Dietary needs Come in Different Ways
• Lipids (Fats)
• Carbohydrates (sugars)
• Proteins
• Vitamins and Minerals
Lipids
• Store Energy in a Fat Cell
• Part of membranes
• Serve as chemical messengers
Where are Lipids Used
• Humans store Energy in the form of fats• Fats produce 50% more energy per gram
than Carbohydrates• Because lipids are insoluble in water, they
work well as membranes to separate compartments in the body
• The structure of lipids makes them water repellent or hydrophobic
• Primary messengers like steroids and Secondary messengers like prostaglandins or thromboxanes
Classification of Lipids
• Classified into four groups
1) Fats and waxes
2) Complex Lipids
3) Steroids
4) Prostaglandins
Properties of Fats
• Physical State - FATS– Animal fats
• generally solids at RT• contain mostly saturated FA
– Plant and Fish oils• generally liquids at RT• contain more unsaturated FA
Properties of Fats
PURE Fats – Colorless, odorless, and
tasteless– Tastes, odors, colors are
caused by substances dissolved in the fats
Hydrogenation
• Treatment with hydrogen gas, H2
• Catalyst required
• NOT difficult to convert unsaturated FA to saturated FA
• Called “hardening”
• Margarine contains more unsaturation than hydrogenated shortenings– Crisco, Spry, etc.
Hydrogenation
• Unsaturated converted to saturated:
HC
H2C
H2C C (CH2)12 CH3O
O
O
O
C (CH2)6 CH2
CH CH
CH2 (CH2)6 CH3
O
C (CH2)6 CH2
CH CH
CH2 (CH2)6 CH3
O
+ H2
catalyst
HC
H2C
H2C C (CH2)12 CH3O
O
O
O
C (CH2)6 CH2
CH2 CH2
CH2 (CH2)6 CH3
O
C (CH2)6 CH2
CH2 CH2
CH2 (CH2)6 CH3
O
Saponification
• Triglycerides are subject to hydrolysis– base hydrolysis is called “saponification”
HC
H2C
H2C C (CH2)12 CH3O
O
O
O
C (CH2)6 CH2
CH CH
CH2 (CH2)6 CH3
O
C (CH2)6 CH2
CH CH
CH2 (CH2)6 CH3
O
+ 3 NaOHH2O
H2C
HC
H2C
OH
OH
OHC (CH2)12 CH3O
O
Na+ -
+
O C (CH2)6 CH2
CH CH
CH2 (CH2)6 CH3
O
Na+ -2
Carbohydrate
• hydrate of carbon – Cn(H2O)m
• Glucose -blood sugar- C6H12O6 or C6(H2O)6
• Sucrose -table sugar- C12H22O11 or C12(H2O)11
Monosaccharides
• Formula CnH2nOn • One carbon is either an aldehyde or
ketone• The suffix ose indicates that the
molecule is a carbohydrate• Use prefix to indicate number of
carbons tri , tetr, pent, hex• Aldose – contain an aldehyde group• Ketose – contain a ketone group
Monosaccharides
• Aldohexoses
Aldohexosesaldehyde function
six carbons
carbohydratesor
saccharides
other examples: ketotetrose, aldotriose, ketopentose
O
O
O
HOCH2
OH
OH
OH
OH
HOCH2
)(O O
OHOCH2
OH
OH
OH
OH
HOCH2
)
(Starch
alpha linkage Cellulose beta linkage
What A Difference One Bond Angle Can Make
Sawdust Cookies anyone??????
Proteins
Functions:– Structure - skin, bones, hair, fingernails– Catalysis - biological catalysts are enzymes– Movement - muscle: actin and myosin– Transport - hemoglobin, transport thru
membranes– Hormones - insulin, oxytocin, HGH, etc.– Protection - antigen-antibody reactions,
fibrinogen in clotting– Storage - casein in milk, ovalbumin in eggs,
ferritin in liver-stores iron– Regulation - control in expression of genes
From yahoo images
Proteins• Protein types:
– 9000 different proteins in a cell– Individual human being >100,000 different – Fibrous Protein
• Insoluble in H2O• Used mainly for structural purposes
– Globular Protein• Partly soluble in H2O• Usually not used for structural purposes
From yahoo images
Amino Acids• The Building Blocks of proteins
– Contains an amino group and an acid group– Nature synthesizes about 20 common AA
COOHC
NH2
R
H
Amino Acids• Amino Acids (AA)
– The twenty common are Called alpha amino acids
– We use one and three letter codes to name the 20 common AA
COOHC
NH2
R
H
Amino Acids• Amino Acids (AA)
– Sometimes classifiedas AA with:
• nonpolar R groups• polar but neutral R groups• acidic R groups• basic R groups
Twenty Essential Amino Acids
http://chemed.chem.purdue.edu/genchem/topicreview/bp/1biochem/amino2.html
Peptides• AA are also called peptides
• They can be combined to form a dipeptide.
a peptide bond
CCHH2N
OH
CCH
CH3
NH OH
O
glycine
CCHH2N OH
OH
+
alanine
CCH
CH3
H2N OH
O-H2O
Peptides• Addition of peptides (head to tail)
– Formation of:• dipeptides• tripeptides• tetrapeptides• pentapeptides• polypeptides• PROTEINS
AA’s
Proteins• Proteins usually contain about 30+ AA• AA known as residues
– One letter abbreviations• G, A, V, L
– Three letter abbreviations• Gly, Ala, Val, Leu
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
Polypeptides• Polypeptides
CCHN
R
OH
CCHN
R
OH
CCHN
R
OH
CCHN
R
OH
CCHN
R
OH
CCHN
R
OH
peptide bonds peptide bonds
side chains
amino acidresidues
AA’s