Unit 4 : The Chemistry of Life

1. Unit 4: The Chemistry of Life

2. Particles Even though organisms exist in many different forms they are all made up of the same thing: elements. An element is a substance that cannot be broken down into simpler substances. You can find a listing of the elements on the periodic table

3. 96% of all organisms are made up of just four very important elements: Oxygen (O), Hydrogen (H), Carbon (C), and Nitrogen (N).

4. Atoms • If you were to break down an element into smaller pieces you would get to the atom. An atom is the smallest unit of an element that still has the properties of the element. They are the building blocks of matter.

5. Compounds • When two or more elements are combined in a fixed ratio (ex. CO2), they form a compound. • A compound has different properties than the elements that it is made from.

6. Compounds are held together by chemical bonds.

7. Solutions • A solution is a mixture that is blended evenly throughout. • Ex: Kool-aid, soda, coffee

8. The solute is the part of the solution that gets dissolved (ex: the kool-aid mix or the sugar) • The solvent is the part of the solution that does the dissolving (ex: the water)

9. Basics of a Chemical Equation ReactantsProducts • Chemical Equations are written representations of chemical reactions.

10. Basics of a Chemical Equation ReactantsProducts • Reactants – what you start with, • on the left side of the equation Reactants

11. Basics of a Chemical Equation ReactantsProducts • Products – what you end with, • on the right side of an equation • If there are multiple reactants and products they are separated with plus signs (+) Products

12. ReactantsProducts • The ARROW () symbolizes the reaction taking place and a chemical change in substance. • It shows the direction the reaction is happening • The arrow means – • yield, produces, makes, causes

13. ReactantsProducts catalyst • Things that speed the reaction up, or get it going, are written above the arrow • Catalyst/Enzyme – added to speed it up, but do not participate in the reaction. • Enzymes or catalysts lower the amount of activation energy needed.

14. GRAPHING REACTIONS • Let’s look at this graph. • On the left you start with reactants.

15. GRAPHING REACTIONS • The reactants have to get a certain amount of energy (represented with a hill) to react and form products (on the right).

16. GRAPHING REACTIONS • The hill represents ACTIVATION ENERGY. • Activation energy is the amount of energy particles must have to react.

17. GRAPHING REACTIONS • The bigger the hill, • the more activation energy needed.

18. ENZYMES • AN ENZYME increases the rate of reaction, but does not actually react. • It is used to speed things up.

19. ENZYME • With an enzyme, the activation energy barrier is LOWER.

20. Enzymes • Lower Activation Energy • = Lower Hill. • Without enzymes, few reactions in the body would occur fast enough for us to survive.

21. Enzyme • Enzymes work by something called the “LOCK and KEY model”. • Each enzyme has one substrate (reactant molecule) with which it will work. Enzymes have a specific shape that fits with the substrate. Substrate

22. The site on the enzyme where the reaction occurs is called the active site. When the enzyme temporarily binds the substrate to its active site it forms what we call the enzyme substrate complex Enzyme Substrate Complex Active Site

23. Once the reaction occurs and the products are formed, the enzyme is released from the complex, and is free to go to a new substrate.

24. Enzyme Substrate Enzyme Substrate complex Enzyme Product

25. FACTORS AFFECTING ENZYMES • Enzymes are affected by pH, salinity, and temperature. • When exposed to changes in pH, salinity, or temperature the enzyme can denature. • denaturation= to change or lose its 3D protein shape (active site loses its shape, so the enzyme no longer works)

26. Most enzymes work best at a temperature around 37*C (human body temperature). • Most enzymes also work best around a pH of 7 (neutral). Stomach enzymes operate best at a very low pH (2).

27. ORGANIC MOLECULES • Most of the molecules that make up living organisms have a backbone of carbon atoms. • They are known as organic molecules.

28. Organic Molecules • They are built through a process called polymerization, where smaller units (monomers) join together to make one big molecule (polymers).

29. Organic Molecules • There are four major types of organic molecules: carbohydrates, lipids, nucleic acids, and proteins.

