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Chemistry of Life


Title: Chemistry of LIfe Author: christy.philippoff Last modified by: e111506 Created Date: 5/9/2007 1:36:09 PM Document presentation format: On-screen Show (4:3) – PowerPoint PPT presentation

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Title: Chemistry of Life

Chemistry of Life
Nature of matter
  • Matter Anything that occupies space has mass.
  • Everything in the universe is made of mass.
  • Atom is the smallest unit of matter that cannot
    be broken down by chemical means.
  • Atoms typically have 1 electron for each proton,
    so they are neutral (no electrical charge)

3 Basic Particles of An Atom
  • Particle Charge Location
  • 1. Proton Positive () Nucleus
  • 2. Neutron neutral (0) Nucleus
  • 3. Electron Negative (-) Electron Cloud

  • The electrons are located in energy levels
    located outside of the nucleus where the
    electrons can move (electron cloud).
  • Level Electrons possible in each level
  • 1 2e-
  • 2 8e-
  • 3 18e-

  • Element is a substance made of only 1 kind of
    atom, and it is a pure substance.
  • Four elements that make up 96 of the human body
  • 1. Carbon
  • 2. Hydrogen
  • 3. Oxygen
  • 4. Nitrogen

  • Atoms can bond together
  • A compound is formed when outer electrons are
    attracted, shared, or transferred from one atom
    to another atom in order to fill the outer
    electron levels.
  • Ex Na Cl- ? NaCl (table salt)

  • A force that joins atoms is called a bond.
  • There are 2 types of bonds
  • 1. Covalent bonds
  • 2. Ionic bonds
  • Ionic and covalent
  • compounds are alike in
  • that they both fill outer
  • electron levels.

  • 1. Covalent Bonds are created when 2 or more
    atoms share electrons and form a molecule.
  • Molecules are held together by covalent bonds.
  • Example H2O, CO2, and O2
  • All organic compounds are held together by
    covalent bonds.
  • Molecules with an unequal distribution of
    electrical charge, such as water molecules, are
    polar molecules.

  • Water has a positive charge on one end and a
    negative charge on the other. Because of its
    uneven charge, water is a polar molecule.
  • A hydrogen bond
  • is a weak chemical
  • attraction between
  • polar molecules.

  • 2. Ionic Bonds are formed by the electrical
    attraction between oppositely charged ions.
  • Ion is a charged atom or molecule.
  • Ions have an elec-
  • trical charge because
  • they contain an un-
  • equal number of elec-
  • trons and protons.

Ionic Bonds Cont.
  • An atom that has lost electrons is positively
  • An atom that has gained electrons is negatively
  • Ions or opposite charges may interact to form an
    ionic bond.
  • Example of an
  • ionic bond
  • Na Cl- NaCl

Water and Solutions
  • Water is an inorganic substance which means it is
    not made from carbon or living things.
  • Water is composed of 1 atom of oxygen and 2 atoms
    of hydrogen.
  • Water molecules are linked by hydrogen bonds.
  • This causes water to heat up
  • and cool down slowly.
  • Water, which is essential for
  • life, stores heat efficiently and
  • binds to itself and other sub-
  • stances.
  • The most abundant inorganic
  • substance in a cell is water.

  • The hydrogen bonds between water molecules
    cause the cohesion of liquid water. Cohesion is
    an attraction between substances of the same
    kind. Because of cohesion, water and other
    liquids form drops and thin films. The thin
    films allow some insects to stand on the surface
    of water because water is cohesive and adhesive.
    This attraction between water molecules (to
    itself) causes a condition known as surface

  • Water molecules are also attracted to many other
    polar substances.
  • Adhesion is an attraction between different
    substances. Because water stick to solids
    (adhesion), water has the property of
  • Capillarity is the ability to spread through fine
    pores or to move upward through tubes (such as
    the stem of a plant) against the force of
    gravity. The attraction of water to the walls of
    the tube sucks the water up more strongly than
    gravity pulls it down.

