e. facilitated transport
c. phagocytosis
11. Which of the following is characteristic of cell membrane?
a. permeable c. semi permeable
b. impermeable d. none of these
12. Which refers to a solution containing a greater concentration of solvent than the
solution
it is being compared with?
a. isotonic c. hypertonic
b. hypotonic d. equilibrium
13. Which solution contains a higher concentration of solute than the solution it is being
compared with?
a. isotonic c. hypertonic
b. hypotonic d. equilibrium
http://www.bse.ph/download/EASE%20MODULES/SCIENCE/BIOLOGY/Biology%20M3%
20Movement%20of%20Matls%20thru%20the%20Cell%20Membrane.pdf