11TH GRADE AP BIOLOGY - Unit 1 ___ Notes

Lesson 1: Structure of Water and Hydrogen Bonding

All life needs water to survive and is made up of water

  • H2O has 2 lone electron pairs on the oxygen

    • O is electronegative - hogs electrons

  • Electrons are always moving so there is no definite structure

  • Connections of H2O’s to other H2O’s is called a hydrogen bond

    • Water Properties: water’s ability to take in heat, water’s ability to regulate temperature (specific heat), why lakes don’t freeze over, properties of evaporative cooling, surface tension, adhesion, and cohesion, and its ability to be a solvent

  • Water is polar

  • Hydrophilic - anything that interacts with water and is dissolved by it

  • Hydrophobic - things that don’t interact and aren’t dissolved by water

In a container, water forms a meniscus

  • Concave - fluid is more attracted to the container 

    • Molecules in glass are polar → water has kinetic nrg → stick/adhesion

    • Cohesion - something sticking to itself – H2O

  • Capillary action - the movement of water within the spaces of a porous material due to the forces of adhesion, cohesion, and surface tension

Hydrogen bonds keep water at a standard temp and pressure

  • Water molecules are cohesive - attracted

    • Surface tension - surface water can become denser and have a stronger IMF than the body and is less attracted to the surrounding air

      • Helps resist rupture when water is under stress or pressure

    • Adhesion - attraction of molecules of one kind for molecules of a different kind

      • Allows water to climb upward through a glass (capillary action)

Water is a solvent; easy for things to be dissolved in water

  • Its polarity makes it able to dissolve lots of molecules (ex. NaCl with H2O)

    • Opposites attract

    • If something is an ion or has polarity it will be easy to dissolve in water

    • Molecules that don’t have charge or aren’t polar will not dissolve in water (ex. hexane)

  • Solute - something that can dissolve

  • Hydrophilic - water-loving

  • Hydrophobic - water-fearing

  • Liquid water ~ hydrogen bonds are constantly breaking and forming

    • Heat of kinetic nrg breaks these bonds

  • Water vapor ~ when heat is raised the kinetic nrg breaks the bonds completely and the gas flows to the atmosphere

  • When temperatures drop or freeze water molecules form a crystal structure - ice; which is less dense than liquid water → water expands

    • Solidification - allows molecules to pack more tightly than in liquid form, giving the solid a greater density than the liquid

      • Occurs when there are drops in temp and kinetic nrg

  • Specific heat capacity - amount of heat needed to raise the temperature of one gram of a substance by one degree Celsius → water needs a lot of heat

    • calorie

    • Can minimize changes in temp

  • Heat of vaporization - amount of energy needed to change one gram of a liquid substance to a gas at constant temperature → water needs a lot of heat → 100 C

  • Evaporative cooling - as water molecules evaporate, the surface they evaporate from gets cooler


Lesson 2: Elements of Life

Different substances have different properties (reflection, certain color, certain temps = certain states, react with each other, etc.)

  • If you break down carbon to its simplest form, what is it? = atom 

  • Pure substances - elements (lead, carbon, gold, etc.)

    • atom - most basic unit of elements

      • All atoms are made up of more particles that if changed, change the whole element

    • have specific chemical and physical properties and cannot be broken down into other substances through ordinary chemical reactions

    • In hair, the width of carbon atoms is approximately 1 million 

  • Protons and neutrons are the nucleus of an atom

    • Proton - defines an element = atomic number

      • Positive charfe

    • Electron - negative charge

      • Can change

      • Buzz around nucleus 

    • Neturton - neutral

      • Can change

    • Protons and electrons attract

      • If lose an electron in atom then the atom will have a positive next charge

  • Humans could be referenced as the byproduct of chemical and electrical interactions between a very, very large number of nonliving atoms

  • Matter - anything that occupies space or mass


  • Carbon is essential for life – carbon-based life

    • Backbone of imp mlc such as proteins, DNA, RNA, sugars, and fats

    • Valence electrons do the reaction and fulfill the octet rule

    • Methane is an organic molecule (macromolecules - contain carbon atoms) or hydrocarbon - og mlc consisting of carbon and hydrogen  → covalent bonding

      • Forms a tetrahedral shape

    • Octane - msr of a fuel's ability to resist combustion

    • Carbon can create lattice structures

  • Functional groups - chemical motifs, or patterns of atoms, that display consistent “function” (properties and reactivity) regardless of the exact molecule they are found in

    • Hydroxyl (polar)  group combined with carboxyl group = alcohol



  • Hydroxyl can be dissolved into water through H-bonding

  • Sulfydral group - still polar but not as polar

  • R is abbreviation for “rest of molecule” - mainly carbon backbone

  • Carbonyl group is also polar

  • Carboxyl groups donate hydrogens so are viewed as acidic

  • Elements building blocks

    • Amino acids - building blocks of proteins

      • Made of C, H, O, N, sometimes P

    • ATP - a molecule that stores and releases energy in cells, making it essential for life

    • Triglyceride - fat molecule used for nrg storage

    • Backbone of DNA → 5-C sugars and phosphate groups

Lesson 3: Introduction to biological macromolecules

  • Bonding of atoms

    • Bonding is important as atoms want to become stable to support life

    • Ionic bonding - attraction of 2 oppositely charged ions

      • Cations - positbley charged elctrons after losing an electron

      • Anions - negatively charged electrons after gaining an electron

      • Electron transfer - one atoms loses and electron and one atoms gains one

  • Covalent bonding - sharing of electrons between 2 atoms

    • In the case of water – oxygen is more electrongetive which causes electrons to want to be with oxygen

      • Polar covalent bond - atoms with different electrongeatives share electrons 

      • Nonpolar covalent bond - 2 atoms of the same of different element that share electrons almost equally 

    • Key to the carbon-based molecules such as DNA and proteins

  • Hydrogen bonds - a weak bond between 2 molecules resulting from an electrostatic attraction between a proton in 1 molecule and an electronegative atom in the other

  • Lond Dispersion Force - weak attraction between mlc and atoms that depend on temporary imbalances in electron distribution 

  • Van der Waals force -  intermolecular interactions that do not involve covalent bonds or ions

    • LDF and H-bonds follow this

  • Strong covalent bonds hold chemical building blocks to make strand of DNA

    • Weak covalent bonds hold together the 2 strands of DNA → keep stable

  • Macromolecules – 4 groups

    • Carbohydrates (sugars), lipids (fats), proteins, and nucleic acid (DNA and RNA)

      • Carbohydrates - large nrg storage

      • Lipids - some key structural components of cell membrane

      • Proteins - structural support and catalyzing metabolic reactions or receiving and transmitting signals

      • Nuclec acid - store and transfer genetic info

    • Polymer - long chain of monomers (subunit of polymers)

    • Dehydration synthesis - 2 monomers form a covalent bond realsing a water mlc in the process

  • All macromolecules can contain multiple different monomers that create a specific sequence 

  • Hydrolisis rxn - bond is broken with the addition of a water molecule

  • Enzyme catalyze speed up dehydration synthesis and hydrolysis rxn