This exercise helps students gain skill at performing dilutions without using reagents, bacterial cultures, or viral cultures, while being able to visualize the process. Standard obligations in laboratory experiments such as preciseness in calculating and measuring numerous substances, as well as meticulousness are undoubtedly vital. C serial dilution of unknown to find proper dilution that gives a 595 values between 0. Serial dilution lab in this unit we will be discussing measurements of concentration that us e both very big and very small numbers. It is critical that you master both serial and simple single dilutions. The main purpose of this experiment was to use of serial dilution agar plate technique in order to determine the number of cells in bacterial. This exercise is intended to familiarize us with using scientific notation to express big and small number easily and the process of using serial dilutions to make concentrations of known values.
Dissolve the 18g of cuso4 in 100ml of distilled water. Enumeration of microorganisms is especially important in dairy microbiology, food microbiology, and water microbiology. Using a new pipette, 1 ml from the 10 1 dilution tube is transferred aseptically to the 102 dilution tube. Pdf lab report of microbiology akbar haqi academia. To make our dilution we would use 200ul of serum and 200 ul, or 800 ul of water. Since a great deal of experimental lab work in biology involves solutions, the ability to work with and manipulate them is very important. Use an appropriate dilution of the mixture with regard to the number of cells to be counted. This type of dilution series is referred to as a serial dilution. A serial dilution is a series of sequential dilutions used to reduce a dense culture of cells to a more usable concentration. In an experiment involving concentration curves, you can use a serial dilution to create a series of solutions with dilutions of 1, 1. Dilutions and concentrations introductory chemistry. Calculating serial dilutions serial dilutions are a way of dividing up a large dilution into a number of successive dilution steps with dilution factors of 100fold or less. Extend this procedure to perform longer serial dilutions.
To determine the standard curve of absorbance versus concentration, several steps were necessary. A microbe is an organism that is microscopic and submicroscopic, which is too tiny to be viewed under a naked eye. This exercise is intended to familiarize us with using scientific notation to express big and small number easily and the process of using serial dilutions to make. In this basic laboratory experiment, 100 ml 1 m solution of nacl and water was calculated and later mixed, before 1 ml of it was dropped into a 25 ml flask and was filled with water.
Solutions containing a precise mass of solute in a precise volume of solution are called stock or standard solutions. Using this same procedure, 1 ml from the 10 2 dilution tube is transferred to the 103 dilution. For example, for water that is not turbid, the maximal dilution needed is 106 because we know that if there were 107 or more. However, the numbers of microbes in a given specimen are required to identify in particular aspect such as diary manufacturing, diseases research and study, and. The objectives of this experiment are to learn the process of enumeration to determine the number of. Lab reports are due the beginning of the following lab period the. How to write an experimental report or lab report bos54. This general microbiology practical lecture explains the serial dilution techniques in pour plate method to isolate bacteria. The method maintains this accuracy even in the presence of dilution errors of up to 10% for both the aliquot and diluent volumes, microbial counts between 104 and 1012 colonyforming units. Dilution and concentration theory dilution and concentration theory sounds ominous but you use dilutions and concentrations fairly frequently outside of your scientific life.
Mass of chromium iii nitrate required to prepare 100. The sample is then diluted in 10 fold serial dilutions and plated in appropriate medium. No observations to report other than diluted solutions made were progressively lighter in colour. The main purpose of laboratory report writing is to communicate the results of your.
They will need to understand dilution in order to be able to do these experiments in any kind of meaningful way. Hopfully when going into the lab, you are able to know the following skills. To perform three dilutions with your prepared solution. Even on this basic laboratory experiment requires of those standard obligations. Davidsonb a rdecom, edgewood chemical biological center, aberdeen proving ground, md 21010, usa b science and technology corporation, belcamp, md 21017, usa article info abstract article history. Spectrophotometry page 7 of 10 single dilutions background stock solutions are constantly diluted in biological lab settings. Calculate the mass of sucrose needed to prepare 200 ml of 1.
They are described as ratios of the initial and final concentrations. Serial dilution is often a difficult concept for students to understand. Sample chem217 laboratory reports formal report format. Samedayessays is where students get professionally written papers, very quick. Dilutions in the range 101 110 to 108 1100,000,000 are generally used, although with particular types of samples the range of dilutions can be restricted. The objective of the serial dilution method is to estimate the concentration number of colonies, organisms, bacteria, or viruses of an unknown sample by counting the number of colonies cultured from serial dilutions of the sample, and then back track the measured counts to the unknown concentration. Serial dilutions making fixed volumes of specific concentrations from liquid reagents. Lab report overview each student is responsible for 50% of lab work, and for individual, original reports. Ic50 assays, commonly used to evaluate drug efficacy, and assay development. Serial dilutions are widely used in experimental sciences, including biochemistry, pharmacology, microbiology, and physics. In this lesson an attempt has been made to relate dilution to the real world. Multiply one less than the dilution factor by the unit volume to obtain the amount of water that should be added to the solute in the volumetric flask. Each student might be required to turn in a separate lab report, but they are. In order to calculate the total dilution from tube obc, simply multiply your two dilutions.
