Microscope Conversion Worksheet - PDF by wls53296

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									               BIOL 1406 Supplemental Lab Materials

                                Spring 2008


Contents                                               Page

  1. Science is a Process                               1
  2. Practice Identifying Data, Inferences, and PKBs    3
  3. The Scientific Method                              5
  4. Metric Conversion Worksheet                        7
  5. Dissecting Microscope Worksheet                    9
  6. Effect of Molecular Weight on Rate of Diffusion   11
  7. Osmosis in Animal Cells                           13
  8. Enzyme Activity - Salivary Amylase                15
  9. Cellular Respiration in Germinating Seeds         17
  10. Data Sheet for Chi Square Analysis               21
  11. Isolation of DNA from Animal Cells               23
  12. Transcription and Translation Worksheet          25




                                   -0-
Section _______                                      Name _________________________
Instructor ______________                            Date _____________



                   Science is a Process: Activity Instructions

"When you think about it, the fossil record is like a series of photographs: frozen moments from
what is really a moving, ongoing reality. Looking at the fossil record is like thumbing through a
family photo album. You know that the album isn't complete. You know life happens in
between, you only have the pictures. So you study them, and study them. And pretty soon, you
begin to think of the album not as a series of moments, but as reality itself." (p. 192 of Michael
Crichton's The Lost World).
Today you will work with a set of "snapshots in time" as you attempt to make sense of
past events. As is true with records of any historical event, the information available to
you is incomplete. With some attention to the data provided in these cards and your
prior knowledge and beliefs about how stories like this one unfold, you should be able to
make many inferences about what has occurred, despite the incompleteness of the
record.

This is an opportunity to carefully examine the ways that we make sense of the past by
examining artifacts from these events. In other words, how we generate hypothesis
given a set of observations. Using the cartoon cards provides a non-technical context
so that we can "step back" and explicitly examine our reasoning.

Your assignment is to make sense of these pictures by placing them in chronological
order. As your group works to "reconstruct the past" you should pay particular attention
to the ways that you make decisions about the order of the cards. Read over the writing
assingment below now so that you can think about it while you work with the cartoon
cards.


Writing Assignment

While you were working with your group to place the cards in order you had to make
many inferences based on the cards themselves and knowledge you already have. In
the space below, describe one inference (decision) your group made about the order of
the cards in terms of the data (observations) you used and the prior knowledge and
beliefs you brought to bear in developing the sequence of cards. In other words,
describe the decision (for example, why you put one card before another) and then write
about the data and prior knowledge you used to make that decision. Definitions of these
terms are available on page 5 of this packet.




                                           -1-
Card Sequence

____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____



Inference based on DATA:




Inference based on PRIOR KNOWLEDGE:




                               -2-
Section _______                                 Name _________________________
Instructor ______________                       Date _____________

Homework Assignment: Practice Identifying Data, Inferences, and PKBs
In science, what we claim to know is dependent on a network of connections between
what we observe and what we think we already know. These connections between
observations and ideas exist at a variety of levels, that we are only partly conscious of
as we think and reason. Learning to trace those connections and identify those often-
unconscious ideas will help us understand which knowledge is sound, which is
questionable, and which is clearly false. Working to learn about knowledge in this sense
will further help us understand the nature of science itself-an activity devoted to making
sense out of events in the natural world that often seem unrelated and confusing.
Making claims about what we know (knowledge claims), as described above, is rarely
straightforward (especially in science). In this homework assignment you will use your
understanding of data, inferences, and prior knowledge and beliefs to analyze a section
of popular science writing.
      Data: What can be sensed directly; observations of the natural world.
      Prior Knowledge: What we believe to be true about the world; and Beliefs
      information we bring to a situation based on previous experience.

      Inferences: Conclusions drawn from what we see (observe) and what we
      know; in other words, our interpretation of data based on our prior
      knowledge and beliefs.
Read the following paragraph, taken from David Attenborough's 1979 book Life on
Earth and answer the questions on the following page.
      At Dinosaur National Monument a museum has been built around a cliff
      face where a single layer of stone, some four meters thick, has yielded
      fourteen different species of dinosaur. Some were no bigger than a
      chicken. Others were the biggest land-living creatures the world has ever
      seen. Thirty complete skeletons have been taken away but bones of many
      more remain. The rock which now forms the cliff-face was once a
      sandbank in the middle of a river. Gigantic rotting carcasses of dinosaurs
      floated down, beached on the sandbank and were dismembered there
      partly by putrefaction and partly by smaller dinosaurs that came to feast
      on carrion. All the long bones, such as those from the limbs and sections
      of the backbone, lie pointing in roughly the same direction and from them
      we can deduce which way the river ran. The whole deposit seems to have
      been laid down in the space of not more than a hundred years or so. It is
      an astonishing demonstration of how abundant these creatures once
      were.




