Chemistry and the body

1. Chemistry and the body What chemicals are found in the body? What chemical reactions happen in the body- and why? Where do the chemicals come from?

2. Chemical bonds can be formed or broken • Synthesis: A + B  AB (also known as condensation) glucose + galactose  lactose (+ water) • Decomposition: AB A + B Starch plus water  maltose 3. Exchange: AB +CD  AC + BD HCl + NaOH  NaCl + H2O

3. Why do chemical reactions happen inside the body? • To build large molecules (anabolism) • To break down molecules and use the products in other reactions (catabolism) • To store energy • To release energy to use for cellular work • Metabolism: sum of all these reactions

4. Chemical reactions don’t just happen • In the body, most reactions require biological • catalysts (enzymes) • Enzymes make the reaction happen more quickly • Catalysts do NOT make reactions occur that • would not happen otherwise- the reactions • just occur more quickly • Enzymes themselves are not changed or used • up in the reactions

5. What chemicals are important for living things? Organic- contain carbon and hydrogen Inorganic- everything else

6. Water- essential to all life on Earth • Solvent properties (hydrogen bonds) • Can absorb and distribute heat in the body (what does “warm-blooded” really mean?) • Transport medium • Participates in many chemical reactions in the body

7. Ionic compounds dissolve in water

8. Some electrolytes form acids and bases in water. These can be very damaging to tissues. Buffers minimize pH changes.

10. Organic molecules and macromolecules • Carbohydrates • sugars • Lipids • Triglycerides, phospholipids, sterols, prostaglandins • Proteins • Amino acids • Nucleic acids • Nucleotides • Triphosphates • See Table 2.6 for summary

11. Carbohydrates are made of sugars • Monosaccharides • Disaccharides • Polysaccharides • Oligosaccharides • Primary energy source • Can be structural (cellulose)

12. Lipids are more diverse in structure and function Triglycerides: energy storage and insulation Phospholipids: cell membranes “phospholipid bilayer” Steroids: Building blocks for certain hormones Also support cell membranes

13. Proteins • Made up of amino acids (any combination of • 20 different amino acids) • Extremely diverse in size and structure • Functions: • structure • cell receptors • many specialized functions (hemoglobin, antibodies) • enzymes • Protein structure is complex

14. Form follows function • Proteins can change their shape and revert to their original shape • Proteins can be “denatured”: change in temperature or pH can denature (destroy) a protein • Protein function can be blocked

15. How do we know what a protein will look like? • Amino acid sequence • One or more polypeptide chains • Amino acid sequence is determined by DNA sequence (gene)

16. Nucleic acids • Comprised of nucleotides • DNA, RNA • DNA stores genetic information in the nucleus • RNA “uses” genetic information in DNA to make polypeptides

17. RNA DNA

18. Comparison of DNA and RNA

19. High-energy compounds • ATP (adenosine triphosphate) • Provides energy for chemical reactions in cells

20. How do these molecules “behave” in the watery inside of a cell? • Ionic compounds dissolve into ions • Polar molecules react with water but don’t fall apart (“hydrophilic”) • Nonpolar molecules separate from water (“hydrophobic”) • Cell membranes are made of phospholipids • Implications?

21. Summary • Metabolism is the series of chemical reactions by which cells capture, store and use energy to perform body functions and maintain homeostasis. • Cells utilize/produce many essential substances: water, oxygen, carbon dioxide, salts, ions, organic molecules, and macromolecules. • That’s why we eat food.