1. The Molecules of Life: Structure and Function

2. Objective To understand the structure and function of biomac-
romolecules and to be able to identify them
based on their characteristics.
Essential Question: What are the molecules of life, what
are their general structures, and functions?

3. Molecules of Life “Biomacromolecules”
Carbohydrates
Lipids
Proteins
Nucleic Acids
These make up cells and can be used by cells for energy

4. Polymers vs. Monomers Poly = many; Mer = part Mono = one
In biology, a polymer is a large molecule consisting of many smaller sub-units (often repeated) bonded together.
Mono = one
A monomer is a sub-unit (single unit) of a polymer.

5. Making a Polymer Dehydration Synthesis reactions
Monomers bond to one another through the removal of water.
Why?
Stores energy
Conserves space

6. Breaking a Polymer Hydrolysis Reactions
hydro = water lysis = to break or lyse
Polymers are broken down into monomers with the use of water.
Why?
Access energy
To build new polymers

7. Carbohydrates Each “carbon” is surrounded by a “hydrate” (water)
Molecular formula (C H2 O)n
Store energy in chemical structure
Glucose
most common monosaccharide
produced by photosynthetic autotrophs
Each “carbon” is surrounded by a “hydrate” (water)

8. Carbohydrates are classified according to the size of their carbon chains, varies from 3 to 7 carbons
Triose = 3 carbons
Pentose = 5 carbons
Hexose = 6 carbons

9. In aqueous solutions, many monosaccharides form rings:

10. Disaccharides
“Double sugar” consisting of 2 monosaccharides joined by a glycosidic linkage.
What reaction forms the glycosidic linkage?

11. Example Disaccharides
Sucrose = glucose + fructose
Lactose = glucose + galactose

12. Polysaccharides
Polymers of a few hundred or a few thousand monosaccharides
Function as energy storage molecules or for structural support

13. Example Carbohydrates
Starch = a plant storage from of energy, easily hydrolyzed to glucose units. Polysaccharide.
Cellulose = a fiber-like structural material; tough and insoluble. Used in plant cell walls. Polysaccharide.
Glycogen = a highly branched chain in animals to store energy in muscles and the liver. Polysaccharide.
Chitin = used as a structural material in arthropod exoskeleton and fungal cell walls. Polysaccharide.
Lactose = found in milk and dairy products. Disaccharide.
Glucose = simplest sugar; used by mitochondria in all cells for energy. Feeds brain. Monosaccharide.

14. Lipids Large molecules Diverse in structure
Nonpolar, so insoluble in water
Store energy in chemical structure
Groups: Fats, oils, phospholipids, sterols, waxes

15. Structure of Fatty Acids
Long chains of mostly carbon and hydrogen atoms with an acid (-COOH) group at one end
Resemble long flexible tails

16. Saturated vs. Unsaturated Fats
liquid at room temp
one or more -C=C- (double bonds) between carbons causing “kinks” in the tails
most plant fats
Saturated fats:
solid at room temp
only single C-C bonds in fatty acid tails
Carbons fully surrounded (“saturated”) with H’s
most animal fats

17. Structure of Triglycerides
1 glycerol + 3 fatty acids
Fatty acids and glycerol bound together by ester bonds.
Found in food (oils and fats); long term energy storage

18. Structure of Phospholipids
1 glycerol + 2 fatty acids + phosphate group.
Connected by “phosphodiester” bond
Main structural component of cell membranes, where they arrange in bilayers.

19. Waxes
Lipids that serve as coatings for plant parts and as animal coverings. Prevents dessication due to insolubility in water.

20. Steroids Four carbon rings with no fatty acid tails
Component of animal cell membranes (cholesterol)
Modified to form sex hormones (estrogen, testosterone)

21. Which lipids provide these functions?
Functions of Lipids
Which lipids provide these functions?
Energy storage
Membrane structure
Protecting against desiccation (drying out)
Insulating against cold
Absorbing shock
Regulating cell activities by hormone actions

22. Proteins 3-dimensional “globular” shape
Consist of many peptide bonds between 20 possible amino acid monomers, made by dehydration synthesis
Polypeptide = “many” “peptide bond”s; A chain of amino acids

23. Structure of Amino Acids
Amino acids = monomers
Consist of an asymmetric carbon bonded to:
Hydrogen
Amine group
Carboxyl (acid) group
Variable R group specific to each amino acid

24. Properties of Amino Acids
Grouped by polarity
Variable R groups (“side chains”) confer different properties to each amino acid

25. Example Proteins Enzymes Muscle Contraction
Accelerate specific chemical reactions
Structure
keratin - found in hair and nails
collagen - found in connective tissue
Muscle Contraction
actin and myosin fibers that interact in muscle tissue

26. Example Proteins Immune System Function Carriers
Antibodies recognize and flag foreign substances.
Carriers
Membrane transport proteins move substances across cell membranes
Blood proteins (hemoglobin) carry oxygen throughout the body
Signaling and Communication
Hormones such as insulin (regulate blood sugar levels) and adrenaline (increase heart rate to adjust to needs) used to help body respond

27. Recap: Discuss with your group…
Carbohydrate Functions:
Examples include:
How?
Lipid Functions:
Protein Functions:

28. http://www. youtube. com/watch

29. How to make a Protein in 4 easy steps!
Primary Structure
Secondary Structure
Tertiary Structure
Quaternary Structure

30. Primary Structure
Sequence of amino acids in a protein, bonded by peptide bonds
This creates the “polypeptide”

31. Let’s Model the Primary Structure: Salivary Amylase
Observe the properties of the 20 Amino Acids.
What do the different colors represent?
How do you think they would interact?

32. Make this Primary Sequence:
MSDKRCTYPCAENQ
Make this Primary Sequence:
Place amino acids about 1 inch apart (2 finger widths) and fold pieces
White = polar/hydrophilic
Yellow = nonpolar/hydrophobic
Blue = basic (+ charged)
Red = acidic (- charged)
Green = “sulfur R-group” (bonds only Cysteines)

33. Secondary Structure Repeated folding of backbone of polypeptide
How? H bonds form between atoms in backbone
2 types: a-helix, b-pleated sheets

34. Let’s model Secondary Structure
Look at your string of amino acids.
What do the different colors represent?
Note the order of colors.
Take the “backbone” and create some a-helices and some b-pleated sheets.

35. Tertiary Structure
Behavior of R groups determines folding of polypeptide
How? Interactions between R groups

36. Let’s model Tertiary Structure
Note the colors on your polypeptide.
White = polar/hydrophilic
Yellow = nonpolar/hydrophobic
Blue = basic (+ charged)
Red = acidic (- charged)
Green = “sulfur R-group” (bonds only Cysteines)

37. Quaternary Structure 2 or more polypeptides bonded together
How? Attraction between backbones and R groups of neighboring globs

38. Let’s model Quaternary Structure
Find a neighbor, and attach R groups that might be attracted to each other. What types would?

41. Factors That May Impact Protein Folding
Depends on physical conditions of environment
pH, temperature, salinity, etc.
Change in environment may lead to denaturation of protein
Denatured protein is biologically inactive
Can renature if primary structure is not lost
What happens when protein folding goes wrong?

42. Your Tasks Protein Activity Wrap Up
Stamps for journal activity (models)
Draw your last diagram!
Homework due Thursday The Structure and Function of Macromolecules Reading (linked to website) and WS