Apologia Biology: DNA Extraction Lab

Update: The last photo has a decent shot of the DNA.  It is white threads which float into the alcohol.

Update:  This week (after Thanksgiving) we're doing the DNA lab.  Yesterday's class went as expected.  The girls extracted mounds of DNA; the boys all need to try again.  See pix below.
Tomorrow, we're doing the DNA extraction lab with split peas--the instructions are in the Apologia textbooks.  (The first edition uses onions instead of split peas.  The link has directions for extracting DNA from just about anything.)  The key is to use fresh meat tenderizer.  My class is doing the lab as an inquiry project.  I bought three types of alcohol: denatured ethanol, and two different percentages of isopropyl or rubbing alcohol.  I also bought salt with and without iodine.  My materials include two brands of dish detergent, shampoo, and hand soap (clear).  The students will hypothesize which factor produces the most DNA.  (Remember, it's fresh meat tenderizer.)  The kids are going to test the different types of alcohol, salt, and detergent.  So, they'll do a number of trials.  I expect to take two class periods to do the lab; the kids will write another formal written lab report.  Here is my plan.

1.  Explain how to extract DNA and distribute lab instructions.  Our class will use 50 grams of split peas, 100 mL of cold water, two grams of salt, 15 mL of soap or detergent, and one gram of meat tenderizer.  The kids may need to adjust these measures.  I want the kids to weigh with a digital scale and measure volume with graduated cylinders instead of using cups and teaspoons, which are cooking measures.

2.  The next step is for each lab group to form a two-part hypothesis.  Here is an example.
    Null Hypothesis:  The type of detergent will have no effect on the amount of DNA produced.
    Alternative Hypothesis: Dawn dish soap will produce more DNA than Gain dish soap.

3.  Each group must identify controls and take note of the materials the group uses.

4.  Each group will perform at least three trials with different independent variables.  The groups chose which variable to test: alcohol, soap, or salt.


When I first did DNA extraction labs, I used expensive kits, chilled the alcohols,  used only ethanol, and timed each step precisely.  The kids may compare chilled alcohols to room-temperature alcohol.  This lab is usually a favorite.  I'll post pix this week.

Apologia Biology: Mitosis and Meiosis

Yesterday, we had an organelle quiz and resumed work on the mitosis and meiosis yarn models.  The kids are using the diagrams from the text book to create and label.  I know that this activity may seem pointless--it's not!  In the past, I had the kids use yarn, petri dishes, and chalk to duplicate the stages of mitosis and meiosis on lab desks.  It's like drawing microscope slides; it forces the child to study the diagram more closely and involves other parts of the brain.  Yes, it does take loads of time to do well.  I sent home a boat-load of coloring pages to complete--due after the Thanksgiving break next week.  On Thursday, we're doing the DNA extraction lab. 

Apologia Biology: Cells, Cell Cycle, and Mitosis

The Co-op is reviewing for a series of cell quizzes and beginning with paper plate cell cycle models and mitosis with yarn.  The first thing we did was a brief review of the cell topics.  I'm dividing my quiz into two parts: cell structure and function quiz (or this quiz), a cell transport quiz.  I don't like lengthy lectures.  I gave the kids a study guide (p 24).  The kids spent the remainder of class making the paper plate cell cycle model and the mitosis model.  All class.  Really.  It is worthwhile to have the kids make 'hands-on' models.  Believe me, the lesson stays with them.

Apologia Biology: Lab Reports

Update—yes, it took all class to teach the kids how to write a lab report using complete sentences and correct grammar.     Aaaaaaaarrrrrrggghhhhh.  On Thursday, I’m reviewing for a test.  That will be fun.  Here is an example from one of the younger students, who is 11.

Last week, we did another lab, Elephant’s Toothpaste.  Now, the class should learn how to write a report and draw conclusions.  Lab design, creating hypotheses, and drawing conclusions are tedious to teach.  Here is the lab rubric I use for Chemistry.  Last week Elephant’s Toothpaste uses hydrogen peroxide, yeast, and dish soap.  The kids varied the number of grams of yeast and timed the soapy solution as it reached the top of the test tube.  Here goes the lesson.
1.  What is the hypothesis?  A hypothesis has two parts: null and alternate
   a. The null hypothesis for this lab is, “There is no relationship between the number of grams of yeast and the time it takes for the soapy solution to reach the top of the test tube—or The time of reaction is independent of the amount of yeast.”
   b.  The alternate or alternative hypothesis (your best guess) is, “The more grams of yeast, the shorter the time for the soapy solution to reach the top of the test tube—or The more yeast, the faster the reaction.”

2.  The next section is background material.  Yeast contains the enzyme, catalase, in the cell’s peroxisome  organelles.  Hydrogen peroxide is a common waste product in cells. (Waste is bad.). The catalase breaks down hydrogen peroxide.  In this lab, the yeast is allowed to bloom and produce catalase, which breaks down hydrogen peroxide.  Kids can write the background in quotes—but must cite the source.

3.  Next is the chemical reaction for this experiment., if pertinent.  Hydrogen peroxide breaks down in the presence of catalase into water and oxygen.  Students may write the balanced reaction neatly in pen or 2 H2O2 —— H2O + O2

4.  On to the materials.  The materials include the following items:  test tube rack, six test tubes, a test tube holder, scoopula, one disposable, graduated, transfer pipette, a 50 mL graduated cylinder, a 10
mL graduated cylinder, cell phone stop watch, three plastic beakers, one digital thermometer, a tray or trough for overflow, a digital scale, one weigh boat, 20 grams of yeast, 30 mL dish soap, 200 mL water, and one craft stir stick.  Note the grammar!  Numbers ten or fewer are spelled and greater are written in Arabic character, one and 50.  Please note a colon follows a noun.  The sentence above is an example of the use of third person, present tense, active voice, and indicative mood.

5.  The next section, results, includes the data, ideally a table or chart.  The student may write the results.  For example, the results are five grams of yeast produces suds in 4.9 seconds.

6.  The procedures must be discussed step by step.  The controlled variables are the water temperature, the amount of water, dish soap, and hydrogen peroxide.  The independent variable is the number of grams of yeast.  The student completes three trials.  For each trial, the student adds one milliliter of yeast solution to one milliliter of dish soap and five milliliters of hydrogen peroxide in a 25 mL test tube.  The student measures each trial with a stopwatch to assess the time the soapy solution travels to the top of the test tube.  The student records each trial in a table.


7.  The discussion section follows the data.  This section has any observations or mistakes.  The student notes that 25 grams of yeast causes an eruption of suds to quick to measure.  This is the point
the student determines if the results support or refute the null or alternate hypotheses.  It is not
unusual for the results to refute both.  Here, the child should use the Claim Evidence Reasoning approach to describe the results.  The claim is that more yeast results in a faster reaction.  The student’s data table should indicate shorter intervals.  The reasoning is that more yeast produces more catalase, consequently breaks down more hydrogen peroxide.

8.  Lastly is the conclusion.  My standard conclusion is this one, “More trials are indicated.”  “More study is needed to determine the results support the alternate hypothesis.”

It will take all class period on Tuesday to teach this process.    Aaaaaaarrrrrggggh.