Basic Biology I: CellsOutlineChemistrySlide 4AtomsChemical BondsIonic BondsCovalent BondsPolar Covalent BondsHydrogen BondsWaterSlide 12BiochemistryOrganic CompoundsFour Basic Types of MacromoleculeCarbohydratesSugarsComplex CarbohydratesLipidsTriglycerides and PhospholipidsProteinsAmino AcidsProtein StructureNucleic AcidsDNA and RNACellsThe Cell TheoryBasic Cell OrganizationCell MembraneTransport Across the Cell MembranePassive and Active TransportWater in the CellMitochondria and ChloroplastsEndosymbiont HypothesisNucleusCell Division and GenesSummary of MitosisGene ExpressionTranscriptionGenetic CodeTransfer RNATranslationInternal Membrane SystemEndoplasmic ReticulumGolgi Body and SecretionLysosomes and PeroxisomesEnzymes and EnergyEnergy in the CellThermodynamicsATPMetabolic ReactionsEnzymesOxidation of GlucoseRespiration: Three StepsGlycolysisKrebs CycleElectron TransportBasic Biology I: CellsHow organisms workOutline•Chemistry (pp. 8-10): atoms, molecules and bond, polar bonds, water•Biochemistry (pp. 11-17): four basic macromolecules•Cells (pp. 20-29): membrane, osmotic pressure, organelles, endosymbiosis, cell division, gene expression•Enzymes and energy generation (pp. 57-58 and 64-69)Chemistry•Name the components of atoms and their role in determining the atom’s identity and in forming chemical bonds.•Distinguish between the 3 main types of chemical bond•Understand the relationship between water, polar and non-polar, and hydrophilic and hydrophobicChemistry•At the bottom, biology is nothing but applied chemistry•All matter is composed of atoms•Elements such as carbon and oxygen are a group of atoms of the same type. For instance, a nail made of iron is just a large group of iron atoms.•There are 92 naturally occurring elements, plus about 25 artificially-created elements.•Living things are mainly composed of the elements carbon, hydrogen, oxygen, and nitrogen. Another dozen or so elements are also used: phosphorus, iron, magnesium, sodium, potassium, chlorine, to name a few.Atoms•Atoms have 3 components: protons, neutrons, and electrons–The type of element (carbon, iron, etc. ) is entirely determined by how many protons are in the nucleus.•protons and neutrons are in the nucleus –Protons have a +1 charge–Neutrons have no charge•Electrons circle around the nucleus, in a series of shells.–Electrons have a -1 charge–Chemical bonds are created by movements of the electrons between atoms•The number of protons determines which element the atom is. –Hydrogen: 1 proton, carbon = 6 protons, oxygen = 8 protons.–Biological and chemical processes never change the number of protons in any atom.•Normally, the number of electrons is equal to the number of protons, so the atom has no electrical charge: it is neutral.Chemical Bonds•Atoms can combine with each other to form molecules.•A molecule is a defined number of atoms grouped into a defined spatial relationship. For example, water, H2O, is 2 hydrogen atoms connected to an oxygen atom. The oxygen is in the middle, and the hydrogens are attached at an angle to it. •A large group of the same molecule is called a compound (just as a large group of the same atom is called an element).•Molecules are held together by chemical bonds. Chemical bonds are formed by the movement of electrons.•Chemical bonds are the result of 2 forces:• 1. The octet rule, which means that atoms want to have 8 electrons in their outer shell (2 in the case of hydrogen).• 2. The attraction between atoms of opposite electrical charge.•The three main types of chemical bond are; ionic bond, covalent bond, and hydrogen bond.Ionic Bonds•In an ionic bond, one atom gives an electron to another atom. This makes both atoms ions, and they are held together because their opposite charges attract each other.↑ In sodium chloride (table salt), sodium starts out with 1 electron in its outer shell. The next shell down has 8 electrons, so by giving 1 electron away, the sodium atom gets a full outer shell. It then has a +1 charge.•Chlorine starts out with 7 electrons in its outer shell. By gaining one more electron, it gets 8 in the outer shell, and a -1 charge.↑ The + charged sodium and the – charged chlorine attract each other, and they pack together in salt crystals.Covalent Bonds•Covalent bonds occur when 2 atoms share a pair of electrons. The electrons spend part of their time with both atoms, so the octet rule is satisfied sufficiently.•A molecule of hydrogen gas, H2, has 2 hydrogen atoms. Each atom provides 1 electron, so in the bond each atom shares 2, a complete shell for hydrogen.•The bond is symbolized as a line connecting the 2 H’s: H-H↑ In water (H2O), the oxygen has 6 electrons in its outer shell, and it shares one with each of the 2 hydrogens, giving 8 shared electrons for oxygen and 2 for each hydrogen. •Covalent bonds are the most common type in biological molecules.Polar Covalent Bonds•Sometimes the electrons in a covalent bond aren’t shared equally, because one atom attracts electrons more strongly than the other. When this happens, the electrons spend more time with one atom, and that atom becomes slightly negatively charged. The other atom becomes slightly positively charged. This is a polar covalent bond, because the atoms form positive and negative poles. •Water is a polar compound, because the oxygen is slightly negative and the hydrogens slightly positive. –Oxygen attracts electrons more than hydrogen •Note that the total charge on the molecule is balanced, same number of electrons as protons, but within the molecule the charges are slightly separated. (Bonds where the electrons are shared equally are called non-polar.)•Polar molecules attract each other: the opposite charges attract.Hydrogen Bonds•The slight + and – charges in polar bonds attract each other. In biological molecules, it is common for the partial + charge on a hydrogen to attract the partial – charge on a nearby oxygen or nitrogen. This attraction is called a hydrogen bond. A hydrogen bond is the attraction between a hydrogen atom and the small negative charge on another atom.↑ Hydrogen bonds are very weak compared to covalent bonds, but large numbers of them can add up to a strong bond. The strands of DNA are held together by hydrogen bonds. •Hydrogen bonds also form between different parts of the same molecule, and between water and other