1. The Chemical Building Blocks of Life
CHAPTER 3

2. Molecules and atoms from the environment are necessary to build new molecules
Carbon moves from the environment to organisms where it is used to build carbohydrates, proteins, lipids or nucleic acids.
Carbon is used in storage compounds and cell formation in all organisms.
Nitrogen moves from the environment to organisms where it is used in building proteins and nucleic acids.
Phosphorus moves from the environment to organisms where it is used in nucleic acids and certain lipids.

3. Carbon is the framework of organic molecules
Carbon forms 4 covalent bonds
Carbon-based molecules form a variety of structures:
Linear chains
Rings
Branches
Hydrocarbons (carbon and hydrogen chains) are relatively stable at body tempoeratures

4. Carbon Functional Groups
Functional groups contain other atoms with different electronegativities
Functional groups can be polar, non-polar, acidic, basic, and charged
The chemical properties of functional groups determine the structure and function of biological molecules

5. Carbon Functional Groups
Amino

6. Carbohydrates, proteins, lipids, and nucleic acids form polymers
The subcomponents of biological molecules and their sequence determine the properties of that molecule.
The structure and function of polymers are derived from the way their monomers are assembled.
Polymers are long molecules built by linking smaller similar subunits (monomers)
Carbohydrates, proteins, lipids, and nucleic acids form polymers
All macromolecules can be formed by the process of dehydration synthesis
Water is removed from two monomers as they form a polymer
All macromolecules can be digested by the process of hydrolysis
Water is added and a polymer disassemble into monomers

7. Dehydration Synthesis

8. Hydrolysis – molecules are hydrolyzed by hydrolytic enzymes

9. Carbohydrates
Carbohydrates are composed of sugar monomers whose structures and bonding with each other by dehydration synthesis determine the properties and functions of the molecules.
Glucose is the most common carbohydrate monomer
Other monomers:
Ribose
Deoxyribose
Fructose
Glyceraldehyde
Monomer carbohydrates functions:
Energy release
Subunits of larger polymers such as RNA, DNA, starch, cellulose, and glycogen

10. Carbohydrates Polymers
Disaccharides – contain two carbohydrate monomers
Maltose
Sucrose
Lactose
Polysaccharides – contain three or more carbohydrate monomers
Structural Polysaccharides
Cellulose – forms cell walls of plants
Chitin – forms cell walls of fungi and insect exoskeletons
Storage Polysaccharides
Starch – stores energy in plants
Glycogen – stores energy in animal tissues (liver and muscles)

11. Carbohydrate Polymers
Note the individual monomers
Cellulose has a slightly different bonding pattern which forms rigid fibers
Glycogen is branched
Starch and glycogen are more flexible

12. Lipids Generally non-polar molecules with hydrocarbon chains
Most lipids are hydrophobic
Contain fatty acid chains
Exist as saturated or unsaturated fatty acids
Form solids fats Form soft fats and oils

13. Lipids
Saturated and unsaturated fatty acids

14. Lipids Non-polar lipids Polar Lipids Triglycerides – energy storage
Waxes – waterproofing; cuticles on plants and insects
Oils – protection; prevent water loss
Steroids – form hormones and vitamins
Polar Lipids
Phospholipids
Contain polar and non-polar regions
Form membranes – separate two aqueous solutions

15. Lipids
Triglycerides

16. Lipids
Phospholipid Structure

17. Lipids
Steroids
Aromatic rings with short fatty acid chains

18. Nucleic Acids
Nucleic acids biological information is encoded in sequences of nucleotide monomers.
Each nucleotide has 3 structural components:
five-carbon sugar (deoxyribose or ribose),
phosphate
nitrogen base
(adenine, thymine, guanine, cytosine or uracil).
DNA and RNA differ in function and differ slightly in structure, and these structural differences account
for the differing functions.

19. Nucleic Acids DNA Structure
Double helix – two polymer chains linked by hydrogen bonds between nitrogenous bases
Adenine links with Thymine (or Uracil in RNA)
Cytosine links with Guanine
Phosphates form strong covalent bonds with the deoxyribose sugar
Forms a sugar-phosphate backbone
Phosphodiester bonds hold backbone in place
Benefits of DNA structure
permits easy replication
Provides a stable structure to maintain genetic sequences

20. Nucleic Acids
DNA Structure in Detail

21. Nucleic Acids RNA Structure Single stranded polymer of nucleotides
Five types of RNA with different functions
mRNA – complementary copy of a DNA base sequence
rRNA – forms ribosome
tRNA – carries amino acids
snRNA – processes RNA in eukaryotes only
preRNA – newly formed RNA in eukaryotes only
Limited base-pairing
Present in some forms of RNA
Ribose is the 5-carbon sugar
Uracil replaces Thymine as a nitrogenous base

22. Nucleic Acids
RNA Structure

23. Proteins Polymers comprised of amino acid sequences
The specific order of amino acids in a polypeptide (primary structure) interacts with the environment to determine the overall shape of the protein
Proteins structure involves secondary, tertiary and quaternary structure and function.
The R group of an amino acid can be categorized by chemical properties (hydrophobic, hydrophilic, and ionic)
R group interactions determine the structure and function of that region of the protein.

24. Proteins
Proteins have an amino (NH2) end and a carboxyl (COOH) end and consist of a linear sequence of amino acids

25. Proteins
Amino acids are connected by the formation of peptide bonds by dehydration synthesis between the amino and carboxyl groups of adjacent monomers

26. Proteins
Proteins form several different structures as a result of R group interactions

27. Proteins

28. Proteins
Tertiary Structure

29. Proteins
Quaternary proteins contain 2 or more polypeptide chains

30. Protein Denaturing Excessive heat or pH can alter protein structure
Why do proteins denature?
Hydrogen bond interactions are disrupted and the protein changes shape