Molecules of Life

1. Molecules of Life

2. Molecules of Life • Molecules of life are synthesized by living cells • Carbohydrates • Lipids • Proteins • Nucleic acids

3. Organic Compounds • Consist primarily of carbon and hydrogen atoms • Carbon atoms bond covalently with up to four other atoms, often in long chains or rings • Functional groups attach to a carbon backbone • Influence organic compound’s properties

4. An Organic Compound: Glucose • Four models

5. Functional Groups: The Importance of Position

6. Processes of Metabolism • Cells use energy to grow and maintain themselves • Enzyme-driven reactions build, rearrange, and split organic molecules

7. Building Organic Compounds • Cells form complex organic molecules • Simple sugars → carbohydrates • Fatty acids → lipids • Amino acids → proteins • Nucleotides → nucleic acids • Dehydration synthesis combines monomers to form polymers

8. Dehydration synthesis and Hydrolysis

9. Carbohydrates – The Most Abundant Ones • Three main types of carbohydrates • Monosaccharides (simple sugars) • Oligosaccharides (short chains) • Polysaccharides (complex carbohydrates) • Carbohydrate functions • Instant energy sources • Transportable or storable forms of energy • Structural materials

10. Oligosaccharides: Sucrose

11. Complex Carbohydrates: Starch, Cellulose, and Glycogen

12. c Glycogen. In animals, this polysaccharide is a storage form for excess glucose. It is especially abundant in the liver and muscles of highly active animals, including fishes and people. Structure of cellulose

13. Greasy, Oily – Must Be Lipids • Lipids • Fats, phospholipids, waxes, and sterols • Don’t dissolve in water • Dissolve in nonpolar substances (other lipids) • Lipid functions • Major sources of energy • Structural materials • Used in cell membranes

14. Fats • Lipids with one, two, or three fatty acid tails • Saturated • Triglycerides (neutral fats ) • Three fatty acid tails • Most abundant animal fat (body fat) • Major energy reserves

15. Triglyceride Formation

16. Phospholipids • Main component of cell membranes • Hydrophilic head, hydrophobic tails

17. Waxes • Firm, pliable, water repelling, lubricating

18. Steroids: Cholesterol • Membrane components; precursors of other molecules (steroid hormones)

19. Protein Structure • Built from 20 kinds of amino acids

20. Four Levels of Protein Structure 1. Primary structure • Amino acids joined by peptide bonds form a linear polypeptide chain 2. Secondary structure • Polypeptide chains form sheets and coils 3. Tertiary structure • Sheets and coils pack into functional domains

21. Four Levels of Protein Structure 4. Quaternary structure • Many proteins (e.g. enzymes) consist of two or more chains

22. Levels of Protein Structure

23. Levels of Protein Structure

24. Levels of Protein Structure

25. Levels of Protein Structure

26. Why is Protein StructureSo Important? • Protein structure dictates function • Sometimes a mutation in DNA results in an amino acid substitution that alters a protein’s structure and compromises its function • Example: Hemoglobin and sickle-cell anemia

27. Normal Hemoglobin Structure

28. VALINE HISTIDINE LEUCINE THREONINE PROLINE VALINE GLUTAMATE b One amino acid substitution results in the abnormal beta chain in HbS molecules. Instead of glutamate, valine was added at the sixth position of the polypeptide chain. sickle cell c Glutamate has an overall negative charge; valine has no net charge. At low oxygen levels, this difference gives rise to a water-repellent, sticky patch on HbS molecules. They stick together because of that patch, forming rod shaped clumps that distort normally rounded red blood cells into sickle shapes. (A sickle is a farm tool that has a crescent-shaped blade.) normal cell

29. Clumping of cells in bloodstream Circulatory problems, damage to brain, lungs, heart, skeletal muscles, gut, and kidneys Heart failure, paralysis, pneumonia, rheumatism, gut pain, kidney failure Spleen concentrates sickle cells Spleen enlargement Immune system compromised Rapid destruction of sickle cells d Melba Moore, celebrity spokes-person for sickle-cell anemia organizations. Right, range of symptoms for a person with two mutated genes for hemoglobin’s beta chain. Anemia, causing weakness,fatigue, impaired development,heart chamber dilation Impaired brain function, heart failure

30. Denatured Proteins • If a protein unfolds and loses its three-dimensional shape (denatures), it also loses its function • Caused by shifts in pH or temperature, or exposure to detergent or salts • Disrupts hydrogen bonds and other molecular interactions responsible for protein’s shape

31. Nucleotides, DNA, and RNAs Nucleotide structure, 3 parts: • Sugar • Phosphate group • Nitrogen-containing base

32. Nucleotide Functions: Reproduction, Metabolism, and Survival • DNA and RNAs are nucleic acids, each composed of four kinds of nucleotide subunits • ATP energizes many kinds of molecules by phosphate-group transfers

33. Nucleotides of DNA

34. DNA, RNAs, and Protein Synthesis • DNA (double-stranded) • Encodes information about the primary structure of all cell proteins in its nucleotide sequence • RNA molecules (usually single stranded) • Different kinds interact with DNA and one another during protein synthesis

35. covalent bonding in carbon backbone hydrogen bonding between bases