Home School Life Journal ................................................................................................................painting by Katie Bergenholtz
Genetics, Part I: DNA
Sam making DNA model, 3/30/09
For the next few weeks we are going to be studying genetics using the book My Name is Gene, which is written for grades 5-8, but I will also be doing some additional hands-on activities that even my younger boys can do. The first chapter includes information about Crick and Watson who discovered the molecular structure of DNA and also about the double helix structure and the nucleotides. For the activity for this chapter, I wanted the boys to make models of DNA, including the appropriate pairing of the nucleotides.
Sam did this activity a few years ago, (and years ago at a co-op class with Katie) but I was pretty sure he would do it again, and help his little brothers with it.
What You Will Need:
Four pipe cleaners, any color
50 pony beads (or you can use pieces of colored straws): 17 in one color (color 1), 17 in another color (color 2), four in four other colors (colors 3, 4, 5 and 6)
Cut two pipe cleaners into 6-inch lengths. Alternate stringing color 1 and color 2 beads on each pipe cleaner until you have 17 beads on each. Fold back the excess length of pipe cleaner to hold the beads in place. These will be the strands of your DNA.
Cut the remaining pieces of pipe cleaner into eight 2 1/2-inch strips. String four pieces with pairs of color 3 and color 4. String the remaining four pieces of pipe cleaner with pairs of color 5 and 6. These will form your base pairs. These represent the four nucleotides adenine, cytosine, guanine and thymine. Adenine always pairs with thymine and cytosine always pairs with guanine. Have your students pick what colors represent the different nucleotides and then make a color key.
Twist your base pair pieces around the strands of your DNA to attach so that there are two strand beads between each set of base pairs. Position each base pair horizontally and evenly around your strands. Make sure to attach these identically on both sides so that your color 1 and color 2 beads match up. Hot glue your pieces in place if desired.
Twist your strands to form your DNA into a double helix. Now you have a model of a DNA sequence.
We attached two together to make this long strand.
And, if this is too complicated for you, Journey Into Unschooling has an even simplier way of doing it with Post-It Notes. And this one will lay flat in a notebook!
Next week we will be studying plant and animal cells and making models of those. You will need a package of light colored Jello, some chocolate chip cookie dough and various candies for that one.