1. Chapter 6 Chemistry in Biology
6.1 Atoms, Elements and Compounds

2. Elements Everything is made of substances called elements
About 90 elements occur naturally
About 16 elements are man made
Of the 90 naturally occurring elements, only 25 are essential to living things

3. Periodic Table of the Elements

4. Reading the Periodic Table

5. Periodic Table of the Elements

6. Needed in Macro-amounts
Oxygen 65%
Carbon 18.5%
Hydrogen 9.5%
Nitrogen 3.3%
Other elements are needed in trace amounts

7. Trace Elements
All organisms need trace elements even though they are needed in very small amounts they are essential for life
Plants absorb the trace elements from the soil
Animals eat the plants and other animals
Examples: iron, magnesium, gold, arsenic, copper and many others

8. Atoms: The Building Blocks of Elements
Atoms is the smallest particle of an element that has the characteristics of that element
Nucleus contains protons (+) and neutrons (0)
Electrons (-) in “cloud” around nucleus
Carbon atom

9. Electron Energy Levels
Certain numbers of electrons can occupy different regions around the nucleus of an atom
Energy Levels
1st- closest to nucleus: 2 electrons
2nd- next level out: 8 electrons
3rd- further level out: 18 electrons

10. Electron Energy Levels
Closest energy levels are always filled first
Carbon atoms have 6 electrons
2 electrons are in the first energy level
The remaining 4 electrons fill the second energy level

11. Potassium Energy Levels
19 total electrons
2 electrons in first energy level
8 electrons in second energy level
9 would be in third energy level but this is unstable
8 electrons in third
1 electron in fourth

12. Isotopes of an Element

13. Isotopes of an Element
Atoms that have different numbers of neutron but the same number of protons
Have same protons (atomic number) but different numbers of neutrons (atomic mass)
Most isotopes are unstable and the nuclei break apart and give off radiation
Useful for X rays
Useful for radioactive dating

14. Chapter 6
Chemistry in Biology
6.1 Atoms, Elements, and Compounds
van der Waals Forces
When molecules come close together, the attractive forces between slightly positive and negative regions pull on the molecules and hold them together.
The strength of the attraction depends on the size of the molecule, its shape, and its ability to attract electrons.

15. Compounds and Bonding
Compounds: composed of two or more different elements that are chemically combined (bonded)
Chemical bonds hold atoms together so that they are more stable
Atoms are more stable when they have their outer electron energy levels filled
Bonds can be covalent or ionic

16. Covalent Bonds Atoms share electrons Covalent means cooperate
A molecule is a group of atoms held together by covalent bonds

17. Ionic Bonds Ionic bonds involve gaining or losing electrons
Na has lost an electron and now has a positive charge
Cl has gained and electron and now has a negative charge
Opposite charges attract

18. Ionic Bonds Ions are atoms that have gained or lost electrons
Lose electron have a positive charge
Gain electrons have a negative charge
Ionic bonds are not as common as covalent in living organisms

19. Chapter 6 Chemistry in Biology
6.2 Chemical Reactions

20. Chemical Reactions
When chemical reaction occur, bonds between atoms are formed or broken causing substances to combine and recombine as different molecules
All of the chemical reactions that take place in an organism is called metabolism
Chemical reaction depend on many things: temperature, concentration and pH

21. Balancing Chemical Reactions
Matter cannot be created or destroyed only changed in form
So all atoms must be accounted for in a chemical reaction

22. Balancing Chemical Reactions
What you start with (reactants) must equal what you end up with (products)
2H2 + O H2O
2 x H 2 x 2
2 O 2 x 1

23. Chapter 6
Chemistry in Biology
6.2 Chemical Reactions
Energy of Reactions
The activation energy is the minimum amount of energy needed for reactants to form products in a chemical reaction.

24. This reaction is exothermic and released heat energy.
Chapter 6
Chemistry in Biology
6.2 Chemical Reactions
This reaction is exothermic and released heat energy.
The energy of the product is lower than the energy of the reactants.

25. This reaction is endothermic and absorbed heat energy.
Chapter 6
Chemistry in Biology
6.2 Chemical Reactions
This reaction is endothermic and absorbed heat energy.
The energy of the products is higher than the energy of the reactants.

26. It does not increase how much product is made and it does not get used
Chapter 6
Chemistry in Biology
6.2 Chemical Reactions
Enzymes
A catalyst is a substance that lowers the activation energy needed to start a chemical reaction.
It does not increase how
much product is made and it does not get used
up in the reaction.
Enzymes are biological catalysts.

27. The reactants that bind to the enzyme are called substrates.
Chapter 6
Chemistry in Biology
6.2 Chemical Reactions
The reactants that bind to the enzyme are called substrates.
The specific location where a substrate binds on an enzyme is called the active site.