  • Water dissolves many substances
  • Due to waters polar nature (uneven charge),
    water makes a good solvent, pulling apart other
    molecules. Nonpolar molecules do not dissolve
    well in water. When nonpolar substances, such as
    oil are placed in water, the oil forms lumps or
    beads in water.

Nonpolar molecule and water
Polar Molecules and water
High Specific Heat
  • The ability of water to stabilize temperature
    depends on its relatively high specific heat.
  • The specific heat of a substance is defined as
    the amount of heat that must be absorbed or lost
    for 1 g of that substance to change its
    temperature 1 C.
  • The specific heat of water is 1.00 cal/g C.
  • Compared with most other substances, water has an
    unusually high specific heat.
  • Because of high specific heat, water will change
    its temperature less when it absorbs or loses a
    given amount of heat.

Acids and Bases
  • pH is a measure of how acidic or basic (alkaline)
    a solution is. A change of one pH unit reflects
    a 10X change.
  • The pH scale ranges from 0-14 and is used to
    measure pH.
  • An acid is any substance that forms hydrogen ions
    (H) in water.
  • This solution contains more H (hydrogen) ions
    and has a pHlt7
  • Sour and corrosive
  • Tend to burn
  • Turn litmus paper red
  • Examples battery acid, sulfuric acid, stomach

Acids and Bases
  • A base (alkaline) is any
  • substance that forms OH-
  • (hydroxide) ions and
  • has a pHgt7
  • Are bitter and feel slippery
  • Turn litmus paper blue
  • Examples soaps,
  • household cleaners
  • A pH of 7indicates a
  • neutral between
  • acidic and alkalinity.

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Chemistry of cells
  • Organic compounds contain carbon atoms that are
    covalently bonded to other elements, typically
    hydrogen, oxygen and other carbon atoms.
  • All organic compounds contain the element carbon.
  • Carbon is the essential element that all life
    depends on.
  • Carbon can form up to 4 covalent bonds with other
  • Its nature allows the ability to form straight
    chains, branched chains, and rings.
  • Carbons ability to form covalent bonds is
    important in allowing for a wider variety of
    organic molecules. Living things require such a
    variety to carry out life processes.

Four Classes of Organic Compounds Found in Living
  • 1. Carbohydrates
  • 2. Lipids
  • 3. nucleic acids
  • 4. proteins
  • Without these compounds cells could not function.
  • All of these compounds are long repeating units
    called polymers.
  • Polymers are large molecules formed when many
    smaller molecules bond together usually in long
  • Each unit of a polymer is called a monomer
    (simple molecule).

  • 1. Carbohydrates are organic compounds made of
    carbon, hydrogen, and oxygen atoms in 121
  • All carbohydrates are made of carbon, hydrogen,
    and oxygen.
  • They are the main source of energy for living
    things, and they are found in most foodslike
    fruits, vegetables, and grains. Most energy that
    is used in the human body is stored as

There are 3 types of carbohydrates
  • 1. Monsaccharides or simple sugars. They are
    the building blocks of carbohydrates.
  • Examples of monosaccharides
  • 1. Glucose is manufactured by plants during
    photosynthesis. It is the main source of energy
    for plants and animals.
  • 2. Fructose is found in fruits and is sweet.
    These have the same molecular formulas, C6H12O6,
    but different structural formulas, which make
    them isomers.

Carbohydrates Cont.
  • 2. Disaccharides are 2 monosaccharide
    molecules linked.
  • Example of a disaccharide is sucrose (table
    sugar), which is composed of fructose and
    glucose. Lactose that is found in milk is an
    example of a disaccharide.

