DNA Extraction

Update:  We had the best results using 90% isopropyl alcohol, Dawn detergent, and iodized salt.  BTW, I keep my DNA supplies in a kit.  The meat tenderizer is supposed to be good for a year.  I’ll check next year when I teach Bio again.

Today, the Bio class is extracting DNA.  Here are instructions to extract DNA from just about anything.  The key is to use fresh meat tenderizer.  We use split peas.  Additionally, this lab is more inquiry-based.  I have two types of dish soap and different percentages of alcohol.  When I have a large group I add ionized salt vs sea salt, rubbing alcohol vs ethyl alcohol, and chilled vs room-temperature alcohol.  The kids can form a hypothesis.  For example, one group might hypothesize that sea salt will produce more DNA than iodized salt or chilled ethanol may produce more DNA than room-temperature ethanol.  My kids are using this lab for their third, formal lab report since they need to write at least four for several online schools to receive lab credit.  This lab might take two class periods to complete because kids need to perform two tests for each trial.  The white threads on top of the pea solution are DNA.

Macromolecule Food Tests

Every time I teach Biology we do  food tests.  Identification of Biomolecules.  This lab has a good data sheet which allows students to mark down their predictions.  Biomolecules are also called macromolecules.  Here is a Google slide deck demonstrating positive tests for carbohydrates, lipids, and proteins.  These tests require Benedict’s solution and biuret solution.  Home Science Tools has both.  What is the point?   I like to reinforce concepts.  This lab introduces kids to identifying substances with test reagents.  (BTW, the orange beakers are for wastes.)

Chemistry on a Budget: Colorful Lather Prints

 I just saw a cool take on Colorful Lather Printing.  Try making prints with wooden ornaments.  The video from Albina Manning Art is below.  Usually, we use food coloring in the shaving cream.  But, I’ve used tempera paint as a substitute for the food coloring.  You can combine Science with making homemade Christmas ornaments.

Biomolecules

 We finished working through the questions in the Lab-aids kit.  It takes three class periods to build and run through the questions.  This worksheet has the main components of the worksheet from the kit.  It helps enormously to build and synthesize the molecules.  

My never ending quest for an inexpensive molecular modeling kit.

I use molecular modeling kits for Bio and Chem.  I’ve collected several kits because I teach Bio and Chem regularly and consider the kits an investment.  But many home-school families only teach Bio and Chem once or twice.  These families need an inexpensive kit.  One reason my kids get through Biochem is because we take the time to build the molecules.    We’re in the middle of Biochem.  So I built molecules with both kits.  My test molecule is D-glucose.  I bought both kits from Amazon, October 10th.  One kit arrived October 19th and the other Oct. 25th—fairly timely.  Sometimes very inexpensive kits do not arrive for months.  Neither kit had enough atoms to build D-glucose.  The $6.95 kit had enough carbon and hydrogen atoms.  I had to substitute three oxygen molecules with another atom.  The hydrogen atoms are orange.  Weird.  Usually hydrogen is white.  The $11.98 molecule kit did not have enough oxygen atoms for D-glucose.  Boooooo!  The $6.95 kit is sturdy.  You might want to just make your own molecules.  Here is the CPK color chart.  Scroll down to see the colors for carbon, hydrogen, oxygen and nitrogen.  Make the hydrogen atoms small; the other atoms are usually the same size.  Link the clay atoms with toothpicks.  Meanwhile I’m still looking for cheap molecule kits.

$6.95 and $11.98