Biological Molecules

1
Biological Molecules
2
Biological Molecules

• Life is carbon-based chemistry
• Hydrolysis and Synthesis of Biological Molecules
• Carbohydrates
• Lipids
• Proteins
• Nucleic Acids

3
Life is carbon-based chemistry

• Organic is used to describe molecules that have a
  carbon skeleton and some additional hydrogen
  atoms
• Life is composed of organic molecules
• Inorganic molecules include carbon dioxide, water
  and all other non-carbon molecules

4
Life is carbon-based chemistry

• The tremendous diversity of organic molecules is
  due to the diverse functional groups that attach
  themselves to common carbon skeletons
• Hydrogen (-H)
• Hydroxyl (-OH)
• Carboxyl (-COOH)
• Amino (-NH2)
• Phosphate (-H2PO4)
• Methyl (-CH3)

5
Hydrolysis and Synthesis of Biological Molecules

• Small organic molecules are used as subunits to
  synthesize longer molecules
• The individual subunits are called monomers
• The longer molecules are called polymers

6
Hydrolysis and Synthesis of Biological Molecules

• Monomers are linked to monomers in a chemical
  process called dehydration synthesis
• The H group is removed from one monomer and the
  OH group is removed from the second monomer
• The two monomers join by forming a covalent bond
• The H group and OH group bond to form a water
  molecule

7
(No Transcript)
8
Hydrolysis and Synthesis of Biological Molecules

• Polymers are disassembled into monomers through a
  process called hydrolysis
• The polymer splits into monomers
• A water molecule splits and releases a H group
  and a OH group
• The H group and OH group bond to the monomers
  to complete their structure

9
(No Transcript)
10
Carbohydrates

• Contain carbon, hydrogen and oxygen in the
  constant ratio of 121
• Carbohydrates are hydrates of carbon
• C1H201 or CH20
• All carbohydrates are either small, simple sugars
  or polymers of these simple sugars

11
Carbohydrates
Monosaccharides One sugar molecule Glucose Fructose Galactose
Disaccharides Two sugar molecules Sucrose Lactose Maltose
Polysaccharides Many sugar molecules Starch Glycogen Cellulose
12
Lipids

• Lipids contain large regions of H and C atoms
  joined by non-polar covalent bonds
• Non-polar regions are hydrophobic
• Lipids are not soluble in water
• Three major groups of lipids
• (1) oils, fats and waxes
• (2) phospholipids
• (3) steroids

13
Oils, Fat and Waxes

• Contain only C, H and O atoms
• Composed of one or more fatty acids subunits
  attached to a glycerol subunit
• Are straight chains do not have ring structures
• Function as source of energy

14
Oils, Fat and Waxes

• Fatty acid chains that have no CC double bonds
  are said to be saturated with H atoms
• Fatty acid chains that have CC double bonds are
  said to be unsaturated with H atoms
• Saturated fatty acid chains are straight
• Unsaturated fatty acid chains are kinked

15
Oils, Fat and Waxes

• Oils are liquid at room temperature because they
  are unsaturated ? kinks
• Waxes are solid at room temperature because they
  are saturated ? straight

16
Phospholipids

• Similar to structure of fats, waxes and oils
  except one of the three fatty acid chains is
  replaced by a phosphate group containing a polar
  functional group
• The two fatty acid chains are hydrophobic
• The phosphate head (being polar) is hydrophilic
• Function as basic component of membranes

17
Steroids

• Composed of four rings of carbon fused with
  various functional groups
• Steroids are synthesized from cholesterol
• Function as hormones and components of animal
  cell membranes

18
Proteins

• Proteins are polymers of amino acid subunits
• The bond between amino acid subunits is called a
  peptide bond (formed by dehydration synthesis)
• Diversity of proteins is due to diversity of
  amino acids and the diverse ways amino acids
  arrange themselves
• Proteins function as enzymes, structural
  components, transport proteins, energy storage,
  cross-membrane transport, and hormones

19
Proteins

• Amino acids are composed of a central C atom
  bonded to four different functional groups
• (1) amino group (-NH2)
• (2) carboxylic acid group (-COOH)
• (3) hydrogen group (-H)
• (4) variable group (-R)

20
Proteins

• The R group creates the diversity of amino acids
• Some -R groups are small, others large
• Some R groups are hydrophobic, others
  hydrophilic
• The type of R group directly affects the
  structure of the protein

21
Proteins

• Proteins have four levels of structure
• (1) Primary Structure sequence of amino acids in
  the linear protein polymer
• (2) Secondary Structure simple repeating pattern
  created by hydrogen bonding between amino acid
  subunits
• Secondary structure can be either a helix or
  pleated sheet

22
Proteins

• (3) Tertiary Structure complex 3 dimensional
  shape formed by folding over of secondary
  structure
• Tertiary structure is due to disulfide bridging
  between neighbouring cysteine amino acids size
  of R group hydrophobic/hydrophilic interactions

23
Proteins

• (4) Quaternary Structure due to joining together
  of smaller proteins in order to form a larger
  protein complex

24
Nucleic Acids

• Nucleic acids are polymers of nucleotide subunits
• Nucleotides are composed of three components
  themselves
• (1) a five C sugar (ribose/deoxyribose)
• (2) a phosphate group
• (3) a N containing base

25
Nucleic Acids

• It is the diversity in N containing bases that
  creates diversity in nucleotides
• It is the diversity in sugars that adds to the
  diversity of nucleic acids

26
Nucleotides
DNA (deoxyribose sugar) RNA (ribose sugar)
Adenine Adenine
Thymine Uracil
Guanine Guanine
Cytosine Cytosine
27
Nucleic Acids

• Nucleic acids function primarily as the molecules
  of heredity and the blueprint for protein
  synthesis (DNA and RNA)
• Nucleic acids also act as intracellular
  messengers (cAMP), coenzymes and energy carrier
  molecules (ATP)