Transcript Functional Groups and Macromolecules

FUNCTIONAL GROUPS & MAJOR
MACROMOLECULES
Functional Groups
 An organic compound has unique properties that
depend upon
– The size and shape of the molecule and
– The groups of atoms (functional groups) attached to it
 A functional group affects a biological molecule’s
function in a characteristic way
Functional groups affect the properties of
molecules
 Compounds containing functional groups are
hydrophilic (water-loving)
– They are soluble in water
– Necessary for their roles in water-based life
Functional Groups
 The functional groups are
– Hydroxyl group—consists of a hydrogen bonded to an
–
–
–
–
–
oxygen
Carbonyl group—a carbon linked by a double bond to
an oxygen atom
Carboxyl group—consists of a carbon double-bonded
to both an oxygen and a hydroxyl group
Amino group—composed of a nitrogen bonded to two
hydrogen atoms and the carbon skeleton
Phosphate group—consists of a phosphorus atom
bonded to four oxygen atoms
Methyl group-not a functional group, but important in
methylating certain compounds (CH3)
 There are four classes of biological molecules
– Carbohydrates
– Proteins
– Lipids
– Nucleic acids
Macro=Big
 The four classes of biological molecules contain
very large molecules
– Called macromolecules because of their large size
– Called polymers because they are made from identical
building blocks strung together
– Building blocks=monomers
Monomer to Polymer
 A cell makes a large number of polymers from a
small group of monomers
– Proteins=20 different amino acids
– DNA=four kinds of nucleotides
 Monomers used to make polymers are universal
Makin and Breakin Molecules
 Dehydration reactions remove water to link
monomers together
 Polymers are broken apart by hydrolysis, the
addition of water
 These biological reactions rely on enzymes to
speed the process up
Carbohydrates
 Small monosaccharide sugars like glucose to
larges polysaccharide sugars like starch
– Monosaccharides=glucose/fructose
– Polysaccharides=starch, glycogen, cellulose, chitin
– Don’t forget the deydration reactions and hydrolysis
needed to make or break these guys
Monosaccharides are small carbs
 Monosaccharides like glucose are important for
cellular work and contribute to bigger molecules
 Disaccharides can be formed from two
monosaccharides (Dehydration or Hydrolysis)
 Ex. sucrose
HFCS
 So what’s the deal with High Fructose Corn
Syrup?
Polysaccharides
 Polysaccharides=Polymer (storage/structure)
 Starch is a storage polysaccharide composed of glucose
monomers and found in plants
 Glycogen is a storage polysaccharide composed of
glucose, which is hydrolyzed by animals when glucose is
needed
 Cellulose is a polymer of glucose that forms plant cell
walls (glucose energy not available to us b/c we lack
enzymes to digest it, cows/termites have help from
bacteria
 Chitin is a polysaccharide used by insects and
crustaceans to build an exoskeleton
Polysaccharides
 Polysaccharides are hydrophilic (water-loving)
– Cotton fibers, such as those in bath towels, are water
absorbent
Lipids=Fats
 Lipids
 water insoluble (hydrophobic, or water fearing)
 important in energy storage
 contain twice as much energy as a polysaccharide
 Fats made from glycerol and fatty acids
Fatty acid
 Fatty acids link to glycerol by a dehydration
reaction
– A fat contains one glycerol linked to three fatty acids
– Fats are often called triglycerides because of their
structure
Glycerol
Fatty acid
Saturated vs. Unsaturated
 Some fatty acids contain double bonds
– causes kinks or bends in the carbon chain
– maximum number of hydrogen atoms cannot bond to the carbons at the
double bond
– called unsaturated fats because they have fewer than the maximum
number of hydrogens
– Fats with the maximum number of hydrogens are called saturated
fats
Liquid at room temp
Solid @ room temp
Phospholipids
 Phospholipids are structurally similar to fats and
are an important component of all cells
– major part of cell membranes
– cluster into a bilayer of phospholipids
– hydrophilic heads are in contact with the water of the
environment and the internal part of the cell
– The hydrophobic tails band in the center of the bilayer
Steroids
 Steroids (the good ones) are lipids composed of
fused ring structures
– Cholesterol is an example of a steroid that plays a
significant role in the structure of the cell membrane
– In addition, cholesterol is the compound from which we
synthesize sex hormones
Proteins
 The idea of structure fitting function is never
more apparent than with this group
 They are polymers built from 20 different
amino acid monomers (ex. tryptophanphenylalanine-glycine)
 Many proteins are enzymes=metabolic
catalysts that regulate chemical reactions
within cells
Proteins have many functions
 Structural- provide associations between






body parts
Contractile- found within muscle
Defensive- include antibodies of the immune
system
Signal- hormones
Receptor- serve as antenna for outside
signals
Transport-carry oxygen (hemoglobin)
Storage-storage of amino acids, ex. Casein
Amino Acids
 Amino acids-building blocks of proteins,
 Consist of an amino group and a carboxyl group
covalently bonded to a central carbon atom
 Also bonded to the central carbon is a hydrogen
atom and some other chemical group symbolized
by R
 This R group determines the amino acid’s
properties
Amino Acids
 Some R groups are nonpolar and
hydrophobic & some R groups are polar and
hydrophilic
 These properties will affect how the protein
folds (remember, structure equals function)
Amino Acids and Polypeptides
 Amino acid monomers join to form
polypeptides
 This process uses a dehydration reaction and help
from enzymes (covalent bond between each
amino acid is called a peptide bond)
Shape is essential to
function
 Different factors can cause a protein to lose
its shape or become denatured
 Ex. Temp, Salinity, pH, inhibitors
Levels of protein structure
 A protein can have four levels of structure
– Primary structure
– Secondary structure
– Tertiary structure
– Quaternary structure
4 Levels of structure
 Primary-specific amino acid sequence
 Secondary-polypeptide folds or coils
(hydrogen bonding is important at this level)
 Tertiary-Overall 3D shape of polypeptide
(interactions between R groups is important)
 Quaternary-Two or more subunits join
together to create functioning protein
DNA & RNA
 DNA-Deoxyribonucleic Acid
 RNA-Ribonucleic Acid
 Both composed of monomers called nucleotides
 Nucleotide has 3 parts
– A five-carbon sugar called ribose in RNA and
deoxyribose in DNA
– A phosphate group
– A nitrogenous base
Nitrogenous Bases
 DNA’s nitrogenous bases are Adenine (A),




Guanine (G), Cytosine (C), and Thymine (T)
RNA has all of these except Uracil (U), instead
of Thymine
DNA is a double helix with sugar-phosphate
backbones
The bases pair up in the middle, A pairs with
T, and G pairs with C (hydrogen bonds hold
pairs together)
RNA is a single nucleotide strand
DNA Structure
DNA and Genes
 A particular nucleotide sequence that can
instruct the formation of a polypeptide is
called a gene
– Most DNA molecules consist of millions of base
pairs and, therefore, many genes
– These genes, many of which are unique to the
species, determine the structure of proteins and,
thus, life’s structures and functions