Macromolecules
1
The Molecules of Life
• Cells are made of 4 main chemical elements:
– carbon, nitrogen, oxygen, and hydrogen
• These atoms form 4 macromolecules they are:
– carbohydrates, lipids, proteins and nucleic
acids.
• These molecules serve as: energy source,
structural materials, metabolic workers, cell-tocell signals, and libraries of hereditary
information.
2
Life supporting molecules
• Molecules that contain Carbon, Hydrogen and
Oxygen in some ratio are called organic.
– Macromolecules are large organic molecules.
– Organic molecules are so diverse because they
have carbon skeletons (backbones) that vary
greatly in arrangement.
• Inorganic life supporting molecules that
have no specific ratio of C, H, and O
– Water (H2O), Carbon Dioxide (CO2)
3
Carbon’s Bonding Behavior
• Carbon’s importance in life arises from its versatile
bonding behavior.
• Carbon atoms can share pairs of electrons with as
many as four other atoms.
• Each bond is stable and strong.
• Each bond joins atoms covalently into chains which
form the backbones to which other elements, such
as hydrogen, oxygen, and nitrogen, become
attached.
4
Monomers & Polymers
• Macromolecules are actually made up of even smaller
subunits. Each subunit of a macromolecule is called a
monomer.
• The macromolecules themselves are called polymers,
because they are made up of many of these subunits.
Monomer: one basic unit
or subunit
Polymer: a chain of many
basic units
Question:
How Are
Macromolecules
Formed?
6
Answer: Dehydration Synthesis
• Also called
“condensation reaction”
it is the combining of
simple molecules to form
a more complex one
with the removal of
water.
• Forms polymers by
combining monomers by
“removing water”.
Dehydration
Synthesis
of a carbohydrate
7
Question:
How are
Macromolecules
separated or
digested?
8
Answer: Hydrolysis
• Addition of water to a compound to SPLIT
it into smaller subunits
• Also called “chemical digestion”
• Separates monomers by “adding water”
Hydrolysis
of a carbohydrate
9
Dehydration Synthesis of a
lipid
10
Hydrolysis of a lipid
11
Dehydration Synthesis of a
protein
12
Hydrolysis of a protein
13
Carbohydrates
Sugars
starches
and
cellulose
14
Carbohydrates
• Living things use carbohydrates as a key source
of ENERGY!
• Plants use carbohydrates for structure
(cellulose) not digestible by animals
– Include sugars and starches
– Contains the elements: carbon, hydrogen, and
oxygen (in a 1:2:1 ratio) (CH2O)
• Carbohydrates dissolve easily in water.
• Monosaccharide is the monomer of
carbohydrates.
15
Carbohydrates
Monosaccharide:
glucose
• one sugar unit (simple sugar)
• All have simple ring structure
• Energy for cells (provides energy for the process
of respiration)
• Examples:
–
–
–
–
–
Glucose (C6H12O6) – main source of energy for all
cells
Deoxyribose - DNA
Ribose - RNA
Fructose – found in fruits and is the sweetest
Galactose – part of milk sugar (lactose)
16
Carbohydrates
Disaccharide:
• two sugar unit
• Energy for cells
glucose
glucose
• Examples:
– Sucrose (glucose+fructose) table sugar
– Lactose (glucose+galactose) milk sugar
– Maltose (glucose+glucose) brewing beer
17
Carbohydrates
Polysaccharide:
• Long chains of sugar polymers (Not sweet)
• Function: energy storage, structural support
• Examples:
– Starch used as energy storage found in plants
– glycogen (animal starch stored in liver & muscles)
– cellulose (indigestible in humans – forms the cell
walls of plants)
glucose
glucose
glucose
glucose
cellulose
glucose
glucose
glucose
glucose
18
Carbohydrates: Food Sources
• Simple carbs (simple
sugars) are found in
most candy and sweet
drinks, fruit,
vegetables, and milk.
They are quickly
digested and give a
short burst of energy.
• Complex carbs (like
starches) are found in
pasta, bread,
potatoes, legumes &
corn. They take longer
to digest, and provide
energy longer.
