Chapter 2: Chemistry Comes Alive

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Chapter 2 Chemistry Comes Alive
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• The human body is made of thousands of chemicals
  that are continuously interacting with another at
  an incredible pace.
• Biochemistry- is the study of the chemical
  composition and reactions of living matter and
  includes two major types.

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Types of Biochemistry Compounds

• 1. Inorganic Compounds- include water, salts, and
  many acids and bases.
• 2. Organic Compounds- all contain carbon and are
  covalently bonded molecules.
• Carbon is unique because it never gains or loses
  electrons it always shares them. It also has
  four valence electrons which allows for large
  uniquely shaped molecules suited for specific
  roles in the body.

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There are 4 major organic compounds.

• Carbohydrates- a group of molecules that includes
  sugars and starches, and represents 1 to 2 of a
  cells mass.
• Made of carbon, and hydrogen and oxygen at a 21
  ratio.
• Classified according to size and solubility
• Monosaccharide- one sugar
• Disaccharide- two sugars
• Polysaccharide- many sugars

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Carbos (cont.)

• The major role of carbos in the body is to
  provide a ready, easily used source of cellular
  fuel.
• Most cells can only use a few simple sugars for
  energy (glucose is the main fuel)

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Carbos (cont.)

• Glucose is broken down and oxidized in the cell
  causing a transfer of electrons which releases
  energy that is used to synthesize ATP.
• When ATP levels are sufficient, excess carbos
  are converted and stored in our bodies as
  glycogen or fat.

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Lipids

• 1. Lipids- are insoluble in water, but dissolve
  readily in other lipids and in other organic
  solvents.
• Made of carbon, hydrogen, and oxygen but the
  proportion of oxygen to hydrogen is much less
  than in carbos.
• More complex lipids contain phosphorous.

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Types of Lipids include

• A. Neutral Fats- made from fatty acids and
  glycerol.
• Neutral fats are the bodys most concentrated
  source of usable energy fuel.
• Neutral fats are nonpolar molecules. (water is
  polar and that is why water/oil do not mix)

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Types of Lipids (cont.)

• B. Phospholipids- are modified triglycerides and
  are used in building cell membranes.
• Phospholipids are unique because they have a
  polar head made of phosphorous and a nonpolar
  tail containing two fatty acid
  chains.(molecules that have polar and nonpolar
  regions are called amphipathic)

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Types of Lipids (cont.)

• C. Steroids- are flat molecules made of four
  interlocking hydrocarbon rings.
• The single most important molecule in steroids is
  cholesterol.
• Cholesterol is necessary for cell membranes. It
  is the raw material for Vitamin D, steroid
  hormones, and bile salts.
• Cholesterol is essential for life, but excessive
  amounts can lead to arteriosclerosis.

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Types of Lipids (cont.)

• D. Eicosanoids- are derived from a 20-carbon
  fatty acid, and are found in all cell membranes.
• Also important in blood clotting, inflammation,
  and labor contractions.

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Lipids
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Proteins

• 3. Proteins- Composes 10-30 of a cells mass and
  is the basic structural material of the body.
• -Examples of proteins include enzymes,
  hemoglobin, and contractile proteins of muscles.
• -All proteins contain carbon, oxygen, hydrogen,
  and nitrogen. Many also contain sulfur and
  phosphorous.

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Proteins (cont.)

• Proteins are made of amino acids.
• (20 common types)
• All amino acids have two important functional
  groups 1. Basic group (amine group-NH2)
• 2. Organic acid group (-COOH)
• Therefore a protein can act as a base (proton
  acceptor) or an acid (proton donor).

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Protein (cont.)

• All amino acids are identical except for a single
  group of atoms called their R group.
• Bonding of amino acids is called peptide and it
  is common to have 100-10,000 amino acids bound
  together in macromolecules.

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Proteins can be described in four structural
levels

• Primary structure- is a linear sequence of amino
  acids.
• Secondary structure-(ex. Alpha helix) a twisted
  or bent chain of amino acids. They also can be in
  pleated or ribbonlike sheets (ex. Beta pleated
  sheets).
• Tertiary structure-are when alpha or beta regions
  fold upon one another to produce a compact
  ball-like, or globular molecule.

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Proteins Structural Levels (cont.)

• 4. Quarternary structure- this is the most
  complex protein and includes two or more
  polypeptide chains arranged in a regular manner.
  (ex. Hemoglobin)

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Protein Classification

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Denaturation

• When a protein loses its specific shape due to
  heat or acidity it is called Denaturation.

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Proteins are classified by appearance and shape

• Fibrous proteins- are extended, stranded-like,
  water insoluble, and stable.
• Used for mechanical support and tensile strength.
  (aka-structural proteins)
• Globular proteins- are compact, spherical
  proteins.
• These are water soluble, chemically active, and
  play major roles in life processes.
• (aka-functional proteins)

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Enzymes

• Enzymes- are globular proteins that act as
  catalysts.
• Catalysts- are substances that regulate and
  accelerate the rate of biochemical reactions, but
  are not used up or changed in those reactions.
• Enzymes increase reaction rates by more than a
  million fold.

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Enzymes (cont.)

• Enzymes bind to reacting molecules temporarily
  which then presents them to each other in the
  proper position for a chemical reaction.
• (This eliminates randomness and wasted energy)

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There are 3 basic steps in the mechanism of
enzyme reactions

• The enzyme must first bind to the substances that
  are to react.
• (aka-substrates)
• The enzyme-substrate complex undergoes internal
  rearrangement that forms the new product.
• The enzyme releases the product.

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Enzyme (Basic steps cont.)
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4. Nucleic Acids (DNA RNA)

• These are the largest molecules in the body.
• They are made up of
• Pentose sugar
• Nitrogen- containing base
• Thymine
• Adenine
• Cytosine
• Guanine
• phosphate

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Nucleic Acids include two major classes

• Deoxyribonucleic acid (DNA)- is found in the
  nucleus.
• It contains the genetic material
• It reproduces itself before cell division
• It has the instructions for building every
  protein in the body.
• Ribonucleic acid (RNA)- is located chiefly
  outside the nucleus.
• It carries out the orders of the DNA for protein
  synthesis.

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Adenosine Triphosphate (ATP)

• ATP is made through the catabolism of glucose.
• ATP is an adenine-containing RNA nucleotide to
  which two additional phosphate groups have been
  added.
• (the tail of ATP is like a coiled spring due to
  the closeness of the 3 negatively charged
  phosphate groups)

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ATP (cont.)

• The release of a phosphate group releases energy
  and produces ADP.
• Without ATP, there is no life.

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