The Chemistry of Life

1. The Chemistry of Life 24.1 A Strategy for Life 24.2 Carbohydrates 24.3 Amino Acids and Their Polymers 24.4 Lipids 24.5 Nucleic Acids 24.6 Metabolism Created by C. Ippolito July 2007

2. A Strategy for Life Objectives Identify the two major cell types that occur in nature Describe the chemical changes that occur during photosynthesis Created by C. Ippolito July 2007

3. The Structure of Cells • Prokaryotic Cells • primitive cells • only cell membrane • chromosome • cytoplasm • Karyotic Cells • organelles • nucleus • ER • mitochondria Created by C. Ippolito July 2007

4. Energy and the Carbon Cycle • Photosynthesis • uses sunlight’s energy to reduce carbon dioxide to form compounds with C-H bonds, most commonly glucose(C6H12O6) • Respiration • releases energy from glucose to reform carbon dioxide and water Created by C. Ippolito July 2007

5. Photosynthesis & Respiration Created by C. Ippolito July 2007

6. Carbohydrates Objectives Identify where glucose is found in nature Describe how two simple sugars can be linked Created by C. Ippolito July 2007

7. Monosaccharides • Carbohydrates • monomers and polymers of aldehydes (aldose) and ketones (ketoses) with numerous hydroxide groups • Monosaccharide • simple “single” sugars • most common are the “hexoses” C6H12O6 • glucose – corn, blood, grape sugar (aldose) • fructose – fruit, honey sugar (ketose) Created by C. Ippolito July 2007

8. Disaccharides & Polysaccharides • Disaccharides • two monosaccharides joined by condensation (dehydration) reaction • Sucrose – glucose + fructose • Maltose – glucose + glucose • Lactose – glucose + galactose • Polysaccharides • multiple monosaccharides or disaccharides joined to form a large polymer • Amylose (starch) – glucose or α-maltose • Cellulose – glucose or β-maltose Created by C. Ippolito July 2007

9. Amino Acids and Their Polymers Objectives Diagram the structure of an amino acid Describe how peptide bonds form and identify what determines the properties of peptides and proteins Created by C. Ippolito July 2007

10. Amino Acid • Consist of a central carbon atom with: Carboxyl group Amino group Hydrogen atom Side Chain (variable group) Created by C. Ippolito July 2007

11. Amino Acid Structure Hydrogen atom Carboxyl group Amino group Side Chain Created by C. Ippolito July 2007

12. Peptide Bond • DehydrationSynthesis that joins amino acids • Carboxyl group of one reacts withamino group of another. • Water is removed. Created by C. Ippolito July 2007

13. Peptide Bond Forming Created by C. Ippolito July 2007

14. Dipeptide Created by C. Ippolito July 2007

15. Levels of Protein Structure • Primary Structure • which amino acids used • total number joined • order of the amino acids • Secondary Structure • based on primary • interaction between -C=O groups and -NH groups • forms -helix or -pleat • Tertiary Structure • based on both primary and secondary structures • due to interactions between residue groups • disulfide bond of cysteine • Quaternary Structure • based on all previous levels • due to residue interactions on different protein chains • not in all proteins Created by C. Ippolito July 2007

16. Enzymes • biologicalcatalysts • Catalysts - speed up reactions by lowering activation energy; they are not changed by the reaction. • All enzymes are proteins with a 3-D shape which helps to explain how they work. Created by C. Ippolito July 2007

17. Lock and Key Theory • Part of that shape is the activesite. • The active site is a region that can hold the substrates - materials an enzyme catalyzes  Active Site • enzyme Created by C. Ippolito July 2007

18. Substrates without Enzyme • To react substrates mustcollideexactly right to form a new molecule. • If they hit any other way no molecule will form. Created by C. Ippolito July 2007

19. Substrate fit Active Site • Substrates fit only one way, assuring proper collision. Created by C. Ippolito July 2007

20. Enzyme Substrate Complex • The substrates are held together forming an enzymesubstratecomplex that lowers the activationenergy allowing the new molecule to form. Created by C. Ippolito July 2007

21. Catalysis is completed • The enzyme releases the combined substrates and is now free to repeat the process. Created by C. Ippolito July 2007

22. Enzyme Cofactors • Some enzymes cannot form an active site by themselves. • They need a “non protein” cofactor or coenzyme to complete the site. • Most cofactors are vitamins • Cofactor  Created by C. Ippolito July 2007

23. Lipids Objectives Identify the physical property that distinguishes lipids from other biological molecules Describe the structure of a lipid bilayer Created by C. Ippolito July 2007

24. Triglycerides • Lipids • water insoluble compounds • Fats • solid at room temperature • Oils • liquid at room temperature • Triglyceride • triesters of fatty acids and glycerol • used for long term energy storage Created by C. Ippolito July 2007

