anomeric

1
anomeric carbon
2
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3
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Relationship between Haworth (flat ring)
depiction and chair-form
Flat ring (Haworth projection) just gives the
relative positions of the H and OH at each
carbon, one is above the other. But it does
not tell the positions of the groups relative to
the plane of the ring (up, down or out)
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Polymers are built by removing a molecule of
water between them, known as dehydration, or
condensation.

• R-OH HO-R
• ? R-O-R HOH
• This process does not happen by itself
• (It is NOT like glucose ring formation)
• Rather, like virtually all of the reactions in a
  cell, it requires the aid of a CATALYST

Dimer formation
6
AND Polymers are broken down by the reverse
process, ADDING a molecule of water between them,
known as DIMER HYDROLYSIS

• R-O-R HOH? R-OH HO-R
• This process does not happen by itself
• Rather, like virtually all of the reaction in a
  cell, it requires the aid of a CATALYST

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Building a polymer from glucose
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Cellobiose with right-hand glucose shown as
beta
C4 equatorial out (always in glucose)
H
O
CHOH
4
2
HO
H
H
O
CHOH
4
H
2
H
H
HO
HO
H
H
OH
HO
HO
H
H
Beta-glucose residue
Beta-glucose residue
C1 equatorial out (in beta glucose)
The two glucose molecules are connected in a
straight line in cellobose
Beta conformation is now locked in here
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Maltose with right-hand glucose shown as beta
C4 equatorial out (always in glucose)
H
O
CHOH
4
2
HO
H
H
H
Alpha-glucose residue
HO
HO
H
C1 axial down (in alpha glucose)
Alpha conformation of OH is now locked in here
Beta-glucose residue
But not here
The two glucose molecules are connected with an
angle between them in maltose
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down
out
H
Starch or glycogen chain
H
Tinker toys
Cellulose
Tinker toys
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Branching in starch
Branches at carbon 6 hydroxyl Branching ? compact
structure Starch or glycogen granules, A storage
form of glucose for energy
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Cytoplasm
Nucleus
Organelles
Starch granules
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down
out
H
H
or glycogen chain
Cellulose
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Cellulose
Cell wall of green algae
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anomeric carbon
anomeric carbon
ribose
fructose
glucose
glucose
From handout 2-6
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More sugarsMannose C6H12O6 (different
arrangement of OHs and Hs)Galactose C6H12O6
(different arrangement of OHs and
Hs)Deoxyribose C5H10O4 (like ribose but C2s
OH substituted by an H) More disaccharides
Lactose b-1-glucose to C4 of galactose (milk
sugar)Sucrose b-2-fructose to C1- a-1-glucose
(table sugar, cane sugar)
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Metabolic intermediate
(Bacterial cell walls)
(Insect exoskeleton)
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Lipids

• Soluble in organic solvents (like octane, a
  hydrocarbon)
• Heterogeneous class of structures
• Not very polymer-like (in terms of covalently
  bonded structures)

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A steroid
(Abbreviation convention Always 4 bonds to
carbon. Bonds to H not shown.)
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Fats
A fatty acid
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Effect of fatty acid structure on physical
properties
Solid fats
cis
Oils
cis
trans
25
Adipocyte (fat storage cell)
Fat globule
Nucleus
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Handout 2-10
NH2
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HO
HO
Handout 2-10
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HO
HO CH2CH2NH3 (alcohol ethanolamine)
HO
Handout 2-10
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Biological membranes are phospholipid bilayers
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Incidentally, note the functional groups we have
met so far Hydroxyl Amine Amide Carboxyl Carbony
l Aldehyde Ketone Ester Carboxylic acid
ester Phosphoester And Glycosidic bonds CC
double bonds (cis and trans)
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PROTEINS
Amino acids (the monomer of proteins)
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At pH 7, ,most amino acids are zwitterions (charge
d but electrically neutral)
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Net charge
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Numbering (lettering) amino acids
e-amino group
e
d
?
ß
Alpha-carboxyl (attached to the a-carbon)
Alpha-amino
Alpha-carbon
36
Amino acid examples
Molecular weights 75 203 (MW)
Glycine (gly) Side chain H Smallest (75)
Aspartic acid (asp, aspartate) One charge ß-carboxyl -CH2-COOH
Tryptophan (trp) 56 membered rings Hydrophobic, largest (203)
Lysine (lys) One charge e-amino
Alanine (ala) One carbon (methyl group) -CH3
Arginine (arg, guanido group) One charge -(NH-C (NH2)NH2),
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Shown uncharged (as on exams)
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Amino acids in 3 dimensions

• Asymmetric carbon (4 different groups attached)
• Stereoisomers
• Rotate polarized light
• Optical isomers
• Non-superimposable
• Mirror images
• L and D forms

From Purves text
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Mannose
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Condensation of amino acids to form a
polypeptide (must be catalyzed)
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Parts of a polypeptide chain
44
Handout 3-3
The backbone is monotonous
(Without showing the R-groups)
The backbone is monotonous
It is the side chains that provide the variety
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Polypeptides vs. proteins

• Polypeptide amino acids connected in a linear
  chain (polymer)
• Protein a polypeptide or several associated
  polypeptides (discussed later)
• Often used synonymously
• Peptide (as opposed to polypeptide) is smaller,
  even 2 AAs (dipeptide)