Macromolecules
The Molecules of Life!
Most macromolecules are polymers
Monomer
Polymer
Macromolecule
Polymerization Reactions
Chemical reactions that link two or more small molecules to form larger molecules
Condensation Reactions
Also known as dehydration synthesis
Monomers are linked covalently producing a net removal of water.
One monomer loses an H the other an OH or hydroxyl.
Requires energy and enzymes
Hydrolysis
“Water breaking”A reaction that breaks the
covalent bonds between monomers by the addition of water molecules
Structural variation
Structural variation of macro-molecules is the basis for the enormous diversity of life.
Unity= only about 40-50 monomersDiversity- new properties emerge as
various monomers are put together
Carbohydrates
Quick energyMade from monomers called
monosaccharideClassified on the number of
simple sugars
MonosaccharideSimple sugars
Ratio = CH2O
Major nutrients for cell –glucoseCan be made by the sun
PhotosynthesisEnergy stored in their chemical bonds
which are broken in cell respirationCarbon skeletons used for other organic
molecules.
Characteristics of sugar
An OH- group is attached to each carbon except one which is double bonded to a carbonyl
Size of skeleton varies 3 to 7 carbons
Spatial arrangements vary
3 Monosaccharide
Glucose
Fructose
Galactose
Disaccharides
“Double sugar”Two monosaccharides joined by
a GLYCOSIDIC linkage.A covalent bond between two
sugar monomers resulting from a condensation reaction.
Examples of Disacchrides
Maltose glucose + glucose= malt sugar
Lactose glucose + galactose= milk sugar
Sucrose glucose + fructose= fruit sugar
Polysacchrides
Macromolecules that are polymers of a few hundred or thousand monosaccharides
2 important biological functionsEnergy storage- starch/glycogenStructural support- cellulose/chitin
Starch
Energy storage for plantsHelical glucose polymer with alpha
helix 1-4 glycosidic linkages. Stored in plastidsAmylose- simplest formMost animals can digest
Glycogen
Storage polysaccharide in animals
Stored in the muscle and live of humans and other vertebrates
Structural Polysaccharides
Cellulose- Linear unbranched polymer of D-glucose in Beta 1-4 linkages.
Major component of cell walls/ reinforcesDifferent from starch in its glycosidic
linkages! (important!)Cannot be digested by most organisms.Exception- some bacteria, fungi.
Chitin
A polymer of an amino sugar
Forms exoskeletons of arthropods
Lipids
Fats, Phospholipids and SterolsInsoluble in water but will
dissolve in nonpolar solvents like ether, chloroform benzene
FATS composed of C,H,O
Macromolecules made from:1. Glycerol- a 3-carbon alcohol
2. Fatty Acid (carboxylic acid) A carboxyl group at one end and a
attached (non polar) hydrocarbon tail
Ester Linkage
Bond formed between a hydroxyl group (OH-) and a carboxyl group (-COOH)
Triacylglycerol- a fat composed of three fatty acids bonded to one glycerol by 3 ester linkages.
SEE BOOK for pictures!!!
Characteristics of fat
Insoluble in water due to long fatty acid chains which have lots of nonpolar C-H bonds
Vary by fatty acid composition, length, and location of Carbon to Carbon bonds.
Saturated Fat
No double bonds, Carbon bonded to maximum # of hydrogen's
Solid at room tempMost animal fats
Unsaturated Fats
One or more double bonds between carbons in fatty acid tail
Tail kinks at each C=C so molecules do not pack close enough to solidify.
Liquid, plant fats
Why is Fat important?
Energy storage- 1 gram of fat has 2x the energy as a gram of polysaccharide
More compact fuel reservoir than a carbohydrate
Cushions vital organsInsulates against heat loss
Phospholipids
Compound make up of a glycerol, two fatty acids and a phosphate
The head is hydrophilic The tails are hydrophobic
Importance of Phospholipids
Major constituents of cell membranes. Because phospholipids are ambivalent towards water. they are able to form a type of barrier around the cell’s cytoplasm.
Steroids
Lipids which have four fused carbon rings with various functional groups attached.
See picture in book
Cholesterol- an important steroid
Precursor to many other steroid including
Vertebrate sex hormonesHas an important role in the keeping the
cell membrane fluidOverproduction and over consumption
can contribute to atherosclerosis
Proteins
Composed of Carbon, Hydrogen, OxygenAnd Nitrogen
Proteins are building blocks
The monomers are amino acids. There are 20 amino acids which form a
huge variety of proteinsPolypeptide chains- polymers of amino
acids arranged in a specific linear sequence and linked by peptide bonds.
