DNA (Deoxyribonucleic acid) is a chemical structure found in the chromosomes which are found in the nucleus of the cell; it’s a piece of a chromosome that dictates a particular trait otherwise known as a gene. DNA is a double helix structure. It looks like a twisted ladder; two strands of genetic material are spiraled around each other. Each strand contains a sequence of bases (also called nucleotides). A base is one of four chemicals (adenine, guanine, cytosine and thymine). The two strands of DNA are bonded at each base: Adenine (A) will only bond with thymine (T), and guanine (G) will only bond with cytosine (C).
DNA fingerprints provide strong evidence for identification, paternity testing and criminal identification. Every individual has a unique chemical makeup or "barcode" of these chemicals. Scientists extract the DNA from a cell, place it in an agar gel and use electricity to move the DNA. The longer pieces move faster than the slower pieces. The DNA is then stained and the result looks like a bar code. Some bands are darker and others are lighter.
Blood Type is a classification of blood based on the antigens and antibodies in red blood cells. The antigens are located on the surface of the red blood cells and the antibodies are in the blood plasma. Individuals have different types and combinations of these molecules. The blood group you belong to depends on what you have inherited from your parents. Each blood type is either positive "+" (has the Rh protein) or negative "-" (no Rh protein). This method of testing is less expensive than DNA fingerprinting but does not give an exact match for identification purposes.
Two copies of the blood type genes are inherited to the offpsring, one from each parent. The possible combinations of alleles produce blood types in the following way:
Blood Type Alleles
Type A AA or AO (A is dominant over O)
Type B BB or BO (B is dominants over O)
Type AB AB (A and B are co-dominant)
Type 0 OO (O is recessive)
For part of this lesson, students will be examining vials of "blood". The blood vials are just for a visual and will have to be labeled by the teacher to show different types, but the mixtures are not different. All the "blood" will look and be the same but the students will be able to tell them apart by the labels. The fake blood is just to increase student interest, engagement and create a visual.