The structure of DNA is orderly, fitting together in one specific way regardless if the DNA is in a human, a whale, a gardenia or E. coli. Students assemble DNA models not only to demonstrate their understanding of DNA's structural components, but also to examine its double-helical structure. In addition, students can disassemble the DNA model to examine the processes of replication and transcription.
DNA contains all the information necessary to produce any protein in a living organism. To do this, the DNA undergoes transcription, whereby a series of proteins convert DNA to RNA. The RNA is then translated into a linked series of amino acids. A set of three RNA nucleotides, called a codon, codes for one or more specific amino acids, of which there are only 20. Give students a random series of RNA nucleotides. Ask the students to translate the code into a series of amino acids. The acids follow a universal genetic code, a list of all possible codon combinations and their related amino acids. The website Scitables offers a copy of the universal genetic code, and Learn Genetics provides a short interactive lesson to use as an introduction to the concept.
A karyotype is a chart of all the chromosome pairs from a specimen, typically human. Human genetic diseases are identifiable by the appearance or number of chromosomes present in a test subject. To see these chromosomal abnormalities, scientists stop dividing cells during metaphase, when the chromosomes become clearly visible, and take a picture of the chromosomes. The chromosomes are then cut out and arranged by size and similarity. The resulting groupings are analyzed for extra chromosomes, missing chromosomes or chromosomes with missing or extra parts. Examples of unassembled and assembled chromosomes can be found online at Learn Genetics and The Biology Corner. The students assemble a karyotype in the classroom and then analyze the resulting picture to identify one of the chromosomal anomalies discussed in class.
You may have seen a television show where a person suspected of a crime has a cotton swab brushed over the inside of his cheek. This procedure, known as a buccal swab, collects cheek cells from which the forensic scientist will extract DNA. This technique is highly effective, requires little effort and produces significant quantities of testable DNA. It is possible to purchase buccal kits for use in high school and college biology classes. These kits allow the student to become familiar with common DNA laboratory techniques. For health reasons, each student would only be able to test his own DNA sample, and your school should have a biological waste disposal in place.