LIFE102 Week 2 Notes
LIFE102 Week 2 Notes Life 102
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This 8 page Class Notes was uploaded by Sydney Dingman on Sunday January 31, 2016. The Class Notes belongs to Life 102 at Colorado State University taught by Erik N Arthun in Winter 2016. Since its upload, it has received 25 views. For similar materials see Attributes of Living Systems in Biology at Colorado State University.
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Date Created: 01/31/16
Week 2 Life 102 Notes 1/25/16, Chapter 3: Properties of Water Water is essential for all life on Earth Organisms are 70-95% water What is special about water? o Cohesive (sticky) o Moderates temperature o Expands upon freezing o Excellent solvent All of these are due to the fact that water is polar Cohesiveness of water o Polar covalent bonds within water molecules (Partial negative on oxygen molecules and partial positive on hydrogen) o Hydrogen bonds between water molecules o Sticking of water allows for it to be transported into the photosynthesis process and nutrients go with it o Also means that water has a high surface tension: measure of how hard it is to stretch/break the surface of a liquid Water moderates changes in temperature o Water has an unusually high specific hear: amount of energy required to change 1 gram of water by 1 degree Celsius o Water changes its temperature less than other liquids when it absorbs the same amount of energy o Water heats up: hydrogen bonds are broken, heat is absorbed o Water cools down: hydrogen bonds form, heat is released o Because of the hydrogen bonds: water has a high heat of vaporization: it takes a lot of energy to vaporize water o As liquid evaporates, its remaining surface cools= evaporative cooling o Evaporative cooling of water helps stabilize temperatures in organisms and bodies of water. Water is most-dense at 4 degrees Celsius, not 0 o Frozen water floats When water reaches freezing, it expands by pushing against the hydrogen bonds. The molecules are then so far apart that the hydrogen bonds don’t break. o If ice sank, all bodies of water would eventually freeze solid, making life impossible on Earth Water is a Polar Solvent o Hydrophilic substances: High affinity for water Ions Polar Molecules o Hydrophobic substances: Low affinity for water Non-polar molecules Non-ionic elements o Compounds dissolve in water to form a solution Most biological reactions occur in water o Important properties to know about solutions Solute concentrations Rates of biological reactions depend on the concentration of reactants High concentrations of certain compounds can influence other chemical reactions pH A hydrogen atom in a hydrogen bond between two water molecules can shift from one to the other o The hydrogen atom leaves its electron behind is transferred as a proton, or hydrogen ion (H+) o The molecule with the extra proton is now a hydronium ion (H30+), though it is often represented at H+ o The molecule that lost the proton is now a hydroxide ion (OH-) Pure water: H+ and OH- concentrations are equal The dissociation of water molecules produces H2O 2 pH: a measure of the concentration of H+ ions in a solution The greater the H+, the more acidic the solution SHORTCUT: what is the power of hydrogen? See PowerPoint for example pH < 7 = acidic pH = 7 = neutral pH > 7 = basic Acids and bases have huge impact on how we function o Acid: any substance that increases the H+ of a solution o Base: any substance that reduces the H+ of a solution o EX: NH3 + H+ = NH4 Controlling pH is important for cells o Biological reactions have optimal pH o Buffer: Substances that minimizes changes in H+ and OH- in a solution o Solvent: the dissolving agent of a solution o Solute: the substance that is dissolved o Concentration: how much solute is present per volume of solvent in moles 1/27/16, Chapter 4: Organic Molecules: Carbon-based molecules The dry matter of organisms consist mainly of organic molecules (e.g., proteins, DNA, fats, sugars, acids etc.) Advantage of Carbon as Building Block for Life o Carbon is tetravalent Needs 4 electrons to fill valence shell Capable of making 4 chemical bonds 3 Large complex, and diverse molecules When two carbons are bonded together, the molecule will be flat and inflexible. Shape equals function Carbon compounds vary in their: o Carbon Skeleton: how individual Carbons are joined o Side Groups: Accessories to the Carbon Skeleton Carbon Skeletons o Length Ethane is short, 2 carbons Propane