Chemistry of Life

1. Chemistry of Life

2. Chemistry of Life • Flowers emit a chemical perfume that attracts butterflies, but the plant also makes a noxious chemical in its leaves which discourages the butterfly from laying her eggs there. • Insects interact via chemical messages that range from “stay away” to “come mate with me”.

3. Rattlebox Moth • Secrete a noxious chemical for defense, particularly against spiders. • This moth is a native of Central Florida. • Its name comes from the rattlebox plant, the source of the moth’s defensive chemical. • This chemical also has an important role in its mating strategy. • While the moth was a caterpillar, it ate the leaves from the rattlebox plant and stored this chemical in its body.

4. Rattlebox Moth • While both male and female caterpillars contain this chemical, the female moth receives an extra dose at mating. • During the eight hour copulation, the male passes a large mass of sperm, nutrients, and this chemical to the female, supplying additional protection for her and for their offspring. • Only a human bridegroom would buy life insurance for his bride. • This classy moth gives a gift she can really use-- a life insurance policy that pays off every time her life is in danger.

5. 0 • Nature’s Chemical Language • The rattlebox moth • Produces chemicals important for mating and defense

6. Rattlebox Moth • During the courtship dance, the male moth release is into the air puffs of this chemical; the female, sensing it, can assess how much of this chemical he has. •  There are some kinds of chemical signaling in humans as well. For instance, chemicals in the armpit of a male can apparently regularize a female companion’s ovulatory cycle. •  Chemicals play many more roles in life than signaling. Chemicals make up our bodies as well as the bodies of other organisms, and they also make up the physical environment. To understand biology, we should first look at where it all begins: chemistry.

7. Outermost electron shell (can hold 8 electrons) First electron shell (can hold 2 electrons) Electron Nitrogen (N) Atomic number = 7 Oxygen (O) Atomic number = 8 Hydrogen (H) Atomic number = 1 Carbon (C) Atomic number = 6 0 An element is an atom with a certain number of protons (electrical charges) circling around it in an orbit.

8. ELEMENTS • 96% of the human body is composed of just four elements. • Carbon (C) • Hydrogen (H) • Oxygen (O) • Nitrogen (N) • The other 4% of elements in our body • Calcium, phosphorus, potassium, sulfur, sodium, chlorine, and magnesium. • These elements are involved in important functions such as bone formation, nerve signaling, and DNA synthesis.

9. Trace Elements • Iron • Needed by all forms of life for transporting the oxygen in the blood. • Iodine • only required by certain species; it is an ingredient of a hormone produced by the thyroid gland. Iodine is commonly added to table salt to prevent the formation of goiters. • Fluorine • added to water in some communities to reduce tooth decay • Zinc • Manganese

10. 0 Goiter

11. Vitamin-Fortified Foods • Chemicals are added to food to help preserve it, make it more nutritious, or simply to make it look better. • Iron, for example, is a trace element that is commonly added to foods. • You can actually see the iron that has been added to a fortified cereal by crushing the cereal and then stirring a magnet through it. • Vitamins are also frequently added to cereal. • A vitamin consists of more than one element and is an example of a compound, which we will consider next: Elements combine to larger units called compounds.

12. 0 Trace elements are essential to human health and may be added to food or water

13. Compounds • Two or more elements • Compounds are much more common than pure elements. • In fact, few elements exist in a pure state in nature. Many compounds consist of only two elements; for instance table salt (sodium chloride) has equal parts of the elements sodium and chlorine. • Pure sodium is a metal and pure chlorine is a poisonous gas. Chemically combined, however, they form a common seasoning. • This example shows the emergence of novel properties with a higher level of structural organization. We will see this in biology to, as we study the adaptations of organisms as they evolved.

14. Sodium Chloride Chlorine Sodium 0 Elements can combine to form compounds

15. Compounds • Hydrogen (H) and Oxygen (O) = H2O • Sodium (Na) and Chlorine (Cl) = NaCl • Demonstrates new properties with a higher level of structural organization • Carbon, hydrogen, oxygen, and nitrogen form most of the compounds in living organisms

16. Sodium and chloride ions • Bond to form sodium chloride, common table salt

17. Compounds • Most of the compounds in living organisms contain at least three or four different elements, mainly carbon, hydrogen, oxygen, and nitrogen. • Vitamin K, for example, is formed of just carbon, hydrogen, and oxygen. • Proteins are compounds containing carbon, hydrogen, oxygen, nitrogen, and a small amount of sulfur. • Different arrangements of the elements determine unique properties for each compound. • There are two groups of compounds in our bodies; organic and inorganic.

