Biochemistry

• Biochemistry is the study of chemical composition and reactions of living matter
• Organic compounds contain carbon, are usually large, and are covalently bonded
• Carbohydrates, fats, proteins, and nucleic acids are major organic compounds
• Exceptions of organic compounds: CO2 and CO
• Inorganic compounds do not contain carbon
• Water, salts, and many acids and bases are examples of inorganic compounds
• Water is the most abundant inorganic compound
• Accounts for 60%–80% of the volume of living cells
• Polar solvent properties, dissolves and dissociates ionic substances
• Salts are ionic compounds that dissociate into separate ions in water
• All ions are called electrolytes because they can conduct electrical currents in solution
• Acids are proton donors, release hydrogen ions (H+)
• Bases are proton acceptors, pick up H+ ions in solution
• Important bases: Bicarbonate ion (HCO3–) and ammonia (NH3)
• The pH scale measures the concentration of hydrogen ions [H+] in a solution, ranges from 0-14
• Acidic solutions have high [H+] but low pH
• Alkaline (basic) solutions have low [H+] but high pH
• Neutral solutions have equal numbers of H+ and OH- ions, pH 7
• Buffers resist abrupt and large swings in pH
• Buffers can release hydrogen ions if pH rises or bind hydrogen ions if pH falls
• Buffers involve weak acids and weak bases
• Carbohydrates are major organic compounds
• Monosaccharides are single sugars, important ones include pentose and hexose sugars
• Disaccharides are double sugars, formed by dehydration synthesis of two monosaccharides
• Polysaccharides are many sugars bonded together, important ones include starch and glycogen
• Lipids contain C, H, O, and sometimes P
• Triglycerides are fats when solid and oils when liquid, composed of three fatty acids bonded to a glycerol molecule
• Phospholipids contain glycerol, two fatty acids, and a phosphate group, important in cell membrane structure
• Steroids consist of four interlocking ring structures, important steroid is cholesterol
• Proteins have varied functions, built from amino acids
• Amino acids are joined by peptide bonds
• Proteins have four levels of structure: primary, secondary, tertiary, and quaternary
• Proteins can denature, losing their functional 3-D shape
• Nucleic acids are made up of nucleotides
• DNA is found in the nucleus, provides instructions for protein synthesis
• RNA carries out protein synthesis orders from DNA, contains ribose sugar and uracil
• ATP powers chemical reactions in cells, offers immediate energy
• ATP structure: Adenine-containing RNA nucleotide with two additional phosphate groups