                                       -3-
1. Write down two references to data from Attenborough's writing.




2. List two inferences that are included in the passage.




3. For each of the inferences you identified above, list at least one belief or piece of
prior knowledge that was used to make that inference.




                                         -4-
The Scientific Method

LABORATORY OBJECTIVES

Upon completion of this laboratory exercise the student will be able to:

   1. Identify the components of the scientific method and explain each.
         Experimental group
         Control group
         Independent Variable
         Dependent Variable
         Hypothesis
         Null Hypothesis

2. Design a simple scientific experiment.

3. Perform and evaluate a simple scientific experiment.


INTRODUCTION

Science has been described as a way of knowing. It emerges from man's curiosity about
ourselves and the world around us. Seeking to understand seems to be one of our basic drives.
We ask questions that arise from our observations of natural things; and we seek discovery of
answers. Striving to reveal the secrets of nature, scientists have devised a method of getting at
the truth or solving problems. This is called the scientific method. Actually, there are many
methods but they all bear common features or rules.

Is the scientific method something that only scientists can use? Certainly not; its usefulness
extends to all of us, even in our daily lives. For example, I can use it to find why my car will not
start. Or, I can find out what foods give me a stomachache.

Despite what the scientist wants to find out and the exact procedure used, certain features of the
scientific method are common. Scientists make observations that lead them to ask questions.
They make educated guesses about possible answers, and then devise ways to test their guesses.
In its classical form the scientific method involves the following steps:

1. Observation and Stating of a Problem - Scientific investigations usually begin with an
   observation that stimulates a desire to know or understand. The scientist then states the
   problem as clearly and concisely as possible.

2. Collection of Pertinent Information - An attempt should be made to assemble the pertinent
   facts concerning the problem. The scientist seeks to tap into as much available information
   about the problem as possible. This information may come from the library, the worldwide
   web, colleagues, or from other available sources.


                                            -5-
3.    Formulation of a Hypothesis - Based on information assembled in step two above, a
     tentative explanation or hypothesis is advanced. Some call this an educated guess. This is a
     trial idea, a possible solution to the problem. A key feature of the hypothesis is that it can be
     tested or falsified. This is done by testing the null hypothesis (the hypothesis reworded such
     that the independent variable has no effect). This serves as the basis for the expected or
     predicted outcome. This can then be compared to the observed which is generated by
     experimentation, see step 4.

4. Testing of the Hypothesis - In this step the scientist designs and executes an experiment to
   test the validity of the hypothesis. The exact design of this test can vary greatly and depends
   upon the nature of the study and the creativity of the investigator. The experiment must be
   carefully planned and conducted with great precision. Scientists strive to eliminate all human
   and instrumental bias. Accurate records as quantifiable data must be kept of every phase of
   the experiment. Results of the experiment are gathered and analyzed. Many experiments
   consist of a control group and an experimental group. The experimental group is identical
   to the control group in every respect except one, called the variable, or more specifically, the
   independent variable. This is the one substance, situation or condition that is being tested
   or varied. All other factors are kept constant in both the experimental group and the control
   group. Therefore, the control serves as the basis or standard by which it is determined if the
   one variable is responsible for any differences in results. In other words, it is used as a basis
   of comparison. A key feature of the experiment is that it must be repeatable. That is, other
   researchers must be able to repeat the experiment under the same conditions and achieve the
   same results.

5. Conclusion - When the experiment is complete, the researcher must evaluate the results in an
   effort to reach a conclusion. The conclusion either supports or fails to support the original
   hypothesis. In either case, knowledge is gained and the researcher moves on.

6. Publication of Results - While your personal use of the scientific method does not involve
   this step, it is vital to the scientist. This requires publication, in appropriate scientific
   literature, of a detailed report of the problem, the hypothesis, all experimental methods and
   results, and the conclusions reached by the investigator. This allows other scientists to repeat
   the investigation if they choose, as a way of confirming the validity of the study.




