MOLECULES OF LIFE CH5 All living things are made up of 4 classes of large biomolecules: o Proteins o Carbohydrates o Lipids o Nucleic acids Molecular structure and biological function are intricately related

I. Macromolecules Large molecules made of thousands of atoms covalently bonded 3 of the 4 biomolecules are polymers: proteins, carbs, nucleic acids Polymer: a macromolecules made of repeating units called monomers

The Synthesis and Breakdown of Macromolecules Macromolecules are made by dehydration reactions Macromolecules are broken down by hydrolysis reactions

II. Carbohydrates Sugars and the polymers of carbohydrates o Monosaccharides o Disaccharides o polysaccharides

A. Monosaccharides (CH 2 O) structure o A single sugar ex: glucose o Classified by number of carbons in chain and location of carbonyl

function o Quick energy source o Immediately enters into cellular respiration for production of ATP

Most monosaccharides exist as a ring

isomers o Molecules with same structural formula but different arrangement of atoms o Ex: glucose, fructose, and galactose

B. Disaccharides Structure o 2 monosaccharides linked via dehydration reactions o EX: sucrose, lactose Function Energy

C. Polysaccharides Long chain of GLUCOSE molecules linked via dehydration reactions 2 groups of polysaccharides o Storage: starch and glycogen o Structural: cellulose chitin

1. Storage polysaccharides Glycogen – Stores glucose in animals – Many glucose molecules linked via α1-4 linkages Starch – Stores glucose in plants – Many glucoses linked by α1-4 linkages – nt/chp03/ html nt/chp03/ html

2. structural polysaccharides cellulose o forms cell wall in plants o many glucoses linked via β1-4 linkages chitin o forms exoskeleton in arthropods and cell wall in fungi

Most animals have enzymes to break α1-4 linkage but not β1-4 linkage. Most cellulose consumed exits as insoluble fiber Only some bacteria have enzymes to break β1-4 linkage

III. Lipids Diverse group of hydrophobic molecules Only macromolecule that doesn’t form polymer

A. Triglycerides (fats and oils) One glycerol + 3 fatty acids linked via dehydration reactions em.htm

Fatty Acid Long chain of C and H with a carboxyl group Usually 14 to 20 Cs Fatty acids can be – Saturated: no carbon to carbon double bonds. Solid at room temp – Monounsaturated: 1 carbon to carbon double bond. Liquid at room temp – Polyunsaturated: more than 1 carbon to carbon double bond. Liquid at room temp

– Function of triglycerides Long term energy storage Seeds use stored triglycerides as energy during germination Insulation in mammals content/chp03/ html content/chp03/ html

B. Phospholipids Structure o One glycerol + 2 fatty acids + 1 phosphate head

Property o Amphiphathic: polar charged phosphate head and nonpolar uncharged fatty acid tails Function: o Make up phospholipid bilayer found in all biological membranes

C. Waxes and Steroids Waxes – Function as protective barrier Steroids – Function as chemical messengers

IV. Proteins About 50% of all macromolecules are proteins

A. Functions of Proteins

Polypeptide: long chain of amino acids Protein: biologically functional molecule made of 1 or more polypeptides

B. Amino Acids: monomer of proteins general structure o all contain amino and carboxyl group but differ in their R group

Groups of amino acids: based on the characteristics of R group

Linking of amino acids Link to form peptide bond by dehydration reaction Amino end of incoming amino acid links to carboxyl end of growing chain Each polypeptide has a unique order of amino acids

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Protein Structure Protein structure is determined by the sequence of amino acids Structure determines its function As protein is being synthesized, it begins to fold into its correct shape Proteins fold as a result of the interactions between amino acids in the polypeptide chain =structure =structure

There are 4 levels of protein structure primary structure

number and order of amino acids in the protein chain primary structure is determined by______________ all proteins have a different primary structure

secondary structure – Hydrogen bonding between amino and carboxyl groups – 2 forms: α helix and β sheet

Tertiary structure – Interaction among the R groups of amino acids – Interactions include ionic bonds, hydrogen bonds, hydrophobic interactions, and covalent bonds – What type of amino acids involved in each?

Quaternary structure 2 or more polypeptide chains associated together to form a functional protein

In a cell, special proteins called chaperonins help proteins fold into their shape rch/folding/proteinA.php rch/folding/proteinA.php

D. Protein unfolding Denaturation: unfolding of a protein as a result of changes in pH and temp

V. Nucleic Acids The information molecules: contain the code to make proteins

Structure – Long chains of nucleotides Nucleotides – Made of a: 5 carbon sugar Phosphate group One of 4 bases Function – DNA: stores hereditary info – RNA: expresses it