Introductory Lecture on Biochemistry

Introductory Lecture on Biochemistry Chemistry of Water • Water is a polar molecule o The oxygen atom has a partial negative charge and the hydrogen atoms have a partial positive charge. • The slightly positive hydrogens are attracted to the slightly negative oxygens and form hydrogen bonds between molecules. o This also allows water to be a good solvent because the partial charges will be attracted to the charges of other molecules or ions. • The polarity of water allows it to be cohesive and adhesive. o Cohesion: the attraction between water molecules ▪ Causes surface tension o Adhesion: the attraction between water and other molecules ▪ Causes capillary action • Water has a high specific heat capacity o It needs to absorb a lot of energy in order to change its temperature. ▪ This helps keep aquatic environments stable and helps moderate the temperature on land too! • Water becomes less dense when it freezes, which causes ice to float. Carbon • Carbon has 4 valence electrons, which allows it to form up to four bonds with other atoms. o This allows carbon to create large, complex molecules. Monomers and Polymers • Monomers are molecules that can bond together to create larger molecules called polymers. o Monomers are like building blocks! • Monomers will bond together through a process called dehydration synthesis. o A water molecule is a byproduct of this reaction. • Polymers can be broken down into their monomers through hydrolysis. o A water molecule is needed for this reaction to occur. Biological Macromolecules • Organic molecules contain carbon and are produced by living systems. o The four main macromolecules include carbohydrates, lipids, proteins, and nucleic acids. • Carbohydrates: o Monomers: monosaccharides (glucose, fructose, galactose) o Polymers: polysaccharides (glycogen, starch, chitin, cellulose) o ▪ ▪ ▪ Structure: Carbon, Hydrogen, and Oxygen Similar amounts of C and O (C6H12O6) Ring structures o ▪ ▪ ▪ Function: Short term energy storage (bodies first source of energy) Used in cellular respiration to make ATP Structural support (cellulose, chitin) • Lipids: o Monomers: Fatty acids, glycerol o Polymers: fats, oils, waxes, cholesterol, hormones o ▪ ▪ ▪ Structure: Carbon, Hydrogen, and Oxygen Lots of C and H, little amounts of O Long chains of carbon and hydrogen - does not dissolve in water! o ▪ ▪ ▪ Function: Long term energy storage (bodies second source of energy) Makes up the plasma membrane (phospholipid bilayer Hormones - testosterone and estrogen • Protein: o Monomers: Amino Acids o Polymers: polypeptides, protein (hemoglobin, lactase, keratin) o ▪ ▪ ▪ ▪ Structure: Carbon, Hydrogen, Oxygen, Nitrogen, (Sulfur) Each amino acid has a different “R” group Proteins will fold into complex structures that help determine their function The structure of proteins can change (denature) with high temperature or change in pH o ▪ ▪ ▪ ▪ Function: Enzymes (catalysts) - usually end with -ase Storage, transport, structure Protection, regulation Hormones • Nucleic Acids: o Monomers: Nucleotides o Polymers: DNA, RNA o ▪ ▪ ▪ ▪ Structure: Carbon, Hydrogen, Oxygen, Nitrogen, Phosphate Nucleotides are made up of a sugar-phosphate backbone and a nitrogenous base DNA - double helix, deoxyribose sugar, A T C G RNA - single strand, ribose sugar, A U C G o Function: ▪ DNA stores genetic information that contains the instructions to make protein ▪ RNA stores copies of the genetic information to make protein (mRNA), helps to transport amino acids to make protein (tRNA), and makes up the structure of the ribosome (rRNA) Enzymes • Enzymes are proteins that act as catalysts for cellular reactions - they help reactions occur. o Catalysts lower the activation energy - the amount of energy needed to start a reaction. o Enzymes are not used up or changed during the reaction Without Enzyme A, more energy is needed for the reaction to occur. Enzyme A lowers the energy needed so the reaction can occur. • Enzymes work on substrates. o Substrates fit into the active site of an enzyme. If they don’t fit, then the reaction will not occur. Enzymes work best in specific conditions. If it is too cold, there will not be enough energy for the reaction to occur. If it is too hot, the protein will denature and not have the correct shape for the substrate.