The purpose of this experiment is to learn the procedure of enumeration to. For example, if you need to make 500 ml of dilute copper sulfate solution using a dilution factor of 10, then add 101 x 50 ml 450 ml of water to the solute in the flask. Mccc bio201 microbiology laboratory instructional videos. A serial dilution is the dilution of a sample, in 10fold dilutions. Before doing plate counts, serial dilutions are required. It is often necessary to have a solution whose concentration is very precisely known.
Estimation method for serial dilution experiments avishai bendavid a. A peak wavelength was recorded for use in the next step in the experiment. To prepare a standard solution a piece of lab equipment called a volumetric flask should be used. Perform a serial dilution of a bacterial sample according to instructions in the lab manual and plate out samples of each dilution using the spinplate technique. Received 9 may 2014 received in revised form 29 august 2014. As shown in the illustration below, it begins when 1 ml of the bacterial sample is added to 9 ml, and it is mixed together creating a 101 dilution.
The usage of burette was involved in the second experiment, disposing it up to 8. We will solve this problem by doing a serial dilution. Often, a worker will need to change the concentration of a solution by changing the amount of solvent. First, serial dilutions of the stock solution were made. Assuming that each organism gives a single colony the number of. Dilution is the addition of solvent, which decreases the concentration of the solute in the solution. Serial dilutions are used to accurately create extremely diluted solutions, as well as solutions for experiments that require a concentration curve with an exponential or logarithmic scale. Prelab questions show work and include in your lab report 1. Prepare replicates of this optimal dilution and repeat the a 595 measurement. Preparation of the chromium iii nitrate stock solution i. The concentration of bacteria in this tube is 1100 of the original sample.
As such, microbiologists have employed serial dilution and various plating techniques. If the technique is done correctly, then the living viable cells will be counted as a colony forming unit cfu that will decrease following the increasing of total dilution and the original sample cell could be calculated based on the result. Serial dilutions are often performed in steps of 10 or 100. Once college students grasp learn how to write an summary for a lab report, all of it becomes a stroll within the park. Then, 1 ml from that mixture is added to 9 ml, and it is mixed together a 102 dilution. Lab math solutions, dilutions, concentrations and molarity. For example, when you are making orange juice from a frozen concentrate, you. The following formula can easily be used to carry out a simple dilution. Again, exactly onetenth of your cells in tube 1 are transferred to tube 2, with a final volume of 10 ml. Calculating concentrations based on dilution factors. Prior to the lab, you will also need to complete your prelab report, which will test your understanding of the following concepts. Because of this, a variety of methods have been developed. In this video i discuss how we made a serial dilution during the lab, as well as why we made that serial dilution in the first place. Laboratory report outline laboratory report scoring guide these sheets can be laminated to use in all of your classes.
In this lab you will investigate several techniques for working with solutions. Upon completion of this lab, the student should be able to proficiently calculate molarities for solutions. Booker microbiology 2310 lab report 3 serial dilutions october 15, 2017 introduction. Introduction microorganism is an organism that is microscopic or submicroscopic, which is too small to be seen under naked eyes.
Serial dilution simulation lab the american biology teacher. This process may be repeated as many times as necessary to achieve the desired solution. Pdf estimation method for serial dilution experiments. Hypothesis predict how the serial dilution of your drink solution will affect the colour, flavor, and other properties of the solution. The easiest method is to make a series of 1 in 10 dilutions. Repeated serial dilutions will be necessary to determine accurate concentration. Carolina biological supply has everything you need to complete your classroom life science activities and experiments. In this short dry lab exercise, students perform serial dilutions using seed beads. In this method the substance to be tested if not in liquid form,is grinded and dissolved in suitable liquid medium. Your microbiology lab instructor taught you the basics of serial dilution and how to use it to determine the number of cells in an original bacterial culture. This is a one millionfold dilution clearly too big to do at once. Predict how the serial dilution of your drink solution will affect the colour, flavor, and other properties of the solution. If the sample is not dissolved well, the cells become crowded and will be difficult to count.