Carbohydrates

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Carbohydrates

• hydrated (H2O) carbon
• Contain carbon, hydrogen, and oxygen
• Their major function is to supply a source of
  cellular fuel for energy creation by the body
• Examples
• simple sugars (glucose) and complex sugars
  (starch)

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Carbohydrates

• Carbohydrate names end in the suffix -ose
• glucose, maltose, amylose, fructose, sucrose
• CarbonHydrogenOxygen in a 121 atomic ratio
• glucose C6H12O6
• Because they contain oxygen, they are polar
  molecules (hydrophilic or lipophobic)
• The monomer of carbohydrates is the
  monosaccharide (one sugar) of which there are a
  number of types
• glucose is the most biologically important

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Monosaccharides

• Simplest carbohydrates
• General formula is C6H12O6
• structural isomers
• same molecular formula, but different molecular
  structure

• Three major monosaccharides
• glucose, galactose and fructose
• mainly produced by hydrolysis of dietary complex
  carbohydrates during the process of digestion

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Disaccharides

• Pairs of monosaccharides covalently bonded via
  dehydration synthesis
• Three major disaccharides
• sucrose
• glucose fructose
• lactose
• glucose galactose
• maltose
• glucose glucose

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Polysaccharides

• Long chains of glucose form polysaccharides
• Starch
• the storage form of sugar produced by plants
• the source of dietary carbohydrates for the body
• hydrolyzed to glucose in the digestive tract then
  delivered to all cells of the body for fuel for
  energy

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Polysaccharides

• Excess glucose in the body following the
  hydrolysis of dietary carbohydrates is taken up
  by the liver and is used to synthesize the
  polysaccharide glycogen
• the liver gradually hydrolyzes glycogen to
  glucose between meals and releases it to the rest
  of the body

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Lipids

• Nonpolar organic molecules made mostly of carbon
  and hydrogen
• Energy rich molecules that can be used for energy
  production
• typically occurs when there is an absence of
  glucose in the body
• 4 primary types
• fatty acids
• triglycerides
• phospholipids
• steroids

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Fatty Acids

• Hydrocarbon chains of 4 to 24 carbon atoms
• always an even number of carbons
• Has more energy per molecule than glucose
• 2 different functional groups are at each end
• carboxylic acid group
• provides acidic properties to the molecule
• methyl group
• 2 different types exist
• Saturated
• solid at room or body temperature (RT/BT)
• Unsaturated
• some are solid but most are liquid at RT/BT

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Fatty Acids

• Saturated fatty acid
• each carbon in the hydrocarbon chain is saturated
  with hydrogen (bonded to 2)
• no double bonds between carbons (CC)
• Unsaturated fatty acid
• each carbon in the hydrocarbon chain is not
  saturated with hydrogen
• contains at least one CC

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Triglycerides

• Three fatty acids bonded to one glycerol (glucose
  derived molecule) through the process of
  dehydration synthesis

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Triglycerides

• Functions
• energy storage in adipose (fat) tissue
• each fatty acid of a triglyceride contains
  approximately 4 times more energy than a single
  molecule of a monosaccharide (glucose)
• insulation
• prevents excessive heat loss from the body
• protection
• provides shock absorption for organs that are
  surrounded by adipose tissue

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Phospholipids

• Similar in structure to a triglyceride consisting
  of
• 1 glycerol
• 2 fatty acids
• 1 phosphate group (PO4-)
• Amphiphilic (both loving) molecule
• has BOTH polar and nonpolar portions
• Hydrophobic tails consist of two fatty acids
• Hydrophilic head consists of a negatively
  charged phosphate group
• Found in a liquid state at body temperature
• Predominant molecule in cellular membranes

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Phospholipid Structure
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Cholesterol

• Hydrocarbons are arranged in a 4 rings
• Used to make steroid hormones including
• cortisol
• aldosterone
• estrogen
• testosterone
• Found in cellular membranes

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Proteins

• Polymer of amino acids which are bonded together
  through covalent bonds called peptide bonds
• Proteins vary greatly in size
• some are as small as 9 amino acids in length
• some are as large as 4650 amino acids in length

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Protein Functions

• PERFORM EVERY FUNCTION IN THE BODY
• Each protein is structurally and functionally
  unique
• Catalysts
• enzymes speed up biochemical reactions
• Structural
• hold the parts of the body together
• Communication
• act as signaling molecules between body areas
• Cell Membrane Transport
• allow substances to enter/exit cells
• Recognition
• monitor any/all changes in the body
• Movement
• muscle contraction