                                             -6-
Section _______                                     Name _________________________
Instructor ______________                           Date _____________

Complete the following worksheet using Appendix B in your lab manual.


1. Metric Conversions

78cm = __________ m              56 g = __________ kg              1.06 liters = __________ ml

33.3 km = __________ m           5.2 km = __________ cm            67 mm = __________ cm

456 l = ___________ ml           1.56 ng = __________ mg           12.4 cm = __________ m


2. English/Metric Conversions


80oF = __________ oC             67 miles = __________ km          25 oC = __________ oF

5 liters = __________ quarts     125 pounds = __________ kg        5.0 km = __________ miles


3. The veterinarian tells you to give your horse a 25 cc shot (1 cubic centimeter = 1 ml) of
   penicillin.

   How many microliters ( l) of penicillin should you give your horse? ________

   How many liters (l)? ________


4. The doctor tells you to take 5 mg of medicine/day for your high blood pressure.

   If each tablet contains 125 g of medicine how many tablets should you take? _________


5. The offensive tackle for Whatsamata U. weighs 275 pounds. The defensive tackle for
   Clinging Vine College weighs 121 kg.

   Which tackle weighs more? ________        How many pounds more? ________




                                           -7-
6. Scientific Notation

Scientific notation is a convenient way to express a number that is very large or very small.
Your instructor will explain how to write numbers using scientific notation.

Covert from a real number to scientific           Convert from scientific notation to a real
notation                                          number

1.1732 g = _______________ g                      34.34 x 102 = __________________

801 km = _______________ km                       8.9 x 10-6= _________________

512 ml = ______________ ml                        76.1 X 101 = __________________




                                           -8-
Section _______                                          Name _________________________
Instructor ______________                                Date _____________

I.         Examine your fingerprints.

      1.   Turn the magnification knob to its lowest magnification power.
      2.   Place your left index finger upside down on the stage.
      3.   Turn the focusing knob until the dermal ridges on you finger come into focus.
      4.   Adjust the magnification & focus knobs to look at your finger in greater detail.

Common fingerprint patterns




                                                          Tented Arch                          Accidental
 Radial Loop          Ulnar Loop
                                                           Center of                              Whorl
                                       Arch                  pattern       Whorl              Two or more
Opens towards Opens towards
                                                           contains a                         patterns in the
   thumb       little finger
                                                         sharp up thrust                        same print

           5. Examine all of the fingers on you left hand & record your fingerprint pattern below.

 Thumb _______________ Index finger ________________ Middle finger _______________

        Ring finger ______________ Little finger _______________


II.      Examine your fingernails & then examine your watch or other jewelry you may be
      wearing in order to answer the following.

               1. How does the use of the dissecting scope differ from that of the compound light
                  microscope? List as many differences as possible.




                                               -9-
III.      Examine your driver’s license.

       1. What does it say around the Texas flag? _______________________________

       2. What does it say around the state seal? ________________________________


IV.       Examine a check

       1. What does it say on the line where you place your signature?
       _____________________________


V. Examine and sketch other items that your instructor has provided.




                                            - 10 -
Section _______                                      Name _________________________
Instructor ______________                            Date _____________

To be performed by the instructor as a demonstration only.

Two gases, HCl and NH3 (derived from NH4OH), will be released at opposite ends of a closed
space (glass tube). Because these 2 gases react with one another to form an ammonium chloride
gas cloud, the location of their meeting can be seen as a diffuse white band.


           Side A Gas                                                           Side B Gas

            ________                                                            ________



The Null Hypothesis for this experiment is that molecular weight has no effect on the rate of
diffusion.

1. If the H0 is supported, where would you predict the formation of the gas cloud to occur within
the tube?


2. Calculate the molecular weight for each of the gases used.

           HCl __________________

           NH3 __________________

3. Describe the results observed relative to the movement of the gases introduced into the tube.



4. State the relationship of molecular weight to the rate of diffusion.



5. Was the Null Hypothesis Accepted or Rejected?

6. If this experiment was repeated using 2 different molecules (listed below), which would you
   predict would diffuse more quickly?     NO2 and SO2



7. Why?



                                           - 11 -
- 12 -
Supplement - Osmosis in Animal Cells
This exercise is intended to complement the one that demonstrated osmosis in plant cells,
(Elodea).

