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� Organic Compounds ¡ Complex Carbohydrates ¡ Lipids ¡ Proteins ¡ Nucleic Acids
What are the molecules of life?
From Structure to Function Ø Carbon’s importance to life stems from its versatile bonding behavior
Carbon can make four bonds
Ø Many organic molecules have a backbone: chain of carbon atoms
Ø Carbon can bond to other carbon atoms and to many other elements
Functional Groups
An atom or group of atoms that is attached to the carbon skeleton of the organic molecule and gives it its unique chemical properties
Molecular Formula Structural Formula
Isomers: Molecules with same molecular formula but different molecular structures Arrangement of atoms/ Emergent properties
Glucose: C6H12O6 Fructose: C6H12O6
Molecules of Life: Biological Molecules
All biological systems are based on the same biological molecules The details of those molecules differ among organisms
Ø Monomers: subunits of larger molecules
Ø Polymers: consist of multiple monomers
Ø Cells build polymers from monomers, and break down polymers to release monomers
Simple organic building blocks bonded in different numbers and arrangements form different versions of the molecules of life
Molecules of Life: Organic Macromolecules Essential for Life
Condensation Reactions/ Dehydration Synthesis
The Process by which cells link monomers to form a polymer
Carbohydrates
Monosaccharides/ Simple sugars
Polysaccharides/ Complex carbohydrates/ Long chains
Structure, Energy and Storage C, H, O (1:2:1)
Oligosaccharides/ Short chains
Monomers of carbohydrates
Monosaccharides One sugar
Common monosaccharides have a backbone of five or six carbon atoms
Glucose
Ø Cells use monosaccharides for cellular fuel Ø Breaking the bonds of sugars releases energy
that can be harnessed to power other cellular processes
Ø Monosaccharides are also used as: Ø Precursors for other molecules Ø Structural materials to build larger molecules
Oligosaccharides
Ø Oligosaccharides are short chains of covalently bonded monosaccharides
Ø Disaccharides consist of two monosaccharide monomers
Ø Examples: Ø Lactose: composed of glucose + galactose Ø Sucrose: composed of glucose + fructose
Polysaccharides
Ø Formed by the process of dehydration synthesis
Ø Chains of hundreds or thousands of monosaccharide monomers § Cellulose § Starch § Glycogen
Ø Main structural component of plants cell wall Ø Tough and insoluble Ø Composed of chains of glucose monomers
stretched side by side and hydrogen-bonded at many —OH groups
Cellulose
Starch Ø Main energy reserve in plants Ø Stored roots, stems, leaves, seeds, and
fruits Ø Composed of a series of glucose
monomers that form a chain that coils up
Glycogen
Ø Main energy reserve in animals
Ø Very abundant in muscle and liver cells
Ø Highly branched chains of glucose monomers
Lipids Ø Very diverse group with diverse functions/ energy, hormones, ….
Ø No typical monomers or polymers
Ø Fats, Phospholipids, Waxes and Steroids Ø Hydrophobic: they do not mix well with water
C, H, O
Hydrogenated Oils and Trans Fats Ø Created in an industrial process that adds hydrogen to unsaturated
fats (breaking the double bonds) Ø Associated with cardiovascular diseases: Plaque build up within
the walls of blood vessels
Read the labels
Phospholipids/ lipid with a phosphate group
Ø Phospholipids make a bilayer in an aqueous solution
Ø Major component of cell membranes
Waxes Ø Complex, varying mixture of lipids with long
fatty acid tails bonded to alcohols or carbon rings
Ø Molecules pack tightly, so waxes are firm and water-repellent Ø Plants secrete waxes to restrict water loss and
keep out parasites and other pests
Steroids/ no fatty acid tails Carbon skeleton contains four fused rings
Cholesterol/ remodeled
Functional groups attached to the rings define the type of steroid
Types of Proteins � Structural (hair, feathers, spider web) � Contractile (Actin and Myosin in muscles) � Signal (built in the membrane of nerve cells) � Hormones (Insulin) � Transport (Hemoglobin in red blood cells and
transport proteins embedded in the cell membrane) � Defensive (antibodies) � Storage (Albumin in egg white to nourish the
embryo) � Enzymes (digestive enzymes to hydrolyze polymers
of food)
Amino Acids are linked together to form a polypeptide chain through the process of dehydration synthesis
Protein Structure Secondary polypeptide chain that forms twists and folds/ hydrogen bonds between amine and carboxyl groups
Protein Structure
Ø More folding and coiling of the helices and sheets by interactions between the R groups
Tertiary
Ø It determines the function of the protein
Globular Proteins Fibrous Proteins
Classes of Proteins Some types of proteins aggregate into much larger structures
Protein’s Specific Shape Determines its Function
Denaturation: Proteins losing their function as a result of losing their specific three dimensional shape/ conformation
Ø Heat, salt and acidity can denature proteins by breaking the hydrogen bonds
Nitrogenous bases: Adenine Guanine Thymine Cytosine Uracil
Purines
Pyrimidines
A T C G in DNA A U C G in RNA
The Monomers of Nucleic Acids: Nucleotides
Adenosine Triphosphate ATP (a nucleotide)
base (adenine)
phosphate groups
Energy currency of the cell