AP Biology- Biochemistry 1
Mrs. Stahl
A Chemical Connection to Biology
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 Example- Some ant species use formic acid to protect themselves against
predators and microbial parasites.
o “When a crazy ant is smeared with the venom in a fight with a fire ant, it secretes formic
acid from its abdominal glands, transfers it to its mouth and then spreads it on its body - a practice that makes crazy ants almost invincible in combat with fire ants over
resources such as food and nesting sites. In lab experiments, the crazy ants that were
allowed to detoxify themselves had a 98 percent survival rate, according to the study,
published in the journal Science Express.” http://www.ibtimes.com/crazy-ants-useformic-acid-wash-fire-ant-venom-becoming-dominant-invasive-species-us-southeast
The Nature of Atoms
 Matter- ______________________________________________________
 Atom-________________________________________________________
 1913- Niels Bohr and The Atomic Theory
o Protons-__________________________
o Neutrons-__________________________
o Electrons-__________________________
o Nucleus-_________________________________________________
o Electron Cloud-___________________________________________
AP Biology- Biochemistry 2
Mrs. Stahl
Elements and Compounds
 Matter is made up of elements.
 Element:
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 Compound:____________________________________________________
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The Elements of Life
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 Trace Elements:
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An element’s properties depend on the structure of its atoms
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Subatomic Particles
 _____________________________________________________________
 Relevant subatomic particles include:
o Neutrons- no electrical charge
o Protons- positive charge
o Electrons- negative charge
 Neutrons and protons for the _______________________________
AP Biology- Biochemistry 3
Mrs. Stahl
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Label according to the picture.
Atomic Number and Atomic Mass
 Atoms of the various elements differ in number of subatomic particles.
 _____________________________________________________________
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AP Biology- Biochemistry 4
Mrs. Stahl
Isotopes
 All atoms of an element have the same number of protons but may differ in
number of neutrons.
 Isotopes_____________________________________________________________
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 Radioactive isotopes_____________________________________________________________
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Radioactive Tracers
• Radioactive isotopes are often used as diagnostic tools in medicine
• Radioactive tracers can be used to track atoms through metabolism
• They can also be used in combination with sophisticated imaging
instruments
Radiometric Dating
 _____________________________________________________________
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 In radiometric dating, scientists measure the ratio of different isotopes and
calculate how many half-lives have passed since the fossil or rock was
formed.
 _____________________________________________________________
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o Example- Carbon dating of fossils
 ___________________________________________________
 ___________________________________________________
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 ___________________________________________________
 ___________________________________________________
 Allows scientists to pinpoint when materials formed.
AP Biology- Biochemistry 5
Mrs. Stahl
The Energy Levels of Electrons
 Energy_____________________________________________________________
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 Potential Energy_____________________________________________________________
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o Example- grapefruit:
 If you hold a grapefruit in your hand, above the ground= posses
potential energy.
 If you drop the grapefruit and it falls, PE decreases.
 Carry it to the top of a building, PE increases.
 _____________________________________________________________
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 _____________________________________________________________
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 Each level corresponds with a specific amount of energy
 Every atom has a ladder of potential energy values
 _____________________________________________________________
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AP Biology- Biochemistry 6
Mrs. Stahl
Fill it in
according to
the diagram
on the slide.
Electron Distribution and Chemical Properties
 _____________________________________________________________
_____________________________________________________________
 We cannot pinpoint the location of any given electron at any time. Electron
could be anywhere.
AP Biology- Biochemistry 7
Mrs. Stahl
 Orbital_____________________________________________________________
_____________________________________________________________
 The periodic table of the elements shows the electron distribution for each
element.
 Oxidation_____________________________________________________________
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 Reduction-____________________________________________________
 Valence Electrons_____________________________________________________________
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 _____________________________________________________________
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How does oxidation / reduction help organisms?
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Chemical Bonds
 Molecule_____________________________________________________________
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 Compound- molecule of more than one element.
AP Biology- Biochemistry 8
Mrs. Stahl
 Chemical bonds_____________________________________________________________
_____________________________________________________________
Bonds and Interactions
Name
Covalent Bond
Basis of Interactions
Strength
Strongest Bond
Ionic Bond
Hydrogen Bond
Hydrophobic
Interaction
Van der Waals forces
Weakest
AP Biology- Biochemistry 9
Mrs. Stahl
The Molecule that Supports all of Life
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 The structure of the water molecule allows it to interact with other molecules
and this was true in the beginning when other molecules would around and
interact.