Carbohydrates: Indicator Tests
• Simple Sugars:
– Benedict’s solution
– Blue solution turns
orange/green/brown
• Complex Carbs:
– Iodine
– Turns from orangered-brown to blackpurple
Lipids
Fats, oils, phospholipids, and
steroids – all are hydrophobic
(water fearing)
21
Lipids (Fats)
• Lipids are nonpolar hydrocarbons. This means
they are mostly made of carbon and hydrogen
with small amounts of oxygen.
• Element ratio of C, H, and O: (1:2: very few)
22
Fatty Acids
• Fatty Acids are the monomers of lipids.
• Fatty acids are unbranched carbon chains that make up
most lipids.
• One end is polar (hydrophilic – water loving) and the
other end is nonpolar (hydrophobic – water fearing).
23
Lipids
• Fatty acids are tails of fat – with1, 2, or 3 tails
attached to a glycerol head.
1.Saturated fat: no double bonds (bad) solid at room
temp. most animal fats:(bacon, lard, and butter) Sources
of bad cholesterol are foods rich in trans fatty acids,
refined carbohydrates, such as white sugar, and flour.
2.Unsaturated fat: double bonds (good) liquids at room
temperature (olive oil, canola oil, Omega 3 and 6 fish
oils and avocados)
24
Lipids
Function as…
• Long term energy storage: stores 2X the energy of glucose
• Cushions and insulates the body and nerves.
• Nerves wrapped in a lipid rich layer called: myelin sheath.
• Protects against heat loss (insulation)
• Structure and function - major component of cell
membranes (phospholipids)
• Maintain membrane structure
• Through cholesterol
• Hormone production
• Sex hormones
25
Lipids
• A triglyceride is composed of three molecules of fatty
acids joined to one molecule of an alcohol glycerol.
• Quantities of triglycerides are stored as droplets in the
cells of body fat (adipose tissue) in every vertebrate.
• Triglycerides under the skin helps penguins and some other animals
survive harsh climates.
Lipids
• Triglycerides are the body’s most abundant lipids and
its richest energy source.
– composed of 1 glycerol head and 3 fatty acid tails.
H
H-C----O
H-C----O
H-C----O
H
O
C-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH3
O
C-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH3
O
C-CH2-CH2-CH2-CH
fatty acids
glycerol
27
• Phospholipids:
Lipids
– A phospholipid has
two fatty acids
attached to a
molecule of glycerol
with a phosphate
group attached to
the glycerol head.
– They make up most
of the cell
membrane, which
are composed of
two layers of lipids.
28
Lipids
• Waxes:
– Waxes have long-chain fatty acids tightly
packed and linked to long-chain alcohols or
carbon rings.
– All have a firm consistency.
– All repel water.
– Waxy secretions protect, lubricate, and
impart pliability to skin and to hair.
• Bees have beeswax, birds secrete waxes that make their feathers
waterproof, aboveground plant parts are covered with waxes.
• Earwax helps prevent microorganisms from entering the ear canal.
29
• Sterols:
Sterols
– are among many lipids with no fatty acids.
– Sterols differ in the number, position, and type of their
functional groups, but all have rigid backbones of four
fused together carbon rings.
– Eukaryotic cells have sterols in their membranes: the
most common is cholesterol.
• Animal hormones are made from sterols: (testosterone,
estrogen and progesterone)
• Cholesterol also gets remodeled into compounds
such as vitamin D, steroids, and bile salts.
30
Lipids: Food Sources
• As you might have guessed, fatty foods contain
lipids.
• Lipids are found in meat and fish, oils, avacados,
eggs & nuts.
Lipids: Indicator Test
• Paper Bag Test:
– Smear substance onto paper bag
– If see-thru, it contains lipids
Proteins
33
FUNCTIONAL GROUPS
• Protein molecules contain certain groups of atoms that
are attached to them, they are called functional
groups.(patterns)
• The carboxyl and hydroxyl groups are functional
groups that define the compounds they are part of as
organic acids and alcohols, respectively.
Proteins
• Amino acids is the monomer.
• No particular ratio of elements.
