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CSU / Biology / BC 102 / What makes water an excellent solvent?

What makes water an excellent solvent?

What makes water an excellent solvent?


School: Colorado State University
Department: Biology
Course: Attributes of Living Systems
Professor: Erik arthun
Term: Winter 2016
Tags: Biology and Life 102
Cost: 25
Name: LIFE102 Week 2 Notes
Description: Covers the second week of lecture
Uploaded: 01/31/2016
8 Pages 49 Views 1 Unlocks

Week 2 Life 102 Notes

What makes water an excellent solvent?

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

What happens to hydrogen when water heats up?

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

How do acids and bases affect how we function?

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 We also discuss several other topics like How did islam spread in the arabian peninsula?

o Frozen water floats

 When water reaches freezing, it expands by pushing  Don't forget about the age old question of What are the various forms or types of grants?

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 If you want to learn more check out How do the outermost electrons determine how atoms interact?

∙ High concentrations of certain compounds can  

influence other chemical reactions

 pH If you want to learn more check out How much light bends when it hit a different substance depends on the refractive indices of the media forming the interface?

∙ 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


∙ pH: a measure of the concentration of H+ ions in a  


∙ 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 Don't forget about the age old question of What determines if an individual will be male or female and is located on the y chromosome

∙ pH > 7 = basic

∙ Acids and bases have huge impact on how we  


o Acid: any substance that increases the H+ of a


o Base: any substance that reduces the H+ of a  


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 If you want to learn more check out What is the debate of nature vs nurture?

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 


 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  


∙ 2-Butene: double-bonded at the middle gap between  

4 carbons

o Presence of rings

 Structural formulas omit the carbons and attached  


∙ 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


 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  


 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  



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


 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


∙ 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



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