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Laboratory Orientation

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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.

Objectives

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Time for practical session is 2 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.

1- Lab Instructions

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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.

2- Laboratary regulations

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1. 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 mess 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.

Laboratory rules

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1. Wear safety goggles any time chemicals, heat, or glassware are used.

2. No Contact lenses to be worn in lab.

3. Dress properly during lab 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

3- Safety measures

a. CLOTHING

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3- Safety measures

1. Examine glassware before each use Never use chipped, cracked, or dirty glassware

2. 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.

b. Handling glass ware and equipment

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3- Safety measures

1. During using hot plate, take care that hair, clothing, and hands are at a safe distance from the hot plate at all times. 

2. Use tongs or heat protective gloves if necessary.

3. Heated glassware should be set aside in a designated place to cool, and picked up with caution. 

4. Never look into a container that is being heated.

5. Do not place hot apparatus directly on the laboratory desk.  Always use an insulated pad. 

c. Heating substances

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3- Safety measures

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. 

d. Handling chemicals

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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. 

All pipetting must be performed with the use of a mechanical device. 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.

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Fume hood

A fume hood or fume cupboard used to limit a person's exposure to hazardous fumes

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Different labels used in labs

Corrosive

Harmful Dangerous to the environment

ExplosiveInflammable Oxidizable

Carcinogenic or dangerous

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4- General Laboratory supplies

Laboratory ware

Most of laboratory ware used in biochemistry laboratory is made of

either glass or plastic.

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Test 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

Centrifuge tubesSample tubes

Test tubes

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Test tube Racks

•Made from wood, iron or plastic.•Available in different sizes

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Beakers•A simple container for liquids.

•Very commonly used in laboratories for boiling and preparing solution.

•Generally cylindrical in shape, with a flat bottom.

•Available in a wide range of sizes, from 1 mL up to several litres

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Flasks• A flask has a wide "body" and narrow neck with an opening at the top• They have different sizes• They are 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 flasksErlenmeyer flasks Boiling flasks

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Erlenmeyer 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.

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Boiling Flask- Florence Flask

• 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.

Round Bottom Boiling FlasksFlat Bottom Boiling Flasks

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Volumetric Flasks

• Used to measure a very precise and accurate amount of a liquid.

• Come with a stopper or cap.

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Measuring cylinders

• Graduated cylinders are used for accurate measurements of different volumes of liquid.

Plastic cylindersGlass cylinder

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Funnels•Uses:

•To hold filter papers when filtering fluid •For pouring liquid into narrow neck containers.

•They have different sizes.

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Reagents Bottles

They are available in different sizes and may be made of brown colored glass.

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Dispensers

Used to deliver liquids including strong acids, alkalis and solvents.

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Thermometers

A thermometer is a device which measures temperature

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Pipettes

• Used to transport a measured volume of liquid.

• Types: 1. Automatic pipettes 2. Glass pipettes

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1. Automatic pipettes

• They may be of fixed or variable volume

• Types– Micropipettes:

dispense from 1 μl to 1000 μl

– Macropipettes: dispense a greater volume of liquid. Replacement tips

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2. Glass pipettes

2.Graduated pipettes:• Straight-walled, • Graduated for

different volumes as 1, 2, 5 & 10 ml.

1. Bulb pipettes:• Calibrated for a single volume. • Typical volumes:

10, 25, and 50 ml.

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Pipette Pumps and Bulbs

Bulbs

Pumps

Both Pumps and Bulbs are used to fill glass pipettes

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Pasteur pipettes

Used to transfer small quantities of liquids.

Glass Pasteur pipettes: glass tubes tapered to a narrow point, and fitted with rubber bulb at the top

Plastic Pasteur pipettemade of single plastic piece.

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Droppers

Graduated droppersUngraduated

droppers

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Burette

•Used to dispense known amounts of a Liquid reagent in titration experiments.

•They vary in sizes

•The outflow of liquid from burette is usually controlled by a stopcock.

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Wash Bottles

Formed from Polyethylene

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5- General Laboratory Equipments

•Centrifuge

•Vortex mixer and magnetic stirrer

•Water bath and shaker

•Hot plate and Hot oven

•Balances

•Colorimeter and Spectrophotometer

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Centrifuge

• An instrument that accelerates gravitational separation of substances which have different masses

• 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 2 liquids of different densities (e.g. extracting solute from aqueous to organic solvents)

Figure 8 Centrifuge

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Magnetic stirrer with magnets

Stirrer bar: is a magnetic bar used to stir a chemical mixture or solution.

Vortex mixer for stirring and mixing of liquids in test tubes and other small vessels

Vortex mixer

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Water Bath

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Hot plate

Used for heating tasks

Hot ovens

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Electronic Balance

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Colorimeter/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.

• Widely used in biochemistry for quantitative analysis of bio-molecules

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Difference between colorimeter and spectrophotometer

• Spectrophotometers are used in the UV and visible regions of the spectrum.

• Colorimeters are used only in the visible regions of the spectrum.