30. Carbohydrates organic compounds made up of carbon, hydrogen, and oxygen in a ratio of 1:2:1. • Examples: breads, candy, fruit, potatoes, pasta

31. The indicator tests for carbohydrates are Benedicts solution and an Iodine test. Benedicts solution will turn orange if sugars are present, Iodine will turn blue/black if starches are present.

32. Carbohydrates • Most carbohydrates are categorized as monosaccharides, disaccharides, or polysaccharides. • Saccharides is just a fancy word for sugar. The prefixes refer to the number of sugars in the molecule. • mono- means one sugar, di- means two, poly- means many, etc.

33. Monosaccharides, the simplest sugars serve as energy sources for cells. • The two most common are glucose and fructose. They are six carbon sugars with the formula C6H12O6. Glucose Fructose

34. Disaccharides are formed when two monosaccharides are brought together. • The hydrogen (H) from one sugar combines with the hydroxyl (OH) group in the other sugar to make water. The water is removed in what’s called a dehydration synthesis or condensation. The two monosaccharides are then linked. Dehydration Synthesis

35. If you wanted to break up the disaccharide once it’s made, all you would have to do is add the water back. That’s called hydrolysis.

36. Polysaccharides are made up of many repeating monosaccharides. The most common polysaccharides are starch, cellulose, and glycogen. • Starch is a polysaccharide made of glucose that plants store for energy. • Cellulose is a major part of the cell wall in plants. • Glycogen is a polysaccharide that animals store (particularly in the liver) for energy.

37. Like carbohydrates, lipids consist of carbon, hydrogen, and oxygen, but not in the 1:2:1 ratio. • They are used for storing energy and for providing structure. • The most common type of lipids are fats.

38. A typical molecule of fat consists of three fatty acids and one molecule of glycerol. The word triglyceride is just a big word for fat.

39. We use the brown paper bag test in order to see if lipids are present. If the brown paper bag turns translucent, then lipids are present (like your Mickey D’s bag full of fries).

40. Proteins Proteins serve a variety of different functions in living organisms. Here are a few- • Enzymes are proteins that speed up the rate of chemical reactions • Structural proteins reinforce cells and tissues • Transport proteins, like hemoglobin, move materials around cells and around the body.

41. Amino acids are the building blocks of proteins. • There are 20 different amino acids, but they all basically look the same except for the R-group, which can be drastically different.

42. When two amino acids join (through dehydration synthesis) they form what’s called a dipeptide. • When many group together to form a chain they form a polypeptide. • The bond between two amino acids has a special name: peptide bond. • Once a polypeptide folds and twists into its structure, it is called a protein.

43. We use a Biuret solution to test for proteins. If proteins are present in the substance, then the solution turns purple.

44. Nucleic Acids • Nucleic acids are large molecules that contain all the genetic information for an organism. • They are made up of strands of nucleotides.

45. Each nucleotide has three components of its own: • A nitrogen base (adenine, thymine, guanine, cytosine, uracil) • A 5 carbon sugar (deoxyribose or ribose) • A Phosphate group

46. DNA • DNA is important because it contains all the genes, the hereditary material of all living organisms. • DNA is made up of two strands of nucleotides that are arranged in a way that makes it look like a twisted ladder.

47. The sides of the ladder are made up of the deoxyribose sugar and phosphate molecules (the “sugar-phosphate backbone”) The “rungs” of the ladder are made from a nitrogen base pair. • Adenine pairs with Thymine • Cytosine pairs with Guanine

48. Ribonucleic Acid • RNA plays an important role in the creation of new proteins. The structure of RNA is slightly different from that of DNA. • There is only one strand of nucleotides, instead of two. • The sugar is ribose instead of deoxyribose. • Adenine pairs with Uracil, rather than Thymine.

49. Scientists use gel electrophoresis when testing DNA. • This technique separates DNA molecules by size. • The large particles have trouble passing through the agarose gel, so the particles get spread out into different bands. Bands are used to identify specific types of DNA.