[BIOL 110] - Midterm Exam Guide - Everything you need to know! (32 pages long)

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6 Feb 2017
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BIOL 110
MIDTERM EXAM
STUDY GUIDE
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01-11-2017 BIOL 110
Lecture 2: Water and Biological Macromolecules
I. Buildig lok oleules
a. Responsible for all living organisms
b. Carbon, Hydrogen, Oxygen, Nitrogen, Phosphorus (N-CHOP)
i. Nucleic acids (DNA, RNA, etc.)
ii. Macronutrients (proteins, carbohydrates, lipids)
1. Amino acids/triglycerides
c. Valence electrons
i. Electrons in the outermost shell are valence electrons determine atomic
behavior
1. Lose/gain 1/2 electrons
2. Form atomic bonds
ii. Electron shells want to be full of valence electrons (usually 8)
iii. Valence electrons and ions
1. Atoms will gain or lose electrons to obtain a full shell
2. By this process these atoms become ions
3. EX: Na only has one outer shell electron; readily loses it and becomes
Na+
4. EX: Cl has seven outer shell electrons; readily gains another and
becomes Cl-
d. Atomic bonds
i. Ionic bonds: unequal sharing of electrons
1. Held together by positive and negative charges
ii. Covalent bonds: equal sharing of electrons
1. Multiple covalent bonds: atoms can share multiple electron pairs
(double, triple and even quadruple covalent bonds are possible)
2. Covalent bonds may be depicted by solid lines between the atomic
abbreviations of each molecule (ex: the double bond in O2 can be
depicted as O=O)
3. Polar covalent bonds
a. Electrons can be shared unequally due to differences in internal
charges electronegativity
b. Electronegativity tends to increase going upwards and
rightwards across the periodic table
iii. The molecular charges of ions are written in superscript (Fe3+); number of atoms are
written in subscript (H2O).
II. Water
a. Oxygen
i. Incredibly electronegative
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1. Responsible for the dipole in water
ii. Electrons shared unequally between oxygen and hydrogens
1. Electrons pulled to the oxygen resulting in negative pole
2. Hydrogens become positive poles
b. Polarity
i. Water is easily able to dissolve polar/ionic molecules because of its polarity
ii. This polarity is also responsible for the surface tension of water
1. Surface tension is caused by hydrogen bonding between water
molecules
c. Hydrogen bonding
i. Attraction between the positive poles of hydrogen molecules and negative poles
of other molecules (oxygen in water)
ii. Responsible for cohesive (water attracts water) and adhesive (water attracts
other polar molecules) properties of water
1. Surface tension occurs because of the cohesive properties of water
d. Interactions of water molecules
i. Photosynthesis
1. Ours in the plant’s leaes
2. The ater is soured y the plant’s roots
3. Water molecules travel from the soil to the leaves by the processes of
adhesion and cohesion
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