AP Biology - Unit 1

Chemistry Foundations:

Atomic Mass = Protons (= Electrons) + Neutrons

Most Important Biological Elements: %%Oxygen%%, %%Carbon%%, %%Hydrogen%%, %%Nitrogen%% (Calcium, %%Phosphorus%%, ==Potassium==, %%Sulfur%%, ^^Iron^^, %%Iodine%%, etc.)

Valence Electrons (Outer Shell) are the most important in determining properties

Covalent Bond - when electrons are shared between elements

• Polar - electrons aren’t shared equally
• Non-polar - electrons are shared equally

Ionic Bond - when electrons are transferred between elements

Bond Strengths - single (-), double (=), triple (≡), etc.

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Isomers are molecules with the same formula but different shapes/properties:

• structural - different covalent arrangements
• cis-trans - different arrangement around a double bond
• enantiomers - mirrored

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Water:

Cohesion - the molecules of water are attracted to one another because of the hydrogen bonds (due to polarity)

Adhesion - the molecules of water are attracted to other molecules because of the hydrogen bonds

Surface Tension - the cohesive properties of water are strong at the surface

High Specific Heat - since water is heat resistant, the amount of energy required to increase the heat is greater than most substances

High Heat of Vaporization - since water is heat resistant, the amount of energy required to vaporize it is high

Ice - when water freezes, the molecules spread further apart, which makes ice less dense than water

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Compounds that are hydrophilic are attracted to water molecules, and compounds that are hydrophobic repel from water molecules

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Acidity - sometimes, water molecules disconnect into H+ and OH-, more H+ makes water more acidic, more OH- makes water more basic, and if they are equal water is neutral

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Biomolecules:

Functional Groups (common groups found in biomolecules) -

Carbohydrates -

• Monomer: Monosaccharides
• Polymer: Polysaccharides
• Bond: Glycosidic (dehydration (condensation) reaction and hydrolysis)
• Structure: made of carbon chains and rings, contains carbon, oxygen, and hydrogen
• Properties: combustible
• Usage: energy use and storage (starch and glycogen)

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Lipids -

• Monomer: Glycerol, Fatty Acids
• Polymer: Lipids
• Bond: Ester
• Structure: Fats (Glycerol + 3 Fatty Acids), Phospholipids (Glycerol + 2 Fatty Acids), Steroids (4 Carbon Rings), Wax (Fatty Acid Chain + Alcohol Chain)
• Properties: bilayers
• Use: energy storage

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Nucleic Acids -

• Monomer: Nucleotides (Pentose Sugar, Phosphate Group (nucleoside), Nitrogenous Base)
• Polymer: Deoxyribonucleic Acid (DNA) or Ribonucleic Acid (RNA), also called Polynucleotides
• Bond: Phosphodiester (between sugar and phosphate group), Hydrogen (between nitrogenous bases)
• Structure: DNA - sugar (deoxyribose) attaches to phosphate group, and two chains connect in a double helix antiparallel shape with base pairs connecting (A-T, C-G); RNA - sugar (ribose) attaches to phosphate group to create a chain, and sometimes base pairs connect (A-U, C-G)
• Properties: N/A
• Use: stores and express genomic information to create proteins

Example: Adenosine triphosphate (ATP) stores energy and splits to release it

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Proteins -

• Monomer: Amino Acids
• Polymer: Proteins, Polypeptides
• Bond: Peptide
• Structure: Primary (chain of amino acids), Secondary (α helix, β-pleated sheets; interactions between amino and carboxyl groups), Tertiary (Hydrogen Bonds, Ionic Bonds, Disulfide Bridges, Hydrophobic Interactions, etc.; interactions between R-groups), Quaternary (interactions between multiple polypeptides)
• Properties: changes between proteins
• Use: many different uses (enzymes speed up and are required for some biological chemical reactions)
• Other Notes: Proteins require very specific chemical conditions to form properly, and when this strays and the shape is altered, it is called denaturation

Review Resources:

• https://www.youtube.com/watch?v=nlnsJ5kgXqs&list=PLCEja84uspXsN8Cxx-p-RK6pMpwghiJ4d
• https://apclassroom.collegeboard.org/6/home?unit=1
• https://docs.google.com/forms/d/1V7wWAJlnUpDfjoL10G0ZZMWHmp3OfNLdbeJpGjDFcTg/prefill

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