The Molecules of Life

1
The Molecules of Life
2
Key Players in Organic Chemistry

• H C O
  N
• Valence 1 4 6 5
• of e- 1 4 2
  3
• needed
• of 1 4 2
  3
• bonds potentially formed

3
Single, Double, Triple Bonds

• SINGLE BOND (one shared pair of electrons)
• DOUBLE BOND (two shared pairs of electrons)
• TRIPLE BOND (three shared pairs of electrons)

4
Organic Molecules

• Any molecule that contains at least carbon and
  hydrogen.
• CH4
• C2H4
• C6H12O6
• Is carbon dioxide CO2 an organic molecule?

5
Inorganic Molecules

• All non-carbon based molecules
• H2O
• HCl
• O2
• NaOH
• H2SO4

6
Hydrocarbons

• Molecules that ONLY consist of Hydrogen and
  Carbon
• CH4
• C2H4
• C2H2
• CH3CH2CH2CH3

7
Isomers

• Organic compounds that have the same molecular
  formula but different structural formulas and
  therefore different chemical properties.
• Butane (C4H10) Isobutane (C4H10)

8
Guidelines for Drawing Isomers

• Draw out the straight chain carbon backbone
  first.
• Remove an end carbon and attach it to a non-end
  carbon (count your hydrogens to make sure they
  match up to the molecular formula).
• Count the longest continuous chain.
• Keep your perspective the same. If you draw the
  molecules horizontally, keep them all this way.
• Abbreviate the Hs as ? (dots next to the carbons)

9
Draw 3 Structural Isomers of C5H12

• Double Check do all carbons still have four
  bonds? Do you have all of the hydrogen atoms
  accounted for?

10
Draw 5 Structural Isomers of C6H14
11
How Many Isomers Exist for C7H16 ?

• Use the space below and on the next slide to draw
  out your answer to the question above.

12
Isomers of C7H16
13
From Molecular Formula to Structural

• For each of the following molecular formulas,
  draw (one) structural formula that corresponds.
• CH4
• C2H6
• C2H4
• C4H4

14
Cont

• C5H8
• C6H12
• C8H14

15
Functional Groups

• The components of organic molecules that are most
  commonly involved in chemical reactions.
• Functional groups are merely attachments that
  replace one or more of the hydrogens bonded to
  the carbon skeleton of a hydrocarbon.
• MOST of the cells organic compounds have two or
  more functional groups.

16
Functional Groups that you need to MEMORIZE!!!!

• Hydroxyl
• Carbonyl
• Carboxyl
• Amino

17
Hydroxyl

• The chemistry of the hydroxyl group
• The OH group is negative as a result of the
  oxygen atom having a higher affinity for the
  electron shared between the hydrogen and oxygen
  atom.
• Consequently H2O molecules are attracted to the
  OH group, thus making the hydroxyl group
  hydrophilic. This helps dissolve organic
  compounds containing hydroxyl groups.
• SUGARS have hydroxyl groups.

18
Carbonyl

• This group consists of a carbon atom attached to
  an oxygen atom by a double bond (thus sharing two
  electrons between the two atoms).

19
Carboxyl group

• Compounds containing the carboxyl group are known
  as CARBOXYLIC ACIDS.
• Why does a carboxyl group have acidic properties?
• The covalent bond between the O and the H is so
  polar that the hydrogen tends to dissociate
  reversibly from the molecule as an ion (H). If
  the double bonded O were on a separate carbon
  atom, the H would be much less likely to
  dissociate.
• So why are hydroxyl groups considered to have
  acidic properties?

20
Amino

• Organic compounds with this functional group are
  called amines.
• They have an ability to act as a weak base.
• Exception to the octet rule

21
Monomers Polymers

• A MONOMER is a small molecular unit that is the
  building block of polymers.
• A POLYMER is a long chain of monomers.
• Every living cell contains thousands of different
  polymers each created from fewer than 50 types of
  monomers.
• Monomer Polymer
• Glucose Glycogen
• Glucose Cellulose
• Glucose Starch
• Amino Acid Polypeptide Protein

22
Dehydration Synthesis

• When two monomers bind, the hydroxyl group from
  one monomer binds with a hydrogen atom from
  another monomer ultimately creating water. The
  open ends of the monomers then link together to
  form a polymer.
• This process requires an INPUT of ENERGY!!!