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Characteristics of Enzymes

• Enzymes are chemically specific for a particular
  substrate (chemical on which an enzyme acts upon)
• each enzyme can only act upon one substrate
• Enzymes are unchanged by reactions that they
  catalyze and are able to repeat the process many
  times over
• Enzymes increase the rate of a chemical reaction
  by lowering the activation energy of the reaction
  
• amount of energy required to initiate a chemical
  reaction
• Enzymes are frequently named for the type of
  reaction they catalyze or by their substrate
• Enzyme names usually end in the suffix -ase

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Enzymes and Activation Energy
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Enzyme Structure and Action

• The region of an enzyme that recognizes a
  substrate is called the active site
• recognizes the specific molecular structure of a
  substrate
• An enzyme temporarily binds its substrate(s) and
  allows the appropriate chemical reaction proceed
• Synthesis
• Decomposition
• Exchange
• RedOx

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Enzymatic Catalysis of a Biochemical Reaction
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Amino Acids

• 20 different amino acids exist
• Each amino acid unique due to the functional
  group located at the R position on the molecule
• The chemical nature of each amino acid is
  determined by the chemistry of the R group
• possibilities are
• polar
• nonpolar

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Amino Acids

• The chemical nature of the amino acid is
  determined by the chemistry of the R group
• Possibilities are
• polar
• nonpolar

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Bonding of Amino Acids
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Protein Structure

• Primary structure
• the amino acid sequence of the protein
• Secondary structure
• simple shapes that segments of amino acids make
  within the protein
• a helix (coiled), ß-pleated sheet (folded) shapes
  are held together by intramolecular hydrogen
  bonds between nearby amino acids

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Protein Structure

• Tertiary structure
• the overall 3 dimensional shape of the protein
• determined by polar and nonpolar interactions
  between the amino acids of the protein and the
  surrounding water stabilized by more
  intramolecular hydrogen bonds
• Quaternary structure
• two or more separate polypeptide chains
  interacting with one another to create a
  functional unit

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Protein Conformation and Denaturation

• Conformation
• overall 3 dimensional shape (tertiary/quaternary)
  that is required for function (activity)
• the function of some proteins requires an ability
  to change their conformation
• Denaturation
• drastic conformational change in a protein caused
  by the breaking of hydrogen bonds within a
  protein
• increases in temperature
• increases of decreases in pH
• can be partial or complete
• when a protein is partially denatured, its
  function is impaired
• when a protein is completely denatured, its
  function is lost

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Nucleic Acids

• Largest molecules in the body
• Molecules of instruction and heredity
• Two major classes
• deoxyribonucleic acid (DNA)
• ribonucleic acid (RNA)
• The monomers of nucleic acids are nucleotides

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Nucleotides

• A nucleotide has 3 parts
• a nitrogen containing base (arranged in a
  ring(s))
• a sugar
• a phosphate group
• 5 different nucleotides are used to make nucleic
  acids
• Each nucleotide is different based on 2 criteria
• the identity of the nitrogen base
• double ringed bases are called purines
• adenine (A) and guanine (G)
• single ringed bases are called pyrimidines
• cytosine (C), thymine (T) and uracil (U)
• the identity of the sugar (DNA uses deoxyribose
  while RNA uses ribose)
• Nucleotides are covalently bound to one another
  between the sugar of one nucleotide and the
  phosphate of another nucleotide to make long
  straight (linear) molecules referred to as
  nucleic acid strands

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Nucleotides
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DNA

• Double-stranded helical molecule
• looks like a ladder that has been twisted
• each strand is between 100 million to 1 billion
  nucleotides in length
• 2 strands are held together by H-bonds between
  complimentary nucleotides on opposite strands
• H-bonds can only be made between a purine on one
  strand and a pyramidine on the other strand
• A can only bind with T
• G can only bind with C
• U is NOT part of DNA (only found in RNA)
• The sequence of nucleotides in one of the strands
  contains the genetic code
• the amino acid sequence of all proteins

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Structure of DNA
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RNA

• Single-stranded molecule
• made from the nucleotides A, U, G and C
• Three varieties of RNA
• messenger RNA
• transfer RNA
• ribosomal RNA

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Adenosine Triphosphate (ATP)

• Source of immediately usable energy for the cell
• Nucleotide derivative bound to 3 phosphate groups
• second and third phosphate groups are attached by
  high energy covalent bonds
• phosphate groups are negatively charged and
  naturally repel each other
• Enzymes that hydrolyze the high energy bond of
  ATP produces releases chemical energy
• ATP ? ADP P energy
• the body can convert the ADP and P back into ATP
  using the energy stored in the covalent bonds of
  carbohydrates and lipids as a fuel

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ATP