molecules 9.12.07 of life
chirality
sugars
DNA proteins
Which one of these is a dipole?
O=C=O
H3C-OH O=O
pH
Suppose we add 0.010 moles of HCl to 1 liter of pure water at STP. What is the resulting pH? By how many units would the pH change due to the addition of the acid?
pH = log(0.010) = ( 2) = 2.0 so, 5.0 pH units lower than pure water.
Le Chatelier's Principle
Henry Louis Le Chatelier (1850-1936)
CO2 + H2O
HCO3 + H+
Today's Mantra: "Tiny differences, huge consequences"
Biomolecules
sugars nucleotides carbohydrate polymers nucleic acids
amino acids lipids
proteins
Monosaccharides
The simplest of the carbs:
(CH2O)n
Aldoses
Triose sugars (C3H6O3)
Pentose sugars (C5H10O5)
Hexose sugars (C6H12O6)
Glyceraldehyde
Ribose
Glucose
Galactose
Monosaccharides
The simplest of the carbs:
(CH2O)n
Ketoses
Triose sugars (C3H6O3)
Pentose sugars (C5H10O5)
Hexose sugars (C6H12O6)
Dihydroxyacetone
Ribulose
Fructose
Sugars: Ring Formation
glucose ring form
glucose linear form
glucose ring form
Disaccharides
Formed by a dehydration reaction
H2O
1-4 glycosidic linkage
Glucose
Glucose
Maltose
Disaccharides
Formed by a dehydration reaction
H2O
Glucose
Fructose
Surcrose
Polysaccharides
o
Starch: an
glucose polymer (1-4 linkage)
Polysaccharides
o
Starch: an -glucose polymer (1-4 linkage)
o
Cellulose: a -glucose polymer (1-4 linkage)
Polysaccharides
o
Starch: an difference, huge consequence -glucose polymer (1-4 linkage) Tiny
o
Cellulose: a -glucose polymer (1-4 linkage)
Polysaccharides
Chitin Monomer: a glucosamine
Chitin Polymer
, 1-4 glycosidic linkage
Draw one linkage of the chitin polymer.
Remember: It uses , 1-4 glycosidic linkages...
What is the chemical formula of the polysaccharide formed when 10 glucose monomers are linked by dehydration?
Isomers
Same formula, different connectivity
C5H12
(pentane)
C5H12
(2-ethylpropane)
Structural Isomers
Isomers
Same formula, different geometry (double bonds) C4H8
H3C
C H C H (cis-2-butylene)
C4H8
(trans-2-butylene)
CH3
H3C
H
C
C
CH3
H
Cis-Trans Isomers
Isomers
Same formula, mirror images (non-superimposible)
C2H5 H C OH
C2H5
H OH C
asymmetric carbon:
CH3
CH3
attached to four different groups
Enantiomers
Isomers
Where are the asymmetric carbons?
H3C
OH C O
H
C
NH2
Alanine Glucose
Alanine enantiomers
Thalidomide
Tiny difference, huge consequence
Nucleic Acids
Deoxyribonucleotides
DNA
Ribonucleotides
RNA
Base
Phosphate
Sugar
Nucleotide
DNA molecule
DNA molecule
O O P O-
DNA molecule
O O P O-
O O P
O-
DNA molecule
5' end
O O P O-
O O P
O-
phosphodiester bonds
O
O P O-
3' end
DNA molecule
DNA molecule
-
DNA is a doublestranded molecule
-
-
DNA is a negatively charged molecule
-
-
A-T pairs have 2 H-bonds
-
G-C pairs have 3 H-bonds
-
-
DNA molecule
DNA is a double helix
Proteins
Amino Acids
Protein
amino acid:
(an asymmetric carbon)
amino acids
In proteins, only L-isomers are used!*
*there are some rare exceptions in certain "exotic" organisms
a m i n o a c i d s
serine
cysteine
arginine
polar
threonine
acidic
tyrosine
basic
glutamine
charged
aspartic glutamic acid acid
histidine lysine
arginine
glycine
alanine
valine
leucine
isoleucine
nonpolar
proline methionine phenyalanine tryptophan
amino acids link up via peptide bonds:
peptide bonds are planar _
+
proteins fold up to a globular structure
folded state denatured state
protein denaturation is reversible
Denaturation
Christian B. Anfinsen
Folded protein Renaturation
Denatured protein
proteins fold into amazing structures
alpha helix
beta strand
sucrose-specific porin (Salmonella) triose-phosphate-isomerase (TIM)
alpha helix
Linus Pauling
beta sheet
proteins fold into amazing structures
Hemoglobin (tetramer)
Self-Quiz: p.67 & p.91 9.12.07 molecules of life Read: 6.1-6.5 & 7.1
Stare inquisitively at Fig. 6.9 for at least 10 minutes.
chirality
sugars
DNA proteins