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CSU / Life Science / LIFE 102 / What makes water an excellent solvent?

What makes water an excellent solvent?

What makes water an excellent solvent?


School: Colorado State University
Department: Life Science
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 146 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 Don't forget about the age old question of What does "jihad" translate to in english?

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?

Don't forget about the age old question of What is the focus of regulations administered by a government agency?

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 If you want to learn more check out Which cell type protects the body from infections?

∙ 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  Don't forget about the age old question of How much light bends when it hit a different substance depends on the refractive indices of the media forming the interface?

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

∙ pH > 7 = basic

∙ Acids and bases have huge impact on how we  

function Don't forget about the age old question of How androgen-insensitivity syndrome happens?

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 Don't forget about the age old question of What is the debate of nature vs nurture?

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 


 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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