MICROSCOPY AND CELLS
BIO 171 – WEEK 3
MICROSCOPY – THE COMPOUND LIGHT
MICROSCOPE
System of lenses arranged
to produce an enlarged,
focusable image of a
specimen.
MICROSCOPY – THE MICROSCOPE
Illuminating System
• Light source
• Condenser lens
Condenser lens
Light source
MICROSCOPY – THE MICROSCOPE
Ocular lenses
Imaging System
• Objective lenses
• Ocular lenses
• Body tube
Objective lens
Body tube
MICROSCOPY – THE MICROSCOPE
Other parts
• Stage
• Stage clips
• Arm
• Base
• Course adjustment knob
• Fine adjustment knob
Stage
Base
Arm
Course Adjustment
Knob
Fine Adjustment Knob
Stage
MICROSCOPY – RULES AND USE
 Always carry upright with one hand under the base and the
other around the arm.
 Only clean lenses with lens paper
 Always start on low-power objective.
 If shifting to a higher power objective, rotate carefully.
 Always use fine adjustment knob when using a higher power
objective
USING A COMPOUND LIGHT MICROSCOPE
 1) Ensure that lowest-power objective is in place.
 2) Place specimen on the stage.
 3) Adjust slide so that the area of interest is in view.
 4) Use the course adjustment knob to focus on the
specimen.
 5) Slowly rotate the high-power objective into place, making
sure that the lens does not touch the slide.
 6) Use the FINE ADJUSTMENT KNOB ONLY to further
refine your focus.
ACTIVITIES - MICROSCOPY
 3.1 – Using a compound microscope
 3.2 – Magnification
 3.3 – Field of view
 3.4 – Depth of field
 3.5 – Preparing a Wet Mount
CELL THEORY
 All living organisms are composed of cells
 The cell is the basic unit of life
 Cells arise from pre-existing cells
 Cells contain hereditary information which is passed from cell to cell during cell
division
Scientific Theory: Explanation of some aspect of the natural world that has been
substantiated through repeated experiments or testing.
Examples: Atomic theory, Germ theory, Theory of Evolution, Theory of
Homeostasis, Theory of Gravity, Theory of Molecular Bonds
INTRO CYTOLOGY REVIEW
Prokaryotes
INTRO CYTOLOGY REVIEW – PROKARYOTES
 Prokaryote = “before nucleus”
 No nucleus or membrane-bound organelles
 Regions of concentrated DNA – Nucleoid
 Ribosomes – particles involved in protein synthesis
 Flagella – used for movement
 Pili – attach to surfaces or exchange genetic material
ENDOSYMBIOTIC THEORY
 Prokaryotic organism is engulfed or parasitizes early
eukaryote
 Mitochondria – consume oxygen to extract energy
(ATP) from glucose, produce carbon dioxide and
water.
 Chloroplasts – consume water and carbon dioxide;
capture energy from light, transforms light energy into
chemical energy (glucose) and releases oxygen.
 Both mitochondria and chloroplasts have their own
DNA.
INTRO CYTOLOGY REVIEW – EUKARYOTES
See Table 4.1 for differences
between cell types
PLANT CELLS
 Elodea slide
 Onion
ACTIVITIES
 Chapter 3 - Microscopy

3.1 – Using a compound microscope

3.2 – Determining magnification

3.3 – Alternate Procedure – Field of view

3.4 – Determine depth of field

3.5 – Prepare wet mount of pond water

3.6 – Look through dissecting scope
 Chapter 4 – The Cell

4.1 – Cyanobacteria (Merismopedia, Nostoc, and Oscillatoria)

4.2 –Yogurt

4.3 – Elodea – Prepared slides

4.5 – Stained Onion Cells – Stain with Iodine (IKI)

4.7 – Examine amyloplasts (in potato)

4.9 – Examine amoeba

4.10 – Examine Paramecium

4.11 – Examine Spirogyra

4.12 – Examine Unknown/Pond Water
CYANOBACTERIA
 Sometimes called “blue-green algae”
 Large prokaryotes with chlorophyll and other
pigments for photosynthesis
 Surrounded by mucilaginous sheath
 Contributed to early oxygenation of ancient earth’s
atmosphere
BACTERIA
 Yogurt – Lactobacillus
 Gram positive bacteria
 Converts lactose into lactic acid (milk  yogurt)
 How does the size of Lactobacillus compare to
the Cyanobacteria?
ELODEA
 Look for chloroplasts, nucleus, cell wall, central
vacuole.
ONION CELLS
 Stain with IKI (Iodine)
 Compare stained VS unstained onion cells
AMYLOPLASTS
 Plastids that store starch
 Stain potato with iodine
SPIROGYRA
 Filamentous green alga
 Named for spiral arrangement of
chloroplasts.
ACTIVITIES
 Chapter 3 - Microscopy

3.1 – Using a compound microscope

3.2 – Determining magnification

3.3 – Alternate Procedure – Field of view

3.4 – Determine depth of field

3.5 – Prepare wet mount of pond water

3.6 – Look through dissecting scope
 Chapter 4 – The Cell

4.1 – Cyanobacteria (Merismopedia, Nostoc, and Oscillatoria)

4.2 –Yogurt

4.3 – Elodea – Prepared slides

4.5 – Stained Onion Cells – Stain with Iodine (IKI)

4.7 – Examine amyloplasts (in potato)

4.9 – Examine amoeba (prepared slide)

4.10 – Examine Paramecium (prepared slide)

4.11 – Examine Spirogyra

4.12 – Examine Unknown/Pond Water
Answer questions in lab manual
Dispose of pipettes in BIOWASTE
Dispose of used slides in can on desk