Download Organic Molecules

The Chemical Building Blocks of
Life
Organic Chemistry
Comparison of Molecules
• Inorganic – Chemistry of elements other than carbon
• Organic – Carbon-based chemistry
Inorganic
•Usually with
+ & - ions
•Usually
ionic bonding
•Always with
few atoms
•
Often associated with
nonliving matter
•
Organic
•Always contain
carbon and hydrogen
•Always
covalent bonding
•Often quite large, with
many atoms
•
Usually associated
living systems
•
• All living things are mostly composed of 4
elements: C, H, O, N “CHON"
• Compounds are broken down into 2 general
categories:
– Inorganic Compounds:
• Do not contain carbon
– Organic compounds
• Contain significant amounts of carbon.
• Often found with common "functional groups" …
more on this in a minute!
Why Carbon?
• Carbon is essential to
life for several reasons:
– It can form strong
stable (usually
nonpolar) covalent
bonds
– It can form up to 4
chemical bonds due to
4 valence electrons
– It can form multiple
bonds
More on the Carbon Atom
• Carbon atoms:
– Contain a total of 6
electrons
– Often bonds with
other carbon atoms to
make hydrocarbons
– Can produce long
carbon chains like
octane
– Can produce ring
forms like cyclohexane
• Carbon skeletons vary in many ways
Ethane
Propane
Carbon skeletons vary in length.
Isobutane
Butane
Skeletons may be unbranched or branched.
1-Butene
2-Butene
Skeletons may have double bonds, which can vary in location.
Cyclohexane
Skeletons may be arranged in rings.
Benzene
Figure 3.1, bottom
part
Functional groups help determine
the properties of organic
compounds
• Functional groups
– specific groups of atoms attached to carbon
backbones
• retain definite chemical properties
• Functional groups are the groups of atoms
that participate in chemical reactions
– Ex. Hydroxyl groups are characteristic of
alcohols
– Ex. The carboxyl group acts as an acid
Table 3.2
Macromolecules
• Some molecules called macromolecules because of
their large size
• Usually consist of many repeating units
– Resulting molecule is a polymer (many parts)
– Repeating units are called monomers
• Some examples:
Category
•
Example
•
•
Lipids
•
Fat
•
Glycerol & fatty acids
•
Carbohydrates
•
Polysaccharide
•
Monosaccharide
•
Proteins
•
Polypeptide
•
Amino acid
•
Nucleic Acids
•
DNA, RNA
•
Nucleotide
•
Subunit(s)
Cells make a huge number of large
molecules from a small set of smal
molecules
• Most of the large molecules in living
things are macromolecules called polymers
– Polymers are long chains of smaller molecular
units called monomers (building blocks)
– A huge number of different polymers can be
made from a small number of monomers
Dehydration and Hydrolysis
• Dehydration - Removal of water molecule
– Used to connect monomers together to
make polymers
– Polymerization of glucose monomers to
make starch
• Hydrolysis - Addition of water molecule
– Used to disassemble polymers into
monomer parts
– Digestion of starch into glucose monomers
• Specific enzymes required for each reaction
– Accelerate reaction
– Are not used in the reaction
• Cells link monomers to form polymers by
dehydration synthesis, removes OH and H
during synthesis of a new molecule.
1
2
3
Short polymer
Unlinked monomer
Removal of
water molecule
1
Figure 3.3A
2
3
Longer polymer
4
• Polymers are broken down to monomers
by the reverse process, hydrolysis.
(Breaks a covalent bond by adding OH and
H.)
1
2
3
Addition of
water molecule
1
Figure 3.3B
2
3
4
The Major Organic Groups
What you need to know:
•
•
•
•
The monomer of each group…
The function of each group…
The characteristics of each group…
Unique properties of each group…
Carbohydrates
• Carbohydrates are loosely defined as
molecules that contain carbon, hydrogen,
and oxygen in a 1:2:1 ratio.
– monosaccharides - simple sugars
– disaccharides - two monosaccharides joined
by a covalent bond
– polysaccharides –
made of many
monosaccharide
subunits
Function
• Primary
Function:
Quick Energy!
Monosaccharides are the
simplest carbohydrates
• Monosaccharides are single-unit sugars
• These molecules typically have a formula
that is a multiple of CH2O
• Hydrogen to oxygen ratio is 2:1.
Hi Honey… I’m
• Monosaccharides
home!
are the fuels for
cellular work
Figure 3.4A
• The monosaccharides glucose and
fructose are isomers
–
They contain the same atoms but in different
arrangements
Figure 3.4B
Glucose
Fructose
Isomers
• isomers - alternative forms of the same
substance
• ex. 8 isomers of “glucose”
Cells link single sugars to form disaccharides
• Monosaccharides can join to form
disaccharides, such as sucrose (table
sugar)
Sucrose
• and maltose
(brewing sugar)
• Which type of
• reaction forms a disaccharide?
Glucose
Glucose
Figure 3.5
Maltose
• Polysaccharides are long chains of sugar units.
These large molecules are polymers of hundreds
or thousands of monosaccharides linked by
dehydration synthesis.
Starch granules in
potato tuber cells
Glycogen granules in
muscle tissue
Cellulose fibrils in
a plant cell wall
Cellulose
molecules
Figure 3.7
Glucose
monomer
STARCH
GLYCOGEN
CELLULOSE
Storage polysaccharides….
• Starch - plant storage
• Glycogen - animal
storage
– stored in the liver
Electron micrograph of a section of a liver
cell showing glycogen deposits as
accumulations of electron dense particles
(arrows). Mitochondria are also shown.
x30,000.
Structural Carbohydrates
• Cellulose - plants
– alpha form or beta form of ring
– animals can not digest cellulose - “fiber”
– most abundant form of living terrestrial
biomass.
• Chitin - exoskeleton of
arthropods and in fungi
cell walls
– modified form of
cellulose