Chapter 2: The Chemical Basis of Life
Chapter 2: The Chemical Basis of Life BIOL 1030-003
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This 5 page Class Notes was uploaded by Alexa Rosenfeld on Thursday August 27, 2015. The Class Notes belongs to BIOL 1030-003 at Clemson University taught by Kristi J. Whitehead in Fall 2015. Since its upload, it has received 264 views. For similar materials see General Biology I in Biology at Clemson University.
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Date Created: 08/27/15
8242015 Dr Whitehead CHAPTER 2 The Chemical Basis of Life SECTIONS 21216 SECTIONS 2124 Elements Atoms and Compounds Single most toxic compound is naturalBOTOX 0 1g in food kills 14000 people 0 1g inhaled kills 123 million people 0 1g injected kills 83 million people Matter 0 Everything in the world is made of matter 0 Takes up space 0 Has mass 0 There are 3 states of matter 0 Solid 0 Liquid 0 Gas 0 Matter is made up of elements 0 Elements cannot be broken down at least in normal ways 0 Periodic table 0 Human elements 0 Carbon Hydrogen Oxygen and Nitrogen BIOL 1030 I Trace elementssmall amount of What is in the human body but is completely essential to live 0 Salt iron I Compounds 0 More than one elements in a fixed ration H 2 0 0 Emergent properties I Hydrogen Oxygen Water I Atoms 0 Made up of subatomic particles I Protons charge I Neutrons neutral charge I Electrons charge 0 Structure I Protons and neutrons in the center I nucleus I Electrons on the outside 0 Electron cloud 8242015 Dr Whitehead BIOL 1030 0 Size of an atom I Yankee Stadiumatom nucleuspea electrons2 gnats Atomic Number number of protons Mass Number number of protons and neutrons 0 Atomic Mass approximately equal to the mass number daltons I Don t count the weight of the electrons I Electron 12000 dalton OO 0 Isotopes 0 Same atomic number I Same amount of protons 0 Differ in the mass number I Number of neutrons are different 0 There is a stability or lack of stability to the nucleus depending on the amount of neutrons Extra neutrons make the nucleus unstable making it randomly release energy and decay breaking chemical bonds causing mutations and other issues SECTIONS 2529Chemical Bonds Chemical Properties of Atoms I Number of electrons is the bonds that really matter and are the only ones that impact the chemical properties 0 Electron shells 0 Where the electrons are located 0 Energy levels surrounding the nucleus 0 Outermostvalence shell I Chemical properties are found here 0 Orbitals are found within each electron shell I Space where the electron spends a lot of time I Different electron shells have different amounts of orbitals I A single orbital cannot have more than a pair of electrons but it can have less I You have to have an electron in each orbital before you can start pairing in orbitals electron distribution 0 With bonds we are looking for how bonds are in the valence shell and if they are paired or unpaired with another electron O Neonunreactive Chemical Bonds 0 Intramolecular within 0 Covalent O Ionic 0 Intermolecular between 0 Hydrogen 8242015 Dr Whitehead BIOL 1030 O Bonds between the molecules 0 Covalent bonds 0 Strongest 0 Two atoms SHARE outer shell electrons 0 When two or more atoms are held together by covalent bonds molecules are formed Sharing is not always equally shared 0 When two atoms are unlike each other they won t pull on the electrons equally electron negativity I More electronegativestronger pull I Not evenly distributed between atoms 0 If the molecule has atoms being shared fairly equally it is a nonpolar covalent bond I Equal distribution 0 If the molecule has atoms not being shared equally it is a polar covalent bond I Not evenly distributed 0 Water I Electrons then spend more time towards the atom with the stronger pull creating opposite charges 0 0 Ionic Bonds 0 Too drastic of a pull electro negativity between the electrons 0 Electron moving from one atom to another weak strong 0 Because one has gained and one has lost an ion is created I IONS O Opposite atoms attract pulling each other together 0 Hydrogen Bonds 0 Protein structures Intramolecular amp mostly Intermolecular bonds Weaker bonds Very important bonds The hydrogen bond forms where the positive and negative part of the molecule is I Positivehydrogen O O O 0 Chemical Reactions 0 A chemical reaction is the breaking and forming of chemical bonds 0 A chemical reaction causes a change in the composition of matter and how it is formed 0 We cannot create or destroy matter we just move things around when chemical reactions are happening 0 2 H2 oz2 H20 HH OO HOH HOH HH 8242015 Dr Whitehead BIOL 1030 0 Not gaining or losing anything just rearranging them SECTIONS 210216 Water s LifeSupporting Properties 0 Water is everywhere 0 All living organisms require water Cohesion O Likelihood that like molecules would stick to each other 0 Water has higher cohesion than other molecules due to surface tension Adhesion 0 Different molecules stick together 0 Adhesion and cohesion can work together 0 Heatenergy Speedintensity Temp increase higher speed Temp decreaselower speed Has to do with how many hydrogen bonds are formed and broken Heat being absorbedEIincreased breakage of hydrogen bondsincreased temp Decreased tempheat releasedl increasing formation of hydrogen bondsEIdecreased speed 0 Evaporation coolingljmost quickly moving water molecules are released making the average speed slower O Humidityl harder for body to cool itself as the molecules don t release OOOOOO Density 0 Water as a solid is less dense than as a liquid 0 Hydrogen bonds 0 Freezing has stable hydrogen bonds 0 Less molecules in ice because they are structured and stabled 0 Liquid has more molecules that are compact making it more dense 0 Ice protects living organisms in the water in the winter as it oats on top and acts and a barrier Solvent 0 Solution liquid that consists of a mixture of at least two substances 0 Solvent does the dissolving 0 Solute what is being dissolved O Aqueoussolution where water is the solvent 8242015 Dr Whitehead BIOL 1030 Water is a versatile solvent because they are polar because they are attracted to the opposite charges Life is sensitive to pH With blood All living organisms have to have tight control over internal pH Few water molecules separate from each other during the breaking and forming leaving ions hydroxide and oxide HOH 0 Both are very reactive making balance important Acid increases concentration of hydrogen ions Base lowers concentration of hydrogen ions in a solution 0 Dissociating O Combining 0 Hydrogen ions then get pulled out Buffer maintains pH keeps it stable and can do either What a base or acid does pH loglo H pH01Mole H larger concentration 14 pH14 1quot 10 Moles H smaller concentration A pH of 2 is 100 X more than a pH of 4 Most cells have a fairly neutral internal pH 0 Relative to the external environment even if the environment is acidic the organism remains neutral normally due to buffers Small variations can cause extreme problems Most biological uids contain buffers to fix any problems With the hydrogen ions 0 Too many hydrogen ionsaccept out of solution 0 Not enough hydrogen ions donate into solution Acidification of water is extremely dangerous because living organisms must stay neutral and live off of water so if the water contains a change in pH it can be very difficult to handle Water is What is looked for When looking for extraterrestrial life since all living things need water to live
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