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The Chemistry of Life

The Chemistry of Life. Chapter 2 Biology – Miller • Levine. Atoms. Basic unit of matter From the Greek word atomos , which means “unable to be cut” Subatomic particles: Protons – positive charge (p + ) Neutrons – neutral, no charge (n 0 ) Electrons – negative charge (e - ). Atoms.

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The Chemistry of Life

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  1. The Chemistry of Life Chapter 2 Biology – Miller • Levine

  2. Atoms • Basic unit of matter • From the Greek word atomos, which means “unable to be cut” • Subatomic particles: • Protons – positive charge (p+) • Neutrons – neutral, no charge (n0) • Electrons – negative charge (e-)

  3. Atoms • Nucleus – contains protons & neutrons • Electron cloud – area where electrons are located around the nucleus • Atoms are neutral because p+ = e-

  4. Element • A pure substance that consists entirely of one type of atom • Periodic Table of Elements: • Represented by a 1 or 2 letter symbol • Atomic number - # of protons • Mass number – protons + neutrons

  5. Elements

  6. Isotopes • Atoms of the same element that have a different number of neutrons • Radioactive isotopes – isotopes that are unstable and give off radiation • Can be used in geological dating, to treat cancer, to kill bacteria in food, & as “tracers” in medical diagnosis

  7. Isotopes

  8. Chemical Compounds • Compound – a substance formed by two or more different elements • Chemical formula – shows the number of each element in a compound • Ex. H2O

  9. Chemical Bonds • Atoms in compounds are held together by chemical bonds • Valence electrons – electrons that are available to form bonds • 3 major types of bonds – ionic, covalent, and hydrogen

  10. Ionic Bonds • When one or more electrons are transferred from one atom to another • Oppositely charged ions are attracted to each other • Ex. NaCl

  11. Covalent Bonds • Form when electrons are shared between atoms • Molecule – when atoms are joined together by a covalent bond • Ex. H2O

  12. The Water Molecule • Water is a polar molecule, where the electrons are not shared equally • There is a – charge near the O and a + charge near the H • Hydrogen bonds – attraction between the H of one water to the O of another • Weaker than covalent or ionic

  13. Hydrogen Bonds

  14. Cohesion & Adhesion • Cohesion – the attraction between molecules of the same substance • Adhesion – the attraction between molecules of different substances

  15. Mixtures • When two or more elements or compounds are physically mixed together but not chemically combined • Suspension – a mixture of water and nondissolved materials • Will settle back out over time

  16. Mixtures • Solution – a mixture in which all the components are evenly distributed • Solute – the substance that is dissolved • Solvent – the substance in which the solute dissolves • Water is the greatest solvent

  17. Solutions

  18. Acids, Bases, and pH • A water molecule can react to form hydrogen (H+) and hydroxide (OH-) ions • Acid – any compound that forms H+ ions in solution (pH less than 7) • Base – any compound that forms OH- ions in solution (pH greater than 7)

  19. Acids, Bases, and pH • pH scale – a measurement system that indicates the concentration of H+ ions in a solution (0-14) • Buffer – weak acids or bases that react with strong acids or bases to prevent sudden changes in pH

  20. Chemical Reactions • Process that changes one set of chemicals into another set of chemicals • Fe + O2→ Fe2O3 • Reactants – in front of the arrow • Products – after the arrow • Law of Conservation of Matter – matter can be neither created nor destroyed • Equations must be balanced

  21. Energy in Reactions • Endergonic – reactions that require an input of energy or store energy • Exergonic – reactions that release energy • Activation energy – the energy needed to start a reaction

  22. Enzymes • Some chemical reactions are too slow or have too high an activation energy • Catalyst – a substance that speeds up the rate of a chemical reaction by lowering the activation energy • Enzymes – proteins that are catalysts

  23. Effect of Enzymes

  24. Enzyme Action • The enzyme-substrate complex • Substrates – the reactants • Active site – the place where the substrates bind to the enzyme • When the substrates bind to the active site they form the enzyme-substrate complex

  25. Enzyme-Substrate Complex

  26. Regulation of enzyme activity • Can be affected by pH and temperature • Most enzymes have an optimal pH and temperature • Can be turned “on” or “off” • Can be used over and over again

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