1 14 Chemistry of life A atoms and elements Elements Made up of one or two atoms 90 naturally occurring types 25 man made 4 that predominate oxygen hydrogen carbon nitrogen Atomic Structure Nucleus made up of protons and neutrons USUALLY same of protons and neutrons Electrolytes Around nucleus Stable atom will have same number of electrons and protons Atoms identified by atomic of protons Electron shells Electrons at different levels around nucleus electron shells Inner shell up to 2 electrons 2nd shell and any additional up to 8 electrons Is empty spaces in their outermost shell considered unstable atoms React readily with other atoms Isotopes Ions Atoms with more or fewer neutrons than their atomic number Charged atoms Atom that looses one or more electrons becomes positively charged Atom that acquires electrons becomes negatively charged Covalent strongest bond sharing electrons Ionic negative and positive charged atoms attracted to one another donate electrons to change other atoms charge Hydrogen bond H bond occurs between molecules not atoms atoms combine to form molecules In water molecule 8 positively charged protons attract electrons more than single proton in hydrogen atom Electrons oxygen side of molecule makes it slightly while hydrogen side is slightly positive H slightly positive charged hydrogens of slightly negatively charged oxygen B Chemical Bonds oxygen s readily pulled toward negatively charged bonds formed b n one molecule and the atom of another C Biological Molecules Water high surface tension Strong cohesiveness high heat capacity lower density when frozen Good solvent helps maintain stable internal environment in humans Ions and polar substances dissolve in water Acids Bases Buffers Hydrogen and Hydroxide ions H and OH if H concentration higher than OH acid OH concentration higher base pH scale Buffers lower than 7 acid higher than 7 base 7 water Help neutralize acids and bases Carbon dioxide buffer for ph level of blood When too acidic buffer absorbs h ions too basic buffer releases H ions Macromolecules large molecules Carbohydrates Made up of subunits of sugar Principle atoms Carbon Hydrogen Oxygen C6H12O6 glucose Simple sugars most effective source of energy monosaccharides glucose fructose Glucose in blood 3 fates if energy is needed bonds broken to extract energy don t need energy right away energy stored short term glycogen linked together long term converted into fat Complex carbs are time released packets of energy Disaccharides and polysaccharides formed by joining 2 or more simple sugars Larger molecule more energy needed to break it down Starch 100 s of glucose molecules joined together Barley wheat rye corn Cellulose fiber and chitin exoskeletons not digestible galactose rice Lipids macromolecules with several functions including energy storage hydrophobic fear of water oil non polar hydrophilic love of water Non polar that don t dissolve in water Greasy significant source of energy storage 3 types Fats Glycerol head region Fatty acid tails Triglycerides Saturated each carbon bound to 2 hydrogen atoms Unsaturated Not all carbons bound to 2 Hydrogen atoms Fatty acid become crooked Can artificially add hydrogen atoms to an unsaturated fat improves taste and shelf life Increase risk disease Cholesterol Sterols important to cell membranes in animals Can attach to and become plaque Used to produce testosterone Phospholipids Major component of cell membrane Strongly hydrophobic tails hydrophilic heads Proteins Versatile macromolecules that serve as building blocks Amino acids strung together to make proteins 20 different types of amino acids Bound together by peptide bonds Hydrogen bonding between amino acids Causes polypeptide chain to change shape Can get multiple secondary structures that form 3d shapes structure Two or more polypeptide chains quaternary structure Denatured protein extreme environment disrupts protein shape and function tails of heart vessel walls in arteries estrogen and tertiary Nucleotides nucleic acids DNA RNA Blueprint in cells stays in nucleus Leaves nucleus and travels to part of cell that makes proteins to read Message that goes from DNA to ribosomes Cells Prokaryotes No nucleus DNA floats around simpler DNA Bacteria single celled organism Eukaryotes Nucleus Larger more complex than prokaryotes Organelles and cytoplasm DNA in nucleus Single or multi cellular Plasma membranes Hydrophilic heads hydrophobic tails Tails face inwards heads outwards Simple diffusion low concentration Requires no energy other diffusion molecules pass through membrane from high concentration to Transport molecule helps other molecule across membrane Osmosis Water passes through membrane from high to low concentration Hypertonic higher salt concentration outside cell Hypotonic More salt inside cell Isotonic Balanced salt concentration inside and out Solute dissolves into something else Solvent dissolves solute