Principles of Biology Chapter 3 Macromolecules Principles of Biology Chapter 3

Chapter 3 Molecules of Life Carbon is essential to life Cells are mostly carbon molecules & water Carbon is the basic building block of the 4 macromolecules Carbohydrates, lipids, proteins, DNA Carbon Can form very large molecules - 4 bonds Basis of Organic chemistry

Fig. 3.2

Carbon skeletons Can be very large and varied Hydrocarbon Linear or branched Bonded to carbon atoms or other molecules Hydrocarbon Simplest organic molecule Methane Gasoline Consists of carbon and hydrogen atoms Unique 3-D shape

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Functional groups Attached to hydrocarbon skeleton Participate in chemical reactions OH - called hydroxyl or alcohol group Sugars and alcohols Carbonyl - O = C (double bond to carbon) Found in sugars NH3 - amino group found in proteins COOH - carboxyl group Found in amino acids, fatty acids and vitamins

Fig. 3.6

Synthesis and digestion Macromolecules - very large Polymers - many (repeating)parts Monomer - one unit Dehydration synthesis -builds Bonds monomers together Release water molecule Digestion - breaks Aka hydrolysis ( water breaking) Adds water ions to the broken ends

Carbohydrates Monosaccharides In aqueous solutions forms rings One sugar unit- molecular formula of CH2O Glucose - C6H12O6 Fructose - C6H12O6 Honey has both monosaccharides In aqueous solutions forms rings Main fuel for cellular work Can used to make other molecules Can be chained together Disaccharides - two sugar units

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Polysaccharides Complex sugars - many sugar units Starch Glycogen Glucose chain molecules Energy storage in plants Glycogen Glucose chain molecule Energy storage in animals Cellulose Structural molecule in plant cell walls

Lipids Hydrophobic Fats and steroids Fats Water hating Glycerol molecule and 3 fatty acids Triglyceride Store twice as much energy as carbs Cushion and insulate Saturated - no double bonds- all possible H Unsaturated- double bonds - fewer H atoms

Fig. 3.14

Steroids Lipids because they are hydrophobic Carbon chains form 4 fused rings Cholesterol Form other steroids from it Make into sex hormones Estrogen Testosterone Component of cell membranes

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Anabolic steroids Mimic testosterone First used for anemia / muscle disease Abused by athletes Misuse can cause Facial bloating/acne Violent mood swings Liver damage Increase cholesterol levels Reduce sex drive and fertility

Phospholipids Two regions with opposite properties Phosphate ‘head’ is polar Hydrophillic water loving Fatty acid tails are non-polar Hydrophobic - water fearing Forms plasma membrane Phosphate group faces out Watery environment inside/outside cell - Tails face each other - Form barrier

Fig. 3.18

Proteins Greek word meaning “first place” Polymer of amino acids Have thousands of proteins in us Monomer Amino acid Central carbon Amine group Carboxyl group Hydrogen “R” group - remainder - what differs from amino acid to amino acid

Proteins Amino acids linked by peptide bonds Forming a polypeptide (aka protein) Chain of amino acids 100 or more Primary structure Order of amino acids 20 different amino acids Change in order can cause disease Sickle cell anemia One amino acid changed

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Protein structure Secondary and tertiary structure Twisting and folding Bonding between different parts of molecule 3-D shape Quaternary structure Interaction between more that one polypeptide All this leads to a particular shape that allows the protein to do its job

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Protein shape Must twist, fold, and coil correctly to function Hydrophobic region inside Hydrophilic regions outside in watery environment of cell 3-D shape is critical Denaturation Caused by change in pH or temperature Changes 3-D shape - non functional Shape determines function

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Enzymes Enzymes are a kind of protein Many different enzymes in our bodies Metabolism is the sum total of all chemical reactions in an organism Most require a specific enzyme to happen Catalyst - stimulate a reaction to occur Reactions require a input of energy to get started - activation energy Enzymes lower the energy required Result is that chem rxns are effective

How is structure determined? Order of amino acids specified by a gene - recipe for a polypeptide Proteins include Structural Storage Contractile Transport Defensive Signal proteins ENZYMES!

Nucleic acids DeoxyriboNucleic Acid - DNA DNA is a recipe book for proteins Genes direct the order of amino acids Two types of nucleic acids DNA RNA - RiboNucleic Acid Chemical code Nucleic acid to protein language RNA helps with this process

Fig. 3.26

Nucleic acids Polymer Dehydration synthesis makes the polymer Repeating unit is a nucleotide consisting of: Sugar Phosphate Base Adenine - A Cytosine - C Guanine - G Thymine - T (only in DNA) Uracil - U (only in RNA) Dehydration synthesis makes the polymer

Fig. 3.27

DNA One strand has 100’s to 1000’s of genes DNA double helix 2 strands Bonded to each other by hydrogen bonds A pairs with T, vice versa C pairs with G, vice versa RNA is a single strand of nucleotides Replication (DNA copying) Strands separated New complementary nucleotides join

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