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AP Bio Unit 1 Cheat Sheet by

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Macrom­ole­cules Structure


monomer: monosa­cch­arides (linked together into polysa­cch­arides by dehydr­ation synthesis)
functions: energy storage (ex: starch in plants and glycogen in animals) and structural support (ex: cellulose for plan cell walls and chitin for exoske­leton of arthropods and cell walls of fungi)
have a ratio of CH2O (1 carbon: 2 Hydrogen: 1 Oxygen)


Monomer: amino acids (which are linked by peptide bonds, which are formed by dehydr­ation synthesis between amino and carboxyl groups of adjacent amino acids)
functions: antibo­dies, movement, membrane receptors
Primary Structure- unique sequence of amino acids
Secondary Structure- folding of the amino acid chain through hydrogen bonds into alpha ­helices and beta s­heets
Tertiary Structure- overall three-­­di­m­e­ns­­ional shape of the protein and often minimizes free energy (hydro­­phobic intera­­ct­ions, disulfide bridges, H-bonds, ionic bonds)
Quaternary Structure- arrang­­ement of polype­­ptides (only occurs in some) ex: hemoglobin
Denatu­ration: unfolding of protein structure due to unideal temper­ature or pH levels


Monomer: N/A because lipids aren't polymers since they are assembled from a variety of components (ex: fats, oils, waxes, & steroids) ALL HYDROP­HOBIC
Function: energy storage, protec­tion, insula­tion, phosph­olipid bilayer
Fats (aka trigly­cer­ides): made of a glycerol molecule and 3 fatty acid molecules (fatty acids: nonpolar hydroc­arbon chains)
Saturated Fatty Acids: no double bonds between carbons, pack solidly at room temp, max number of hydrogens, commonly produced by animals)
Unsatu­rated Fatty Acids: have some carbon double bonds which result in kinks, liquid at room temp, commonly produced by plants)
Phosph­olipids have a hydrop­hilic (polar) head that includes a phosphate group and 2 hydrop­hobic fatty acid tails
Steroids have a carbon skeleton of 4 rings that are fused together (ex: choles­terol in animal cell membranes, and estrogen and testos­terone)

Saturated vs. Unsatu­rated Fatty Acids

Nucleic Acids

Monomer: nucleo­tides
Function: genetic info that codes for amino acid sequences
Nucleo­tides are made of 3 parts: nitrog­enous base, pentose (5-carbon) sugar (deoxy­ribose in DNA and ribose in RNA), and the phosphate group (PO4)

Chemical Reactions

Covalent Bonds
Nonpolar covalent bonds: electrons are shared equally
polar covalent bonds: one atom has a greater electr­one­gat­ivity --> unequal sharing of electrons
Ionic Bonds
chemical bonds formed by the attraction of oppositely charged ions
ex: table salt
Hydrogen Bonds
weak chemical intera­ctions that form between a partial positively charged hydrogen atom of one molecule and the strong electr­one­gative oxygen or nitrogen of another molecule
ex: hydrogen bonds between water
Van der Waals intera­ctions
very weak, short-­lasting connec­tions that are a result of asymme­trical distri­bution of electrons within a molecule
contribute to the 3d shape of molecules

Acids and Bases

pH scale: Measures relative acidity and alkalinity of aqueous solutions (between 0 and 14)
Acids: excess of H+ ions and H+>OH-
Bases: excess of OH- ions and OH->H+
Pure water is neutral (pH=7)
Buffers: substances that minimize changes in pH by accepting H+ from a solution when hydrogen molecules are in excess and donate H+ when hydrogen molecules are depleted
Buffers are essential in living tissues to minimize pH changes
Carbonic Acid (H2CO3): important buffer in living systems because it moderates pH changes in blood plasma and the ocean


Major elements of life are carbon, hydrogen, oxygen, nitrogen, sulfur, and phosphorus CHNOPS
All organic compounds contain carbon and most contain hydrogen
Carbon is unpara­lleled in its ability to form large, complex, and diverse molecules because it has 4 valence electrons, which means it can form up to 4 covalent bonds (which can be single, double, or triple), and it can form large molecules (which can be chains, ring-s­haped, or branched)
Isomers: molecules that have the same molecular formula but differ in atom arrang­ement, which can result in molecules that are very different in their biological activities (ex: glucose and fructose)

Dehydr­ation Synthesis

Hydrolysis Reaction

Functional Groups


Properties of Water

Water molecules are polar
oxygen region of molecule has a partial negative charge and each hydrogen region has a partial positive positive charge
Hydrogen bonds form between water molecules
the slightly negative oxygen atom from one water molecule is attracted to the slightly positive hydrogen end of another molecule
Each water molecule can form up to 4 hydrogen bonds
Hydrogen Bonds are key to each of the following properties of water and what makes water unique
Cohesion: Linking of like molecules
Adhesion: clinging of one substance to another
Capillary Action: movement of water molecules up very thin xylem tubes and their evapor­ation from stomata in plants; the water molecules cling to each other by cohesion and to the walls of the xylem tube by adhesion
Cohesion is respon­sible for surface tension, which means that water droplets will resist rupture when stress and pressure are added to the system
Water has a high specific heat. Specific Heat is the amount of heat required to raise or lower the temper­ature of a substance by 1 degree Celsius. High specific heat makes the temper­ature of Earth's oceans relatively stable and able to support vast quantities of life
Water is less dense as a solid than as a liquid, so ice floats, which keeps larger bodies of water from freezing solid, allowing life to exist in bodies of water
Water is an important solvent (hydrop­hilic substances are water soluble and hydrop­hobic substances are nonpolar and don't dissolve in water).


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