Lab skills
Safety Issues
• Follow instructions, use all instruments
correctly.
• Wear safety goggles
• Report injuries and defective equipment
• Tie back loose hair and clothing.
• Beware of hot glassware,
• Do not heat stoppered bottles,
• Never point a test tube in you partners direction
• Never taste or directly inhale anything, use a
wafting motion.
• Do not pour back into reagent bottles.
• Clean area before and after activity.
•
• Triple Beam Balance
•
• Make sure zero mark- all weight at zero
• Start moving 100’s first. If too much go back a
notch.
• move tens and then move ones if necessary
• Add all sliders up for total mass of object.
• When using a paper or some sort of dish be
sure to deduct the mass of the dish from the
mass of the dish with the substance.
• Or zero the scale out with the dish on it.
•
Graduated Cylinder
• Mensicus: the curved surface of the liquid
that is where the reading is taken.
Metric ruler
• Meters = Length or distance
• Liters = Volume
• Grams = Mass
• Compound Light Microscope: Consists of 2
lenses the eyepiece (ocular) and the objective
(low power and High power) parts-label and
define.
•
• Eyepiece: The lens the viewer looks through to
see the specimen. The eyepiece usually
contains a 10X or 15X power lens.
• Body tube : The body tube connects the
eyepiece to the objective lenses.
• Arm: The arm connects the body tube to the
base of the microscope.
• Coarse adjustment: Brings the specimen into
general focus. Used with Low power objective
• Fine adjustment: Fine tunes the focus and
increases the detail of the specimen. Used
with the high power objectives
• Nosepiece: A rotating turret that houses the
objective lenses. The viewer spins the
nosepiece to select different objective lenses.
• Objective lenses: One of the most important
parts of a compound microscope, as they are
the lenses closest to the specimen.
• A standard microscope has three, four, or five
objective lenses that range in power from 4X
to 100X. When focusing the microscope, be
careful that the objective lens doesn’t touch
the slide, as it could break the slide and
destroy the specimen.
• Specimen or slide: The specimen is the object
being examined. Most specimens are mounted
on slides, flat rectangles of thin glass.
• The specimen is placed on the glass and a cover
slip is placed over the specimen. This allows the
slide to be easily inserted or removed from the
microscope. It also allows the specimen to be
labeled, transported, and stored without
damage.
• Stage: The flat platform where the slide is
placed.
• Stage clips: Metal clips that hold the slide in
place.
• Aperture: The hole in the middle of the stage
that allows light from the illuminator to reach
the specimen.
• On/off switch: This switch on the base of the
microscope turns the illuminator off and on.
• Illumination: The light source for a
microscope. Older microscopes used mirrors
to reflect light from an external source up
through the bottom of the stage; however,
most microscopes now use a low-voltage bulb.
• Iris diaphragm: Adjusts the amount of light
that reaches the specimen. .
• Condenser: Gathers and focuses light from the
illuminator onto the specimen being viewed.
• Base: The base supports the microscope and
it’s where illuminator is located.
• Find object using low power (see large
amount with less detail). Use Coarse
adjusting knob (larger knob). Brighter image
• Flip to high power (zoom) (see less of image
but more detail). Use Fine adjusting knob
(smaller knob). Darker image Be careful not
to disrupt the specimen of crack the slide or
lens.
• Lighting system: consists of a mirror,
diaphragm(controls the amount of light
reaching the specimen)
• Disc diaphragm: flat plate with a number of
different sized openings.
• Iris diaphragm is made of overlapping plates
and the size of the opening may be adjusted
and substage illuminator.
• Total magnification =
• eyepiece x objective
• Images are upside down and backwards.
• Microscopes are used to make small details
more visible.
•
• Resolution: the ability of the microscope to
show two points close together.
• Controls the sharpness of the image.
•
• Optical Microscope: uses light to produced
enlarged images( light microscope)
• Lenses are pieces of curved glass that bend
the light and make the image appear larger.
• Simple Microscope: magnifying glass.
• Stereomicroscope: two oculars.
• Electron Microscope-Excellent magnification
and provides a very detailed picture. Good for
examination of nonliving specimens
• Dissecting Microscope- images are magnified
but seen as they are. Two oculars. Three
dimensional image. Good for viewing external
features
• Phase Contrast Microscope: makes unstained
elements visible.
• Prep of wet mount.
• Staining object makes them more visible.
• No air bubbles this interferes with the item
you are trying to view.
• Certain stains bind to specific proteins
therefore some stains are used to make
specific items visible
• A vital stain is used on living tissue only other
stains will kill the tissue cells.
• Apply the stain to one side of the wet mount
and use a paper towel to draw the water and
stain across the slide and under the coverslip.
This leaves the slide in tact.
•
Prep of a wet mount
Staining a slide
• Types of Stains•
Methylene Blue
•
Lugol’s Iodine
•
• Indicators•
Chemicals when added in small amounts
will indicate or show the presence of a specific
substance.
•
•
•
• Benedicts (Fehling’s) solution. (glucose
solution) Blue----(heating)---yellow(+).
•
• Lugol’s solution (Iodine). Test for starch.
Orange ------ Purple(+)
•
• Bromthymol Blue (CO2). Blue (O2) --------yellow (CO2)(+).
• Centrifugation: The instrument used is the
centrifuge. It spins the specimen in a circular
motion and separates materials according to
their densities. Most Dense (Heavy) bottom,
least dense (lightest) top.
• Ultracentrifuge: same principle only stronger
spinning action so there is more separation.
• Microcentrifuge: same principle only
separating a small sample
• Dissection: the separation of a large organism
into its parts.
• Micro-dissection: dissection on a very small
object with small instruments being used.
• Tissue Culture: a live tissue sample that is
used for research.
• Chromatography:
• Is used to separate and analyze complex
mixtures.
• The mixture is placed on a paper.
• A solvent is placed in a container.
• .
• The paper is placed in the container with the
liquid touching the very bottom.
• The mixtures particles will separate according
to their size.
• By comparing the known materials to the
unknown materials we can identify the
components in a mixture.
• The particles moving are in the mobile phase
and the paper is the stationary phase (not
moving)
• Electrophoresis:
• the particles are separated thru the use of an
electric current.
• This method can both identify and measure
the amount of a substance in a test solution.
• The electric current causes the particles to
migrate (move) based on their size and
charge.
• The test solution results are compared to
known results and the particles of a mixture
are identified
• Always stop both procedures before the liquid
runs off the paper.
• If that happens the test results are invalid and
need to be repeated (provided there is
enough test sample left over)