Protein
A macromolecule that consists of one or more polypeptide chains folded and coiled into specific conformations.
Each kind has its own unique 3-D shape
Importance of Proteins
Structural support (collagen) Storage (of amino acids) Transport (hemoglobin) Signaling (Chemical messengers) Cellular response to chemical stimuli Movement (contractile proteins) Defense (antibodies) Catalysis of Biochemical reactions Enzmyes
Amino Acids
Building block of proteinMost consist of an asymmetric carbon
covalently bonded to: H OHydrogen atom H3N+- C
Carboxyl group R OAmino groupVariable R group (side chain)
Unique properties of Amino Acids
A. acids contain both a carboxyl group and an Amino group. Since one group acts like a weak acid (carboxyl) (-) the other acts as a weak base (amine) (+) so an amino acid can exist in three anion states.
Some have polar side groups, some nonpolar.
Peptide Bond
Covalent Bond formed by a condensation reaction that links the carboxyl group of one amino acid to the amino group of another.
Has polarity with the –COOH group on one end and the NH2 group on the other
Backbone= N-C-C-N-C-C-
A Proteins Shape
3-D unique shapeNative conformationEnables a protein to recognize and bind
specifically to another moleculeConsequence of linear arrangement of
amino acids, folded and coiled and stabilized by chemical bonds and weak interactions.
Four levels of Protein Structure
PrimarySecondary
TertiaryQuaternary
Primary
Unique sequence of amino acids(Like beads on a string)Pioneer in sequencing- Frederick
Sanger who sequenced insulin in the late 40’s.
Secondary
Regular repeated coiling and folding of a protein’s polypeptide backbone
Contributes to proteins overall conformation
Stablized by HYDROGEN bonds between peptide linkages
2 Types: Alpha Helix and Beta Pleated See book pictures
Tertiary Structure (important!)
Irregular contortions of a protien due to bonding between side chains ® groups; third level of protein structure imposed on primary and secondary structure.
Covalent linkage( disulfide bridges) and weak interactions (ionic bonds, hydrogen bonds and hydrophobic interactions) contribute to bonding stability.
Quaternary Structure
Structure that results from the interaction among several polypeptides in a single protein
Example: Collagen, HemoglobinSee the book for a picture
What determines protein conformation?
A protein’s 3-D shape is the result of the interactions responsible for the secondary and tertiary sturcture
Influenced by physical and chemical environmental conditions
If altered may become DENATURED and lose its native conformation
Denaturation
A proteins shape can be altered by:Transfer to an organic solvent. Chemical agents that disrupt hydrogen
bonds, ionic bonds and disulfide bridgesExcessive heat
Some can return to their original state.
A proteins shape..
Even though the primary structure determines the proteins conformation, many other factors affect the final shape which can not always be determined ahead of time.
Nucleic Acids
Protein structure is determined by primary structure which is determined by GENES- heredity units that consist of DNA- a type of nucleic acid
There are two types: DNA and RNA
DNA characteristics
Contains coded information that programs ALL cell activity
Contains directions for its own replication Is copied and passed from one generation to
the next In eukaryotic cells found primary in the
nucleus Makes up genes that code for Protein
Synthesis
RNA characteristics
Functions in the actual synthesis of proteins
Sits of synthesis are on ribosomes in the cytoplasm
Messenger RNA carries the encoded genetic message from the nucleus to the cytoplasm
DNA---RNA---Protein
What makes up a nucleic acid?
Monomers are nucleotides linked together by condensation synthesis.
A nucleotide is: 1. nitrogenous base (A,T,C,G,U)2. a five carbon sugar (Pentose)3. A phosphate group
The bases
Pyrimidine= nitrogenous base with a six- membered ring made up of carbon and nitrogen atoms
Cytosine, Thymine (DNA), Uracil (RNA)Purine- nitrogenous base with a 5-
membered ring fused to a six-membered ring:
Adenine and Guanine
Functions of nucleotides
Monomers of nucleic acidsTransfer energy from one molecule to
another. (ATP)Are electron acceptors in enzyme
controlled redox reactions (NAD)
The structure of DNA
Double helixBackbone of Sugar and phosphate. The
backbone is the result of phosphodiester linkages between the phosphate of one nucleotide and the sugar of the next.
The sugar is deoxyriboseThe bases in DNA are A,T,C,G
The end………… TEST