Biochemical Reactions

1. Biochemical Reactions The chemical reactions associated with biological processes

2. Learning Focus • To identify and describe the 4 main types of biochemical reactions: • neutralization, • oxidation-reduction, • condensation, and • hydrolysis reactions

3. What is a biological Rx? • Any ideas? Generally 3 broad categories… • metabolic rx – any reaction in a living system. • Anabolic rx – reactions that produce larger molecules. • Catabolic rx – reactions that breakdown larger molecules.

4. 1. Acid-Base (neutralization rx) • Neutralization Rx is a chemical reaction that occurs between an acid and a base (reactants), that results in water and a salt (products) • Result – the acidic and basic properties of the aqueous solution where the reaction took place are nullified (i.e. cancelled out)

5. Acid/Bases review: • Review – what is an acid? • A substance that produces hydrogen ions (H+) when it dissolves in H2O • What is a base? • A substance that produces hydroxide ions (OH-) when it dissolves in H2O • Note: a base can also be defined as a substance that accepts or reacts with H+

6. pH scale review: • Review – what is the pH scale? Take a second to define and describe it. • It’s a numerical scale ranging from 0 – 14 that is used to classify aqueous solutions as acidic, basic, or neutral.

7. What is considered to be normal? • The normal pH range of blood is 7.35 – 7.45 • Given this is blood considered to be acidic or basic (alkaline)? • What do you think the consequence is of blood pH falling below 7.0 or above 7.8? • Acidosis (7.3 or lower) versus alkalosis (7.5 or higher) • (you tube: precision nutrition kitchen tip)

8. Consequences of pH imbalance • With a pH higher or lower than normal range, blood cells will be damaged. • Acids can denature or change the shape of proteins, same with heat or high temperature • Strong acids and lemon juice can be used to cook fish (cheviche) and eggs • Bases make oils and fats to fall apart. - e.g. bile in digestion; oven cleaners contain lye, a strong base that dissolve grease and burn fats in ovens

9. Acid-base reactions in living organisms • What do living cells use to resist changes in pH? (i.e. how do organisms neutralize acidic or basic environments?) • Buffers! • A substance that minimizes changes in pH by donating or accepting hydrogen ions as needed

10. Acid-base reactions in living organisms • Buffers are chemical systems that contain a substance that can donate H ions when they are required and contain a substance that can remove H ions when they are too many in solutions • Buffers usually consist of conjugate acid-base pairs in equilibrium • Carbonic acid – bicarbonate buffer is important in human extracellular fluid

11. Let’s take a look at the questions you answered so long ago!Pg. 23

12. 2. Oxidation-reduction (Redox) Rx • reactions involving electron transfer

13. Redox Reactions • Oxidation = chemical reaction where an atom loses electrons • Reduction = chemical reaction where an atom gains elections • Therefore a REDOX reaction = a chemical reaction that involves the transfer of electrons from on substance to another

14. Redox Reactions • How to remember what happens? • Use mnemonic: LEO GER Loss Gain Electron Electron Oxidation Reduction LEO the lion says GER

15. Redox Reactions Reducing Agent – substance that LOSES electrons; it causes the other substance to be reduced Oxidizing Agent – substances that GAIN electrons; it causes the other substance to be oxidized e.g. C3H8+ 5O2 3CO2 + 4H2O + energy Combustion of propane

16. Redox in the Cell Many metabolic processes consist of chains of redox reactions. A- B- C- D- D A B C e.g. C6H12O6 + 6O2 6CO2 + 6H2O + energy

17. 3. Condensation Rx • Involved in the assembly of all four types of biological macromolecules (as are Hydrolysis Rx) = a chemical rx that results in the formation of a covalent bond between two molecules with the production of a water molecule

18. Condensation Rx

19. 3. Condensation Rx • Because the reaction involves a release of water, condensation rx are also called dehydration reactions • Always involves the removal of a H atom from the functional group of one monomer (or subunit) and an –OH from the other monomers (or subunits) functional group • This type of reaction alwaysabsorbs energy • Also considered to be an anabolic reaction = synthesis of molecules

20. Anabolic Rx in Nucleic Acids • bond that forms from the dehydration reaction between 2 (or more) nucleotides is called a phosphodiester linkage; • occurs between the –OH group of one nucleotide, and the phosphate group of the next + H2O

21. Anabolic rx in carbs glucose fructose sucrose • bond that forms from the dehydration reaction is a glycosidicbond; occurs between an –OH group on each molecule involved in the reaction

22. Anabolic rx in fats glycerol + 3 fatty acid  fat (triglyceride)

23. Anabolic rx in fats • bond that forms from the dehydration reaction in the creation of a fatty acid is an ester linkage; occur between the –OH group on a glycerol molecule and the –COOH group on a fatty acid

24. Anabolic Rx in Proteins • bond that forms from the dehydration reaction between 2 (or more) Amino acids is called a peptide linkage or bond; occurs between the carboxyl of one AA and the amino group of another

25. 4. Hydrolysis Rx • Involved in the breakdown of macromolecules into their monomers (smaller subunits) = a chemical rx that results in the cleavage of a covalent bond with the addition of a water molecule • This type of reaction alwaysreleases energy • Also considered to be an catabolic reaction = breaking down

26. Macromolecules:What you need to know! • Structure of the basic unit (carbohydrates, lipids, proteins, nucleic acids) (what are the monomers) • How they react to form larger molecules (what are the polymers) (examples) • How the larger molecules are broken down into basic units • Functions of the molecules in living organisms

27. Testing Carbohydrates

28. Benedict’s Test • testing for reducing sugars Benedict’s reagent is used to detect reducing sugars. The blue-coloured, copper-based solution will produce a red to orange precipitate in the presence of a reducing sugar and heat.

29. Starch Test • tests for the presence of starch Lugol’s iodine is a yellow solution that will turn a dark purple / black colour in the presence of starch molecules.

30. Testing for Proteins

31. Biuret’s Test • testing for the presence of proteins Biuret’s solution is a blue-coloured, copper-based solution that turns purple in colour in the presence of protein.

32. Testing for Lipds

33. Sudan Test • testing for the presence of lipids Sudan dye is a water-insoluble, black-red dye that will stain solutions containing lipids a red colour.