23
Glucose Monomer
24
Glucose Glucose Maltose

• Dehydration synthesis reaction

25
Synthesis reaction

• Also known as a HYDROLYSIS reaction
• The REVERSE of the dehydration synthesis is
  hydrolysis which breaks bonds between monomers by
  adding water.

26
An example of hydrolysis working in our bodies is
the process of digestion. The bulk of the
organic material in our food is in the form of
polymers that are much too large to enter our
cells. Within the digestive tract, various
enzymes attack the polymers, speeding up the
hydrolysis. The released monomers are then
absorbed into the blood stream for distribution
to the body cells. These cells can then use the
dehydration synthesis reactions to assemble the
monomers into new polymers that differ from the
ones that were digested.
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CarbohydratesFuel Building Material

• Monsaccharides (single sugars)
• Glucose, Galactose, Fructose
• Disaccharides (double sugars)
• Glucose Glucose maltose
• Glucose Galactose lactose (milk sugar)
• Glucose Fructose sucrose (table sugar)
• Polysaccharides (hundreds to thousands of
  monosaccharides)
• Storage
• Starch in plants, glycogen in animals
• Structure
• Cellulose provides structural support for plant
  cells, Chitin is used to build the exoskeleton of
  some invertebrates.

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Sugars cont

• Sugars contain the elements carbon, hydrogen, and
  oxygen in a
• 1Carbon 2Hydrogen 1Oxygen ratio
• Which of the following ARE sugars?
• C6H12O6 C3H6O4 C2H4O2 CH2O
• C5H10O5 C7H13O7 C6H10O4
  C7H14O7,
• CHO2

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Lipids

• The ONE class of biological molecules that does
  not include polymers.
• The compounds called lipids are grouped together
  because they share one important trait
• They have little or no affinity for water due to
  their typically non-polar structures.
• Hydrophobic water fearing
• Includes Fats, Phospholipids, and Steroids

30
Fats

• Store large amounts of energy
• A fat is constructed from two kinds of molecules
  glycerol and fatty acid chains
• A fatty acid has a long carbon skeleton, usually
  16 or 18 carbon atoms in length. Has a carboxyl
  group at one end.

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Glycerol Fatty Acid Chains(dehydration
synthesis)
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Saturated vs Unsaturated

• Saturated fat
• all three chains contain single bonds
• typically solid at room temp
• Unsaturated fat
• at least one of the chains contain 1 or more
  double bonds.
• typically liquid at room temp.

33
Phospholipids

• Similar to fats but they only have two fatty acid
  chains rather than three.
• The third hydroxyl group of glycerol is joined to
  a phosphate functional group which is negative in
  electrical charge (another exception to the octet
  rule)
• Cell Membrane Phosphate Functional Group

34
Steroid

• Lipids that are characterized by a carbon
  skeleton consisting of 4 fused rings. Different
  steroids vary in the functional groups attached
  to the rings.
• A type of estrogen Cholesterol

35
Proteins

• The small molecular tools of the cell.
• A polymer constructed from a set of just 20 kinds
  of monomers called amino acids. Polymers of
  amino acids are called polypeptides.
• General Structure of an Amino Acid

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Each amino acid consists of

• A central carbon atom.
• An amino group
• A carboxyl group
• A single hydrogen atom, and
• A side group that determines the function of the
  amino acid (the R group)

37
Protein Synthesis

• The order of the amino acid sequence determines
  the uniqueness of the protein. The shape of the
  protein determines the function.
• Dehydration synthesis reaction of a protein.

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20 Amino Acids

• Non Polar Amino Acids
• Glycine
• Alanine
• Valine
• Leucine
• Isoleucine
• Methionine
• Phenylalanine
• Tryptophan
• Proline
• Acidic Amino Acids
• Aspartic Acid
• Glutamic Acid

• Polar Amino Acids
• Serine
• Threonine
• Cysteine
• Tyrosine
• Asparagine
• Glutamine
• Basic Amino Acids
• Lysine
• Arginine
• Histidine