The chicken eggs that will be used for this experiment have been de-shelled by dissolving the
shell (calcium carbonate) in an acidic solution (vinegar). The result is an egg that represents an
animal cell with a semi-permeable membrane.

To observe the effects of osmosis on these cells, each of three eggs will be placed in a
hypertonic, hypotonic, and isotonic solution and the results recorded.

Procedure:

1. Obtain 3 beakers containing the following solutions:

       Distilled water
       0.3M Sucrose
       1.0M Sucrose

1. Obtain 3 de-shelled eggs and record their initial weight by gently blotting them with a paper
   towel and then taking their weight using an electronic balance. Record your readings, in
   grams in the chart below under the column indicated by the time 0.

2. From what you already know about osmosis, predict what might happen under each
   condition.

       Distilled water – H0: ___________________________________________
       0.3M Sucrose – H0: ___________________________________________
       1.0M Sucrose – H0: ___________________________________________

3. Place each egg in one of the beakers making sure to place them in the solution corresponding
   to the data recorded in the chart. Make sure each egg is totally submerged.

4. At 15 minute intervals, remove the eggs, gently blot them, and record their weight. Do this
   until 1 hour has elapsed or you run out of time whichever comes first.

5. Plot your results as a series of lines on the graph provided.

6. Label each line that corresponds to the egg placed in a hypertonic, hypotonic, and isotonic
   solution.

7. Did your results support your hypothesis? _________________________




                                           - 13 -
Section _______                            Name _________________________
Instructor ______________                  Date _____________


DATA

                                            Time
Solution          0’        15’              30’        45’         60’
  Distilled
   Water
   0.3M
  Sucrose
   1.0M
  Sucrose




Weight in
 grams




                                           Time




                                  - 14 -
Enzyme Activity - Salivary Amylase
When you chew food in your mouth you begin to mechanically
digest the food while mixing it with saliva. Saliva contains water to
moisten the food and mucin (a glycoprotein) to protect the lining of
the mouth and lubricate the food for swallowing. Saliva also
contains antimicrobial agents, buffers that neutralize acids to prevent
tooth decay and a single enzyme-salivary amylase.

Salivary amylase begins the chemical digestion of starch (a
polysaccharide found in plants) and glycogen (a polysaccharide
found in animals). Amylose, which is the simplest form of starch is
an unbranched polymer of glucose subunits linked together by alpha-
1,4 glycosidic bonds. The hydroxyl (OH) group involved in the formation of the glycosidic bond
lies below the plane of the sugar ring in alpha-linked polysaccharides or above the plane in beta-
linked polysaccharides. Amylopectin is another form of starch but it contains branched chains
with alpha-1,6 linkages. Glycogen is similar to amylopectin but is more highly branched.

Salivary amylase hydrolyzes the alpha-1, 4-glycosidic bonds between glucose molecules &
breaks starch/glycogen down into shorter polysaccharide chains, maltose (a disaccharide) and/or
glucose.


  -Glucose                     Maltose                     Starch: chain of -glucose subunits




Amylose (Starch)     Amylopectin (Starch)              Glycogen




In this simple lab activity you will examine your own salivary amylase as an introduction to
enzyme activity.

                                           - 15 -
Section _______                                         Name _________________________
Instructor ______________                               Date _____________

Procedure: Work in groups of two.

1. Obtain a starch plate and two cotton swabs.
2. Using a Sharpie or marker, draw a line on the bottom of the plate to divide the plate in half or
   thirds.
3. Insert the cotton tip in your mouth to wet the swab with saliva.
4. Streak your initials onto one section of the plate using the saliva on your cotton swab. Be
   careful not to puncture the agar. You may write your initials if you like.
5. After your partner(s) has streaked their part of the plate, replace the lid and let incubate at
   room temperature for 10 minutes. Make sure to dispose of your cotton swab in the biohazard
   waste container provided by your instructor.
6. Remove the lid and flood the entire surface of the plate with a dilute iodine solution.
7. The solution can then be carefully decanted into a waste beaker.
8. Observe the results and answer the review questions.