18. INORGANIC COMPOUNDS • Contain NO carbon atoms • SALTS • Found in body fluids and is needed for muscle contraction and nerve conduction. • WATER • The body is 70% water. • It keeps the body from overheating • It also prevents drastic changes in temperature.

19. Water • If you have ever burned your finger on a metal pot while waiting for the water in it to boil, you know that water heats up much more slowly than metal. • Water has a better ability to resist temperature change than most other substances. • Earth's giant water supply moderates temperatures, keeping them within limits that permit life.

20. Water • A large body of water can store a huge amount of heat from the sun during warm periods. • At cooler times, heat given off from the gradually cooling water can warm the air. • That's why coastal areas generally have milder climates than inland regions. • Water's resistance to temperature change also stabilizes ocean temperatures, creating a favorable environment for marine life. • And at 70% of your body weight, water helps moderate your internal temperature.

21. Water • Liquids vaporize into a gas when some of their molecules move fast enough. • When heat is applied to a liquid, it makes the molecules move faster and bump into each other, causing the hydrogen bonds break, allowing vaporization to occur.

22. (–) (–) O H H (+) (+) 0 Water Molecule

23. (–) Hydrogen bond (+) H O (–) (+) H (+) (–) (–) (+) 0 Water molecules form weak bonds between each other called hydrogen bonds

24. Hydrogen bond Ice Hydrogen bonds are stable Liquid water Hydrogen bondsconstantly break and re-form 0 Ice is less dense than liquid water • Hydrogen bonds hold molecules in ice farther apart than in liquid water

25. 0 • Insects can walk on water due to surface tension

26. Water • Another way water moderates temperatures is by evaporative cooling. • When a substance evaporates, the surface of the liquid remaining behind cools down as the hottest molecules leave. • Evaporative cooling helps prevent land-dwelling organisms from overheating. • Evaporation from a plant’s leaves keeps them from becoming too warm in the sun, just as sweating helps to dissipate our excess body heat. • On a much larger scale, the evaporation of surface waters cools tropical seas.

27. How do land organisms keep from overheating? • Evaporative cooling • Plant’s leaves • Human sweating • Evaporation of surface waters cools tropical seas.

28. Water is the solvent of life • Solution: a liquid consisting of a uniform mixture of two or more substances. • Solvent: the dissolving agent • Solute: the substance that is dissolved • Water is the solvent inside all cells, in blood, and in plants, and it dissolves an enormous variety of solutes necessary for life.

29. The chemistry of life • The chemistry of life is sensitive to acidic and basic conditions • In water solutions, a very small percentage of the water molecules actually break apart into ions. • The ions formed are called hydrogen ions (H+) and hydroxide ions (OH-). • The proper balance of these ions is very critical for the proper functioning of an organism.

30. Acids and Bases • Some water molecules break apart into ions. • Hydrogen ions (H+) • Hydroxide ions (OH-) • Acid: excess hydrogen ions (H+) • hydrochloric acid in your stomach • Base: excess hydroxide ions (OH-) • Ammonia is a base

31. Acids and Bases • We use the pH scale to describe how acidic or basic a solution is. • The scale ranges from 0 (most acidic) to 14 (most basic). • Pure water and other solutions that are neither acidic nor basic are said to be neutral; they have a pH of 7. • The pH of the solution inside most living cells is close to 7. • Even a slight change in pH can be harmful.

32. pH scale 0 1 H+ H+ H+ OH– H+ 2 Lemon juice, gastric juice OH– H+ H+ H+ H+ Increasingly ACIDIC(Higher concentration of H+) 3 Grapefruit juice, soft drink Acidic solution 4 Tomato juice 5 6 Human urine OH– OH– NEUTRAL[H+]=[OH–] OH– 7 Pure waterHuman blood H+ H+ OH– OH– H+ H+ 8 H+ Seawater Neutral solution 9 10 Increasingly BASIC(Lower concentration of H+) Milk of magnesia 11 Household ammonia OH– OH– 12 OH– OH– H+ Household bleach OH– OH– 13 OH– H+ Oven cleaner 14 Basic solution pH scale • Neutral: pH = 7 • Acid: pH < 7 • Base: pH > 7

33. Acid Rain • Imagine arriving for a long awaited vacation at a mountain lake only to discover that since your last visit a few years ago, all fish and other forms of life in the lake have perished because of increased acidity of the water. • Over the past quarter-century, thousands of lakes in North America, Europe, and Asia have suffered that fate. This problem is due to acid rain.