 Water’s unique emergent properties help make Earth suitable for life.
 Life began in the water for two billion years before moving onto land.
 _____________________________________________________________
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What is the difference between a tropical rainforest biome and a desert
biome?
 _____________________________________________________________
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Polar covalent bonds in water molecules result in hydrogen bonding
 In the water molecule, the electrons of the polar covalent bonds spend more
time near the oxygen than the hydrogen.
AP Biology- Biochemistry 10
Mrs. Stahl
 _____________________________________________________________
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Draw and Label the diagram of the water molecule:
AP Biology- Biochemistry 11
Mrs. Stahl
Hydrogen Bonds:
 _____________________________________________________________
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Water is the Universal Solvent:
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 Aqueous Solution: one in which water is the solvent.
 Example: Kool-aid, sugar, and water
o Solvent= water
o Solutes= sugar and Kool-aid
o Solution= all mixed together and the distribution is even
throughout
Other terms to know:
Hydrophilic:_______________________________________________________
__________________________________________________________________
Example: ____________________________________________________
AP Biology- Biochemistry 12
Mrs. Stahl
Hydrophobic:
__________________________________________________________________
__________________________________________________________________
Example:_____________________________________________________
Hydrophobic Exclusion:
 _____________________________________________________________
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_____________________________________________________________
_____________________________________________________________
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 This can affect the structure of proteins, DNA, and biological
membranes.
 Critical to living systems
Amphipathic
 _____________________________________________________________
_____________________________________________________________
 _____________________________________________________________
Properties of Water
• Cohesion and Surface Tension
• Adhesion and Capillary Action
• High Specific Heat
• High Heat of Vaporization
• Low Density of Ice
AP Biology- Biochemistry 13
Mrs. Stahl
Cohesion:
 _____________________________________________________________
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 _____________________________________________________________
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 Surface Tension:
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 _____________________________________________________________
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Adhesion:
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o Example:
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o Example:
________________________________________________________
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Heat
• Kinetic Energy = energy of motion
• Heat= total amount of energy in a system
• Temperature= measure of the average kinetic energy of molecules
• Calorie= the amount of heat needed to raise the temperature of water by 1 C
AP Biology- Biochemistry 14
Mrs. Stahl
High Specific Heat
 _____________________________________________________________
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 Defined as: the amount of heat that must be absorbed or lost for 1 g of
that substance to change its temperature by 1°C
 The specific heat of water is 1 cal/g/°C
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o Heat is absorbed when hydrogen bonds break
o Heat is released when hydrogen bonds form
Why do organisms have a high water content?
 To maintain a constant internal temperature
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Heat of Evaporation
 _____________________________________________________________
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 Heat of vaporization is the heat a liquid must absorb for 1 g to be converted
to gas
 _____________________________________________________________
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AP Biology- Biochemistry 15
Mrs. Stahl
 _____________________________________________________________
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Density of Ice
 _____________________________________________________________
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AP Biology- Biochemistry 16
Mrs. Stahl
Solute Concentrations in an Aqueous Solution
• Most chemical reactions in organisms involve solutes dissolved in water
• When carrying out experiments, we use mass to calculate the number of
solute molecules in an aqueous solution
• Molecular mass is the sum of all masses of all atoms in a molecule
• Numbers of molecules are usually measured in moles, where 1 mole (mol) =
6.02  1023 molecules
• Avogadro’s number and the unit dalton were defined such that 6.02  1023
daltons = 1 g
• Molarity (M) is the number of moles of solute
per liter of solution
Water Can Form Ions
• _____________________________________________________________
• 1 out of every 550 million water molecules spontaneously break
• _____________________________________________________________
• H2O -> OH- + H+
• For some reason a proton, from the hydrogen's nucleus dissociates from the
molecule of water.
• Dissociation=
_____________________________________________________________
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AP Biology- Biochemistry 17
Mrs. Stahl
Explanation of Dissociation: Copy the board
AP Biology- Biochemistry 18
Mrs. Stahl