Download polar charged phosphate head and nonpolar uncharged fatty acid

MOLECULES OF LIFE
CH 4 and 5
I. Carbon is the building block of
the molecules of life
A. Chemistry of Carbon
 Forms 4 covalent bonds
 Bonds can be single double or
triple
 Forms bonds with sulfur,
carbon, nitrogen, oxygen,
phosphorus, hydrogen
 Forms rings chains and
branches
 Result: HUGE variety of
molecules formed from carbon
backbone
B. Macromolecules
 Large molecules many of which are
polymers
 Polymer: a macromolecules made
of repeating units called monomers
 Macromolecules are made by
dehydration reactions: linking of
monomers together with the
removal of water
 Macromolecules are broken down
by hydrolysis reactions:
breakdown of a macromolecule
with the addition of water
 The 4 macromolecules that make
up all living things are:
o Proteins
o Carbohydrates
o Lipids
o Nucleic acids
II. Carbohydrates
A. Monosaccharides
1. structure
A single sugar ex: glucose
Most monosaccharides exist as a
ring
2. isomers
Molecules with same structural
formula but different arrangement
of atoms
Ex: glucose, fructose, and galactose
3.
function
Quick energy source
Immediately enters into cellular
respiration for production of ATP
B. Disaccharides
1. Structure
2 monosaccharides linked via
dehydration reactions
EX: sucrose, lactose
2. Function
Energy
http://www2.nl.edu/jste/biochem.htm
C. Polysaccharides
Long chain of GLUCOSE
molecules linked via dehydration
reactions
2 groups of polysaccharides
Storage: starch and glycogen
Structural: cellulose chitin
1. Storage polysaccharides
a. function
store glucose for later use
b. structure
 Glycogen
o Stores glucose in animals
o Many glucose molecules
linked via α1-4 linkages
o Is highly branched
o The α1-4 linkage is
important in its function
 Starch
o Stores glucose in plants
o Many glucoses linked by
α1-4 linkages
o Not that branched
2. structural polysachharides
a. cellulose
 forms cell wall in plants
 many glucoses linked via β14 linkages
 not branched
b. chitin
 forms exoskeleton in
arthropods and cell wall in
fungi
III. Lipids
Diverse group of hydrophobic
molecules
B. Triglycerides (fats and oils)
1. structure
One glycerol + 3 fatty acids
linked via dehydration reactions
http://www2.nl.edu/jste/biochem.htm
2. Fatty Acid
 Long chain of C and H with a
carboxyl group
 Usually 14 to 20 Cs
 Fatty acids can be
o Saturated: no carbon to
carbon double bonds. Solid
at room temp
o Monounsaturated: 1 carbon
to carbon double bond.
Liquid at room temp
o Polyunsaturated: more than
1 carbon to carbon double
bond. Liquid at room temp
3. Function
 Long term energy storage
 Seeds use stored
triglycerides as energy
during germination
 Insulation in mammals
C. Phospholipids
1. Structure
One glycerol + 2 fatty acids + 1
phosphate head
2. Property
Amphiphathic: polar charged
phosphate head and nonpolar
uncharged fatty acid tails
3. Function:
Make up phospholipid bilayer
found in all biological
membranes
D. Waxes
Function as protective barrier
E. Steroids
Function as chemical messengers
IV. Proteins
Large polymer made of repeating
monomers called amino acids
A. Functions of Proteins
 Enzymes: catalyze cell’s
reactions
 Defense: antibodies destroy
foreign invaders
 Transport: move molecules
around body and into and out of
cells
 Support and structure: long
fibrous proteins in hair nails
skin
 Movement: contractile proteins
in cells
 Regulation: proteins involved in
maintaining homeostasis
B. Amino Acids
1. general structure
2. Groups of amino acids: based on
the characteristics of R group
 Nonpolar amino acids
o R group is hydrophobic
o Includes aromatic amino acids
o Involved in hydrophobic
interactions
 Polar uncharged amino acids
o Involved in hydrogen
bonding
 Polar charged amino acids
o Basic R groups have NH2
o Acidic ones have COOH
o Involved in ionic interactions
 Special function amino acids
Nonpolar
Glycine
(Gly or G)
Alanine
(Ala or A)
Leucine
(Leu or L)
Valine
(Val or V)
Isoleucine
(Ile or I)
Proline
(Pro or P)
Methionine
(Met or M)
Phenylalanine
(Phe or F)
Trypotphan
(Trp or W)
Polar
Serine
(Ser or S)
Threonine
(Thr or T)
Cysteine
(Cys or C)
Tyrosine
(Tyr or Y)
Asparagine
(Asn or N)
Glutamine
(Gln or Q)
Electrically
charged
Acidic
Aspartic acid
(Asp or D)
Basic
Glutamic acid
(Glu or E)
Lysine
(Lys or K)
Arginine
(Arg or R)
Histidine
(His or H)
The R groups in the amino acids
determine the type of interactions they
will form with other amino acids in the
protein chain. This determines how the
protein folds into its 3D shape. The shape
of the protein determines its function.
Different proteins assume different
functions because they fold into different
shapes
How a protein folds into its shape is
determined by the order of amino acids
in the chain
3. Linking of amino acids
 Linked together via dehydration
reactions
http://www2.nl.edu/jste/biochem.htm
C. Protein Structure
Protein function is dependent on its
shape
Alter the shape = alter the function
As protein is being synthesized, it
begins to fold into its correct shape
Proteins fold as a result of the
interactions between amino acid R
groups
http://www.ncbi.nlm.nih.gov/sites/entrez
?db=structure
1. General rules on protein folding
 Nonpolar amino acids tend to
cluster in the interior of protein
away from water
 Polar amino acids tend to be on
the surface
2. There are 4 levels of protein
structure
a. primary structure
 number and order of amino
acids in the protein chain
 primary structure is
determined by______________
 all proteins have a different
primary structure
b. secondary structure
 Hydrogen bonding among
amino acids that are relatively
close together.
 2 forms: α helix and β sheet
c. Tertiary structure
 Interaction among the R
groups of amino acids farther
apart in the chain
o Nonpolar amino acids will
interact via hydrophobic
interactions
o Polar uncharged amino
acids will form hydrogen
bonds with each other
o Charged amino acids will
form ionic bonds with each
other
o Disulfide bonds between
cysteines
The driving force for tertiary
structure is the hydrophobic
interactions. As the nonpolar
amino acids interact with each
other, it brings the other amino
acids close enuf to form hydrogen
bonds and ionic bonds and
disulfide bonds
d. Quaternary structure
 2 or more polypeptide chains
associated together to form a
functional protein
Special proteins called chaperonins
help proteins fold into their secondary
and tertiary structures
All proteins have primary and
secondary structure
Most proteins have tertiary structure
Some proteins have quaternary
structure
http://parasolwww.cs.tamu.edu/groups/amatogroup
/research/folding/proteinA.php
3. Protein unfolding
Denaturation: unfolding of a
protein as a result of changes in pH
and temp
V. Nucleic Acids
The information molecules
Contain and express all of the
hereditary info
A. Structure
 Long chains of nucleotides linked
via dehydration reactions
B. Nucleotides
Made of a:
5 carbon sugar
Phosphate group
One of 4 bases
C. Function
 DNA: stores hereditary info
 RNA: expresses it