34. Acid Rain • Acid rain = pH well below 7 • Results from sulfur and nitrogen in the air. • These elements react with water vapor in the air to form sulfuric acid and nitric acid, which fall to the earth in rain or snow. • Acid rain with a pH of 1.7 (almost as acetic as the digestive juices in the human stomach) has been recorded in Los Angeles.

35. Acid Rain • Sulfur and nitrogen in the air comes from the burning of fossil fuels such as coal, oil, and gas. • Electrical power plants that burn coal produce more of these pollutants than any other single source.

36. Sulfur and nitrogen in the air comes from the burning of fossil fuels

37. The Effect of Acid Rain • Lakes: • most pronounced in the spring • Kills eggs and young fish • Forests: • Ions bind with essential minerals needed for plant growth • Leaves behind toxic levels of aluminum • Cities: • corrosion of buildings and statues

38. Acid Rain in Lakes • The surface snow melts first, drains down, and sends much of the acid that has accumulated over the winter into lakes and streams all at once.

39. Lakes Most pronounced in the spring Kills eggs and young fish

40. Acid Rain in Forests • Acid rain has also taken a toll on forests. When acid precipitation falls on land, it washes away mineral ions, such as calcium and magnesium, which are essential nutrients for plant growth. • At the same time, minerals such as aluminum reach toxic concentrations. • In cities, acid precipitation causes a great deal of corrosion of buildings and statues. • That is why laws were enacted that require reductions in emissions to help alleviate the problem.

41. Forests Ions bind with essential minerals needed for plant growth Leaves behind toxic levels of aluminum

42. Cities Corrosion of buildings and statues

43. Chemistry of Life • Every organism has a delicate biochemistry that needs to be maintained. • One spring, a baby finch collapsed with exhaustion on my patio. • Since it was exhausted, it probably wasn’t good at finding food and water yet. • That means it was dehydrated and hungry. • I knew to get an eyedropper and give it water with sugar in it because those are the two main things it needs right away. • We discussed water, now let’s get to sugars.

44. ORGANIC COMPOUNDS • Always contain carbon • Carbohydrates • Lipids • Proteins

45. CARBOHYDRATES • Store energy for a short time • Simple (sugars) • Complex (starches) • Cellulose (fiber) is in plants only

46. SIMPLE CARBOHYDRATES • Known as sugars • Quick source of energy • Burned off fast • Glucose • Sucrose • Fructose • Lactose (some people are lactose intolerant)

47. Lactose Intolerance • Got milk? Most of the world's people cannot easily digest milk-based foods. • Milk and other dairy products have long been recognized as highly nutritious foods, rich and proteins and minerals necessary for good teeth and strong bones. • But for millions of people, those health benefits come with digestive discomfort. • Such people suffer from lactose intolerance, or the inability to properly break down lactose, the main sugar found in milk.

48. Lactose intolerance is common world-wide

49. Lactose Intolerance • For those with lactose intolerance, the problem starts once lactose passes through the stomach and enters the small intestine. • To absorb this sugar, digestive cells need to secrete an enzyme called lactase, which is necessary to break down lactose. • An enzyme is a protein that breaks down larger molecules into smaller ones. • Those with lactose intolerance produce insufficient amounts of the enzyme and the lactose cannot be properly digested. • This leads to symptoms of nausea, cramps, diarrhea, and gas. • .

50. Lactose Intolerance • At birth, nearly everyone produces enough lactase • Therefore, milk provides excellent nourishment for infants. • But after the age of two, lactase levels start to decline in most of the world’s populations. In the United States, 75% of African Americans and Native Americans and 90% of Asian-Americans are lactase deficient once they reach their teenage years. • People of European descent are the only group that does not suffer much from lactose intolerance.