THE BIOLOGICAL BASIS OF LIFE Chapter 3 Human Genome Project In 1990 an effort began to sequence the entire human genome, which consists of some 3 billion bases comprising approximately 25,000 to 30,000 genes. The goal was achieved in Scientists are still several years away from identifying the functions of many of the proteins produced by these genes. HumanNeanderthal? Genome Project sequencedsequenced. The Neanderthal Genome has been sequenced.sequenced Read the press release from the Max Planck Society here here Svante Paabo and a Neanderthal skull Evolutionary significance Tiny differences in protein-coding sequences may explain why humans are susceptible to diseases like cholera, malaria, and influenza while chimpanzees apparently are not. Genetics The study of gene structure and action, and the patterns of inheritance of traits from parent to offspring. Genetic mechanisms are the foundation for evolutionary change. Human Genome Project Overview of Genetics The Cell Cells are the basic units of life in all living organisms. In some forms, such as bacteria, a single cell constitutes the entire organism. Complex life forms (multicellular), such as plants and animals, are made up of billions of cells. Cells Life on earth can be traced back 3.7 billion years to single celled organisms, such as bacteria and blue-green algae. Eukaryotic cells, structurally complex cells, appeared 1.2 billion years ago. A three-dimensional structure composed of carbohydrates, lipids (fats), nucleic acids, and proteins Cells Somatic cells celllular components of body tissues, such as muscle, bone, skin, nerve, heart, and brain Gametes sex cells involved in reproduction and not important as structural components of the body Egg cells produced in female ovaries Sperm cells produced n male testes Zygote union of sex cells to form the potential of developing into a new individual; in this way gametes transmit genetic information from parent to offspring. Structure of a Generalized Eukaryotic Cell DNA Structure For a cell to work, it needs DNA to direct it. An organisms inheritance depends on the structure and function of DNA. DNA is composed of two chains of nucleotides, comprising a double strand or double helix. A nucleotide consists of a sugar, a phosphate, and one of four nitrogenous bases Part of a DNA Molecule DNA Structure Nucleotides form long chains. The two chains are held together by bonds formed on their bases with their complement on the other chain. Guanine(G) is the complement of Cytosine(C) Adenine (A) is the complement of Thymine(T) The DNA Molecule James Watson (left) and Francis Crick in 1953 with their model of the structure of the DNA molecule. DNA Replication Cells multiply by dividing, making exact copies of themselves and enabling organisms to grow and injured tissues to heal. Inside the cell, the DNA must replicate itself first before the cell can split apart. Enzymes Replication begins when enzymes break the bonds between bases throughout the DNA molecule, separating two previously joined strands of nucleotides and leaving their bases exposed Enzyme The DNA Replication Process 1.Enzymes break the bonds between the DNA molecule, creating two nucleotide chains that need complementary nucleotides. 3.Unattached nucleotides pair with the appropriate complementary nucleotide. After DNA Replication The DNA must get its message outside the nucleus of the cell. RNA is another molecule that helps with this, by copying the DNA message and bringing it outside the nucleus (messenger RNA), and into the ribosomes of the cell (transfer RNA). Protein Synthesis Inside a Cell Ribosomes Nucleus DNA After DNA Replication This process of transferring and transcribing DNA bases determines the order of amino acids in a protein, its called PROTEIN SYNTHESIS The entire group of bases responsible for protein synthesis is called a GENE