• Monomers form polypeptides such as enzymes, hormones,
muscles, legumes, and nuts,
• Made of Oxygen, carbon, hydrogen and nitrogen
• Six functions of proteins:
1. Storage - albumin (egg white)
2. Transport – hemoglobin
3. Regulatory – cyclin-regulates the cell cycle
4. Movement – muscles
5. Structural - membranes, hair, nails, horns
6. Enzymes – change the speed of cellular reactions
35
Proteins
• Amino Acids:
– 20 amino acids on the entire planet.
– Each amino acid contains a central carbon atom
covalently bonded to four other atoms of
functional groups:
»A single hydrogen atom at one site
»A Carboxyl group at 2nd site (-COOH)
»An amino group at 3rd site (-NH2)
»And an R group at 4th site (R group
differs among amino acids)
36
Proteins
• Dipeptides and Polypeptides:
• Dipeptides are two amino acids bonded together
covalently by a condensation reaction.
• Polypeptides are very long chains of amino acids
• Proteins are composed of one or more polypeptides.
37
Proteins
• Enzymes:
– Include RNA and protein molecules that act as
biological catalysts.
– Enzymes depend on a physical fit with a substrate
(material/reactants being catalyzed).
– The enzymes reacts with the substrate (material) to
weakening bonds within which reduce activation
energy (the energy needed to start a reaction).
– After the reaction, the enzyme releases the product.
– Like any catalyst, the enzyme itself is unchanged, so
it can be used many times.
– Temperature or pH can greatly influence the
efficiency of enzymes.
38
Proteins
• Lock and Key Theory:
• The lock is the enzyme and the key is the substrate.
• Only the correctly sized key (substrate) fits into the
key hole (active site) of the lock (enzyme).
Smaller keys, larger keys, or
incorrectly positioned
teeth on keys (incorrectly shaped or
sized substrate molecules) do not
fit into the lock (enzyme). Only
the correctly shaped key opens a
particular lock.
39
Proteins
•
Here, the disaccharide sucrose joins with an enzyme water is added and the
products are:
– Glucose and fructose broken apart into their simplest forms to be used
40
by used inside the cell.
Nucleic
Acids
41
Nucleic Acids: Structure
• Nucleic Acids are made up of…
– Monomers (basic unit): nucleotides
– Polymers (chain of units): DNA or RNA
Nucleic acids
• Nucleotides include:
phosphate group (-PO4)
pentose sugar (5-carbon)
nitrogenous bases:
adenine (A)
thymine (T) DNA only
uracil (U) RNA only
cytosine (C)
guanine (G)
43
Nucleotide
Phosphate
Group
O
O=P-O
O
5
CH2
O
N
C1
C4
Nitrogenous base
(A, G, C, or T)
Sugar
(deoxyribose)
C3
C2
44
5
DNA
double
helix
O
3
3
O
P
5
O
C
G
1
P
5
3
2
4
4
2
3
1
P
T
5
A
P
3
O
O
P
5
O
3
5
P
45
Nucleic Acids: Function
• Stores and carries genetic information
Nucleic Acids: Food Sources
• We get nucleic acid components from vitamins and
minerals in our diet. These in turn, come from fruits,
vegetables, grains, meats, & almost anything else you
can think of with some nutritional value (no junk food!).
Nucleic Acids: Indicator Test
• You will not be using an indicator test for these but in
case you’re wondering…
• Dische diphenylamine test (dish diphenyl + amine)
– Turns from clear to light blue - dark blue if nucleic acids are
present
Digestion & Reconstruction
• When macromolecules are eaten, they are digested and
broken down into their subunits (monomers).
– Analogy: taking apart an old brick building
• Inside the cells, these subunits are reconstructed into
the structures we need.
– Analogy: using bricks to build a new building
Digestion Products
Macromolecule
eaten:
Broken down in stomach to:
Carbohydrates
Simple sugars (i.e. glucose)
Lipids
Fatty acids & glycerol
(glycerol further broken down
to glucose)
Proteins
Amino acids
Nucleic Acids
Nucleotides
The End
This ppt is adapted from: cmassengale @
biologyjunction.com
51