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CP Biology Chapter 2 The Chemistry of Life

CP Biology Chapter 2 The Chemistry of Life. Why is chemistry important in the study of biology?. Chemicals make up ALL matter – living and nonliving. All life processes are chemical reactions . Chemical signals between cells regulate metabolism enzymes, hormones

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CP Biology Chapter 2 The Chemistry of Life

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  1. CP Biology Chapter 2The Chemistry of Life

  2. Why is chemistry important in the study of biology? Chemicals make up ALL matter – living and nonliving. • All life processes are chemical reactions. • Chemical signals between cells regulate metabolism • enzymes, hormones • Chemical signals in the environment • Attract a mate; attract pollinators • Scare away predators • Find food

  3. ELEMENTS, ATOMS, AND MOLECULES There are 92 naturally occurring elements • Only 4 make up most of the human body • CARBON • HYDROGEN (C H O N) • OXYGEN • NITROGEN

  4. Major elements Elements of Living Cells Minor elements

  5. COMPOUNDS Elements can combine to form compounds LE 2-3 Sodium Chlorine Sodium Chloride Na Metal, soft Highly reactive Cl Gas toxic Salt Crystal Common, edible Two or more elements in a FIXED RATIO

  6. NaCl is ionic - “crystal lattice” structure LE 2-7b Na+ Cl-

  7. What is an isotope? Isotopes are atoms with the same atomic number but different masses • different number of neutrons • Behave the same way chemically!! • Most elements have at least one isotope

  8. Isotopes of Carbon Isotopes of the same element have the same number of PROTONS and the same number of ELECTRONS. - have the same chemical behaviors

  9. Radioactive Isotopes • Have unstable nuclei • Emit atomic particles as the “decay” • Become a stable atom of a different element

  10. Radioactive isotopes • Also emit radiation • at a steady rate, called “half-life” • Half-life: time for ½ of a sample to decay • Ex. Half-life of C-14 is 5700 years • Can use radiation for many purposes

  11. DATE FOSSILS Carbon-14 and other isotopes • measure amount of C-14 present in a fossil • compare to amount present when it died • tells us how old the fossil is

  12. Use as “tags” or “tracers” • Same chemical properties as stable isotopes • Used the same in life processes • Can show how atoms and molecules are used in living things • Carbon-14 • showed how plants make food from CO2 • Radioactive sulfur and phosphorus • showed how viruses enter cells

  13. PET Scan - MEDICAL DIAGNOSIS PET scan = Positron Emission Tomography • Radioisotope in blood collects in tissues • Amount of radiation shows organ function - more active cells use more food and energy (ex. cancer cells) - more active cells emit more radiation - ”hot spot”

  14. A thyroid scan showing a “hot spot” Scan showing increased uptake in thyroid gland

  15. A body scan showing areas of increased radiation Increased radiation shows abnormal function

  16. PET scans show functionCAT scans show structure

  17. Radiation Therapy – treats cancer ­External therapy • beam of radiation aimed at tumor • from radioisotope, or from therapy X-ray machine

  18. Internal Therapy with Radioisotopes 1. Isotope injected into blood - Concentrates in diseased organ and radiation kills some cells 2. Radioactive “seeds” put directly into tumor - Radiation reaches cancer cells without going through healthy tissue

  19. Radioisotopes kill cancer cells

  20. Uses in Industry • Nuclear energy • Sterilize surgery instruments • Kill bacteria in food

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