Carbohydrates Cont.
  • 3. Polysaccharides are composed of many
    monosaccharide subunits. Polysaccharides
    function as storehouses of the energy contained
  • Three examples of polysaccharides that store
  • 1. Starch which is made by plants (like
    potatoes). Energy is passed from potato to the
    person eating it primarily by the energy stored
    in starch molecules.
  • 2. Glycogen which is made by animals. Both
    starch and glycogen are made of hundreds of
    linked glucose molecules.
  • 3. Cellulose is a polysaccharide that provides
    structural support for plants. Humans cannot
    digest cellulose (wood).

Glycogen in Liver Cells
  • Lipids are non polar molecules that are not
    soluble in water.
  • Lipids are used to store energy (long term
    storage), for insulation, and as protective
  • Lipids are composed of 3 fatty acids bonded to a
    glycerol molecule.
  • Examples of lipids fats, phospholipids,
    steroids, including cholesterol, and waxes.

Lipids Cont.
  • The monomers of lipids are fatty acids
  • Lipids are an important part of the structure and
    functioning of cell membranes.
  • Phospholipids make up the lipid bilayer of cell
  • Fats are lipids that store energy.
  • Saturated Fats are solid at room temperature, and
    they usually come from animals butter
  • Unsaturated Fats are liquid at room temperature,
    and they usually com from plants like core
    peanut, and olive.

Phospholipid Bilayer
Lipids Cont.
  • Waxes are highly waterproof.
  • In plants, wax forms a protective coating on the
    outer surfaces, for example on the leaves.
  • In animals, wax forms protective layers, for
    example ear wax.

  • 3. Nucleic Acids are in all of your cells.
  • The building blocks of nucleic acids are
  • A nucleic acid is a long chain of smaller
    molecules called nucleotides.
  • A nucleotide has three parts
  • 1. a sugar
  • 2. a base
  • 3. a phosphate group

Phosphate Group
  • There are two types of nucleic acids
  • 1. DNA Deoxyribonucleic Acid
  • DNA consists of 2 strands of nucleotides that
    spiral around each other. DNA is a molecule
    shaped like a spiral staircase also known as a
    double helix. The 2 strands of a DNA molecule
    are held together by hydrogen bonds between two
    bases across from one another. Your chromosomes
    consist of very long strands of DNA, which stores
    heredity information (or genetic code) that can
    be use d to make proteins.
  • 2. RNA Ribonucleic Acid
  • RNA consists or a single strand of nucleotides

  • 4. Proteins are a chain of molecules called
    amino acids linked together like parts on a
  • Proteins are made of long chains of amino acids.
  • Amino acids are the building blocks of proteins.
  • There are 20 different amino acids, which bond to
    each other by peptide bonds (covalent bonds
    formed between amino acids).
  • Some proteins called enzymes regulate chemical
    reactions in the body but remain unchanged by the
  • The complete hydrolysis of a protein would result
    in the formation of amino acids. Hydrolysis is a
    chemical reaction in which water is used to break
    down a compound.

Proteins Cont.
  • ATP-Adenosine Triphosphate
  • ATP carries energy in cells.
  • ATP is a single nucleotide with 2 extra
    energy-storing phosphate groups.

Energy and Chemical reactions
  • Energy is the ability to move or change matter.
  • A chemical reaction is a process during which
    chemical bonds between atoms are broken and new
    ones are formed, producing one or more different
  • Reactants Products
  • (starting materials) (forms) (newly formed

  • Activation Energy the energy needed to start a
    chemical reaction.
  • Enzymes Help Biochemical reactions occur
  • Enzymes (proteins) are substances that increase
    the speed of chemical reactions.
  • Enzymes are proteins which are substances that
    reduce the activation energy of a chemical
  • A substance on which an enzyme acts during
    chemical reaction is called a substrate.
  • Each enzyme is specific and
  • only acts on a particular substance
  • called substrate. An enzyme has
  • deep folds on its surface, and these
  • fold form pockets called active sites.
  • Activation Energy Energy needed to start a
  • reaction

  • Factors that affect enzyme activity
  • 1. Temperature
  • 2. pH
  • 3. Enzyme Concentration