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Molecules of Life

Molecules of Life. Section 2 Molecules of Life. Chapter 3. Carbohydrates. Carbohydrates are organic compounds composed of carbon , hydrogen , and oxygen in a ratio of about one carbon to two hydrogen atoms to one oxygen atom.

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Molecules of Life

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  1. Molecules of Life

  2. Section 2 Molecules of Life Chapter 3 Carbohydrates • Carbohydrates are organic compounds composed of carbon, hydrogen, and oxygen in a ratio of about one carbon to two hydrogen atoms to one oxygen atom. • Carbohydrates are a source of energy and are used as structural materials in organisms.

  3. Section 2 Molecules of Life Chapter 3 Carbohydrates • Monosaccharides • Carbohydrates are made up of monomers called monosaccharides. • Disaccharides and Polysaccharides • Two monosaccharides join to form a double sugar called a disaccharide. • A complex sugar, or polysaccharide, is made of three or more monosaccharides.

  4. Section 2 Molecules of Life Chapter 3 Proteins • Proteins are organic compounds composed mainly of carbon, hydrogen, oxygen, and nitrogen. • Proteins have many functions including structural, defensive, and catalytic roles.

  5. Section 2 Molecules of Life Chapter 3 Proteins • Amino Acids • Proteins are made up of monomers called amino acids. The sequence of amino acids determines a protein’s shape and function. • Dipeptides and Polypeptides • Two amino acids are joined by peptide bonds to form a dipeptide. • A long chain of amino acids is called a polypeptide.

  6. Structure of Proteins Section 2 Molecules of Life Chapter 3

  7. Section 2 Molecules of Life Chapter 3 Proteins • Enzymes • Enzymes speed up chemical reactions and bind to specific substrates. • The binding of a substrate with an enzyme causes a change in the enzyme’s shape and reduces the activation energy of the reaction.

  8. Enzyme Activity Section 2 Molecules of Life Chapter 3

  9. Section 2 Molecules of Life Chapter 3 Lipids • Lipids are nonpolar molecules that store energy and are an important part of cell membranes.

  10. Section 2 Molecules of Life Chapter 3 Lipids • Fatty Acids • Most lipids contain fatty acids, unbranched carbon molecules that have a hydrophilic end and a hydrophobic end. • Triglycerides • Triglycerides consist of three fatty acids and one molecule of glycerol.

  11. Section 2 Molecules of Life Chapter 3 Lipids • Phospholipids • Phospholipids, which make up cell membranes, consist of two fatty acids and one glycerol molecule. • Waxes • A wax is made of one long fatty acid chain joined to one long alcohol. • Steroids • A steroid is composed of four fused carbon rings.

  12. Section 2 Molecules of Life Chapter 3 Nucleic Acids • A nucleic acid is a large and complex organic molecule that stores and transports information. • The nucleic acid deoxyribonucleic acid (DNA) contains genetic information for cell activities. • Ribonucleic acid (RNA) molecules play many key roles in building of proteins and can act as enzymes.

  13. Structure of Nucleic Acids Section 2 Molecules of Life Chapter 3

  14. Multiple Choice 1. Which of the following is not a function of polysaccharides? A. energy source B. energy storage C. structural support D. storage of genetic information Chapter 3 Standardized Test Prep

  15. Multiple Choice, continued 2. Which of the following statements is false? A. A wax is a lipid. B. Starch is a lipid. C. Saturated fats are solid at room temperature. D. Unsaturated fats are liquid at room temperature. Chapter 3 Standardized Test Prep

  16. Multiple Choice, continued 3. Which of the following molecules stores hereditary information? A. ATP B. DNA C. protein D. carbohydrates Chapter 3 Standardized Test Prep

  17. Multiple Choice, continued 4. What is the name of the molecule in plants that stores sugars? A. starch B. protein C. cellulose D. glycogen Chapter 3 Standardized Test Prep

  18. Chapter 3 Standardized Test Prep Multiple Choice, continued The figure below illustrates the basic structure of a cell membrane. Use the figure to answer the questions that follow. 5. Which of the following molecules make up the basic structure of a cell membrane? A. waxes B. steroids C. fatty acids D. phospholipids

  19. Chapter 3 Standardized Test Prep Multiple Choice, continued The figure below illustrates the basic structure of a cell membrane. Use the figure to answer the questions that follow. 6. The “tails” of the molecules in the figure orient away from water. Which of the following describes the tail’s movement away from water? A. polar B. adhesive C. hydrophilic D. hydrophobic

  20. Chapter 3 Standardized Test Prep Multiple Choice, continued 7. simple sugars : carbohydrates :: amino acids : A. lipids B. proteins C. nucleic acids D. amino acids

  21. Chapter 3 Standardized Test Prep Multiple Choice, continued The figure below represents the structural formula of a molecule. Use the figure to answer the question that follows. 8. What is the name of the functional group circled in the structural formula? A. amino B. hydroxyl C. phosphate D. carboxyl

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