25. Saponification • Saponification • hydrolysis of a fat or oil with aqueous alkali-metal hydroxide • forms soap Created by C. Ippolito July 2007

26. Phospholipids • Lipids with phosphate groups • hydrophilic end – likes water • hydrophobic end – water hating • forms lipid bilayer of biological membranes Created by C. Ippolito July 2007

27. Cell Membrane Created by C. Ippolito July 2007

28. Nucleic Acids Objectives Describe the function of ATP in cells Identify the functions of DNA and RNA Describe how information is sorted in genetic material and how genes can mutate Describe how DNA fingerprinting and recombinant DNA technology are used Created by C. Ippolito July 2007

29. DNA and RNA • polymers composed of nucleotides • nucleotides • nitrogen base • sugar • phosphate group • DNA – deoxyribonucleic acid – Double Helix • sugar – deoxyribose • bases – adenine, thymine, guanine, cytosine • RNA – ribonucleic acid – Single Helix • sugar –ribose • bases – adenine, uracil, guanine, cytosine Created by C. Ippolito July 2007

30. DNA RNA Connection • DNA controls cell by protein synthesis • RNA transmits information in DNA • Three kinds of RNA • Messenger RNA (mRNA) – carries instructions to ribosome • Transfer RNA (tRNA) – carries amino acids to ribosome • Ribosomal RNA (rRNA) – forms part of the ribosome Created by C. Ippolito July 2007

31. Protein Synthesis • DNA controls through TWO (2) processes: • Transcription – RNA synthesis – DNA acts as a template to form mRNA, tRNA, and rRNA • Translation – protein synthesis – the RNA’s made by DNA interact at the ribosome to join amino acids Interactive Tutorial Link about Protein Synthesis PBS Interactive Link DNA Replication and Protein Synthesis Created by C. Ippolito July 2007

32. DNA Nucleotides Created by C. Ippolito July 2007

33. DNA Double Helix • Base Pairing • Adenine to Thymine • Thymine to Adenine • Guanine to Cytosine • Cytosine to Guanine Created by C. Ippolito July 2007

34. Genetic Code • 20 different amino acids • Only variable in DNA are bases • Bases down side of helix “code” acids • Sense side – makes protein • Anti-sense side –replicates • How many bases name an acid? • 1 base code – only 4 acids named • 2 base code – (4x4) only 16 acids named • 3 base code – (4x4x4) allows 64 unique names • Allows duplicate words (synonyms) for acids • Allows “start” and “stop” codes Created by C. Ippolito July 2007

35. Cracking the Code • Nirenberg Experiment • NIH scientist studied process in bacteria • Made mRNA of one base only “uracil” • 20 test tubes – one for each amino acid • Only test tube with phenylalanine formed a polypeptide • Found first triplet “codon” uuu = phe • Codon – 3 bases in DNA and mRNA that “names” an amino acid • Experiment repeated by others to “translate” all codons Created by C. Ippolito July 2007

36. The Genetic Code • Is the same in ALL LIFE • Note synonyms Created by C. Ippolito July 2007

37. Gene Mutation • Mutation • change in the DNA sequence • substitution • addition • deletion • Genetic Diseases • sickle cell • 1 error out of 4,000 • glutamic acid replaced by valine Created by C. Ippolito July 2007

38. DNA Fingerprinting • DNA fingerprints can be used to identify individuals from samples of hair, skin cells, or body fluids • PCR used to “amplify” DNA sample • Restriction Enzymes used to cut segments • Electrophoresis • used to separate segments • each individual has a different pattern of segments Created by C. Ippolito July 2007

39. Recombinant DNA Technology • methods used to remove DNA from one chain and insert it into another chain • Medical Applications • human insulin gene in bacterium • human growthhormone gene in bacterium • Agricultural Applications • genetically altered crops • pest resistant • Cloning Created by C. Ippolito July 2007

40. Metabolism Objectives Describe the function of ATP in cells Distinguish between catabolism and anabolism Describe the nitrogen cycle Created by C. Ippolito July 2007

41. ATP • ATP stands for Adenosine Triphosphate • energy carrying nucleotide • transports energy from spontaneous (release energy) to nonspontaneous (use energy) reactions • store energy • ADP + P + free energy  ATP • release energy • ATP  ADP + P + free energy • Adenine  • Phosphates • have energy •  • Ribose  • Adenine  • Phosphates • energy released •  • Ribose  Created by C. Ippolito July 2007

42. Metabolism • all the chemical reactions carried out by an organism • Catabolism • reactions that breakdown materials • release free energy • provide building blocks • Anabolism • reactions that build and maintain organism • require free energy • use building blocks Created by C. Ippolito July 2007

43. Nitrogen Cycle • Nitrogen Fixing • N2NH3 Created by C. Ippolito July 2007