Transcript honors Chapter 2.3-2.4 teaching

The chemistry of life is sensitive to acidic and basic conditions
Acid: a compound that forms H+ ions in
solution
Base: a compound that produces OH(hydroxide) ions in solution
Acidity or Alkalinity (base) is measured on
the pH scale:
• From 0 (most acidic) to 14 (most basic)
• The pH of most cells is kept close to 7
(neutral) by buffers (substances that resist
pH change)
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Each step on pH scale is a factor of 10.
(ex: pH 5 is 10x more acidic than?)
Buffer: weak acid or weak base which can
keep a pH stable
ex: Bicarbonate: most important buffer in
body..maintains homeostasis in blood
When the number of H+ is equal to
the number of OH-  water
H+ + OH-  H20
2.3 Organic Chemistry: The Chemistry of Carbon
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“organic”: must contain at least one carbon. CH4 = simplest organic molecule
Carbon has 4 valence electrons
Therefore, carbon will always make 4 bonds with other atoms
Carbon can bond with other carbons, form chains, rings
Ability to form millions of different compounds with other elements
The Four Macromolecules of Life
Macromolecule (polymer) made by joining many monomers (single unit)
Polymerization: chemical rxn which joins monomers to make polymers
The four main classes of biological molecules:
1. Carbohydrates (sugar, starches, cellulose)
2. Lipids (wax, fats, oils, steroids)
3. Proteins (muscle, hair, hormones, enzymes)
4. Nucleic acids (DNA and RNA)
1. CARBOHYDRATES: Monomer = Monosaccharide
•Contain C, H, and O in a 1:2:1 ratio
•Most end with “ose”
•An animal’s main energy source
•Carbs are burned first in the body
•Monosaccharides: (C6H12O6):
glucose, fructose, galactose
•Disaccharides:
sucrose, lactose, maltose
•Polysaccharides: (complex carbohydrates)
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A) glycogen (carb storage animal liver)
B) starch (carb storage in plants)
C) cellulose (cell walls, cotton) “roughage”
D) chitin (exoskeletons of arthropods)
2. LIPIDS: Monomer = Fatty Acids
* Mostly C and H atoms linked by
nonpolar covalent bonds
* reserve energy-storage molecules
(burned after carbs are gone)
* Insoluble in water (polar)
* Soluble in nonpolar solvents (ether)
* More energy in lipids than in carbs
- 9 cal/g Lipid vs. 4 cal/g Carb
* Examples: triglycerides, phospholipids,
steroids (cholesterol), waxes, oils, fats
* Triglyceride = 3 fatty acids + 1 glycerol
* Saturated Fats: all single bonds in chain
- solid at room temp (ex: butter, lard)
* Unsaturated fats: one or more C=C bond in chain
- liquid at room temp (ex: all oils)
3. NUCLEIC ACIDS: Monomer = Nucleotide
• Nucleic acids (DNA and RNA) store and transmit genetic information
• DNA = Deoxyribonucleic acid
• RNA = Ribonucleic acid
• Large macromolecules containing C, H, O, N, P
• One nucleotide = 5-carbon sugar, phosphate (PO4-), nitrogenous base
The sugars and phosphates are
the backbone for the nucleic acid
DNA’s sugar = deoxyribose
RNA’s sugar = ribose
4. PROTEINS: Monomer = Amino Acid
• essential to the structures and
activities of life
• Contain C, H, O, N (S, P)
• 50% of your dry weight
• examples of groups of proteins:
1. enzymes (amylase, sucrase,
maltase, lactase)
2. structural (collagen, elastin)
3. contractile (actin, myosin)
4. transport (hemoglobin, protein
channels)
5. hormones (insulin)
AMINO ACID: Structure
Each amino acid has:
•An amino group (-NH2)
•A carboxyl group (COOH)
•An R group, which distinguishes
each of the 20 different amino
acids
* Each amino acid has
specific properties based
on the R-group
* Peptide bonds link
amino acids together 
polypeptide (protein)
PROTEINS: 4 Levels of Organization
Amino acids are assembled into polypeptide chains according to
instructions coded in the DNA.
Primary Structure: the sequence of
amino acids in its polypeptide chain
Secondary structure: the coiling
or folding of the chain
Tertiary Structure: the overall threedimensional shape of a polypeptide
– created when R-groups bond
Quaternary Structure: the
association of two or more
polypeptide chains
2.4 Chemical Reactions and Enzymes
•Chemical reaction: process that changes or transforms one set of
chemicals into another
•Those chemicals that enter into a reaction are the “reactants”,
those that are made are the “products”
•Chemical reactions change the bonding patterns in the reactants
•Energy is released or absorbed when chemical bonds are formed or
broken during a reaction
•Rxns releasing energy generally happen spontaneously
•Rxns which absorb energy need energy to start them
•Some energy releasing rxns need activation (input of) energy
to get started
Enzymes are vital proteins that run biochemical rxns
• lower the activation energy (EA) of
chemical reactions (they are catalysts)
• The reactants they “work” on are
called “substrates”
• most enzymes are named for their
substrates with an “-ase” ending
Ex: sucrase digests sucrose
lactase digests lactose
• VERY shape specific (“lock and key”)
reaction with active site on enzyme
(where substrate and enzyme join)
One Enzyme : One Substrate
•Enzymes have unique three-dimensional shapes so
they can fit onto their specific substrate
•Shapes determine function and which chemical
reactions they can perform
•All related to their 3-D folding pattern born from?
Factors Which Affect Enzyme Activity:
• temperature, substrate concentration, pH, inhibitors
• enzyme inhibitors can alter enzyme function:
– Competitive inhibitor: blocks active site, substrate can’t attach and remains
unchanged
– Non-competitive inhibitor: alters enzyme’s function by changing its shape
• many poisons, pesticides, and drugs are enzyme inhibitors
Some food for thought:
1. Why do we put lemon juice on apples?
2. What is the purpose of a fever?
3. What happens when a raw egg hits a hot fry pan?
4. Why do we put produce/perishables in the fridge?
5. How does a Siamese cat get it’s color pattern?
GENES = Sequences of DNA
– DNA sequences spell out the amino acid sequences
of proteins
– Mutations in the DNA sequence  wrong amino
acid sequence  wrong protein shape  no
function
– Ex: Lactose Intolerance :
Mutations in lactase gene
mutations in lactase amino acid chain sequence 
defective lactase shape
enzyme can’t fit onto lactose substrate 
lactose does not get digested.
Q: Why is it a big deal?
A: If YOU don’t digest the lactose in your
digestive tract, all the E.coli will…all of
their waste made from eating all this food
will leave you with cramps, bloating, and
diarrhea…not fun!
Lactase enzyme