Transcript Marvelous Macromolecules

Marvelous Macromolecules
Ch 5 Notes
Macromolecules
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Large molecules formed by joining
smaller organic molecules
Four Major Classes
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Carbohydrates
Lipids
Proteins
Nucleic Acids
Polymers
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Many similar or identical building
blocks linked by covalent bonds
Monomers
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Small units that join together to make
polymers
Connected by covalent bonds using a
condensation (dehydration) reaction
One monomer gives a hydroxyl group, the
other gives a hydrogen to form water
Process requires ENERGY and ENZYMES
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Breakdown
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Polymers are disassembled by hydrolysis
The covalent bond between the monomers
is broken splitting the hydrogen atom
from the hydroxyl group
Example – digestion breaks down
polymers in your food into monomers
your body can use
Variety
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Each cell has thousands of different
macromolecules
These vary among cells of the same
individual; they vary more among
unrelated individuals in the same species;
and vary even more in different species
40 to 50 monomers combine to make the
huge variety of polymers
Carbohydrates 
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Used for fuel (energy) and building
material
Includes sugars and their polymers
Monosaccharides – simple sugars
Disaccharides – double sugars (two
monosaccharides joined by condensation
reaction
Polysaccharides – polymers of
monosaccharides (many sugars joined
together)
Monosaccharides
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Molecular formula is usually a
multiple of CH2O
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Ex – Glucose C6H12O6
Classification of Monosaccharides
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Location of carbonyl group
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If carbonyl is on end – aldose
If carbonyl is in middle – ketose
Number of carbons in backbone
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Six carbons – hexose
Five carbons - pentose
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Characteristics of
Monosaccharides
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Major fuel for cellular work –
especially glucose – makes ATP
In aqueous solutions – form rings
Joined by glycosidic linkage
through a dehydration reaction
Disaccharides
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Two monosaccharides joined
together with a glycosidic linkage
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Maltose – formed when 2 glucose
molecules are joined
Sucrose (table sugar) formed by
joining glucose and fructose
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Used to transport sugar in plants
Polysaccharides
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Polymers of sugar
Can be hundreds to thousands of
monosaccharides joined together by
glycosidic linkages
Used in energy storage then broken
down as needed in the cell
Also used to maintain structure in
cells
Examples of Polysaccharides
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Starch – storage polysaccharide
made entirely of glucose monomers
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Plants store starch in plastids
Plants can use glucose stored in starch
when they need energy or carbon
When animals eat plants, they use the
starch as an energy source
Made of ALPHA glucose rings
Examples of Polysaccharides
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Cellulose
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Polymer of glucose monomers
Made of BETA glucose rings
Found in Cell Walls of plants (very tough)
Animals can’t digest cellulose (passes through
making digestion easier)
Herbivores have special microbes in their
stomachs that can digest cellulose (that’s why
they can survive on only plants)
Examples of Polysaccharides
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Glycogen – polysaccharide of
glucose used for sugar storage in
ANIMALS
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Humans and vertebrates store glycogen
in liver and muscles
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Examples of Polysaccharides
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Chitin
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Structural polysaccharide
Used in exoskeletons of arthropods
(insects, spiders, crustaceans)
Forms the structural support for cell
walls of fungi
Lipids 
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Hydrophobic molecules
Nonpolar bonds making them have
little or no affinity for water
Store large amounts of energy
Not “polymers”, but are large
molecules made from smaller ones
Fats
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Made of glycerol (3 Carbons with
hydroxyl attached) and 3 fatty acids
(long carbon skeleton)
Joined by ester linkage in
dehydration reaction
Used in energy storage, cushion
organs, and for insulation
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Saturated Fats
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Fatty acids with no carbon-carbon
double bonds
Pack tightly together making
SOLIDS at room temperature
Most animal fats are saturated
Eating too much can block arteries
Unsaturated Fats
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Fatty acid has one or more carboncarbon double bonds
Kinks from double bonds prevent
tight packing
Liquid at room temperature
Plant and fish fats - oils
