1 / 23

CHAPTER 2 The Chemical Basis of Life

CHAPTER 2 The Chemical Basis of Life. Thomas Eisner and the Chemical Language of Nature. Thomas Eisner pioneered _______ __________ the study of the chemical language of nature He studies how insects communicate via chemical messages. Water in three different states: 5 States of matter .

helki
Download Presentation

CHAPTER 2 The Chemical Basis of Life

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. CHAPTER 2The Chemical Basis of Life

  2. Thomas Eisner and the Chemical Language of Nature • Thomas Eisner pioneered _______ __________ • the study of the chemical language of nature • He studies how insects communicate via chemical messages

  3. Water in three different states: 5 States of matter

  4. ATOMS AND MOLECULES The emergence of biological function starts at the chemical level • Everything an organism is and does depends on chemistry • Chemistry is in turn dependent on the arrangement of atoms in molecules • In order to understand the whole, biologists study the parts (reductionism)

  5. D. Organ: Flight muscle of a moth • A ________ _________ Rattlebox moth C. Cell and tissue: Muscle cell within muscle tissue Myofibril (organelle) B. Organelle: Myofibril (found only in muscle cells) Actin Myosin Atom A. Molecule: Actin

  6. A chemical _____ is a substance that cannot be broken down to other substances by ordinary chemical means • About ____ different chemical elements are essential to _____ lead

  7. Carbon, hydrogen, oxygen, and nitrogen make up the bulk of living matter, but there are other elements necessary for life • _________ Table 2.2

  8. Goiters are caused by iodine deficiency Figure 2.2

  9. 2.4 Atoms consist of protons, ________, and electrons • The smallest particle of an element is an _____ • Different ______ have different types of atoms

  10. The nucleus is surrounded by electrons • An atom is made up of protons and neutrons located in a central nucleus 2 Protons Nucleus 2 Neutrons 2 Electrons A. Helium atom

  11. Each atom is held together by attractions between the positively charged protons and ________charged electrons • Neutrons are electrically _______ 6 Protons Nucleus 6 Neutrons 6 Electrons B. Carbon atom

  12. Atoms of each element are distinguished by a specific number of protons • The number of neutrons may vary • Variant forms of an element are called ________ • Some isotopes are ________

  13. 2.5 Connection: Radioactive isotopes can help or harm us • Radioactive isotopes can be useful tracers for studying biological processes • PET scanners use radioactive isotopes to create anatomical images Figure 2.5A Figure 2.5B

  14. 2.3 Elements can combine to form compounds • Chemical elements combine in fixed ratios to form _________ • Example: sodium + chlorine  sodium chloride Reactants Products

  15. 2.6 Electron arrangement determines the chemical properties of an atom • Electrons are arranged in _______ • The outermost shell determines the chemical properties of an atom • In most atoms, a full outer shell holds _____ electrons

  16. Atoms whose shells are not full tend to interact with other atoms and ___, ____, or ______ electrons Outermost electron shell (can hold 8 electrons) Electron First electron shell (can hold 2 electrons) HYDROGEN (H) Atomic number = 1 CARBON (C) Atomic number = 6 NITROGEN (N) Atomic number = 7 OXYGEN (O) Atomic number = 8 Figure 2.6

  17. 2.7 Ionic bonds are attractions between ions of opposite charge • When atoms gain or lose electrons, charged atoms called ions are created • An electrical attraction between ions with opposite charges results in an ionic bond – + Na Cl Na Cl Na Sodium atom Cl Chlorine atom Na+ Sodium ion Cl– Chloride ion Figure 2.7A Sodium chloride (NaCl)

  18. 2.8 Covalent bonds, the _____ of electrons, join atoms into molecules • Some atoms share outer shell electrons with other atoms, forming covalent bonds • Atoms joined together by covalent bonds form molecules

  19. REARRANGEMENTS OF ATOMS Chemical reactions rearrange matter • In a chemical reaction: • reactants interact • atoms rearrange • products result 2 H2 + O2  2 H2O

  20. 2.15 The chemistry of life is sensitive to acidic and basic conditions • A compound that releases H+ ions in solution is an acid, and one that accepts H+ ions in solution is a base • Acidity is measured on the pH scale: • 0-6 is acidic • 8-13 is basic OH- Hydroxide Ion Alkaline • Pure water and solutions that are neither basic nor acidic are neutral, with a pH of 7

  21. pH scale H+ OH– Lemon juice; gastric juice • The pH scale Increasingly ACIDIC (Higher concentration of H+) Grapefruit juice Acidic solution Tomato juice Urine NEUTRAL [H+] = [OH–] PURE WATER Human blood Seawater Neutral solution Increasingly BASIC (Lower concentration of H+) Milk of magnesia Household ammonia Household bleach Oven cleaner Basic solution

  22. Cells are kept close to pH 7 by buffers • Buffers are substances that resist pH change • They accept H+ ions when they are in excess and donate H+ ions when they are depleted • Buffers are not foolproof

More Related