CHAPTER 7 Summary

• DNA is the hereditary molecule of all living organisms. DNA contains instructions for building an organism.
• DNA sequences determine the genetic uniqueness and relatedness of individuals.
• The DNA in a eukaryotic cell is packaged into chromosomes located in the nucleus.
• Humans have 23 pairs of chromosomes in their cells—one chromosome of each pair inherited from the mother, the other from the father.
• DNA is a double-stranded molecule that forms a spiral structure known as a double helix.
• Each strand of DNA is made of nucleotides bonded together in a linear sequence.
• There are four distinct nucleotides: adenine (A), thymine (T), guanine (G), and cytosine (C).
• The two linear strands of a DNA molecule are bound together by complementary pairing of A with T and G with C.
• Complementary pairing of DNA strands guides DNA replication, a fundamental part of cell reproduction.
• PCR enables scientists to vastly increase the number of copies of specific DNA sequences.
• Forensic scientists use noncoding DNA sequences known as STRs to create a DNA profile.
• STRs are blocks of repeated sequences of DNA. People differ in the number of times the sequences are repeated along their chromosomes.
• A DNA profile is more accurate and reliable than many other forms of evidence.

• MORE TO EXPLORE

  • The Innocence Project http://www.innocenceproject.org
  • National Human Genome Research Institute http://www.genome.gov
  • Scheck B., et al. (2003) Actual Innocence: When Justice Goes Wrong and How to Make It Right. New York: NAL Trade Paperbacks.
  • NOVA, Forensics on Trial, October 17, 2012 http://www.pbs.org/wgbh/nova/techforensics-on-trial.html
  • Mullis, K. (1983) The Polymerase Chain Reaction. Nobel Lecture. www.nobelprize.org/nobel_prizes/chemistry/laureates/1993/mullis-lecture.html