### Understanding the Role of Enzymes, Nucleic Acids, and ATP in the Human Body ###

1. Monday 10-21-13 Objective • SWBAT: Discuss why enzymes, nucleic acids and ATP are important to the body. • Resulting in: A better understanding of the human body. • As measured by: An Exit Slip with 80% mastery.

2. Enzymes • Biological catalysts • Lower the activation energy, increase the speed of a reaction (millions of reactions per minute!)

3. WITHOUT ENZYME WITH ENZYME Activation energy required Less activation energy required Reactants Reactants Product Product Figure 2.20

4. Characteristics of Enzymes • Often named for the reaction they catalyze; usually end in -ase (e.g., hydrolases, oxidases) • Some functional enzymes (holoenzymes) consist of: • Apoenzyme (protein) • Cofactor (metal ion) or coenzyme (a vitamin)

5. Product (P)e.g., dipeptide Substrates (S)e.g., amino acids Energy isabsorbed;bond isformed. Water isreleased. Peptidebond + H2O Active site Enzyme-substratecomplex (E-S) Enzyme (E) Enzyme (E) 1 2 Substrates bindat active site.Enzyme changesshape to holdsubstrates inproper position. Internalrearrangementsleading tocatalysis occur. 3 Product isreleased. Enzymereturns to originalshape and isavailable to catalyzeanother reaction. Figure 2.21

6. Substrates (S)e.g., amino acids + Active site Enzyme-substratecomplex (E-S) Enzyme (E) 1 Substrates bindat active site.Enzyme changesshape to holdsubstrates inproper position. Figure 2.21, step 1

7. Substrates (S)e.g., amino acids Energy isabsorbed;bond isformed. Water isreleased. + H2O Active site Enzyme-substratecomplex (E-S) Enzyme (E) 1 2 Substrates bindat active site.Enzyme changesshape to holdsubstrates inproper position. Internalrearrangementsleading tocatalysis occur. Figure 2.21, step 2

8. Product (P)e.g., dipeptide Substrates (S)e.g., amino acids Energy isabsorbed;bond isformed. Water isreleased. Peptidebond + H2O Active site Enzyme-substratecomplex (E-S) Enzyme (E) Enzyme (E) 1 2 Substrates bindat active site.Enzyme changesshape to holdsubstrates inproper position. Internalrearrangementsleading tocatalysis occur. 3 Product isreleased. Enzymereturns to originalshape and isavailable to catalyzeanother reaction. Figure 2.21, step 3

9. Nucleic Acids • DNA and RNA • Largest molecules in the body • Contain C, O, H, N, and P • Building block = nucleotide, composed of N-containing base, a pentose sugar, and a phosphate group

10. Deoxyribonucleic Acid (DNA) • Four bases: • adenine (A), guanine (G), cytosine (C), and thymine (T) • Double-stranded helical molecule in the cell nucleus • Provides instructions for protein synthesis • Replicates before cell division, ensuring genetic continuity

11. Sugar: Deoxyribose Base: Adenine (A) Phosphate Phosphate Thymine (T) Sugar Adenine nucleotide Thymine nucleotide Hydrogen bond (a) Deoxyribose sugar Sugar-phosphate backbone Phosphate Adenine (A) Thymine (T) Cytosine (C) Guanine (G) (b) (c) Computer-generated image of a DNA molecule Figure 2.22

12. Ribonucleic Acid (RNA) • Four bases: • adenine (A), guanine (G), cytosine (C), and uracil (U) • Single-stranded molecule mostly active outside the nucleus • Three varieties of RNA carry out the DNA orders for protein synthesis • messenger RNA, transfer RNA, and ribosomal RNA

13. Adenosine Triphosphate (ATP) • Adenine-containing RNA nucleotide with two additional phosphate groups

14. High-energy phosphate bonds can be hydrolyzed to release energy. Adenine Phosphate groups Ribose Adenosine Adenosine monophosphate (AMP) Adenosine diphosphate (ADP) Adenosine triphosphate (ATP) Figure 2.23

15. Function of ATP • Phosphorylation: • The addition of a phosphate (PO43-) group to a protein or other organic molecule, helps energize other molecules • Such “primed” molecules perform cellular work (life processes) using the phosphate bond energy • Phosphorylation turns many protein enzymes on and off, thereby altering their function and activity

16. Solute + Membrane protein (a) Transport work: ATP phosphorylates transport proteins, activating them to transport solutes (ions, for example) across cell membranes. + Relaxed smooth muscle cell Contracted smooth muscle cell Mechanical work: ATP phosphorylates contractile proteins in muscle cells so the cells can shorten. (b) + Chemical work: ATP phosphorylates key reactants, providing energy to drive energy-absorbing chemical reactions. (c) Figure 2.24

17. Check your understanding: • 1. How do enzymes reduce the amount of activation energy needed to make a chemical reaction go? • 2. How do DNA and RNA differ in the bases and sugars they contain? • 3. What are two important roles of DNA? • 4. Glucose is an energy rich molecule. So why do body cells need ATP? • 5. What change occurs in ATP when it releases energy?

18. Simple and Stratified Epithelia • Read and Highlight key terms. You will be required to match images to terms or terms to definitions on a quiz. • Use key terms to label diagrams. • Color diagrams as follows: • Purple = nuclei • Blue = cytoplasm • Red = basement membrane

19. Answers to Check your understanding: • Enzymes hold the substrate(s) in a desirable position to interact. • DNA contains deoxyribose sugar and the bases A, T, G, and C. RNA contains ribose sugar and the bases A, U, G, and C. • DNA dictates protein structure by its base sequence and reproduces itself before a cell divides to ensure that the genetic information in the daughter cells is identical.