Title: Graduated Tubes Graduated test tubes are an economical and convenient alternative to graduated cylin
1Laboratory OrientationFor First Year Students
2Objectives
- Practical biochemistry course is designed to
teach - students the fundamental techniques used in
- biochemistry.
- In this course students will be exposed to some
- biochemical procedures and experiments
commonly - used in biochemistry laboratories and to
provide a - basis for understanding how biochemical data
is - obtained, analyzed and presented.
31. Lab Instructions
- Time for practical session is two hours.
- The student must read biochemical background of
- experiment before attending the practical
session. - The biochemical basis of practical session will
be explained - by tutor.
- Quizzes in biochemical basis of practical will
be given - during lab session.
- Quizzes cannot be repeated.
- Quiz questions are designed so that they can be
answered - in 5 minutes.
- Practical work will be performed by students
under - supervision of staff.
- Laboratory report will be presented.
42-Laboratary regulations
- Students are required to attend all lab
sessions. - Student must attend the lab session at proper
group - and proper time.
- The class is divided into groups of
approximately 2-4 - students under demonstrators guidance during
the class. - Students are not allowed to change practical
session - without the permission of the course tutor.
- Change of session is only permitted for
students who - presented official medical excuse.
- Attendance will be recorded by the
demonstrators. - At the end of each laboratory session, students
have to - wash glass wares that have been used and clean
their - work space.
5Laboratory rules
- Do not eat food, drink beverages, or chew gum in
the - laboratory.
- 2. Be prepared for your work in the laboratory
- Read all procedures thoroughly before entering
the - laboratory.
- Never fool around in the laboratory.
- 3. Always work in a well-ventilated area.
- 4. Work areas should be kept clean and tidy at
all times - (keep your bag outside).
- 5. Be alert and proceed with caution at all times
in the laboratory. Notify the tutor immediately
of any unsafe conditions you observe.
63. Safety measures
1. Wear safety goggles any time chemicals, heat,
or glassware are used. 2. Contact lenses may be
not be worn in lab. 3. Dress properly during a
laboratory activity. - Long hair must
be tied back, - Dangling jewelry, and
loose or baggy clothing must be
secured. - Shoes must completely cover
the foot. - A lab coat should be worn
73. Safety measures b. Handling glass ware and
equipment
- Examine glassware before each use. Never use
chipped, cracked, or dirty glassware - Never handle broken glass with your bare hands.
Use a brush and dustpan to clean up broken
glass. Place broken glass in the designated
glass disposal container. - 3. Do not immerse hot glassware in cold water.
The glassware may shatter.
83. Safety measures c. Heating substances
- During using hot plate, take care that hair,
clothing, and hands are at a safe distance from
the hot plate at all times. - Use tongs or heat protective gloves if necessary.
- Heated glassware should be set aside in a
designated place to cool, and picked up with
caution. - Never look into a container that is being heated.
- Do not place hot apparatus directly on the
laboratory desk. Always use an insulated pad.
93. Safety measuresd. Handling chemicals
- All chemicals in the laboratory are to be
considered dangerous. Do not taste, or smell any
chemicals. - Check the label on all chemical bottles twice
before use. - Never return unused chemicals to their original
container. - Never remove chemicals or other materials from
the laboratory area - Dispose all chemical waste properly.
- Labels and equipment instructions must be read
- carefully before use.
- Keep hands away from face, eyes, mouth, and body
while using chemicals or lab equipment. Wash
your hands with soap and water after performing
all experiments.
10- All pipetting must be performed with the use of a
mechanical - device and oral pipetting is to be avoided.
- Strong acids, alkalis and other toxic substances
should always be handled with great care. - Student should develop and display good
techniques and - working habits such as proper and efficient
use of laboratory - reagents, equipment and instruments.
- Students will be held responsible for careless
handling and - breakage of glassware and apparatus.
11Different labels used in labs
Carcinogenic or dangerous
Dangerous to the environment
Harmful
Corrosive
Oxidizable
Explosive
Inflamable
124- General Laboratory supplies
Laboratory ware Most of laboratory ware used in
biochemistry laboratory is made of either
glass or plastic.
13Test tubes
- Available in different lengths and widths to
serve a varying number of needs. - Usually used for liquid samples, during chemical
procedures and experiments. - Often, formed of Pyrex to allow heating of
samples. - Types of tubes
Test tubes
Centrifuge tubes
Sample tubes
14Test tube RacksMade from wood, iron or plastic.
Available in different sizes
15Beakers
- A simple container for liquids.
- Very commonly used in laboratories for boiling
and preprairing solution. - Generally cylindrical in shape, with a flat
bottom. - Available in a wide range of sizes, from 1 mL up
to several litres
16Flasks
- The flask has a wide "body" and narrow neck with
an opening at the top. - They have different sizes
- Used for
- - making, collecting and measuring
solutions - - chemical reactions, mixing,
heating, cooling or dissolving, - Several types having different functions
- The most common types are
Volumetric flasks
Boiling flasks
Erlenmeyer flasks
17Erlenmeyer Flasks (Conical flasks)
- Used for simple measuring, storing and mixing of
liquids. - It has a conical base with a cylindrical neck.
