Organic Molecules:
Lipids and Carbohydrates
Carbon-Based Life Form
 Carbon
is the
backbone for all life on
Earth.
 Carbon
forms the
compounds that make
up all cells and
organisms.
Carbon-Based Life Form
 Organic
molecules make
up living things.
 These
molecules are
composed of carbon and
hydrogen.
 Sometimes they also will
have oxygen, nitrogen,
phosphorus & other
elements
The Uniqueness of Carbon
 Atoms
create molecules by forming
covalent bonds – sharing electrons.
 The
number of covalent bonds
depends upon the atoms that are
interacting.
 Hydrogen
– can only create one
bond since it only has one electron
to share.
The Uniqueness of Carbon
 Carbon
is unique
because it
readily makes
four bonds with
other atoms!
The Uniqueness of Carbon
 Be
H
H2N
X
X
H
O
OH
aware with
the state asking
a question that
looks like this:
What does the X
represent in this
molecule?
The Uniqueness of Carbon
 Carbon
atoms are most
stable when they have all
four bonds filled.
 Typically,
carbon makes
single bonds – like that in
methane.
 However, carbon can
also form double and
triple bonds.
Carbon
Dioxide
Acetylene
The Uniqueness of Carbon
 Carbon’s
unique structure
permits the formation of
four different important
macromolecules:
1.
Lipids
2.
Nucleic Acids
3.
Carbohydrates
4.
Proteins
Lipids: Fats and Oils
 Lipids
include
oils, waxes, fats
and sterols.
Sterols include
cholesterol.
Lipids: Fats and Oils
 Fats
and oils share the
same monomer: fatty
acids attached to a
single glycerol
molecule.
Monomers are basic
structures of
macromolecules!
Lipids: Fats and Oils
 Fatty
acids are long chains
of carbon atoms
connected to each other
with double or single bonds.
 Lipids
are mostly
composed of carbon and
hydrogen with a few
oxygen atoms.
Glycerol
Fatty acids
Lipids: Fats and Oils
 Two
forms of fatty acids: saturated
(bad) and unsaturated (better).
 Saturated
fats has carbon atoms held
together with the maximum number
of single bonds and hydrogen atoms.
 Unsaturated
fats has carbon atoms
held together with single and double
bonds with hydrogen atoms.
Lipid Functions
 Long-term
energy
storage: In animals, such
as us, we store lipids in
adipose tissue.
 Adipose
tissue contains
special cells for lipid
storage.
Lipid Functions
 Cell
Membranes:
Phospholipids help to form
the cell membrane and the
organelles membranes in
cells.
 Phospholipids
are
composed of a polar
phosphate group attached
to a non-polar glycerol.
Cell membranes are
also called plasma
membranes!
Polar
Non-Polar
Lipid Functions
 Chemical
Messengers:
 Sterols
act as chemical
messengers.
 Cholesterol
is the
monomer of estrogen,
progesterone, and
testosterone.
Phospholipids
 The
cell membrane (plasma
membrane) is made up of
phospholipids.
 Two
fatty acid make up the
non-polar tails.
 The
phosphate group
connects the two fatty acids
and makes the polar head.
Phospholipids
 The
lipids in cell membranes
make them impermeable to
water.
 Water
can not freely cross the
cell membrane.
 Water
must pass through
special protein channels.
Phospholipids
When we talk about the cell membrane
we say that the polar heads are
hydrophilic and the non-polar tails
are hydrophobic.
1.
What is hydrophilic?
2.
What is hydrophobic?
Phospholipids
The plasma membrane is made up with a phospholipid bilayer, or
two sheets of phospholipids. Given the structure of a
phospholipid, how are these sheets arranged in the plasma
membrane?
1.
head*tail – head*tail
2.
head*tail – tail*head
3.
tail*head – tail*head
4.
tail*head – head*tail
Cell Membrane
Exterior of cell
?*? - ?*?
Cytoplasm
Carbohydrates
 Carbohydrates
consist of carbon,
hydrogen and oxygen with a 1:2:1 ratio.
 Examples:
 Glucose:
C6H12O6
 Sucrose:
C12H22O11
Carbohydrates
Monosaccharide
 The
simplest form of a
carbohydrate is glucose.
 The
carbohydrate’s monomer
is called a monosaccharide –
glucose is a
monosaccharide.
Monosaccharides
single rings.
tend to be
Single ring
Carbohydrates
Monosaccharide
 Table
sugar (sucrose) is
a disaccharide formed
by bonding two
monosaccharides in a
double ring structure.
Single ring
Disaccharide
Double ring
Carbohydrates
 Many
monosaccharides
tend to be isomers.
 Isomers
are molecules
that have the same
chemical formula but
different arrangement
of atoms.
Polysaccharides
 Monosaccharides
can be
linked together to form long
chains known as
polysaccharides.
 Polysaccharides
as polymers.
 Many
are known
glucose molecules link
together to form starch,
glycogen and cellulose.
Polysaccharides
 Starch
is a
polysaccharide
produced by plants to
store energy.
 Starch
is found in
wheat, rice and
potatoes.
Polysaccharides
 Cellulose
is a
polysaccharide that
composes the plant’s
cell wall.
 It
strengthens and
supports the plant cell.
 It
can only be broken
down by very few
organisms.
Many Functions of Carbohydrates
 Cellular
respiration: all
carbohydrates are broken
down into glucose to be
used in cellular respiration
for ATP production.
Any time you see energy
production in cells …
immediately think ATP!
Many Functions of Carbohydrates
 Energy
storage: Plants and
animals store energy in the
form of carbohydrates
called glycogen and starch.
 Structure:
plant cell walls are
strengthened by cellulose.
Carbohydrate Reactions
 Organisms
depend upon
chemical reactions to join
monomers together and break
polymers apart.
 Dehydration
synthesis joins two
monomers together.
 Hydrolysis
breaks down
polymers into monomers
AWAY FROM
WATER
PROCESS
Dehydration Synthesis
 Dehydration
synthesis links two
monosaccharides such as glucose
and fructose into larger molecules.
 When
this occurs, glucose loses a
hydrogen and fructose loses a
oxygen and a hydrogen.
 Along
with the new disaccharide
being formed, a water molecule is
formed.
H+ + OH- = H2O
Dehydration Synthesis
 When
dehydration synthesis occurs repeatedly longer
chains of carbohydrates are formed.
 Dehydration
synthesis also joins fatty acids to the glycerol
molecule in lipids.
L
I
P
I
D
S
C
A
R
B
S
Water
Breakdown
Process
Hydrolysis
 Hydrolysis
breaks down
polysaccharides into
monosaccharides.
 Water
is used to add back
the –OH group and H+ atom
to the monomers.
 Hydrolysis is the reverse
reaction of dehydration
synthesis
Carbohydrate Reactions
 In
a cell, 132 glucose monomers
are joined to form a straight
chain of starch. Remember, for
dehydration synthesis to occur,
water is formed. How many
water molecules are formed in
this situation?