Molecules of Life
What are the molecules of life? Organic Compounds Complex Carbohydrates Lipids Proteins Nucleic Acids
Organic Compounds Carbon- hydrogen based molecules
From Structure to Function Ø Carbon s importance to life stems from its versatile bonding behavior Carbon can make four bonds
Ø Carbon can bond to other carbon atoms and to many other elements Ø Many organic molecules have a backbone: chain of carbon atoms
Hydrocarbons Organic molecules containing only carbon and hydrogen Generally nonpolar
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 Glucose: C 6 H 12 O 6 Fructose: C 6 H 12 O 6 Isomers: Molecules with same molecular formula but different molecular structures Arrangement of atoms/ Emergent properties
Molecules of Life: Biological Molecules All biological systems are based on the same biological molecules The details of those molecules differ among organisms
Molecules of Life: Organic Macromolecules Essential for Life Simple organic building blocks bonded in different numbers and arrangements form different versions of the molecules of life 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
Condensation Reactions/ Dehydration Synthesis The Process by which cells link monomers to form a polymer
Hydrolysis The process by which macromolecules or polymers are broken down into monomers
Carbohydrates C, H, O (1:2:1) Structure, Energy and Storage Monosaccharides/ Simple sugars Oligosaccharides/ Short chains Polysaccharides/ Complex carbohydrates/ Long chains
Monosaccharides One sugar Monomers of carbohydrates Common monosaccharides have a backbone of five or six carbon atoms Glucose
In aqueous solutions, many monosaccharides form rings 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
How do disaccharides form?
Polysaccharides Ø Chains of hundreds or thousands of monosaccharide monomers Cellulose Starch Glycogen Ø Formed by the process of dehydration synthesis
Ø Main structural component of plants cell wall Ø Tough and insoluble Cellulose Ø Composed of chains of glucose monomers stretched side by side and hydrogen-bonded at many OH groups
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 C, H, O 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
Lipids Many lipids incorporate fatty acids Fatty Acid: Long hydrocarbon chain with a carboxyl group
Saturated vs. Unsaturated Fatty Acids
Fats/ Glycerol with one, two or three fatty acids Triglyceride
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
Proteins Molecular Tools of the Cell
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)
Monomers of Proteins: Amino Acids C, H, O, N There are 20 amino acids
Amino Acids are linked together to form a polypeptide chain through the process of dehydration synthesis
So what functional groups are always present at the ends of a polypeptide chain? NH 2 COOH
Protein Structure Primary Ø Unique amino acid sequence specific to each protein
Protein Structure Secondary polypeptide chain that forms twists and folds/ hydrogen bonds between amine and carboxyl groups
Protein Structure Tertiary Ø More folding and coiling of the helices and sheets by interactions between the R groups Ø It determines the function of the protein
Quaternary Protein Structure Ø Association of many polypeptides (subunits)
Classes of Proteins Some types of proteins aggregate into much larger structures Globular Proteins Fibrous Proteins
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
Nucleic Acids Store and transmit hereditary information C, H, O, N, P
The Monomers of Nucleic Acids: Nucleotides Nitrogenous bases: Adenine Guanine Thymine Cytosine Uracil Purines Pyrimidines A T C G in DNA A U C G in RNA
Adenosine Triphosphate ATP (a nucleotide) Energy currency of the cell base (adenine) phosphate groups
A nucleic acid polymer is built from its monomers by dehydration synthesis Nucleic Acids
Nucleic Acids Two main types: Ø DNA (Deoxyribonucleic Acid) Ø RNA (Ribonucleic Acid)
Differences between DNA and RNA DNA Ø Double Helix Ø ATCG Ø Deoxyribose sugar RNA Ø Single strand Ø AUCG Ø Ribose sugar