- Usually marked on the side (graduated) to
indicate the volume of their contents.
18Boiling Flask- Florence Flask
Round Bottom Boiling Flasks
Flat Bottom Boiling Flasks
- Used for uniform heating and ease of swirling
- Has a round body with a single long neck and with
either a flat or a round bottom.
19Volumetric Flasks
- Used to measure a very precise and accurate
amount of a liquid. - Come with a stopper or cap.
20Measuring cylinders
- Graduated cylinders are used for accurate
measurements of different volumes of liquid .
Plastic cylinders
Glass cylinder
21Funnels
Used to hold filter papers when filtering fluid
or for pouring liquid into narrow neck
containers. They have
different sizes.
22Reagents Bottles
They are available in different sizes and may be
made of brown color glass.
23Dispensers
Used to deliver liquids including strong acids,
alkalis and solvents.
24Thermometers
A thermometer is a device which measures
temperature
25Pipettes
- Used to transport a measured volume of liquid.
- Types
- 1. Automatic pipettes
- 2. Glass pipettes
-
261. Automatic pipettes
- They may be of fixed or variable volume
- Types
- -Micropipettes
- dispense between 1 and 1000 µl
- -Macropipettes
- dispense a greater volume of liquid.
272. Glass pipettes
2.Graduated pipettes - Straight-walled,
and graduated for different volumes such as 1, 2,
5 10mL.
1. Bulb pipettes - Calibrated for a single
volume. - Typical volumes are 10, 25, and
50 mL.
28Pipette Pumps and Bulbs
Bulbs
Pumps
Both Pumps and Bulbs are used to fill glass
pipettes
29Pasteur pipettes
Used to transfer small quantities of liquids.
Glass Pasteur pipettes -glass tubes tapered to a
narrow point, and fitted with a rubber bulb at
the top.
Plastic pasteur pipettes made of single plastic
piece.
30Droppers
Graduated droppers
Ungraduated droppers
31Burette
- They vary in sizes
- The outflow of liquid from buret is usually
controlled by a stopcock. - Used to dispense known amounts of a Liquid
reagent in titration experiments.
32Wash Bottles formed from Polyethylene
33General Laboratory Equipments
- Centrifuges
- Vortex mixer
- Water bath and shaker
- Hot plate and magnetic stirrer
- Hot oven
- Balances
- Coloremeter and Spectrophotometer
34Centrifuges
Is an instrument that accelerate gravitational
separation of substances that differ
significantly in their masses They are used
to 1-Separate particles from solution in
which they are suspended (e.g. separation of
cells from blood to provide cell-free plasma)
2- Separate two liquid phases of
different densities (e.g. extracting solute from
aqueous to organic solvents)
Figure 8 Centrifuge
35Vortex mixer for stirring and mixing of liquids
of test tubes and other small vessels
Stir bar It is a magnetic bar, used to stir a
chemical mixtures or solution.
Magnetic stirrer with magnets
36 Water Bathes
37Hot plate
Hot ovens
Used for heating heating tasks
38Electronic Balance
39Fume hood
A fume hood or fume cupboard used to limit a
person's exposure to hazardous fumes.
40Colorimeter/Spectrophotometer
- Principle
- Many important biological solutions are estimated
as colored solutions, in which the intensity of
the color is proportional to the concentration of
the biological substance. - When light passes in a colored solution, it has
specific wave length therefore, the intensity of
the color is measured as its optical density or
absorbance of its wave length. - Spectrophotometry measures the absorbance or
optical activity of the colored solutions, and
the intensity of colors are read on its scale. -
- The absorbance of an unknown concentration of a
particular - substance is compared with the absorbance of
a known concentration of a standard which reacts
in the same way to produce colored solution to
obtain the exact concentration of the test
unknown sample
41- The following formula is usually used
- Contraction of sample (A )sample X
conc. Of .standard -
(A)standard - A sample Absorbance (optical density, reading)
of sample - A standard Absorbance (optical density,
reading) of standard - Concentration .standard contraction of the
known standard solution - The zero point of the Spectrophotometry should be
first adjusted with a solution known as the
blank. A water blank (colorless solution) or a
reagent blank may be used. Sometimes the zero
point of the colorimeter is adjusted against air
this depends upon the procedure used.
42- Difference between colorimeter and
spectrophotometer - The spectrophotometers are used in the UV and
visible regions of the spectrum. - Historically, spectrophotometers use a
monochromator to analyze the spectrum, but there
are also spectrophotometers that use arrays of
photosensors - The colorimeters are used only in visible regions
of the spectrum. - Optical filters are used.
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