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Phospholipids
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Glycerol joins with 2 fatty acids and 1
phosphate group
Phosphate group carries negative charge
making heads that are hydrophilic
Fatty acids are nonpolar, making tails
that are hydrophobic
Major components of cell membranes –
phospholipid bilayer
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Compare the structure of a fat to
the structure of a phospholipid
Steroids
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Carbon skeleton with four fused
carbon rings
Functional groups attached to rings
make different steroids
Cholesterol – used in animal cell
membranes
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Precursor for all other steroids
Many hormones are steroids
Proteins 
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Function in
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Storage
Transport
Intercellular signalling
Movement
Defense
Structural Support
Speeding up reactions (enzymes)
Polypeptide
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Polymer of amino acids (monomer)
joined by peptide bonds
One or more polypeptides come
together to make protein
Each protein has complex 3-D shape
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Amino Acids
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Made of
 Hydrogen
 Carboxyl group
 Amino group
 R-group – varies from one amino acid to the
next
20 amino acid monomers make thousands of
proteins
Joined together by dehydration reaction that
removes hydroxyl group from one and amino
group of another to make a peptide bond
Structure determines function
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Polypeptides must be folded into a unique
shape before becoming proteins
Order of amino acids determines shape
Shape of protein determines its function
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Ex. – antibodies bind to foreign substances
based on shape
Folding occurs spontaneously
Levels of Protein Structure
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Primary – determined by unique
sequence of amino acids
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Order of amino acids comes from DNA
Changing primary structure can
change the shape of a protein and could
cause it to be inactive
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Ex – sickle cell caused by one amino acid
change
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Levels of Protein Structure
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Secondary – comes from hydrogen
bonds at regular intervals along the
polypeptide backbone
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Alpha helix – coils
Beta pleated sheets - folds
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Levels of Protein Structure
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Tertiary – determined by interactions
among R-groups on amino acids
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Hydrogen bonds
Hydrophobic/hydrophilic interactions
Van der Waals interactions
Ionic bonds (charged R groups)
Disulfide bridges between sulfhydryl groups of
cysteine amino acids (stabilize structure)
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Levels of Protein Structure
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Quaternary – occurs with two or
more polypeptide subunits
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Collagen – three polypeptides coiled
like a rope – good for structure
Hemoglobin – four polypeptide (two
different types) – carries oxygen
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Changing Protein Structure
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Physical and Chemical conditions can
change the shape of a protein
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pH
Salt concentration
Temperature
Others
Changes can disrupt secondary or
tertiary structures = DENATURATION
Some proteins can return to original
shape, but others are permanently
denatured
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Nucleic Acids 
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Polymers formed by joining Nucleotide
monomers with phosphodiester linkages
Store and transmit hereditary information
Inherited from one cell to the next during cell
division
Program the primary structure of proteins
through instructions in the genes of DNA
Information travels from
DNAmRNAprotein
Examples – DNA, RNA, ATP
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Nucleotides
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Made of 3 parts
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Pentose sugar (usually deoxyribose or ribose)
Phosphate group
Nitrogen Base
Backbone – sugar and phosphate
(phosphodiester link)
Steps – Nitrogen base
Make a Double Helix
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Nitrogen Bases
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Rings of Carbon and nitrogen
Purines – two rings
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Pyrimidines – one ring
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Adenine (A)
Guanine (G)
Cytosine (C)
Thymine (T)
Uracil (U)
A always pairs with T, C pairs with G in DNA
Bases are connected in middle of ladder by
HYDROGEN BONDS 
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Polynucleotides
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Connect Sugar of one nucleotide to
phosphate of next making a backbone
Nitrogen bases in the middle vary from
one organism to the next creating a
unique sequence of DNA
DNA creates proteins in cells therefore
different organisms create different
proteins based on the order of bases in
DNA