Lecture 5 Sept 9, 2005

1
Lecture 5 Sept 9, 2005 MACROMOLECULES 1
Carbohydrates
And Lipids
2
Lecture outline
- Polymers

• Carbohydrates
• monomers and polymers

- Lipids
3
Principles of Building Polymers

• biological polymers are built from simple small
  units called monomers

• addition of each monomeric unit occurs with the
• removal of a water molecule

A condensation dehydration reaction

• ends are chemically distinct
• directionality of synthesis

• requires energy input for polymerization
• uses carrier molecules to activate monomers

4
MODULAR DESIGN SIMPLICITY AND
VERSATILITY ASSEMBLY-LINE MENTALITY
Dont have to make every structure from
scratch Simplified chemistry, repeating link
Dehydration Synthesis
5
Monomers
H-XXXX-OH
H-YYY-OH
H-ZZZZZ-OH
Dehydration Synthesis make by taking water away
H-XXXX-
YYY-
ZZZZZ-OH
HOH
HOH
Polymer
6
Endless variety of Polymers Order of
Monomers Different Amounts of each monomer
H-XXXX-
YYY-
ZZZZZ-OH
H-YYY-XXXX-
ZZZZZ-OH
H-XXXX-
ZZZZZ-
YYY-OH
H-ZZZZZ-
YYY-
ZZZZZ-OH
7

• Monomers form larger molecules by condensation
  reactions called dehydration reactions

8

• Polymers can disassemble by
• Hydrolysis

9
Polymers
Monomers
10
CARBOHYDRATES Sugars and Sugar Derivatives
Polymers
Monomers
Polysaccharides
Monosaccharides
Simple Sugars Glucose Fructose
Ribose
Long chains of monomers
storage starch amylose amylopectin
glycogen structure Fiber cellulose
Oligosaccharides Informational structures
11
MONOSACCHARIDES Carbohydrate Monomers
O
O

• 1 Carbonyl - aldehyde or ketone

R-C-H R1-C-R2
R-OH

• All Other CARBONS
• each have ONE alcohol group

Expect them to be HYDROPHILIC
Aldo sugar
Keto sugar
12
Monosaccharides Vary in length 3, 4, 5,
6 or 7 carbons
13
Also differ by SPATIAL GEOMETRY
Carbon with 4 different functional groups
Chiral or asymmetric carbon handed carbon
14
Plane of symmetry
Left handed L form
Right handed D form
Stereoisomers not the same
15
Not chiral
Chiral
Chiral
Chiral
Chiral
Not chiral
16
Spatial Geometry yields a variety of forms
8 Forms!
17
5 and 6 Carbon Sugars CIRCULARIZE in Water To
FORM RINGS
Haworth projection
Fischer projection
18
(No Transcript)
19
Circularization causes another chiral carbon
b-D-Glucose
a-D-Glucose
20
monomeric sugars coupled together by
CONDENSATION REACTION
Glycosidic bond
Holds carbohydrates together
21
Synthesis Requires Energy Input
Breakdown Does not Require Energy Input
22
Disaccharides, Oligosaccharides and
Polysaccharides
(two)
(few)
(many)
Sucrose (glucose fructose) Cane Sugar Lactose
(glucosegalactose) Milk Sugar Maltose
(glucoseglucose) Beer
DiSaccharides
OligoSaccharides
Dextran (short chain of glucose) Digested Starch
Furans (short chain of fructose) Onions
23
Polysaccharides

• Long chains of Millions of monomers
• most common polymers made ONLY of GLUCOSE
  monomers
• Storage reserves
• Starch amylose
• amylopectin, glycogen
• Structure cellulose

24
(No Transcript)
25
Glycogen (or Amylopectin)
Polysaccharides of glucose chains in an a(1-gt4)
linkage, with a(1-gt6) branches
26
Structural Polysaccharides

• Cellulose
• Is also a polymer of glucose

• But has different glycosidic linkages than starch

• We can readily digest starches
• but cannot digest cellulose

27

• Cellulose is indigestable to animals
• Cows and termites have microbes in their stomachs
  to facilitate this process

28
Starches a glycosidic linkage OH down
Cellulose b glycosidic linkage OH up
29
Cellulose ß(1-gt4) linkage Amylose a(1-gt4)
linkage
30
(No Transcript)
31
Starch
Polysaccharides although hydrophillic are general
ly Insoluble in water
polymer effect

• orders too much water around polymer
• Polymer tends to hydrogen bond to itself
• Polymer falls out of solution

32
Polymer forms Secondary Structures Polymer
hydrogen bonding to Itself
33
If Denature Secondary Structure (Break Hydrogen
Bonds of Polymer with Itself) Water will
Hydrogen bond With Polymer
RESULT IS BOUND WATER GEL
34
Can FORCE polymer to stay Hydrated Sugar
Derrivatives

• Disrupt
• Secondary
• Structures
• remain
• Hydrated!

Characteristics?
35
Some Other Sugar Derivatives or Modified Sugars
Missing one or more components a. 5 carbon
RIBOSE and DEOXYRIBOSE
missing one alcohol b. Glycerol - 3 Carbon
Sugar with alcohol in place of an aldehyde c.
Sugar amines, Sugar acids have amine or
carboxylic acid group or something else in
place of an alcohol
a.
H
H
H
H
-
-
-
b.
H - C - C - C - H
-
-
-
OH
OH
OH
c.
36
Questions?
37
LIPIDS hydrophobic character
Steroids
Triglycerides
Phospholipids
Membranes Hormones
FATS OILS -long term storage depot
MEMBRANES
Other
Fatty Acids and Glycerol
38
Fatty Acid carboxylic acid with LONG hydrocarbon
chain
Chain length
saturation
39

• Fats
• Are constructed from two types of smaller
  molecules, a single glycerol and usually three
  fatty acids

H
H
H
H
H
H
H
H
O
H
H
H
H
H
H
H
H
Figure 5.11
(b) Fat molecule (triacylglycerol)
40
ESTER Linkage
41
Triglycerides
Properties in Water
42
FATS
OILS
WHY?
Like Fig 3-28
43

• Saturated fatty acids
• Have the maximum number of hydrogen atoms
  possible
• Have no double bonds

Stack nicely
44

• Unsaturated fatty acids
• Have one or more double bonds

Do not Stack well
45
monolayer
Free Fatty Acids Hydrolyzed Triglycerides
micelle
Fatty Acids
amphipathic
46
(No Transcript)
47
Phospholipids
Glycerol linked to 2 fatty acids
Fig 3-27
Phosphate
Head Group
Glycerol
Fatty acid tails
Fatty acid tails
Nonpolar
Polar
48

• Phospholipid structure
• Consists of a hydrophilic head and hydrophobic
  tails

49
Phospholipid Head Groups
Hydrophillic! Polar groups
50
Phospholipid Bilayer
Form Boundaries
51
WATER
Hydrophilic head
Polar Headgroups
Nonpolar FA tails
Hydrophobic tail
Polar Headgroups
WATER
Figure 5.14
52
Sheet
Outside
Inside
3-D Ball (Sphere) Vesicle or Liposome
Cross section
53
Hormones Signal molecules
54
Summary

• Principles of Building Polymers
• Directional assembly from simple units
• Requires energy input
• Condensation dehydration reactions
• Carbohydrates
• monosaccharides
• polysaccharides
• Lipids
• Triglycerides
• phospholipids
• steroids

55
Next Time More Macromolecules Proteins
Nucleic Acids