Download carbon

NOTES: 2.3, part 1 Macromolecules, Carbs &
Lipids
The Chemistry of Carbon
• Why is CARBON so important to life?
• Living things are made up of molecules
that contain CARBON and other
elements (H, O, P, S, and N)
• Carbon atoms have 4 valence electrons,
allowing them to form strong covalent
bonds with many other elements
• Carbon has the ability to form
millions of different large and
complex structures!
Carbon’s 4 valence electrons:
Polymer Principles
• POLYMER: large molecule
consisting of many identical or
similar subunits connected together
• MONOMER: subunit or building
block molecule of a polymer
• MACROMOLECULE: large organic
polymer
*Examples: carbohydrates, lipids,
proteins, nucleic acids
• POLYMERIZATION REACTIONS:
chemical reactions that link 2 or more small
molecules (monomers) to form larger
molecules (polymers)
• DEHYDRATION SYNTHESIS REACTIONS
(or CONDENSATION): reactions during
which monomers are linked together; an –H
and and –OH are removed, producing net
removal of a water molecule for each
covalent linkage
OH
Glucose C6H12O6
HO
Fructose C6H12O6
H2O
O
Sucrose C12H22O11
Water
• HYDROLYSIS: process that breaks the
covalent bonds between monomers by
the addition of water molecules
*Example: DIGESTION
H2O
O
Sucrose C12H22O11
Water
OH
Glucose C6H12O6
HO
Fructose C6H12O6
Monosaccharides =
single sugars
• are major nutrients for cells
• glucose is most common
*examples: glucose, ribose,
galactose, fructose
Disaccharides = double
sugars
• Also a source of energy
• Formed when 2 monosaccharides
combine in a dehydration reaction;
• Examples:
 lactose (milk sugar): glucose +
galactose
 sucrose (table sugar): glucose +
fructose
Polysaccharides =
hundreds or thousands of
monosaccharides
• formed by linking monomers in
DEHYDRATION SYNTHESIS
REACTIONS.
Disaccharide
Examples of energy storage
polysaccharides:
• starch = glucose polymer in plants used
for energy storage (in roots, tubers, etc.)
• glycogen = glucose polymer in animals
stored in skeletal muscles and liver of
humans & other vertebrates
Examples of structural support
polysaccharides:
• cellulose = structural component of
plant cell walls that cannot be digested
by most organisms
• chitin = forms exoskeletons of
arthropods
LIPIDS
 insoluble in water (because they are
NONPOLAR, or HYDROPHOBIC)
 include:
1. Fats
2. Phospholipids
3. Steroids
1. FATS
• Composed of:
 A large proportion of C-H bonds and
less oxygen than carbohydrates
(the nonpolar C-H bonds make the
chain hydrophobic and insoluble in
water)
 Example: C57H110O6
• during formation of a fat,
dehydration synthesis reactions
link fatty acids to glycerol
• Fatty acids may vary in # of carbon
atoms (usually even #)
Saturated vs. Unsaturated
Fats
SATURATED FAT
 no C-C double
bonds in fatty acid
tail
 usually solid at
room temp.
 most animal fats
 e.g., bacon
grease, lard, butter
UNSATURATED
FAT
 one or more C-C
double bonds in fatty
acid tail
 usually a liquid at
room temp.
 most plant fats
 e.g., corn, peanut,
olive oils
Functions of Fats
• energy storage (1 g of fat stores 2x as
much energy as 1 g of carbohydrate)
• cushions vital organs in mammals (e.g.
kidney)
• insulates against heat loss (e.g. whales,
seals)
2. PHOSPHOLIPIDS
• Important component
of cell membranes
3. STEROIDS
• Important component of some hormones
Cholesterol …
• is used to make many other steroids
(including sex hormones in vertebrates)
• common
component
of cell
membranes
• can cause atherosclerosis (if have too
much)