GENERAL
BIOLOGY 1
MODULE 2 - 4
types
Microscope
COMPOUND MICROSCOPE
A type of microscope that
used visible light for
illumination and multiple
lenses system for
magnification of
specimen. Generally, it
consists of two lenses;
objective lens and ocular
lens. It can magnify
images up to 1000X.
COMPOUND MICROSCOPE
Uses of Compound Microscope
• Used in microbiology to study the morphology of microorganisms
• Used in histopathology to study tissue, cytopathic effects, tumor, etc.
• Used in cytology to study cellular structure of different types of cells
• Used by biologist to observe slides of cells, tissues or segments of
biological components
Limitations of Compound Microscope
• Can’t produce image of objects smaller than wavelength of visible
light (0.4 μm)
• Has lower resolution and image contrast
• Can’t be used to view living internal structures
• Require thin, and stained specimen
PHASE CONTACT MICROCOPE
An optical microscope that
converts small phase
shifts in light into
differences in light
intensity developing more
contrast in images that
can be easily detected by
human eyes.
PHASE CONTACT MICROCOPE
Uses of Phase Contrast Microscope
• Observing living cells in its natural form
• Used in microbiology to observe protozoans, diatoms,
planktons, cysts, helminths and larvae.
• Used to study subcellular structures and cellular processes
• Used to study thin tissue slices
• Used to study lithographic pattern and latex dispersion, glass
fragments and crystals.
Limitations of Phase Contrast Microscope
• Not ideal for thick specimen
• Halo effect and shade-off are common
FLUORESCENCE MICROSCOPE
An optical microscope that
uses fluorescence or
phosphorescence to
generate an enlarged
image of a specimen. It is
a modified light
microscope.
FLUORESCENCE MICROSCOPE
Uses of Fluorescence Microscope
• Study structure of fixed and live cells and cell organelles
• Used to measure physiological state of cells
• Detection of acid fast bacteria, malarial parasites and other
microorganisms in clinical samples
• Used in immunology and biochemistry to study macromolecules and
nucleic acids
• Used in Fluorescent In-situ Hybridization (FISH) technique in study of
microbial ecology
Limitations of Fluorescence Microscope
• Photo-bleaching limits the time interval for observation of specimen
• Phototoxic effects of fluorophore
• Need of specific fluorophore for staining specific structures
ELECTRON MICROSCOPE
a microscope that uses accelerated
electron, beams instead of light
rays, to illuminate the specimen
and get the highly magnified
image. In this microscope, glass
lenses are replaced by
electromagnets. Due to the very
short wavelength of electrons,
this microscope produces a very
high-resolution image with
magnification up to 10,000,000X.
ELECTRON MICROSCOPE
Uses of Electron Microscope
• Used in microbiology to study structure of viruses, flagella, pili, and
bacterial cells.
• Used in crystallography, and nano-technology
• To study morphology of cellular organelles
• Used in forensics for ballistic study of gunshots
• Used in geology for studying rocks, minerals and gems
• Used in quality control, detection of fracture and cracks, drug
development and analysis of atomic structure.
Limitations of Electron Microscope
• Highly expensive and complex system
• Images are in black and white
• TEM requires very thin specimen
• Need of vacuum system
HISTORY of
Microscope
Galileo Galilei
He was also able to make his own
microscope because of his
knowledge about glass and focal
lengths. It has two new lenses same
as his telescope: a bi-convex
objective and a bi-concave eyepiece
zacharias and
Hans janssen
Dutch spectacle-maker who
discovered the first compound
microscope which was later disputed
as many had invented their own
versions of glass lenses across
Europe to be used at that time
Robert Hooke
able to coin the term “cell” by looking
at a piece of cork stripped from the
trunk of the Cork Oak tree under his
microscope. He got the term cell
while looking at the specimen, he
noticed the little chambers which
reminded him of monastery cells,
where monks used to sleep during
that time.
Antony van
Leeuwenhoek
Instead of buying his own
microscope, he made his own very
odd looking version. But, with his
strange looking microscope, he was
able to discover bacteria and
protozoa. Thus, he is now known as
the “Father of Microbiology”.
PARTS OF
MICROSCOPE
MAIN PARTS OF THE MICROCOPE
Magnifying
Illuminating
Mechanical
Magnifying parts
Eyepiece
(Ocular Lens): Located
at the top, it magnifies
the image formed by
the objective lens.
Magnifying parts
Objective Lenses: Attached to
the nosepiece, these lenses
provide the initial magnification
of the specimen.
Magnification
Scanning Objectives = 4x
Lower power Objectives = 10x
High power objectives = 40x
Oil Immersion Objective = 100x
Illuminating parts
Light Source (Illuminator):
Provides the light needed to view
the specimen.
Condenser: Focuses light onto
the specimen.
Diaphragm: Controls the amount
of light passing through the
specimen.
Mechanical parts
Base: Provides support for the
microscope.
Arm: Connects the base to the head
and provides a grip for carrying.
Stage: A platform where the
specimen slide is placed.
Stage Clips: Secure the slide on the
stage.
Mechanical parts
Focus Knobs (Coarse and Fine):
Adjust the position of the stage or
body tube to bring the specimen into
focus.
Body Tube (or Head): Holds the
eyepiece and connects to the
nosepiece.
Nosepiece: Rotates to allow
switching between different objective
lenses.
Cell Theory
Matthias
Schlieden
a German botanist who loves
observing his plants under the
microscope, noticed that every plant
is made up of cells
Theodor
Schwann
studied different animals using his
microscope and later on concluded
that animals are made up of cells
Rudolf Virchow
known as the “Father of Modern
Pathology”. He studied medicine in
Berlin and then spent most of his life
teaching there
He published his now famous
aphorism “omnis cellula e cellula”
which means “every cell stems from
another cell.”
“
• All known living things are made
up of cells.
• The cell is a structural and
functional unit of all living things.
• All cells come from pre-existing
cells by division.
• All cells contain hereditary
“
information which is passed
from cell to cell during
division.
• All cells are basically the
same in chemical
composition.
• All energy flow of life
occurs within cells.
03
Prokaryotic vs.
Eukaryotic
BIOMOLECULES
PROTEINS CARBOHYDRATES
large, complex molecules a range of function such as
playing several critical providing energy, structural
roles in the body. It does support and cellular
most of the work in cells communication. It has the
and are necessary for the most important function as
tissues and organs of the a source of energy
body’s structure, function
and control.
BIOMOLECULES
LIPIDS NUCLEIC ACID
deoxyribonucleic acid
the basic building
(DNA) and ribonucleic
blocks for all cells and
acid (RNA). The “thread
they play many
of life”, as the DNA
important and varied
molecule is sometimes
roles. They are made
called shows why the
up of fatty acids that
discovery of its
can either be saturated
structure suggests its
or unsaturated
function.
Prokaryotes are unicellular organisms that lack membrane-bound
structures, the most noteworthy of which is the nucleus
Eukaryote, any cell or organism that possesses a clearly defined
nucleus. The eukaryotic cell has a nuclear membrane that
surrounds the nucleus, in which the well-defined chromosomes
(bodies containing the hereditary material) are located
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