1. The Structure and Function of Large Biological Molecules
Chapter 5
The Structure and Function of Large Biological Molecules

2. You Must Know
The role of dehydration synthesis in the formation of organic compounds and hydrolysis in the digestion of organic compounds.
How to recognize the 4 biologically important organic compounds (carbs, lipids, proteins, nucleic acids) by their structural formulas.
The cellular functions of all four organic compounds.
The 4 structural levels of proteins
How proteins reach their final shape (conformation) and the denaturing impact that heat and pH can have on protein structure

3. ie. amino acid  peptide  polypeptide  protein
Monomers
Polymers
Macromolecules
Small organic
building blocks of polymers
Connects with condensation reaction (dehydration synthesis)
Long molecules of monomers
With many identical or similar blocks linked by covalent bonds
Giant molecules
2 or more polymers bonded together
ie. amino acid  peptide  polypeptide  protein
larger
smaller

4. Dehydration Synthesis (Condensation Reaction)
Hydrolysis
Make polymers
Breakdown polymers
Monomers  Polymers
Polymers  Monomers
A + B  AB
AB  A + B
+ H2O +
+ H2O +

5. How to build a polymer Synthesis joins monomers by “taking” H2O out
one monomer donates OH–
other monomer donates H+
together these form H2O
requires energy & enzymes
H2O HO H
enzyme
Dehydration synthesis
Condensation reaction 5

6. Dehydration Synthesis (Condensation Reaction)
Hydrolysis
Make polymers
Breakdown polymers
Monomers  Polymers
Polymers  Monomers
A + B  AB
AB  A + B
+ H2O +
+ H2O +

7. How to break down a polymer
Breaking up is hard to do!
Digestion
use H2O to breakdown polymers
reverse of dehydration synthesis
cleave off one monomer at a time
H2O is split into H+ and OH–
H+ & OH– attach to ends
requires enzymes
releases energy
H2O HO H
Most macromolecules are polymers
• build:
condensation (dehydration) reaction
• breakdown:
hydrolysis
An immense variety of polymers can be built from a small set of monomers
enzyme
Hydrolysis
Digestion 7

8. Condensation reaction

9. Differ in position & orientation of glycosidic linkage
I. Carbohydrates
Fuel and building material
Include simple sugars (fructose) and polymers (starch)
Ratio of 1 carbon: 2 hydrogen: 1 oxygen or CH2O
monosaccharide  disaccharide  polysaccharide
Monosaccharides = monomers (eg. glucose, ribose)
Polysaccharides:
Storage (plants-starch, animals-glycogen)
Structure (plant-cellulose, arthropod-chitin)
Glucosidic linkage
Differ in position & orientation of glycosidic linkage

10. The structure and classification of some monosaccharides

11. Linear and ring forms of glucose

12. Carbohydrate synthesis

13. Cellulose vs. Starch
Two Forms of Glucose:  glucose &  glucose

14. Cellulose vs. Starch Starch =  glucose monomers
Cellulose =  glucose monomers

15. Storage polysaccharides of plants (starch) and animals (glycogen)

16. Structural polysaccharides: cellulose & chitin (exoskeleton)

17. II. Lipids Fats (triglyceride): store energy
Glycerol + 3 Fatty Acids
saturated, unsaturated, polyunsaturated
Steroids: cholesterol and hormones
Phospholipids: lipid bilayer of cell membrane
hydrophilic head, hydrophobic tails
Hydrophilic head
Hydrophobic tail

19. Have some C=C, result in kinks
Saturated
Unsaturated
Polyunsaturated
“saturated” with H
Have some C=C, result in kinks
In animals
In plants
Solid at room temp.
Liquid at room temp.
Eg. butter, lard
Eg. corn oil, olive oil

20. Cholesterol, a steroid

21. The structure of a phospholipid

22. Hydrophobic/hydrophilic interactions make a phospholipid bilayer

24. III. Proteins “Proteios” = first or primary 50% dry weight of cells
Contains: C, H, O, N, S
Myoglobin protein

25. Protein Functions (+ examples)
Enzymes (lactase)
Defense (antibodies)
Storage (milk protein = casein)
Transport (hemoglobin)
Hormones (insulin)
Receptors
Movement (motor proteins)
Structure (keratin)

26. Overview of protein functions

27. Overview of protein functions

28. Four Levels of Protein Structure
Primary
Amino acid (AA) sequence
20 different AA’s
peptide bonds link AA’s

29. Amino Acid “amino” : -NH2 “acid” : -COOH R group = side chains
Properties:
hydrophobic
hydrophilic
ionic (acids & bases)
“amino” : -NH2
“acid” : -COOH

32. Four Levels of Protein Structure (continued)
Secondary
Gains 3-D shape (folds, coils) by H-bonding
Alpha (α) helix, Beta (β) pleated sheet

33. Basic Principles of Protein Folding
Hydrophobic AA buried in interior of protein (hydrophobic interactions)
Hydrophilic AA exposed on surface of protein (hydrogen bonds)
Acidic + Basic AA form salt bridges (ionic bonds).
Cysteines can form disulfide bonds.

34. Four Levels of Protein Structure (continued)
Tertiary
Bonding between side chains (R groups) of amino acids
H bonds, ionic bonds, disulfide bridges, van der Waals interactions

35. Four Levels of Protein Structure (continued)
Quaternary
2+ polypeptides bond together

36. amino acids  polypeptides  protein
Bonding (ionic & H) can create asymmetrical attractions

37. Chaperonins assist in proper folding of proteins

38. Protein structure and function are sensitive to chemical and physical conditions
Unfolds or denatures if pH and temperature are not optimal

39. change in structure = change in function

40. Function: store hereditary info
IV. Nucleic Acids
Function: store hereditary info
DNA
RNA
Double-stranded helix
N-bases: A, G, C, Thymine
Stores hereditary info
Longer/larger
Sugar: deoxyribose
Single-stranded
N-bases: A, G, C, Uracil
Carry info from DNA to ribosomes
tRNA, rRNA, mRNA, RNAi
Sugar: ribose

41. Nucleotides: monomer of DNA/RNA
Nucleotide = Sugar + Phosphate + Nitrogen Base

42. Nucleotide phosphate A – T Nitrogen G – C base 5-C sugar Purines
Pyrimidines
Adenine
Guanine
Cytosine
Thymine (DNA)
Uracil (RNA)
Double ring
Single ring
5-C sugar

44. Information flow in a cell: DNA  RNA  protein