Download are organic (based on carbon).

Biological molecules:
•  All are organic (based on carbon).
•  Monomers vs. polymers:
–  Monomers refer to the subunits that, when
polymerized, make up a larger polymer.
–  Monomers may function on their own in some cases.
Four types of biological molecules
•  Carbohydrates - refer to a large group of
biochemicals which in nature include monomers
and polymers.
•  Lipids - not considered as monomers/polymers
like the others; they all have one PHYSICAL
property in common.
•  Proteins - polymers of amino acids with versatile
functions.
•  Nucleic acids - polymers of nucleotides, may be
DNA or RNA.
• Definition: contain
carbon, hydrogen, and
oxygen (carbo+hydrate),
usually in the following
ratio: [C(H20)]n Basic Building Blocks
•  Monosaccharides – Three types, each of
which contains 6
carbon atoms: – glucose
(most popular)
– fructose
– galactose
Monosaccharides
•  Usually, they exist in nature as a "ring" form,
after an ester linkage forms between the #1
carbon and the hydroxyl group of carbon #5 (in
the case of monosaccharides with six carbons).
Building on a theme
•  When two
monosaccharides are
joined together by
dehydration synthesis
(a glycosidic bond), a
DISACCHARIDE
results.
•  Disaccharides always
contain glucose + one
other monosaccharide:
•  Sucrose (common
table sugar) = glucose
+ fructose
•  Lactose ("milk
sugar") = glucose +
galactose
•  Maltose = glucose +
glucose
Other monosaccharides
•  Some have five carbons, like ribose and
deoxyribose, the sugars in the nucleotides of
DNA and RNA (LATER)
Polysaccharides
•  Usually consist of long chains of glucose or modified glucose
monomers, linked by different types of glycosidic bonds and with
different branching properties.
•  Starch - plant storage polysaccharide
•  Cellulose - plant structural polysaccharide (beta-1, 4 linkage that
animals cannot in general digest)
•  Glycogen - animal storage polysaccharide
•  Chitin - makes up fungal cell walls and arthropod exoskeletons polymer of N-acetyl glucosamine (NAG)
•  Peptidoglycan - polymer of alternating NAG and NAM (N-acetyl
muramic acid) subunits, most bacterial cell walls contain it
Functions of Carbohydrates:
•  Mainly, to provide ENERGY for an
organism
•  Structural components of cell walls
•  May be attached to proteins and function as
antigens
In nutrition,
•  Mono- and disaccharides are referred to as
sugars, or simple carbohydrates. •  Polysaccharides are referred to as complex
carbohydrates.
• Definition: biological
molecules that are
insoluble in water (they
are hydrophobic, or
non-polar) Basic Types
• Triglycerides (fats and
oils)
• Phospholipids
• Sterols
Triglycerides
•  Fats are solid at room
•  Triglycerides are
temperature, because
formed when three
they contain saturated
FATTY ACIDS are
fatty acids.
joined to a molecule of
the trialcohol glycerol •  Oils tend to be liquid at
room temperature,
by dehydration
because they possess at
synthesis.
least one point of
unsaturation (C=C
double bond).
Saturated fatty acids
Points of unsaturation (cause double bonds and
"kinks" in the molecule)
Phospholipids
•  Are very similar to triglycerides in
chemistry: one of the fatty acids is replaced
with a phosphate containing group.
•  This causes the molecule to have a "split
personality", being partially hydrophobic
and partially hydrophilic. Molecules like
this are referred to as “amphipathic”.
Sterols, or steroids
•  Are based on ring structures.
•  Cholesterol is the most popular steroid,
although many hormones and other
biological compounds are formed from
cholesterol (testosterone, estrogen, cortisol,
vitamin D).
Functions of LIPIDS:
•  Triglycerides - long term energy storage,
cushioning and insulation in multicellular
organisms.
•  Phospholipids - structural basis of cell
membranes and lipid-transporting lipoproteins
(HDL's and LDL's).
•  Steroids - Cholesterol functions in the
structure of cell membranes; others are
hormones, etc. •  Definition: long chains of subunits
called AMINO ACIDS joined by
PEPTIDE BONDS (dehydration
synthesis again)
•  There are 20 different amino acids.
•  Each one contains a central carbon bound to an
amino group, a carboxylic acid group, a
hydrogen, and an R (variable) group. AMINO ACIDS
Levels of protein structure
•  Primary - sequential order of amino acids in
chains
Levels of protein structure
• Secondary - local hydrogen
bonding interactions between
amino and acid groups form
structures such as the alpha-helix
and the beta-pleated sheet.
Continued
•  Tertiary - hydrogen •  Quaternary bonds, electrostatic,
Sometimes, folded
and hydrophobic
polypeptides
interactions
associate with each
between R groups
other to form a
cause the molecule
functional protein
to fold up in three(e.g., hemoglobin,
dimensional space.
antibodies).
Types of non-covalent interactions that create and
maintain tertiary structure include:
Hydrophobic interactions
Hydrogen bonding (between R-groups)
Ionic/electrostatic interactions
Functions of PROTEINS are
MANY!!
• 
• 
• 
• 
Enzymes (catalyze chemical reactions)
Hormones
Antibodies
Structural (mainly in animals - muscle
tissue, connective tissue)
•  Famous proteins: hemoglobin, collagen,
keratin, insulin
•  Membrane associated transporters…and
more!! In nutrition,
•  We ingest proteins mainly to get amino
acids for building our own proteins.
•  They do however contain calories, and any
excess will be converted to fat.
•  In the process, they become deaminated,
forming the metabolic waste urea, which is
excreted in the urine.
•  Definition: long chains of subunits
called NUCLEOTIDES joined by
PHOSPHODIESTER BONDS.
•  There are two classes of nucleic
acids depending upon which type
of sugar they contain. The two
classes are DNA and RNA. The nucleotide contains:
•  A five carbon sugar (ribose in RNA or
deoxyribose in DNA);
•  A phosphate group;
•  A nitrogen containing base, of which there
are four types in DNA.
Continued
•  DNA bases:
– Guanine
– Cytosine
– Adenine
– Thymine
•  In RNA, thymine
is replaced by
uracil.
Bonding RULES
•  DNA exists in nature as a double helix,
with two nucleotide strands running
antiparallel and joined by hydrogen
bonding between the bases.
•  A binds with T (2 H-bonds).
•  G binds with C (3 H-bonds, stronger bond).
•  In RNA, A binds with U when applicable.
Functions of NUCLEIC ACIDS
•  DNA makes up the genes, which contain
genetic information.
•  RNA functions in various capacities in the
process of protein synthesis (i.e., expression
of the genetic information).
•  ATP, a triphosphate form of an RNA nucleotide,
also functions as the major energy carrying
molecule of the cell!
Ribose