Biology (level 0 part 2)

Biology (level 0 part 2)

1. Properties of Matter

   • Atoms
     • Basic unit of matter; everything is made of atoms
       • Protons
         • Positive charge
       • Neutrons
         • Negative charge
           • Combine to form nucleus
       • Electrons
         • Negative charge
           • Surrounds nucleus
   • Elements
     • pure substance that consists of one type of atom
       • More than 100 elements are known
       • Isotopes
         • Atoms of the same element that differ in the number of neutrons they contain
           • All isotopes of the same element have same number of electrons
   • Chemical Compounds/Bonds
     • Chemical Compounds
       • Substance formed by the chemical combination of two or more elements in definite proportions
         • Shown as chemical formula
           • Example: water is H20
           • Example: table salt is NaCl
         • Physical properties of a compound are usually different from those of the elements from which it formed
     • Chemical Bonds
       • Atoms in compounds are held together by chemical bonds
         • Ionic bonds
           • Formed when one or more electrons are transferred from one atom to another
             • Ions
               • An atom that loses or gains electrons
         • Covalent bonds
           • Formed when electrons are shared by atoms
             • Molecule
               • The structure that results when atoms are joined together by covalent bonds

2. Properties of Water and Suitabilty for Life

   • Polarity
     • A molecule in which the charges are unevenly distributed
     • similar to a magnet with two poles
   • Hydrogen Bonding
     • Solvent
       • Substance in which the solute dissolves
     • Water expands slightly upon freezing
       • Makes ice less dense than water
         • That's why ice floats
     • Attraction between a hydrogen atom with a partial positive and another atom with a partial negative charge
     • Heat Capacity
       • Takes large amount of heat energy to cause the molecules to move faster

3. Importance of Carbon to Life

   • Carbon has four valence electrons, allowing them to form strong covalent bonds with many other elements
     • One carbon atom can bond to another which gives carbon the ability to form chains that are almost unlimited in length
       • Macromolecules
         • Carbohydrates
           • Living things use carbohydrates as their main source of energy; sometimes used for structural purposes
         • Lipids
           • Can be used to store energy. Some are important parts of biological membranes and waterproof coverings
         • Nucleic Acids
           • Store and transmit hereditary, or genetic, information
         • Proteins
           • Control rate of reactions and regulate cell processes. Some form important cellular structures, while still others transport substances into or out of cells or help fight disease

4. Chemical Reactions and Enzymes

   • Chemical Reactions
     • Process that changes, or transforms, one set of chemicals into another
       • Chemical reactions involve changes in the chemical bonds that join atoms in compounds
         • Chemical reactions that release energy often occur on their own
         • Chemical reactions that absorb energy will not occur without a source of energy
   • Enzymes
     • Speed up chemical reactions that take place in cells
       • Temperature, pH, and regulatory molecules can affect the activity of enzymes

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