SBI4U - Biochemistry
Macromolecules
Carbohydrates & Lipids
Organic Chemistry
• originally the chemistry of compounds
produced by living organisms
• in general organic compounds contain
carbon and hydrogen, and usually other
elements such as nitrogen, sulfur and
oxygen
Electronegativity
Homework, p.18 #9,8
• In a bond between nitrogen and
hydrogen (N-H), which atom will the
electrons be closer to? Explain your
reasoning.
• How do polar covalent bonds and nonpolar covalent bonds differ?
Homework, p.18 #10
• Oxygen plays a major role in biological
molecules. Explain how oxygen plays a
role in polarity, bond shape, (and redox
reactions).
Polar vs. Non-Polar
• molecular polarity is determined by:
– polarity of bonds within molecule
– symmetry of molecular structure
• polarity of molecules or functional
groups determines characteristics such
as solubility
Homework, p.18 #6,7
• How can the atomic composition and
shape of a molecule affect its polarity?
• What effect to the polarity, size, and
shape of molecule have on the physical
properties of the molecule?
• How do these factors affect
intermolecular forces?
Homework, p.24 #1,5
• Water is a polar molecule. Explain how
the polarity of water accounts for its
lattice structure.
• How does polarity influence water’s role
as a solvent?
H-bonding
Homework, p.18 #11
• In what ways do hydrogen bonds
produce attractive forces between
molecules? Include a labelled diagram
to illustrate your answer.
• How do hydrogen bonds influence the
physical properties of water?
Functional Groups
• specific clusters of atoms attached to
the carbon backbone
• functional groups react in characteristic
ways, giving chemical properties to
macromolecules, and are involved in
most reactions in living organisms
Functional Groups
Homework, p.28 #4
• Explain how functional groups influence
solubility and the forces of attraction
between molecules.
Macromolecules
• macromolecules are large molecules
that are often composed of repeating
sub-units
• some of the biologically important
macromolecules are:
– carbohydrates
– proteins
-lipids
-nucleic acids
Carbohydrates
• carbohydrates are
the most important
energy source
• animals cannot
synthesize
carbohydrates; they
must be consumed
in plant material
Structure of Carbohydrates
• carbohydrates are made up of either
single sugar molecules, or chains of
many single sugar molecules
– monosaccharides
– disaccharides
– oligosaccharides
– polysaccharides
Monosaccharides
• single sugars in
straight chain or ring
form
• C:H:O usually in
1:2:1 ratio (glucose
is C6H12O6)
• examples: fructose,
galactose, ribose,
deoxyribose
Monosaccharides
• some
monosaccharides
are isomers, e.g.,
glucose, fructose,
and galactose
Disaccharides
• sugar molecules
made from 2 single
sugars
• formed by a
dehydration
synthesis
(condensation)
reaction
•
See animation:
http://www.youtube.com/watch?v=UyDnn
D3fMaU
Find the sugars…
Polysaccharides
• oligosaccharides are shorter-chain
sugars with 3-10 single sugars
• longer chain carbohydrates are called
polysaccharides
• examples: starch, cellulose, glycogen,
chitin
Polysaccharides
Lipids
• 4 groups:
–
–
–
–
fats & oils
phospholipids
steroids
waxes
• Functions:
–
–
–
–
energy storage
insulation
absorption of vitamins
raw materials
Triglycerides
• most common type
of fat
• glycerol + 3 fatty
acid molecules
• saturated and
unsaturated fatty
acid chains
•
See animation:
http://www.youtube.com/watch?v=3xF_L
K9pnL0
Phospholipids
• key component of
cell membranes
• 1 glycerol + 2 fatty
acid chains + 1
phosphate group
• phosphate end is
polar and watersoluble, fatty acid
end is non-polar
Phospholipids
Steroids (Sterols)
• carbon-based
multiple-ring
structure
• used to make
hormones such as
estrogen and
testosterone
Waxes
• long-chain fatty
acids linked to
alcohols/carbon
rings
• suitable as waterproof coating for
plant leaves, animal
feathers, etc.