grade 12 AP biology exam notes

Topics: DNA, Adenosine triphosphate, Metabolism Pages: 19 (2481 words) Published: May 15, 2014
Biochemistry

Essential Elements of Life
Carbon, hydrogen, oxygen, nitrogen (96%)
Calcium, phosphorus, potassium, sulphur (4%)

Isotopes
Atoms of an element that differ in neutrons
Radioactive isotopes decay spontaneously, giving off energy

Cohesion
Hydrogen bonds hold water molecules together
Adhesion is an attraction between two substances
Surface tension measures how hard it is to break the surface tension of a liquid

Hydrocarbons
Organic molecules consisting of only carbon and hydrogen

Isomers
Structural
Have different covalent arrangements of the atoms
Geometrical
Same covalent arrangement but different spatial arrangements Enantiomers
Mirror images of each other

Functional Groups
Hydroxyl
OH
Carbonyl
C=O
Carboxyl
OH-C=O
Amino
NH2
Sulfhydryl
SH
Phosphate
O3-P=O
Methyl
CH3

Macromolecules
Needed in large quantities
Polymers
Carbohydrates
Lipids
Proteins
Nucleic Acids
Three of the four molecules are polymers
Carbohydrates
Proteins
Nucleic Acids

Carbohydrates
Include sugars
Simplest carbs are monosaccharide’s
Usually multiples of CH2O
Glucose is the most common monosaccharide

Polysaccharides
The polymers of sugars having storage and structural roles
Starch is a polysaccharides of plants’ storage
Glycogen is the storage for animals
Cellulose is the cell wall of plants structure
Chitin is a structural polysaccharide in arthropods

Lipids
Do not for polymers
Hydrophobic because consist of mostly hydrocarbons
Most important lipids are fats, phospholipids and steroids

Fats
Made up of glycerol and fatty acids
Glycerol is a 3 carbon alcohol with a hydroxyl group
A fatty acid consists of carboxyl group attached to a long carbon skeleton Saturated have as many hydrogen’s as possible with no double bonds Unsaturated have one or more double bonds

Phospholipids
2 fatty acids and a phosphate group attached to a glycerol
The 2 tails are hydrophobic but have a hydrophilic head

Steroids
Carbon skeleton with four fused rings

Four Levels of Protein Structure
Primary structure
Amino acids in a protein
Secondary structure
Structures of coiled alpha-helix or folded beta pleated sheet Tertiary structure
Assembles a 3-D structure with a variety of bonds
Quaternary structure
Several tertiary structures together

Metabolic Processes

Introduction to Metabolism
Some processes make energy and others absorb it
Metabolism is the totality of an organisms chemical reactions A metabolic pathway begins at a molecule and ends at a product being catalyzed by an enzyme Catabolic pathways release energy and make complex molecules into simple ones (ex. Cellular respiration) Anabolic pathways take energy and build complex molecules from simple ones

Energy
Kinetic is associated with motion
Heat is kinetic energy associated with random movements
Potential energy is the energy that matter has due to its location Chemical energy is potential energy that can be released chemically

Laws of Thermodynamics
First law
Energy can be transferred or transformed, but not created or destroyed Second law
Every transfer or transformation increases entropy (disorder) of the universe

Free Energy
∆G = ∆H – T∆S
∆G is the change in free energy
∆H is the change in total energy
∆S is the change in entropy
T is the temperature in Kelvin
Processes with a negative ∆G are spontaneous

Exergonic and Endergonic Reactions
Exergonic
Releases energy
Spontaneous
Endergonic
Absorbs energy
Nonspontaneous

ATP
A cell does three kinds of work:
Chemical
Transport
Mechanical
To do work, cells use energy coupling, which is changing exergonic processes to endergonic ones ATP (adenosine triphosphate)
Made up of ribose (sugar), adenine (a nitrogenous base), and three phosphate groups The three types of work are powered by the hydrolysis of ATP It a renewable resource that can be generated by adding a...
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