Salivary Amylase Worksheet

1. What is/are the substrate(s) for salivary amylase?
____________________________________


2. What reagent is used to test for starch? ________________________________


3. What compounds are present in the white areas on your plate after staining?

   _____________________________________________________________________


4. How does saliva promote oral hygiene?




5. The iodine stains starch when iodide ions slip into the coils of amylose turning the starch
blue-black. If the agar plate being used contained starch throughout, why did the streaked regions
of the plate appear lighter after staining than the background?
                                              dbf2004




                                           - 16 -
                      Cellular Respiration in Germinating Seeds
Introduction

This lab is an adaptation of labs that have appeared in various textbooks in recent years. It
serves as an important reminder to students that plant cells also do respiration. (A common
misconception is that plants do photosynthesis while only animals do respiration.)

As cellular respiration occurs, oxygen gas is taken in from the air and carbon dioxide gas is given
off. The rates at which these occur and the amounts of the gases involved are very similar. This
lab features a comparison of dormant and germinating seeds to demonstrate these aspects of
cellular respiration.

While a mature seed appears to be dead it is actually alive and in a dormant state. In this
condition, cell respiration is occurring but at a greatly reduced rate. Seeds will germinate when
conditions are right. In the presence of oxygen, favorable temperatures, and available water,
most seeds will germinate. (Some seeds do have additional requirements, but not those used in
this laboratory.) Soaking beans in water should initiate the germination process for the purpose
of this lab. Once germination begins, the rate of cell respiration increases greatly because the
need for energy has suddenly become tremendous. The ATPs yielded by the cellular respiration
are needed to support the rapid growth of the germinating seed. Half of the beans used in this
laboratory have been soaked overnight to initiate germination.

This lab also requires the use of calcium oxide. Be sure to carefully read the proper handling and
disposal procedures included with the agent. During the course of the experiment the calcium
oxide will becomes calcium carbonate, harmless limestone: CaO + CO2 --> CaCO3


Activity

Purpose: Investigate cellular respiration in germinating seeds.

Materials

(per lab group)
    6-15 pre-soaked seeds (field peas or appropriate beans)
    6-15 dry seeds (field peas or appropriate beans)
    3 test tubes
    6 cotton plugs
    1/2 teaspoons pulverized calcium oxide
    100-200 ml beaker
    Lightly colored water
    ruler




                                           - 17 -
Procedure


Day 1 (set up, label with your name and section number)

   1. Using a marker or tape, label test tubes A, B, and C.

   2. Layer the materials in the test tubes as described below. The materials should not packed
      in too tightly, but should be snug enough that they do not fall out when inverted.

             a. 6 presoaked seeds, cotton plug, 1/2 teaspoon calcium oxide, cotton plug
             b. 6 dry seeds, cotton plug, 1/2 teaspoon calcium oxide, cotton plug
             c. No seeds, cotton plug, 1/2 teaspoon calcium oxide, cotton plug

   3. Tape or rubber band the three test tubes together.

   4. Pour the colored water into the beaker.

   5. Invert the three test tubes into the beaker.

   6. Measure the height that the liquid rises to in each of the test tubes and record it.

   7. Store the laboratory set up at room temperature and wait 24 hours.


Day 2

Do not remove the test tubes from the beaker.

   1. Measure the height of the liquid in each of the test tubes in mm and record.

   2. Calculate the difference in the heights, if any and record.


Lab Data


Height (mm)             Tube A                  Tube B                 Tube C

Water, Day 1

Water, Day 2

Difference



                                           - 18 -
Lab Analysis Questions (Take-Home)

   1. What prevented the water from moving up into the test tubes when they initially were
      inverted and placed in the liquid?



   2. Calcium oxide absorbs carbon dioxide. Given this information, explain how cell
      respiration could be responsible for the water rising into some of the test tubes.



   3. What components of the lab are experiencing cell respiration?



   4. What is the purpose of tube C and what does it demonstrate?



   5. Compare the results of tube A to tube B. Why is there a difference?



   6. The seeds in tube “A” were presoaked. How did this affect the rates of cell respiration?
      Why?



   7. If your test tube set-up had been placed in the refrigerator for 24 hours instead of being
      left at room temperature, how do you think that would affect the results? Why?



   8. How do you think the results might have been different if the calcium oxide had been left
      out of the procedure?




                                          - 19 -
- 20 -
Section _______                                       Name _________________________
Instructor ______________                             Date _____________

Complete these analyses using the tabulated class data.


