1.Describe the distinguishing characteristics ofcarbohydrates
2.Describe the important biological functions ofpolysaccharides
3.Explain what distinguishes lipids from other classes ofbiological macromolecules
4.Describe the unique properties, building blocks andbiological roles of fats, phospholipids and steroids
5.Distinguish proteins from the other classes ofmacromolecules
6.List the biological functions which proteinsperform
7.Explain what determines protein conformationand why it is important
8.Define denaturation and explain how proteinsmay be denatured
9.Describe the characteristics that distinguishnucleic acids from the other classes ofmacromolecules
10.Summarize the functions of nucleic acids
Macro = large
Molecules = 2 or more atoms covalentlybonded
Usually referred to as polymers
◦Like a chain
Made from several repeating subunits
◦The repeated subunits are called monomers
◦Like links in a chain
3 of the 4 macromolecules are polymers ofmonomers
Making or Breaking Polymers
•The chemical mechanisms that cells useto make and break polymers are similar forall classes of macromolecules.
There are four of them.
1.Carbohydrates
2.Lipids
3.Proteins
4.Nucleic acids
1.Sugars, the smallest carbohydrates, serve asfuel and carbon sources
2.Polysaccharides, the polymers of sugars,have storage and structural roles
Monosaccharides generally have molecularformulas containing C,H and O in a 1:2:1ratio.
◦For example, glucose has the formula C6H12O6.
◦Most names for sugars end in -ose.
Monosaccharides are also classified by thenumber of carbons in the backbone.
Ex: glucose, galactose, ribose, etc.
•Monosaccharides, particularly glucose, are a major fuel for cellularwork.
•While often drawn as a linear skeleton, monosaccharides are shownas rings.
•Polysaccharides are polymers ofhundreds to thousands of mono-saccharides joined together
•Disaccharides are two moleculestogether.
•Ex: sucrose, maltose, lactose, etc.
glucoseglucose
glucoseglucose
Starch is a storage polysaccharide composedentirely of glucose monomers
◦Great big chain of glucose molecules
1.Fats store large amounts of energy
2.Phospholipids are major components
of cell membranes
3.Steroids include cholesterol and certainhormones
Introduction
•Lipids are an exception among macromoleculesbecause they do not have polymers.
–Though lipid structure is easily recognized
•Lipids all have little or no affinity for water.
•Lipids are highly diverse in form and function.
1. Fats store large amounts ofenergy
•Although fats are not strictly polymers,they are large molecules assembled fromsmaller molecules by dehydrationreactions.
•A fat is constructed from two kinds ofsmaller molecules, glycerol and fattyacids.
•Glycerol consists of a three carbon skeleton witha hydroxyl group attached to each.
•• A fatty acid consists of a carboxyl groupattached to a long carbon skeleton, often 16 to18 carbons long.
•The many nonpolar C-H bonds in the longhydrocarbon skeleton make fats hydrophobic.
•In a fat, three fatty acids are joined to glycerol byan ester linkage, creating a triacylglycerol.
•The three fatty acids in a fat can be the same ordifferent.
•Fatty acids may vary in length (number ofcarbons) and in the number and locations ofdouble bonds.
•If there are nocarbon-carbondouble bonds,then the moleculeis a saturated fattyacid - a hydrogenat every possibleposition.
•If there are one or more carbon-carbon doublebonds, then the molecule is an unsaturatedfatty acid - formed by the removal of hydrogenatoms from the carbon skeleton.
•Saturated fatty acidsare straight chains,but unsaturated fattyacids have a kinkwherever there isa double bond
Saturated vs Unsaturated
•Fats with saturated fatty acids are saturated fats.
–Most animal fats
–solid at room temperature.
•Straight chains allow many hydrogen bonds
–A diet rich in saturated fats may contribute to cardiovasculardisease (atherosclerosis) through plaque deposits.
•Fats with unsaturated fatty acids are unsaturatedfats.
–Plant and fish fats, known as oils
–Liquid are room temperature.
•The kinks provided by the double bonds prevent the molecules from packingtightly together.
2. Phospholipids are majorcomponents of cell membranes
•Phospholipids have two fatty acidsattached to glycerol and a phosphategroup at the third position.
•The “head” likes water
•The “tail” hates water
•The interaction of phospholipids with water iscomplex.
–The fatty acid tails are hydrophobic, but the phosphategroup and its attachments form a hydrophilic head.
•When phospholipids are added to water, they self-assemble into aggregates with the hydrophobic tailspointing toward the center and the hydrophilic headson the outside.
–This type of structure is called a micelle.
•At the surface of a cell phospholipids are arranged as abilayer.
–the hydrophilic heads are on the outside in contact with the aqueoussolution and the hydrophobic tails form the core.
–The phospholipid bilayer forms a barrier between the cell and theexternal environment.
•They are the major component of cell membranes.
3. Steroids include cholesterol andcertain hormones
•Steroids are lipids with a carbon skeletonconsisting of four fused carbon rings.
–Different steroids are created by varying functional groupsattached to the rings.
1.A polypeptide is a polymer of amino
acids connected to a specific sequence
2.A protein’s function depends on its specificconformation
Proteins are instrumental in about everything thatan organism does.
◦ structural support,
◦ storage
◦transport of other substances
◦intercellular signaling
◦ movement
◦defense against foreign substances
◦Proteins are the main enzymes in a cell and regulatemetabolism by selectively accelerating chemical reactions.
Humans have tens of thousands of differentproteins, each with their own structure andfunction.
Proteins are the most structurally complexmolecules known.
◦Each type of protein has a complex three-dimensional shape or conformation.
All protein polymers are constructed from thesame set of 20 monomers, called aminoacids.
Polymers of proteins are called polypeptides.
A protein consists of one or morepolypeptides folded and coiled into a specificconformation
Amino acids consist of four componentsattachedto a central carbon, the alpha carbon.
These components include a hydrogen atom,a carboxyl group, an amino group, and a sidechain.
Polypeptides are made of amino acids
◦Amino acids CONTAIN NITROGEN (N)
The repeated sequence (N-C-C) is thepolypeptide backbone.
Attached to the backbone are the various Rgroups.
Polypeptides range in size from a fewmonomers to thousands.
Contain genetic information
◦Provides instructions for making polypeptides
Each monomer is a nucleotide
Nucleotides are composed of
1.5 carbon sugar
Deoxyribose
ribose
2.Phosphate group
3.Nitrogenous base
Adenine (A)
Thymine (T) in DNA, Uracil (U) in RNA
Guanine (G)
cytosine
Deoxyribonucleic acid (DNA)
◦Sugar is deoxyribose
◦Shape is a double helix
Ribonucleic acid (RNA)
◦Sugar is ribose
◦Uses a different nitrogenous base
Uracil (U) instead of thymine (T)
◦Shape may be a single or double helix
