1. Molecules of Life
Dr. Anderson
GCIT

2. Cells and Molecules Atoms Molecules Organic Molecules Polymers
Carbohydrates
Lipids
Proteins
Nucleic Acids

3. Molecules Other important molecules to life O2 CO2 Ions
Ca, I, Cl-, Fe+, Na+, K+, etc.
Why are these important?

4. Bonding Covalent Bonds Ionic Bonds Electrons are shared between atoms
Electrons are “donated” to atoms depending on their electronegativity

5. Covalent Bonds Covalent bonds are much stronger and difficult to break
CAN be manipulated in the body using enzymes, which lower the activation energy needed for chemical reaction to occur
Creating bonds (building molecules) – anabolism
Breaking bonds (splitting molecules) - catabolism

6. Molecular Characteristics
Polar Covalent – unequal sharing of electrons around the molecule
Results in slightly positive or negative “ends”
Examples?
Non-polar Covalent– equal sharing of electrons around the molecule
Equal distribution of charge around the molecule

7. Ionic Bonds
The “donation” of an electron changes the charges between molecules
Separation of these charges and their recombination leads to electric charge!
How can this happen?
Where does this happen in the human body?

8. Ionic Bond Disassociation
In water, ionic bonds can be separated so that the individual ions (atoms) go into solution
Examples?
NaCl Na Cl-

9. Organic Molecules
Contain carbon
Carbohydrates
Lipids
Proteins

10. Carbohydrates Made of C, H, and O Sugars Starches Monosaccharides
Disaccharides
Starches
Polymers of sugars
Monomer
Polymer

11. Lipids Made of C, H, O How are fats different from carbohydrates?
Saturated
Unsaturated
Triglyceride

12. Special Lipids Phospholipids Steroids Eicosanoids
Make up cell membranes
Steroids
Hormones, cholesterol
Eicosanoids
Immune responses, blood clotting, etc.

13. Proteins Made of H, C, N, O, S Polymers of amino acids
Extremely complex!!
Examples?
Shape dictates function in proteins
Can protein molecules change shape?

14. Primary Structure
Simple peptides – simple “string” of amino acids”

15. Secondary Structure Alpha-helices Beta-pleated sheets
Bonds between the “chains” form these structures
Beta-pleated sheet

16. Tertiary Structure Helices and Sheets cause a complex structure
Globular proteins
What affects the shape?

17. Quaternary Structure
Multiple polypeptide structures combine to form a functional protein

18. Protein Shape What affects the shape of a protein?
What does the shape of a protein affect?
“Lock and Key” - enzymes

19. Enzymes Protein molecules that catalyze chemical reactions
Can either synthesize or decompose molecules

20. Steps in Enzymatic Action
1. The enzyme’s active site bonds with the substrate to make the enzyme-substrate complex
2. Enzyme undergoes internal rearrangements to initiate the reaction
3. Products are formed and released

21. Examples of Enzymes - Catabolism
Often end in
“–ase”
Lipase
Protease
Fructase
Enzyme
Breaks down polymers into monomers to be used by cells in the body! (Catabolism)

22. Examples of Enzymes - Anabolism
Dehydration Synthesis
Water is produced when bond is made

23. Nucleic Acids DNA RNA Proteins
The “blueprint of life” – the order of monomers in the DNA molecule is the key
DNA and RNA – polymers of sugar, nitrogen bases and phosphates
This is the core of to the central dogma of biology
DNA RNA Proteins

24. DNA (Deoxyribonucleic Acid)

25. RNA Created from DNA Also a polymer
Acts as a messenger to encode genetic information for protein synthesis

26. Important Biological Chemical Reactions
Synthesis – combination of smaller molecules or atoms into larger molecules
Decomposition – Breaking a large molecule into smaller ones
Exchange Reactions – parts of molecules exchanged with others

27. Synthesis Reaction (Dehydration Synthesis)
A + B AB
e.g. - Sugar into starch

28. Decomposition Reaction
Hydrolysis – water is used to separate amino acids from proteins (peptides)
Protein
Ala
Lys
Arg
Phe
Trp
Leu
H2O + enzyme
Free amino acid

29. Exchange Reactions Molecular Partners are “swapped”
E.g. Photosynthesis
CO2 + H2O C6H12O6 + O2
Solar Energy
What is the opposite of this reaction?

30. What affects chemical reaction rates?
Temperature – increases in temperature cause an increase in molecular motion, leading to faster reactions
The amount of reactants – reaction can be limited because there are not enough raw materials
pH – highly acidic or alkaline (basic) environments can increase or decrease reaction rates, depending on the specific reaction

31. Example – Enzymes and pH
Where is the enzyme activity highest? Where is it lowest? Why?

32. Temperature Limited Reaction
Asymmetrical activity curve
Why asymmetrical?

33. Reactant-Limited Reactions
In this example, an enzyme is mixed with the substrate that it breaks down.
What is the limiting factor here?

34. ATP – Rechargeable Cellular Battery
Energy is stored in the phosphate bonds of ATP
When bonds are broken, (ATP ADP) energy is released
When bonds are made (ADP ATP) energy is stored