S3 Biology
Cells & Cell Transport
Learning Intentions
1. What is the difference between a
unicellular & a multi-cellular organism?
2. What is the function of the different
structures within a cell?
3. What is the difference in structure
between an animal cell, a plant cell, a
bacterial cell and a fungus?
4. What are specialised cells?
1.
Unicellular & Multi-cellular Organisms
1.
Unicellular organisms have one
cell, while multicellular
organisms are composed of
many different types of cells.
2.
Unicellular organisms are
usually smaller (often always
microscopic in nature) and less
complex than multi-cellular
Organisms
2a) Why do cells need different structures?
S1 Revision!
Can you remember
the job of each of
the parts of an
animal & plant cell?
Ribosome
Activity 1
Cells Matching Cards
Activity 2
Label Diagrams
Activity 3
Complete structure & function
table
Mitochondria
2b) Animal/Plant Cell Structure & Function
Structure of cell
Function
Nucleus
Cytoplasm
Controls all the cell activities
Site of chemical reactions
Cell membrane
Mitochondria
Ribosomes
Allows the exit/entry of substances
Site of Aerobic Respiration
Site of Proteins being made
Chloroplasts
Site of Photosynthesis
Vacuole
Cell Wall
Holds cell sap
Supports the cell and stops it bursting
Made of Cellulose
3a) Comparing Animal/Plant Cells
Cell
Membrane
Nucleus
Cytoplasm
Ribosomes
Mitochondria
Animal Cell
Animal &
Plant Cell
Chloroplast
Vacuole
Cell Wall
Plant Cell
3b) Bacterial Cells
• Bacterial cells come in 3
main shapes – spherical, rodlike and spiral
• Most bacteria have a cell
wall, cell membrane,
cytoplasm, ribosomes, a
capsule and a plasmid
• Bacteria do not have a
nucleus
• Some bacteria have a
flagellum for movement
• Bacteria Example: E. coli
Activity 5
Label a bacterial cell
Spherical
Rod-like
Cell
Membrane
Spiral
3c) Bacterial Cell - Structure & Function
Structure of cell
Function
Cytoplasm
Cell membrane
Ribosomes
Site of chemical reactions
Allows the exit/entry of substances
Site of Proteins being made
Pilus
Flagellum
Capsule
Plasmid
Attaches to other cells
For movement
Protective layer
Ring of extra DNA
Cell Wall
Supports the cell and stops it bursting
Made of Peptidoglycan
3d) Comparing Animal/Bacterial Cells
Nucleus
Mitochondria
Cell
Membrane
Plasmid
Pilus
Cytoplasm
Flagellum
Ribosomes
Capsule
Cell Wall
Animal Cell
Animal &
Bacterial Cell
Bacterial Cell
3e) Fungal Cells
• Have cell walls
made of chitin
• Fungi grow long
branching
structures
called Hyphae
• Fungus example:
Yeast
Activity 6
Draw & label a Fungus
Yeast cells budding
3f) Making & Viewing Cell Slides
1.
2.
3.
4.
5.
Peel a section of onion 1 cell thick &
cut a small square section
Place onion section on slide (making
sure there are no creases)
Add a drop of iodine (to stain the
cells so the nucleus can be seen)
Slowly lower a cover slip over the
section (making sure no iodine has
leaked out over the edge)
View slide under a microscope
Practice viewing slides of animal, plant,
bacteria and fungi
4a) Specialised Cells
1.
2.
Basic plant and animal cells can
become specialised cells to
carry out a particular role.
Examples of specialised cells
include:
Red Blood Cells
Nerve Cells
Egg Cells
Sperm Cells
Root Hair Cell
Palisade Mesophyll Cell
Types of Cell (2:59)
Plant Root Hair Cell
Why do you think it’s
this shape?
Red Blood Cell
Why do you think it’s
this shape?
Animal Cell
Cell Diagram
Function
To carry oxygen
Red blood cells
Nerve cell
Egg Cell
Sperm Cell
Specialisation


To carry nervous impulses
to different parts of the
body
To fuse with a sperm cell
during fertilisation, and
then to provide food for
the new cell that has
formed
To reach the egg cell in
order to fuse with it during
fertilisation



Large surface area for
oxygen
Contains Haemoglobin
which binds the oxygen
Long
Connections at each
end
Can carry electrical
signals


Large
Contains a food store


Long tail for swimming
Head which is able to
penetrate the egg cell
Plant Cell
Cell Diagram
Function
To absorb water from the
soil
Root Hair Cell
To open and close stoma
pore
Guard Cell
When guard cells are
turgid, the stoma pore is
open
Specialisation
Hairs give the cell a large
surface area to absorb
water
The guard cells are curved
to create the stoma pore so
oxygen and water can leave
the cell, and carbon dioxide
enters
When guard cells are
flaccid, the stoma pore is
closed
Palisade
Mesophyll
Cell
The main site of
photosynthesis
Lots of chloroplasts
present for photosynthesis
Learning Intentions
1.
How do substances enter and leave a cell?
2. What substances enter or leave a cell by
diffusion, osmosis & active transport?
3. What happens to cells in a hypotonic,
isotonic and hypertonic solution?
5a) Substances moving into/out of cells
Oxygen &
Glucose
Carbon
Dioxide
5b) Cell Membrane
• Made of proteins
and fats (lipids)
• Selectively
permeable to allow
some substances
through but not
others
5c) Diffusion
Diffusion is the movement of a substance down a
concentration gradient from a region of high
concentration to a region of lower concentration
Example:
Sugar cube in
cup of tea
Sugar
Diffusion Demo
5d) Osmosis
Osmosis is the movement of water from a
region of high water concentration to a
region of lower water concentration
through a selectively permeable membrane
Cell membrane
Osmosis Practical
Osmosis (0:46)
5e) Active Transport
Active Transport is the movement of a
substance against a concentration gradient
from a region of low concentration to a
region of high concentration and it requires
energy (ATP)
Transport across a cell
membrane (2:39)
Low sodium
High sodium
Conconcentration
Conconcentration
5f) Animal cells in different solutions
Hypertonic Solution
Isotonic Solution
Hypotonic Solution
(Lower water conc)
(same water conc)
(Higher water conc)
Shrinks
Bursts
5g) Plant cells in different solutions
Turgid
Normal
Flaccid
(Plasmolysed)