1. CHAPTER 3 The Structure and Function of Macromolecules
“You are what you eat!”

2. What does it mean to be a MACROmolecule?
You must be a large molecule with a complex structure
Macromolecule
“little” molecule

3. Most macromolecules are polymers, built from monomers
What is a polymer?
Poly = many; mer = part.
A long molecule made of monomers bonded together
What is a monomer?
Mono = one; mer = part
A monomer is a sub-unit (building block) of a polymer.

4. Three of the classes of life’s organic molecules are polymers
Carbohydrates, Proteins, Nucleic acids

5. Making Polymers How do monomers bind together to form polymers?
condensation or dehydration synthesis reactions occur (removal of water)

6. Breaking Polymers
How can polymers break down when monomers are needed?
Hydrolysis reaction
Hydro = water; lysis = break
“Water” is added to “break” the molecule apart

7. Hydrolysis

8. Classes of Organic Molecules:
Carbohydrates
Lipids
Proteins
Nucleic Acids

9. CARBOHYDRATES

10. What are Carbohydrates?
Sugars and their polymers
Carbo = carbon, hydrate = water; carbohydrates have the molecular formula (CH2O)n
Functions of Carbohydrates in living things:
Major fuel/energy source
Can be used as raw materials for other Macromolecules
Structural/building material in plants
What is the Carbohydrate Monomer?
Monosaccharide (“mono” = one; “saccharide” = sugar)

11. Structure of Monosaccharides
Contain only C, H, O
Hydroxyl group is attached to each carbon
One carbon contains a carbonyl group

13. In aqueous solutions many monosaccharides form rings:

14. Structure of Disaccharides
Consist of two monosaccharides
Are joined by a glycosidic linkage
What reaction forms the glycosidic linkage?
Dehydration synthesis

16. Polysaccharides
Structure: Polymers of a few hundred or a few thousand monosaccharides.
Functions:
energy storage molecules in animals
structural support in plants

18. Starch is a plant storage form of energy, easily broken down into glucose units

19. Glycogen is the animal short-term storage form of energy
Made up of many glucose monomers linked together

20. Cellulose is a fiber-like structural material made of glucose monomers used in plant cell walls

21. Why is Cellulose so strong? Why can we not break down cellulose?
Cellulose polymers are bonded together with different arrangements and bonds

23. Chitin is a polysaccharide used as a structural material in arthropod exoskeleton and fungal cell walls.

24. PROTEINS

25. Proteins What are Proteins?
Chains of amino acid monomers connected by peptide bonds
Have a 3 dimensional globular shape

26. Examples of Protein Functions
Immune System
Binding of antibodies (proteins) to foreign substances
Transport
Membrane transport proteins that move substances across cell membranes
Hemoglobin carries oxygen, iron, and other substances through the body.
Muscle Contraction
actin and myosin fibers that interact in muscle tissue.
Signaling
Hormones such as insulin regulate sugar levels in blood.

28. Amino Acids Monomers of polypeptides
Molecules with carboxyl and amino groups
Differ in their properties due to differing side chains, called R groups

29. 20 different amino acids exist
The sequence of amino acids and the interactions of the different amino acids determine a proteins shape

30. Peptide bonds connect amino acids to form polypeptide chains
One or more polypeptide chains make up a protein

31. Proteins are very complex
Proteins are very complex! Their specific structure determines their function.
HEMOGLOBIN: Transport of gases and iron in blood
ACTIN: Filament involved in muscle contraction

32. Sickle Cell Disease: A simple change in Primary Structure

33. Enzymes
Are a type of protein that acts as a catalyst, speeding up chemical reactions up to 10 billion times faster than they would spontaneously occur.

34. Environmental Factors That May Affect Protein Structures
Change in environment may lead to denaturation of protein (pH, temperature, salinity, etc.)
Denature = change in structure
Denatured protein is biologically inactive
Can renature IF primary structure is not lost

35. B. LIPIDS What are Lipids?
Fats, phospholipids, steroids, waxes, pigments
Hydrophobic (“hydro”=water; “phobic” = fearing)
Consist mostly of hydrocarbons
Do NOT consist of polymers

36. Functions of Lipids in living things:
Energy storage
membrane structure
Protecting against desiccation (drying out).
Insulating against cold.
Absorbing shocks.
Regulating cell activities by hormone actions.

37. Structure of Fats (Triglycerides)
Consist of a single glycerol and three fatty acids
Glycerol – an alcohol with three carbons
Fatty Acid - Long Hydrocarbon chains with a Carboxyl group at one end.

39. Saturated and Unsaturated Fats
(b) Unsaturated fat and fatty acid
cis double bond
causes bending
Oleic acid
Unsaturated fats :
one or more double bonds between carbons in the fatty acids allows for “kinks” in the tails
liquid at room temp
most plant fats
Saturated fats:
No double bonds in fatty acid tails
solid at room temp
most animal fats
(a) Saturated fat and fatty acid
Stearic acid

41. Saturated fatty acid

42. Why are Unsaturated Fats better for you than Saturated Fats?
Saturated fatty acid
Unsaturated fatty acid
Why are Unsaturated Fats better for you than Saturated Fats?

43. 3. Phospholipids
Structure: Glycerol + 2 fatty acids + phosphate group.
Function: Main structural component of membranes, where they arrange in bilayers.

44. Phospholipids in Water

45. 4. Waxes
Function:
Lipids that serve as coatings for plant parts and as animal coverings.

46. 5. Steroids Structure: Four carbon rings with no fatty acid tails
Functions:
Component of animal cell membranes (Ex: Cholesterol)
Modified to form sex hormones

47. NUCLEIC ACIDS

48. D. Nucleic Acids : The stuff of Genes
Nucleic acids store and transmit hereditary information
Genes
Are the units of inheritance
Program the amino acid sequence of polypeptides
Are made of nucleic acids

49. Two Kinds of Nucleic Acids
DNA (Deoxyribonucleic acid)
double stranded
can self replicate
makes up genes which code for proteins is passed from one generation to another
RNA (Ribonucleic acid)
single stranded
functions in actual synthesis of proteins coded for by DNA
is made from the DNA template molecule

51. Nucleotide Monomer Structure
Both DNA and RNA are composed of nucleotide monomers.
Nucleotide = 5 carbon sugar, phosphate, and nitrogenous base
Deoxyribose in DNA
Ribose in RNA

53. 2. Building the Polymer
Phosphate group of one nucleotide forms strong covalent bond with the #3 carbon of the sugar of the other nucleotide.

54. DNA:
Double helix
2 polynucleotide chains wound into the double helix
Base pairing between chains with H bonds
A - T
C - G

55. Summary of the Organic Molecules: