Chapter 5 The Molecules of Life

1. Chapter 5 The Molecules of Life

2. 5.1 Carbon is the main ingredient of organic molecules. • Life without carbon would be as unlikely as life without water. Other than water, most molecules of a cell are carbon-based. These “biochemicals” are composed of a carbon backbone of carbon atoms bonded to one another. Atoms of other elements may branch off this carbon backbone.

3. Why are carbon atoms so common in living things? • Carbon has only 4 electrons in its highest energy level. • The energy level can hold 8 electrons. • So carbon can form up to 4 bonds with other atoms. • Carbon can form bonds with one or more other carbon atoms, producing an endless variety of carbon skeletons.

5. Organic molecules: • Carbon based molecules. • Inorganic molecules: • Non based carbon molecules. • Ex. Water H20, Oxygen 02, and Ammonia NH3

6. A group of atoms within a molecule that interacts in predictable ways with other molecules is called a functional group. • The carbon skeleton and the attached functional groups determine the properties of an organic molecule.

7. Functional Group • Ex. Hydroxyl groups are hydrophilic. • These molecules tend to become surrounded by water molecules in an aqueous environment.

8. Monomers and Polymers • Biomolecules may be composed of hundreds or millions of atoms. The large molecules are built from many smaller molecules. • The small molecules are called monomers. • Long chains of combined monomers create polymers.

9. Building Polymer Chains • Building up: • Each time a monomer is added to a chain, a water molecule is released.

10. Breaking Polymer Chains • We eat many molecules in our food that are polymers. • We must break them down to make energy for our cells. • Cells will break the bonds between monomers by adding water to them. This is called a hydrolysis reaction. Hydro= water lysis=break down

11. Hydrolysis Reaction

12. Summary • Water is removed to build a polymer. • Monomer + Monomer - Water = Polymer • Water is added to break down a polymer. • Polymer + Water = Monomer + Monomer

13. Macromolecules • There are four macromolecules • Carbohydrates • Lipids • Proteins • Nucleic Acids

14. Imagine you are preparing for a big race or sport event. • What does your body need to give you energy? • Carbohydrates • What should you eat? • Pasta

15. 5.2 Carbohydrates • Carbohydrates is an organic compound made up of sugar molecules. • Sugars are made of • 1 carbon • 2 hydrogen's • 1 oxygen All carbohydrates end with –ose Ex. Glucose

16. Monosaccharide: • Mono= one • Simple sugars containing one sugar unit. • Ex. Glucose, fructose, and galactose. • Glucose is the main fuel supply for cells. It is much like a car engine burning gasoline. • Cells break down glucose molecules and use it for energy.

17. Disaccharides: • Di= two • Double sugar. • Ex. Sucrose • Glucose (monomer) + Fructose (monomer) = Sucrose (polymer) • Sucrose can be found in plants specifically in sap.

18. Polysaccharides: • Poly= many • These are your complex carbohydrates. • Ex. Starch

19. Animal Cells • Animal cells do not contain starch. • Animals store excess sugar in the form of a polysaccharide called glycogen. • When the body needs energy, it breaks down glycogen to release glucose.

20. Plant Cells • Polysaccharide in plant cells use cellulose to serve as building materials. • Cellulose is used to protect cells and stiffen the plant. • They form cable like fibers.

21. Most animals cannot digest cellulose because we lack the molecule that breaks the bonds between glucose monomers in cellulose. • Cellulose is commonly referred to as “fiber” • Fiber passes through our body unchanged. • Helps keep our digestive track healthy.

22. 5.3 Lipids • Why do you have to shake well before using a bottle of salad dressing? • The oil is a lipid and lipids do not mix well with water. Lipids are hydrophobic. • When salad dressing bottle sits the oil and vinegar separates.

23. Types of Lipids • Fats: • Consists of a three carbon backbone called glycerol attached to three fatty acids. • Fat is used for storing energy and providing insulation for your body.

24. Types of Fats • Saturated fat: ( bad fat) • Contain the maximum possible number of hydrogen atoms. • Solid at room temperature. • Ex. Lard, butter. • Unsaturated fat: • Contains less than the maximum number of hydrogen bonds. • Ex. Olive oil, vegetable oil.

26. Steroids • Steroid: • Lipid molecule which the carbon skeleton forms four fused rings. • Circulate our body as chemical signals. Ex. Estrogen, testosterone.

27. 5.4 Proteins • Proteins: • Polymer constructed from a set of 20 kinds of monomers called amino acids. • Are responsible for almost all of the day to day functioning in organisms. • Function: • Form structures such as hair and fingernails. • Defend body from microorganisms. • Acts as signals.

28. Amino acid: • Monomer consists of a central carbon atom bonded to four partners. • Will always have an Amino group, Carboxyl group, and a varying side group.

29. Building a Protein • Cells create proteins by linking amino acids together into a chain called a polypeptide. • Body can make a variety of proteins by arranging different amino acids in different orders. • Each unique order makes unique proteins

30. Protein Shape • A protein in the simple form of amino acids linked together cannot function properly. • Compare a long strand of yarn and a finished sweater. • A sweater is not bundled yarn but yarn that is carefully knitted into a particular shape.

31. Likewise, proteins consists of one or more polypeptides precisely twisted, folded, and coiled in a unique shape.

32. An unfavorable change in temperature, pH, or some other quality of the environment can cause a protein to unravel and lose its shape. This is called • denaturation. • When you fry an egg, the egg white changed from a clear liquid to solid white during cooking because heat denatures egg proteins.

34. 5.5 Enzymes • To start a chemical reaction, it is first necessary to weaken chemical bonds in the reactant molecules. • The activation process requires that the molecules absorb energy. • To burn a candle you need to provide initial energy with a match. • This start up energy is called activation energy. • Activation energy: • Activates the reactants and triggers a chemical reaction.

35. Cellular reactions depend on the assistance of catalysts. • Catalyst: • Compounds that speed up chemical reactions. • The main catalysts of chemical reactions in organisms are specialized proteins called enzymes.

36. Enzymes lower the activation energy to the reacting molecules.

37. How Enzymes Work • The shape of an enzyme fits the shape of only particular reactant molecules. A specific reactant acted upon by an enzyme is called the substrate. • The substrate fits into a particular region of the enzyme called the active site. • Once connected the reactions occurs.