Cell Structure
Animal Cell
Plant Cell
Cell Wall
Made of cellulose
They are fully permeable
Function: They support,
strengthen and protect
the plant cell.
Cell Membrane
Phospholipid
Membranes are composed
of phospholipids and
proteins
Phospholipid bilayer
Phospholipids are arranged
into double layers (bilayer)
The phosphate heads
(hydrophilic) are exposed
to the outer surfaces
The lipid tails
(hydrophobic) face into
the middle
Membrane proteins can also be found embedded
in the phospholipid bilayer
Function of Membrane
• Control what enters and leaves the cell
• Semi-permeable
• Retain cell contents
• Give support to the cell
• Recognise molecules that touch them
The Cell Membrane
A membrane is said to be PERMEABLE to a
substance if the substance can pass through it.
A membrane is said to be IMPERMEABLE to a
substance if the substance cannot pass through
it
Permeable
Impermeable
Selectively/Semi
Permeable
• Cell membranes are
SELECTIVELY/SEMI
PERMEABLE.
• They allow water, Carbon
Dioxide and Oxygen to
pass through freely.(small
molecules)
• They do not allow sugars,
proteins and salts to pass
though easily. (larger
molecules)
Nucleolus
Makes ribosomes
Nucleolus
Cytoplasm
Jelly-like liquid that surrounds
the nucleus.
Organelles (mitochondria,
chloroplast and ribosomes) are
suspended in the cytoplasm,
allowing them to move.
Ribosomes
Tiny bead-like structures
Function: to make proteins
Ribosomes
Mitochondria
Respiration occurs here!
Therefore mitochondria produce ENERGY!!!
Cells that have many mitochondria produce lots of energy
(Muscle cells)
Cells with few mitochondria produce less energy
(Fat cells)
Chloroplast
• Found in plant cells only!
Function: Photosynthesis
Nuclear pores
• Allow a type of RNA
(ribonucleic acid)
called mRNA
(messenger RNA) to
pass in and out!
Cell Membrane
Animal Cell
Plant Cell
Prokaryotic Cells
and
Eukaryotic Cells
Prokaryotic Cells
Do not have a nucleus or membrane-enclosed organelles
• E.g. Bacteria
Eukaryotic Cells
• Have a nucleus and membrane bound organelles.
• Eg. Human cell
Stage clips
Light Source
Base
Arm
Low Power
Eyepiece
Body Tube
Diaphragm
Medium Power
Fine Focus Knob
Objective Lens
Nosepiece
High Power
Coarse Focus Knob
Stage
Objective
Lens
Compound Light Microscope
Uses 2 lenses – objective lens and eyepiece lens
• The total magnification of the image is calculated by
multiplying the power of the two lenses
Light source:
AThe
bulbmicroscope
or mirror that
illuminates the specimen
Diaphragm:
Controls the amount of light
passing into the specimen
Objective Lenses:
Magnifies the specimen by
different powers
Coarse Focus Wheel:
The the
microscope
Bring
specimen into rough
focus
Fine Focus Wheel:
Brings the specimen into
precise focus
Scanning Electron Microscope
Scanning Electron
Microscope (SEM)
• Uses beams of
electrons to
provide a surface
view of the
specimen
Images taken using SEM
Images taken using SEM
Plant Cell
Animal Cell
Bacterium Cell
Transmission Electron Microscope
Transmission Electron
Microscope (TEM)
Sends a beam of electrons
through a thin section of
the specimen
Shows internal structure in
great detail
Preparing and
Examining Cells
Learning Check!
• Why is a thin specimen used?
• How did you collect a sample of this specimen?
• Why is water added to the specimen?
• Name the stain used?
• Why do we use a stain when preparing a specimen?
• Why is a cover slip used?
• Why is a cover slip placed on at a 45 degree angle?
• Why do you always start with the lowest lens?
• Why do you adjust the coarse focus wheel first?
Learning Check!
• What animal cell did you use?
• Give an example of how you can get an
animal cell sample?
• Why is water added to the specimen?
• Name the stain used?
• What colour was the stain?
• Why do we use a stain when preparing a specimen?
• Why is a cover slip used?
• Why is a cover slip placed on at a 45 degree angle?
• What are the differences between a plant and animal cell?