Marvelous Macromolecules
Chapter 5
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Macromolecules Large molecules formed by joining
smaller organic molecules Four Major Classes
Carbohydrates Lipids Proteins Nucleic Acids
Polymers Many similar or identical building blocks
linked by covalent bonds
Monomers 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
Let’s Get Together…Yah, Yah, Yah
Breakdown 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
Breakin’ Up is Hard to Do…
Variety 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
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 Molecular formula is usually a
multiple of CH2O Ex – Glucose C6H12O6
Classification of Monosaccharides ALWAYS HAVE A CARBONYL GRP. and
HYDROXYL GRPS. Location of carbonyl group
If carbonyl is on end – aldose If carbonyl is in middle – ketose
Number of carbons in backbone Six carbons – hexose Five carbons - pentose Three carbons - triose
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Characteristics of Monosaccharides
Major fuel for cellular work – especially glucose – makes ATP
In aqueous solutions – form rings Joined by glycosidic linkage
through a dehydration reaction
Disaccharides
Two monosaccharides joined together with a glycosidic linkage Maltose – formed when 2 glucose
molecules are joined Sucrose (table sugar) formed by
joining glucose and fructose Used to transport sugar in plants
Polysaccharides 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
Starch – storage polysaccharide made entirely of glucose monomers 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 Cellulose
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
Glycogen – polysaccharide of glucose used for sugar storage in ANIMALS Humans and vertebrates store
glycogen in liver and muscles
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Examples of Polysaccharides
Chitin Structural polysaccharide Used in exoskeletons of arthropods
(insects, spiders, crustaceans) Forms the structural support for cell
walls of fungiI crunch when I get I crunch when I get stepped on because ofstepped on because ofChitinChitin
Lipids 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 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 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
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Unsaturated Fats Fatty acid has one or more carbon-
carbon double bonds Kinks from double bonds prevent tight
packing Liquid at room temperature Plant and fish fats - oils QuickTime™ and a
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Phospholipids 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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Steroids Carbon skeleton with four fused
carbon rings Functional groups attached to
rings make different steroids Cholesterol – used in animal cell
membranes Precursor for all other steroids
Many hormones are steroids
Proteins Function in
Storage Transport Intercellular signals Movement Defense Structural Support Speeding up reactions (enzymes)
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Polypeptide 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 Amino AcidAmino AcidAmino AcidAmino Acid Amino AcidAmino Acid
Amino Acids 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
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Structure determines function Polypeptides must be folded into a
unique shape before becoming proteins Order of amino acids determines shape Shape of protein determines its function
Ex. – antibodies bind to foreign substances based on shape
Folding occurs spontaneously
Levels of Protein Structure Primary – determined by unique
sequence of amino acids Order of amino acids comes from DNA Changing primary structure can
change the shape of a protein and could cause it to be inactive
Ex – sickle cell caused by one amino acid change
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Levels of Protein Structure Secondary – comes from hydrogen
bonds at regular intervals along the polypeptide backbone Alpha helix – coils Beta pleated sheets - folds
Levels of Protein Structure Tertiary – determined by interactions
among R-groups on amino acids 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 Quaternary – occurs with two or
more polypeptide subunits 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 Physical and Chemical conditions can
change the shape of a protein pH Salt concentration Temperature Others
Changes can disrupt secondary or tertiary structures
Some proteins can return to original shape, but others are permanently denatured
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Nucleic Acids 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
DNAmRNAprotein Examples – DNA, RNA, ATP
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Nucleotides Made of 3 parts
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 Rings of Carbon and nitrogen Purines – two rings
Adenine (A) Guanine (G)
Pyrimidines – one ring 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 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