Biological Macromolecules

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Biological Macromolecules

1. Carbohydrates
2. Lipids
3. Proteins
4. Nucleic acids

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A. Carbohydrates

• General properties
• Composed mostly of carbon, hydrogen, and oxygen
• Large number of OH groups attached to the
  carbons
• Functions
• Energy source for living cells
• Certain structural components of cells

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A. Carbohydrates

• Monosaccharides
• Simple sugars
• Monomer unit of carbohydrate group
• Examples glucose, fructose
• Disaccharides
• Composed of two monosaccharide units joined
  together
• Examples sucrose, lactose
• Polysaccharides
• Composed of multiple monosaccharide units (100s
  1000s)
• Examples starch, glycogen, cellulose

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B. Lipids

• General properties
• Biological compounds with hydrophobic components
  in their molecular structures
• Functions
• Energy storage
• Structural components
• Glycerides
• A major class of lipid
• Composed of a glycerol molecule attached to one,
  two, or three fatty acid molecules

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B. Lipids

• Generalized structure of a triglyceride

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B. Lipids

• Fatty acid saturation
• Fatty acids with greater saturation have fewer
  CC double bonds Have higher melting points
• Fatty acids with less saturation have more CC
  double bonds Have lower melting points

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B. Lipids

• Phospholipids
• A lipid molecule (for example, a diglyceride)
  with a hydrophilic group attached via a phosphate
  linkage
• Found in membrane structure (details later in
  course)
• Other lipids
• Sterols cholesterol and steroid hormones
• Waxes

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C. Proteins

• General properties
• Composed of chains of amino acids
• There are 20 different amino acids, each with
  distinctive chemical properties
• A protein molecule may contain several hundred
  amino acids
• Each different protein has its own order, or
  sequence, of amino acids
• The correct sequence of amino acids is essential
  for the proteins function

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C. Proteins

• Functions
• Enzymes enzymes are biological catalysts that
  control almost every reaction in living systems
• Cellular recognition and communication
• Structural components of living cells

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C. Proteins

• Amino acid structure
• To the central carbon atom, four things are
  attached
• Hydrogen atom
• Amino group
• Carboxylic acid group
• Side chain R group
• Twenty different R groups, with different
  chemical properties

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C. Proteins

• Peptides
• Chains of amino acids attached by peptide bonds
• May be named by number of amino acids dipeptide,
  tripeptide, tetrapeptide, pentapeptide, etc.
  Polypeptide

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C. Proteins

• Protein
• A polypeptide chain with a specific biological
  function
• Most proteins have from about 50 up to several
  hundred amino acids in their structure

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C. Proteins

• Levels of protein structure
• Primary structure amino acid sequence
• Secondary structure localized folding of a chain
  into regions of helix or sheet structure
• Tertiary structure folding of a single
  polypeptide chain into a three-dimensional
  structure
• Quaternary structure only in proteins with more
  than one polypeptide chain Folding of more than
  one chain together

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D. Nucleic Acids

• General properties
• Composed of chains of nucleotides
• There are 4 different nucleotides
• A nucleic acid molecule may contain several
  thousands or millions of nucleotides
• Each nucleic acid molecule has its own order, or
  sequence, of nucleotides
• The correct sequence of nucleotides is essential
  for the nucleic acids function

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D. Nucleic Acids

• Overall function.
• The sequence of nucleotides in a nucleic acid
  molecule serves as a blueprint to encode the
  correct sequence of amino acids for a protein.
  The code for a specific protein is called a
  gene.
• Deoxyribonucleic acid (DNA) DNA molecules
  (chromosomes) serve as the master blueprint for
  all of the cells proteins. The DNA molecules are
  transmitted to offspring during reproduction.
• Ribonucleic acid (RNA) RNA molecules serve as
  working copies of the genes for the proteins
  that the cell is making at any given time.

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D. Nucleic Acids

• Nucleotide structure
• A nucleotide consists of
• Nitrogenous base
• Pentose sugar
• Phosphate group
• Nitrogenous bases
• Purines adenine guanine
• Pyrimidines cytosine, thymine (in DNA), uracil
  (in RNA)
• Pentose sugars
• Ribose (found in RNA)
• Deoxyribose (found in DNA)