Part 2: Organic Chemistry (Carbon and Macromolecules) BIOCHEMISTRY Part 2: Organic Chemistry (Carbon and Macromolecules)

Organic Chemistry Compounds of carbon (and hydrogen and oxygen). Range from simple to complex molecules The original idea that organic compounds arise only in organisms, was disproved when chemists began synthesizing them in lab. The most famous of these was the MILLER-UREY EXPERIMENT.

Miller-Urey Experiment

Carbon CARBON ATOM: Forms four covalent bonds. Can form long chains, cyclic or branched compounds. Shape is important in determining biological properties and functions. HYDROCARBONS consist of only carbon and hydrogen and can release a lot of energy.

Polymers Joining smaller units (monomers) into longer chained molecules called MACROMOLECULES. DEHYDRATION SYNTHESIS- Linking monomers into large polymers by removing water. HYDROLYSIS - Breaking polymers into monomers by the addition of water.

Carbohydrates Sugars and sugar polymers. Serve as: fuel for cells and raw material for building molecules. General formula: (CH2O)n (2 to 1 ratio of H to O).

Monosaccharides Simple sugars. Most common: 5 Carbon (Pentose sugars): Glucose (C6H12O6)- product of photosynthesis used as energy source in cell respiration Fructose Galactose 5 Carbon (Pentose sugars): Ribose (used in RNA) Deoxyribose (used in DNA)

GLUCOSE FRUCTOSE GALACTOSE

Disaccharides Two monosaccharides joined by dehydration synthesis. Bond formed is called a GLYCOSIDIC LINKAGE. Most common: Maltose (glucose + glucose) Sucrose (glucose + fructose) Lactose (glucose + galactose)

A – GLUCOSE B – DEHYDRATION SYNTHESIS D – MALTOSE E – GLYCOSIDIC LINKAGE C – HYDROLYSIS

Polysaccharides Macromolecules with storage and structural roles. Examples: STARCH- Storage polysaccharide in plants, consists entirely of glucose monomers GLYCOGEN- Storage polysaccharide in animals (humans store this mainly in liver and muscle cells) CELLULOSE- Major component of tough plant cell walls CHITIN- Found in the exoskeleton of arthropods and cell walls of fungi

Lipids These DO NOT form polymers HYDROPHOBIC- “water fearing” due to the fact they are non-polar C, H and (very little) O. Biologically Important Types: Neutral Fats Phospholipids Steroids Waxes

Neutral Fats Most abundant type. AKA TRIGLYCERIDES. Stored in fatty tissue in the body. 2 Major Parts: 3 Fatty Acids- carboxyl group attached to a chain of carbons 1 Glycerol SATURATED FATS – All single bonds between carbons (or maximum hydrogens on carbons). Mostly solid fats at room temperature. UNSATURATED FATS – Double/triple bonds between carbons. Mostly oils at room temperature. Monounsaturated (one double or triple bond) vs. Polyunsaturated (more than one double or triple bond).

Carbon Chain of Fatty Acid Unsaturated Fatty Acid Carboxyl Group Carbon Chain of Fatty Acid Saturated Fatty Acid Unsaturated Fatty Acid Glycerol

Dehydration Synthesis Glycerol Fatty Acid 1 Fatty Acid 2 3 Fatty Acids Fatty Acid 3 Dehydration Synthesis Lipid

Fats in Our Diets HYDROGENATION- process of converting unsaturated fats to saturated fats by adding hydrogen Hydrogenating vegetable oils also creates “trans fats”. These appear to contribute to heart disease and should be avoided as much as possible.

Phospholipids Consists of 2 fatty acids and one phosphate group attached to glycerol. These are AMPHIPATHIC LIPIDS, meaning that one end (fatty acid tails) are hydrophobic and one end (phosphate) is hydrophilic. This is important because these form the lipid bilayer of the cell membrane and are very stable.

Phospholipid Structure

Steroids Characterized by 4 interlocking rings. Important example is CHOLESTEROL, which is a component of animal membranes. Necessary for proper membrane functioning, but high levels in the blood contribute to cardiovascular disease.

General Steroid Structure Progesterone Estrogen Testosterone Aldosterone Cortisol Corticosterone Cholesterol

Proteins Account for well over 50% of the dry mass of most cells! Functions include: Structure, Storage, Transport, Cell communication, Movement, Enzymes, and Immunity ENZYMES act as a catalyst to speed up the rate of chemical reactions and work repeatedly. Building blocks are AMINO ACIDS. They differ in their side chains (R groups) that make up the 20 different amino acids. Amino acids are linked together by PEPTIDE BONDS. Long chains of linked amino acids are called POLYPEPTIDES.

Side Group Amino Group Carboxylic Acid Group Amino Acid

Dehydration Synthesis Amino Acid (Peptide) Dehydration Synthesis Dipeptide Peptide Bond

Protein Structure 4 Major Types: PRIMARY STRUCTURE – Straight chain of amino acids SECONDARY STRUCTURE – Folding of short lengths of an amino acid chain with weak hydrogen bonds interaction. α-helix is coiled and elastic (keratin) β-pleated sheets are flexible TERTIARY STRUCTURE - Overall folding of secondary structure due to multiple bonds among various side chains “R” groups. QUATERNARY STRUCTURE - Two or more polypeptide chains together (e.x. Hemoglobin has 4 polypeptide chains and a heme (Iron) group).

A protein’s structure determines its function! Loss of shape is called DENATURATION (by heat or pH).

Nucleic Acids 2 Major Types: Building blocks are NUCLEOTIDES. Ribonucleic acid (RNA) and Deoxyribonucleic acid (DNA). Building blocks are NUCLEOTIDES. 3 Parts of a Nucleotide: Five carbon sugar (ribose or deoxyribose). Phosphate group. Nitrogenous base.

Bases Double ring bases (PURINES). ADENINE and GUANINE Single ring bases (PYRIMIDINES). CYTOSINE and THYMINE (DNA only) and URACIL (RNA only). Purines always pair up with Pyrimidines. G-C, A-T (in DNA), A-U (in RNA).

Sugar (Deoxyribose) Phosphate Base – Adenine Base – Guanine Purines Base – Cytosine Base – Thymine Pyrimidines

Dehydration Synthesis Phosphate Sugar Base Dehydration Synthesis Nucleotide

Adenine Thymine Phosphate Sugar Hydrogen Bonds Guanine Cytosine

DNA vs. RNA DNA RNA Carrier of genetic code in genes (unit of heredity) Translation of genetic code into amino acid sequence Double helical strand Single helical strand Thymine base present Uracil replaces thymine base 1 Type 3 Types – rRNA, mRNA, and tRNA

ATP ATP (Adenosine TriPhosphate). Adenine, ribose sugar, and 3 phosphate groups. 2 outer phosphate groups joined by energy rich bonds. Energy is released when the bonds are broken