Tobacco Seedling Data

                                   *Expected #       Difference
 Phenotype        Observed #                                             d2           d2/e
                                       (e)               (d)
    Green
    White

        Total:                                                      Total = X2obs=

C = ________ C –1 = ________          X2exp = ________       p = ________


Is the observed ratio statistically similar to what was expected?   _______________________


Corn Color and Texture Data

                                     *Expected #      Difference
    Phenotype         Observed #                                          d2          d2/e
                                         (e)              (d)
 Purple Smooth
  Purple Rough
 Yellow Smooth
  Yellow Rough

             Total:                                                  Total=X2obs=

C = ________ C –1 = ________          X2exp = ________       p = ________


Is the observed ratio statistically similar to what was expected?   _______________________


    The expected numbers are dependent on the predicted ratio. The ratios were determined by
    completing the Punnett squares in section 9.1 and 9.2
    X2obs = chi-square value based on observed data
 2
X exp = chi square values based on theoretical distribution obtained from chi-square table



                                           - 21 -
- 22 -
                           Isolation of DNA from Animal Cells

In this exercise, you will isolate DNA from calf thymus tissue. Tissue from the thymus is a good
choice for isolating DNA because of its high nucleus-to-cytoplasm ratio (see fig.). This feature
offers two advantages. The proportion of the cell that the nucleus takes up, results in minimal
cytoplasm and hence minimal lipid and protein present to interfere with the isolation. In
addition, a greater yield of DNA per unit of tissue can be obtained.

      Ratios / Unit of Tissue                                        Thymus Function
       High             Low                    The thymus gland is a pink-gray organ that lies underneath the
                                               top of the breast bone. In animals it is known as the
                                               sweetbreads.
                                               The thymus processes a type of white blood cell known as a T-
                                               lymphocyte. These T-lymphocytes govern cellular immunity,
                                               which means they help cells recognize and destroy invading
                                               bacteria, virus, etc., abnormal cell growth such as cancer, and
                                               foreign tissue.
                  Nuclei
Procedure
   1. Chill on ice, homogenization buffer.

   2. Slice or chop (using scissors) a small piece (approx. 1 cm3) of thymus tissue and place it
      in a chilled mortar. Add 1-2 ml of homogenization buffer and two to three drops of
      sodium-lauryl-sulfate solution (detergent).

                           Detergent – detergents are amphipathic molecules
                           that have the ability to solubalize lipids. This allows
                           for the breakdown and removal of membranes and
                           other lipids present in the sample.


   3. Homogenize (grind) the tissue over ice (if possible) until the tissue is ground into a slurry
      or paste. Be careful not to over-grind your tissue, as the heat generated from this process
      will cause the DNA to breakdown or denature.

                           Homogenization – This process helps to break the
                           tissue down into individual cells and provides
                           greater surface area on which the detergent can act.
                           It also helps in rupturing membranes.


   4. Obtain a 2M solution of NaCl and add twice your initial volume (2-4 ml) and stir briefly.

                           NaCl – This salt solution helps to stabilize the DNA
                           molecule so as to prevent its premature degradation.
                           In addition, the presence of a high concentration of
                           salt helps to saturate the solution and allow for the
                           precipitation of DNA.

                                              - 23 -
5. Using 2 layers of cheesecloth, strain your slurry into a small beaker to remove the
   majority of unground tissue and other large cellular debris. The cheesecloth and filtered
   tissue may be disposed of in the trash.

6. With a transfer or Pasteur pipette, transfer the slurry from the beaker to several
   microcentrifuge tubes. Make sure to distribute the material evenly so that the sample
   remains balanced for the next step.
                       Balancing – When using a centrifuge, the samples
                       placed in the unit must have their mass evenly
                       distributed. Just as in a washing machine, your
                       centrifuge may wobble uncontrollably due to the
                       force generated when objects are spun at high speed.

7. Centrifuge the tubes for 5-10 minutes at top speed with a clinical microcentrifuge. Make
   sure the centrifuge is balanced prior to proceeding with this step. Once complete, the top
   layer of your sample will contain the DNA.

8. Decant / transfer the liquid portion (top layer) to a chilled flat bottom glass tube (in an ice
   bath).

9. Holding the tube at an angle, slowly add two volumes of cold ethanol to the liquid.
   Using a glass rod or wooden stick spool the DNA fibers.

                       Ethanol – Since DNA is insoluble in high
                       concentrations of alcohol; the addition of 95%
                       ethanol will facilitate the precipitation of the DNA at
                       the buffer/ethanol interface.




                                           - 24 -

								
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