Download UNIT 4 NOTES

UNIT 4 NOTES
I.
Carbon- Based Molecules
A. Carbon atoms have unique properties
1. Each carbon atom has 4 valence
electrons available for bonding
2. Each carbon atom can bond with 4 other
atoms
3. Carbon-based molecules have three
fundamental structures
a. straight chains
b. branched chains
c. rings
4. monomer – subunit of a complete
molecule
5. polymer – large molecule of many
monomers linked together
B. Four types of carbon-based molecules are
found in living things
1. Carbohydrates – starches and sugars
a. monosaccharide – simple sugars
(fructose and glucose)
b. disaccharide – two sugars bonded
together
c. polysaccharide – polymers of
monosaccharide (starch and
cellulose)
2. Lipids – nonpolar molecules that include
fats, oils, and cholesterol
a. fats store large amounts of chemical
energy in organisms
b. saturated fats have a maximum
number of bonds with hydrogen
atoms
c. unsaturated fats have less than the
maximum number of bonds with
hydrogen
3. Proteins – a polymer made up of
monomers called amino acids
a. there are 20 different amino acids to
build proteins
b. your body can make 12 amino acids,
the other 8 must come from the food
we eat
c. amino acids have a carbon atom
bonded to 1) a hydrogen atom, 2) an
amino group, NH2, 3) a carboxyl
group and 4) a side group that makes
them unique
d. polypeptide bonds bind amino acids
together
4. Nucleic acids – polymers made up of
monomers called nucleotides
a. a nucleotide is made up of a sugar,
phosphate group, and nitrogen
containing base
b. nucleic acids make up DNA and
RNA, they are the instructions for
making proteins
II. Chemical Reactions – substances change into
different substances
A. 6O2 + C6H12O6 à 6CO2 + 6H2O
Reactants
Products
B. Bond Energy – amount of energy that will
break a bond between two atoms
C. Equilibrium – when both reactants and
products are made at the same rate
D. Activation Energy – the amount of energy
that needs to be absorbed for a chemical reaction to
start
E. Exothermic reaction – reaction that releases
more energy than it absorbs
F. Endothermic reaction – reaction that absorbs
more energy than it releases
III. Enzymes
A. Catalyst – a substance that decreases the
activation energy needed to start a chemical
reaction
B. Enzymes – catalyst for chemical reactions in
living things
C. Substrate – the specific reactant that an
enzyme acts on
Lock-and-key model – enzymes must fit on to the
substrate