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Understanding Life: Genetics, Cells & DNA

Explore the biological foundations of life through genetics, cell structure, DNA, protein synthesis, genes, and cell division. Learn about mitosis, meiosis, and new frontiers in genetic research.

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Understanding Life: Genetics, Cells & DNA

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  1. Chapter 3 The Biological Basis of Life

  2. Introduction • Genetics is the study of how one trait transfers from one generation to the next • Involves process of evolution

  3. THe Cell • Basic unit of life for all organisms • Prokaryotic Cells • Blue-green algae • 3.7 bya • Eukaryotic Cells • 1.2 bya • Membrane bound nucleus and distinct organelles • Two Cell types • Somatic • Gamates

  4. DNA Structure • Discovered in 1953 • Composed of two complementary chains of nucleotides • A single nucleotide contains • Deoxyribose sugar • Phosphate group • And one of four nitrogenous bases • Adenine • Guanine • Thymine • Cytosine

  5. Structure Continued • Double helix forms because adenine bonds to thymine or guanine bonds to cytosine • Complementary base bonding is key to replicating DNA

  6. DNA Replication • Key to growth and healing of all organisms • It occurs before cell divides

  7. Protein • Protein • 3D molecules • Bind to other molecules • Hemoglobin – carries oxygen • Some are structural • Some are functional • Composed of amino acids, 8 must be obtained through diet

  8. Protein synthesis • Transcription • Translation

  9. Genes • Sequence of DNA responsible for synthesis of protein or part of a protein • Change in the DNA sequence is a mutation • Gene action is very complex since not all segments of DNA are expressed during protein synthesis • Exons • Introns • Regulatory Genes • Can switch DNA segments on or off

  10. Cell Division -Mitosis and Meiosis • Chromosone pairs • Humans = 23 • Chimpanzies and Apes = 24 • Autosomes • Female mammals – XX • Male mammals – XY • Mitosis occurs in somatic cells • Meiosis occurs in gamates

  11. Mitosis

  12. Meiosis • More involved in evolution – sex cells • Influences genetic variation • Problems • Nondisjunction • Down SYndrome

  13. New Frontiers • DNA disc revolutionized biology and genetic research • PCR technique was developed in 1986 and is used to analyze nucleotide sequences in very small segments of DNA • Recombinant DNA • Genetic Manipulation • Controversial • Stem cell research • Cloning • Human Genome Project • Debate topic: Stem cell research?

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