1. The Structure and Function of Macromolecules
Chapter 5

2. Goals Explain how polymers are built from monomers and vice versa.
Identify the names, properties, functions, and examples of the 4 major groups of macromolecules
Discuss the 4 levels of protein structure.

3. Polymers and Monomers
Polymers are long chain molecules made of repeating subunits called monomers.
Example: Starch is a polymer composed of glucose monomers
Proteins are polymers composed of amino acid monomers

4. Making and Breaking Polymers
Dehydration Synthesis creates polymers from monomers.
Two monomers are joined by removing one molecule of water (dehydration)
Hydrolysis occurs when water is added to split large molecules
A polymer is separated into its monomers by adding water

5. Types of Macromolecules
Carbohydrates
Lipids
Proteins
Nucleic Acids

6. 1. Carbohydrates
Carbohydrates include both simple sugars (glucose, fructose, galactose, etc.) and polymers such as starch made from these and other subunits.
All carbohydrates exist in a ratio of 1 carbon: 2 hydrogen: 1 oxygen or CH2O
Ex) C6H12O6

7. Monosaccharides are the monomers of carbohydrates.
“Simple sugars”
Examples include glucose C6H12O6 and ribose C5H10O5
Notice the 1:2:1 ratio above
A disaccharide is formed when dehydration synthesis joins two monosaccharides
This covalent bond is called a glycosidic linkage
Sucrose (table sugar) = glucose + fructose
Polysaccharides are long polymers of monosaccharides.
Examples are starch and glycogen (both storage), and cellulose (structural)

8. Dehydration Synthesis of Carbs

9. Functions of Polysaccharides
Source of energy for your cells
Energy Storage
Starch is a storage polysaccharide found in plants (potatoes, fruits)
Glycogen is a storage polysaccharide found in animals, vertebrate muscle, and liver cells
Structural Support
Cellulose is a major component of plant cell walls
Chitin is found in the exoskeleton of arthropods, such as lobsters and insects and the cell walls of fungi
It gives bugs their “crunch”
Used for surgical thread

10. 2. Lipids Lipids are all hydrophobic
They aren’t polymers, as they are assembled from a variety of components.
Examples: waxes, oils, fats, and steroids

11. Lipids: Fats
Fats (also called triglycerides) are made up of a glycerol molecule and three fatty acid molecules
Fatty acids include hydrocarbon chains of variable lengths.
These chains are nonpolar and therefore hydrophobic
Fatty acids vary in length (number of carbons) and in the number and locations of double bonds

12. Dehydration Synthesis of Fats

13. Saturated vs. Unsaturated
Have no double bonds between carbons
Tend to pack solidly at room temperature
Are linked to cardiovascular disease
Are commonly produced by animals
Examples: butter and lard
Unsaturated
Have some C=C (carbon double bonds); this results in kinks
Tend to be liquid at room temperature
Are commonly produced by plants
Examples: corn oil and olive oil

14. Lipids: Phospholipids
Phospholipids make up cell membranes
Have a glycerol (head), which is hydrophilic
Have two fatty acid tails, which are hydrophobic
Are arranged in a bilayer in forming the cell membrane.
With the hydrophilic heads pointing toward the watery cytosol or extra-cellular environment
The hydrophobic tails are sandwiched in between

15. Lipids: Steroids Steroids are made up of 4 rings fused together
Cholesterol is a steroid
It is a common component of cell membranes
Estrogen and testosterone are steroid hormones
They control the female and male reproductive systems

16. Functions of Lipids Fats Phospholipids Steroids Energy storage
Fats store twice as many calories/gram as carbohydrates!
Protection of vital organs and insulation.
In humans and other mammals fat is stored in adipose cells.
Phospholipids
Cell membrane structure
Steroids
Hormones
Cholesterol helps keep cell membranes flexible

17. 3. Proteins Proteins are polymers made up of amino acid monomers
Amino acids contain a central carbon bonded to a carboxyl group, an amino group, a hydrogen atom, and an R group (variable group or side chain which determines function)
Peptide bonds link amino acids
They are formed by dehydration synthesis
The function of a protein depends on the order and number of amino acids

18. Dehydration Synthesis of Proteins
H2O
Carboxyl Group
Amino Group
Peptide Bond

19. Four Levels of Protein Structure
The primary structure of a protein is its unique sequence of amino acids (polypeptide chain)
Secondary structure consists of coils and folds in the polypeptide chain due to hydrogen bonding
Alpha helix and Beta pleated sheet
Tertiary structure is determined by interactions among various side chains (R groups)
Quaternary structure results when multiple polypeptide chains come together forming a protein

20. More on Proteins… Protein shape is crucial to protein function.
When a protein does not fold properly, its function is compromised.
This can be the result of a single amino acid substitution, such as that seen in the abnormal hemoglobin, typical of sickle-cell disease
Chaperonins are protein molecules that assist in the proper folding of proteins within cells.
Denaturation occurs when a protein loses shape and ability to function because of heat, change in pH, or some other disturbance. (Not due to a mutation)

21. (Occurs because of base substitution)
Sickle Cell Anemia
(Occurs because of base substitution) C T G A
Val-His-Leu-Thr-Pro-Glu-Glu-Lys C A T G U
Val-His-Leu-Thr-Pro-Val-Glu-Lys

22. Proteins: Enzymes
Enzymes are a type of protein that act as a catalyst to lower the activation energy or a reaction and speed it up
Enzymes can perform their functions repeatedly, functioning as workhorses that carry out the processes of life

23. Functions of Proteins Structure – hair, nails, etc.
Carriers – transport molecules through body
Enzymes – chemical reactions
Protect against disease
Receive signals from outside cell
Cell movement
Function typically depends on its ability to recognize and bind to some other molecule.

24. 4. Nucleic Acids
Nucleic acids store and transmit hereditary information
DNA (deoxyribonucleic acid) and RNA (ribonucleic acid) are the two nucleic acids
Their monomers are nucleotides
Nucleotides are made up of three parts
Nitrogenous base (adenine, thymine, cytosine, guanine, and uracil)
Pentose (5 carbon) sugar (deoxyribose in DNA or ribose in RNA)
Phosphate group

25. Pyrimidines vs. Purines
Purines Pyrimidines

26. DNA vs. RNA
DNA is the molecule of heredity – contains the code for amino acid sequence of proteins
It is a double-stranded helix
Its nucleotides are adenine, thymine, guanine, and cytosine
Adenine nucleotides will hydrogen bond to thymine nucleotides, and cytosine to guanine
RNA makes proteins
It is single stranded
Its nucleotides are adenine, uracil, cytosine, and guanine
Note that there is no thymine

27. Function of Nucleic Acids
DNA
molecule of heredity
contains the code for amino acid sequence of proteins
RNA
makes proteins