Bio1151 Chapter 21 9
  1. DNA                can be used to study patterns of gene expression of an organism.
    • A DNA microarray contains hundreds of thousands of single-stranded DNA placed on a glass chip.

      cDNA is made from an individual's mRNA.

      The cDNA is then hybridized to the array to analyze that person's genotype.

      This chip represents all the known alleles in the human genome.

     
  2. Genome               technology has revealed the complete DNA sequences of many species, including humans.
    • Genome sequencing.

    • Cut the DNA into overlapping fragments with endonucleases.
    • Clone the fragments in plasmid or phage vectors.
    • Sequence each fragment with dideoxyribonucleotides.
    • Order the sequences into one overall sequence with computer software.

      A haploid set of human chromosomes with 3.2 billion base pairs was sequenced in 2003.

     
  3. Genome comparisons can reveal                 relationships among species.
    • Three domains of life.

      Genome comparisons of species help us understand evolutionary relationships.

      This diagram shows the divergence among the three domains based on genome evidence.

      Mammals diverged within the eukaryote lineage about 65 million years ago.


      Chimpanzees are the closest species relatives to humans.