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BIOCHEMISTRY: CARBOHYDRATES, PROTEINS, DNA & LIPIDS
BIOCHEMICAL MOLECULES
CARBOHYDRATES
PROTEINS
NUCLEIC ACIDS
LIPIDS
A SIMPLE SUGAR
OR POLYMER
COMPOSED OF
SIMPLE SUGARS
A POLYMER
COMPOSED OF
AMINO ACIDS
A POLYMER
COMPOSED OF A
SUGAR, AN
ORGANIC BASE &
PHOSPHATE
A FAT, OIL, WAX
PHOSPHOLIPID
OR STEROID
CARBOHYDRATES:
function: major source of short term energy from our diet
foods: breads, fruits, vegetables
Monosaccharides- simple sugars
Monosaccharides contain 3-6 carbons:
3 C's triose, 4 C's tetrose, 5 C's pentose, 6 C's hexose
aldoses - a monosaccharide with an aldehyde group & several hydroxyl groups
(glucose, galactose)
ketoses - a monosaccharide with a ketone group & several hydroxyl groups
(fructose)
CHIRALITY AND D,L DESIGNATION
Chiral C - a carbon that has 4 different groups attached
Chiral compound - a compound containing a chiral C
• Chiral compounds have mirror images
D, L tells which of the 2 optical isomers we are referring to
• If the OH group on the next to bottom C points to the right, it is the D
isomer; if it points to the left it is the L isomer
• D isomer is usually the one found in nature
Monosaccharides with 5 or 6 carbons usually exist in a cyclic form. The OH group
on C-5 reacts with the aldehyde or ketone carbonyl group.
Disaccharides - 2 or more monosaccharides held together by glycosidic bond
SUGAR
o
SUGAR
maltose: Malt sugar contains 2 glucose units
lactose: Milk sugar contains galactose and glucose
sucrose: Cane sugar contains fructose and glucose
Polysaccharides- hundreds or thousands of monosaccharides bonded together
glycogen - animals use glycogen as reserve supply of glucose
starch (mixture of amylose & amylopectic) - plants store food as starch
cellulose - plants use cellulose for structural parts
PROTEINS
a large polypeptide containing hundreds- thousands of amino acids
Functions of different proteins: Enzymes, transporters of molecules & ions,
messengers, antibodies, storage, body regulators (e.g. growth), structural
support (e.g. hair, muscle tissue, bone, collagen).
foods: meat, fish, poultry, cheese and milk products
amino acid has amine group and carboxylic acid group (20 amino acids)
amino acids are linked to one another via an amide bond
amino acid
O
||
CNH
amino acid
8 amino acids are essential to diet (not synthesized in body)
LIPIDS: FATS, OILS, WAXES OR STEROIDS
function: used for long term storage of food - gives off 2-3 times as much
energy as carbohydrates, biological membranes, steroids
•
lipids are not water soluble
foods: vegetable oils, margarine, animal fat, milk products
fatty acid is carboxylic acid with a long hydrocarbon chain
glycerol:
HO-CH2CHCH2-OH
|
OH
triglyceride is a fat or oil in which an ester is formed from glycerol and 3 fatty
acids
g
l
y
c
e
r
o
l
fatty acid
fatty acid
fatty acid
animal fat contains mostly saturated fatty acids
vegetable oil contains mostly unsaturated fatty acids
phospholipid contains glycerol, fatty acid, phosphate and amino alcohol
wax: fatty acid combined with long chain alcohol
steroid: contains four 4 fused carbon rings e.g. chlosterol
NUCLEIC ACIDS - DNA, RNA
function: store and direct information for cellular growth and reproduction
DNA - contains all information needed for development of living system
RNA - carries genetic information from DNA to the ribosomes.
•
Both are polymers of nucleotide units DNA - several million nucleotides;
RNA - several thousand nucleotide units
•
nucleotide contains phosphate group, 5 C sugar and organic base
Obase
|
O=P-O-CH2
|
sugar
O-
base can be adenine, guanine, cytosine, thymine, uracil
sugar is ribose or deoxyribose
BIOCHEMICAL WEBLINKS
Carbohydrates - PP presentation by Timberlake
Introduction to Biochemistry - Logan
Structures & Functions of sugars, lipids & DNA - MIT hyper textbook
Carbohydrates, lipids, proteins & nucleic acids - PP presentations by Hardy at U of Akron
Amino Acid Anatomy - John Kyrk at Sirius
Images of biological molecules - U of Kansas