is longer with 3 carbons. o Branching Butane are in an exact line Isobutane has a branched point that changes the shape of the molecule Isomer: same atomic compositions but different structures and properties. o Double bonded position Vary in location 1-Butene: double-bonded at the first gap of 4 carbons 2-Butene: double-bonded at the middle gap between 4 carbons o Presence of rings Structural formulas omit the carbons and attached hydrogens Isomers o Structural Isomers: same atomic composition, but different carbon skeleton structures o Cis-trans Isomers: differing arrangement of side groups around a double bond o Enantiomers: orientation of side groups around a Carbon atom can affect molecular function; mirror-images, like left and right hands 4 Ibuprofen: S-Ibuprofen works 100x better than R-Ibuprofen Albuterol: R-Albuterol is counteracted by S-Albuterol Parkinsons: L-dopa works, D-dopa does not do anything Side Groups o Hydroxyl groups (polar) Composed of hydrogen and oxygen (OH) Called an alcohol Creates a polar covalent charge with carbon where carbon his partial positive o Carbonyl Groups (polar) Carbon and oxygen with double-bond Oxygen receives a partial negative charge o Carboxyl groups (acid) Carbon double bonded to oxygen with an OH group as well The hydrogen can be released and measured by pH in a liquid o Amino groups (base) Nitrogen with two hydrogens Nitrogen will take hydrogens out of the solution Glycine is a building block for proteins o Sulfhydryl groups (bind other sulfhydryl groups) Sulfur and hydrogen bonded to some other atom or molecule One of most important for folding molecules or atoms o Phosphate groups (polar, reactive) Phosphorus bonded to 4 oxygen atoms ATPs are the primary energy-transferring molecule in the cell Consist of an organic molecule called adenosine attached to a string of three phosphate groups Creates energy because of pushing against each other 5 o Methyl groups (non-polar) Carbon with 3 hydrogen atoms Can change the expression of your genes Arrangement of methyl groups can have a huge impact on how they function 1/29/16, Chapter 5: Large Biological Molecules Macromolecules o Nucleic acids o Proteins o Polysaccharides o Lipids o The architecture of large biological molecules helps explain how that molecule works Most macromolecules are polymers o Polymers are strings of monomers o Repeating building blocks linked by covalent bonds (bonds in which electrons are shared) How are polymers created and disassembled? o Dehyration Reaction: synthesis Dehydration removes a water molecule which will form a new bond o Hydrolysis: disassembly Hydrolysis adds a water molecule, breaking a bond Polysaccharides: many sugars put together o Carbohydrates: sugars and their polymers, serve as fuel and building material o Polymers of monosaccharides o Glucose o Monosaccharides differ in a number of different ways Placement of carbonyl groups Aldoses- carbonyl group located at the end 6 Ketoses- carbonyl group located at the second carbon Most 5-carbon and 6-carbon sugars form ring structures o Disaccharides: 2 monomers Maltose connected by dehydration reaction Sucrose o Starch: polymer of alpha glucose, stored in plant energy o Cellulose: polymer of beta glucose, structure for plants o Functions of polysaccharides Energy storage Starch- plants Glycogen- animals Support Cellulose- plants Chitin- animals, insects, crustaceans Lipids o Not polymers, not at big, hydrophobic o Fats Triglygerides Glycerol + 3 fatty acids Dehydration Synthesis reactions attach the 3 fatty acids to the glycerol Fats are hydrophobic due to the nonpolar C-H bonds in the hydrocarbon chains of fatty acids Saturated Fats Animal fats o Lard, butter Solid at room temperature NO double bonds Saturated with hydrogens Unsaturated Fats Liquid at room temperature 7 Double-bonds add kinks Can’t pack together closely enough to solidify o Phospholipids Structure: hydrophilic head + 2 hydrophobic tails Negatively charged. Amphopathic: water loving and fearing Phospholipid bilayer Heads arrange themselves out, tails go in o Steroids Cholesterol and cholesterol-derived molecules Cholesterol- keeps cell membrane “fluid” Steroids-derived from cholesterol Vertebrate sex hormones: testosterone and estradiol Proteins o Structure: polymers of amino acids with R side group o Most structurally sophisticated molecules known o 20 different amino acids in proteins o depending on the side group, amino acids can be polar or nonpolar uncharged or charged acidic or basic o 8