28. Chapter 6
Chemistry in Biology
6.2 Chemical Reactions
The active site changes shape and forms the enzyme-substrate complex, which helps chemical bonds in the reactants to be broken and new bonds to form.
Factors such as pH, temperature, and other substances affect enzyme activity.

29. Chapter 6 Chemistry in Biology
6.3 Water and Solutions

30. Mixtures and Solutions
Mixtures are combinations of substances in which the individual components retain their own properties, like sand and salt mixed together, no chemical reactions have taken place
Solutions are a type of mixture where one substance dissolves in another substance
Solvent does the dissolving: water
Solute gets dissolved: sugar
Solutions are very important in living things as we are ~75% water

31. Acids and Bases
pH is a measure of how acidic or basic a substance is

32. Ph Scale Most of our foods are acidic
Most of our cleaning supplies are basic (alkaline)

33. Blood pH

34. Chapter 6
Chemistry in Biology
6.3 Water and Solutions
Buffers are mixtures that can react with acids or bases to keep the pH within a particular range.

35. Importance of Water
Most life’s process (chemical reactions) can only happen in water
Water is a transport medium: blood and sap
Water has a high specific heat; holds heat and requires more heat to change its temperature; works like an insulator
Water expands when it freezes, less dense; ice floats on top

36. Structure of Water Chemical formula: H2O Water is polar
Oxygen end negative
Hydrogen end positive

37. Polar Covalent Bonds
The electron in the covalent bond between the hydrogen and oxygen spends more time with the oxygen
Causes the oxygen end to be slightly negative, hydrogen end to be slightly positive

38. Hydrogen Bonds Form due to Polarity
Hydrogen bonds are weak bonds between molecule
Positive end of one molecule is attracted to negative end of another molecule
Causes cohesion
Causes adhesion

39. Water’s Hydrogen Bonds

40. Chapter 6 The Chemistry of Life
6.4 The Building Blocks of Life

41. Carbon Carbon is the element present in all life substances
Carbon has a unique structure
Shares four electrons
Forms four covalent bonds
Can have single, double, or triple bonds
Because of bonding some molecules of the same formula can have different shapes
CH4 Methane

42. Carbon Glucose has formula C6H12O6 Fructose has formula C6H12O6
Isomers have same formula but different

43. Carbohydrates Contain carbon, hydrogen, and oxygen Subunit : glucose
Two types simple and complex

44. Simple Carbohydrates: Sugars
Monosaccharides: one sugar
Glucose
Fructose
Galactose
Disaccharides: two sugars
Sucrose: glucose and fructose
Maltose: glucose and glucose
Lactose: glucose and galactose

45. Simple Carbohydrates: Sugars
Fructose

46. Complex Carbohydrates: Polysaccharides
Include starch, cellulose and glycogen
All are chains of glucose
Difference is how the chains are put together and type of bonds holding the glucose together

47. Starch
Carbohydrate storage for plants

48. Cellulose Carbohydrate structural support for plants and algae
Found in the cell wall to give the cell structure and support

49. Glycogen Carbohydrate storage for animals
Found in liver and can move to any location
Found in muscle and only stays in that muscle
Liver Cell

50. Lipids Contain carbon, hydrogen, and oxygen Subunit: fatty acid
Three types:
Diglycerides
Triglycerides
Sterols
Many more carbon-hydrogen bonds to store large amounts of energy

51. Fatty Acids
Can be saturated with hydrogen and have no double bonds (most animal fats)
Can have double bonds and be unsaturated (most plant fats)
Health risks associated with saturated fats

52. Diglycerides A Phosphodiglyceride is the main part of cell membranes
Not a large component of our body
Not a large component of the food we eat
Contain a glycerin backbone and two fatty acid chains

53. Triglycerides The most common lipid Found in our bodies
Found in the food we eat
Called fats and oils
Contain a glycerin backbone and three fatty acid chains

54. Sterols Contain four interconnected carbon rings
Common one is cholesterol
Many other sterols are made from cholesterol
Some hormones are sterols

55. Proteins Contain, carbon, hydrogen, oxygen and nitrogen
Subunit: amino acid
20 different amino acids
Linked by peptide bond
Types: structural protein and enzymes
Structural- build a part
Enzymes- control the rate of chemical reactions

57. Enzymes Works on a specific substrate
Lock and key fit with the substrate
Products are released
After reaction the enzyme resumes its original shape and can react again with another substrate

58. Nucleic Acids
Contain carbon, hydrogen, oxygen, nitrogen and phosphorus
Subunits: nucleotide
Phosphate group
Sugar
Nitrogen base
Types: RNA and DNA
Nucleotide

59. DNA and RNA

60. DNA Deoxyribonucleic acid
Information storage for cell in cell’s nucleus
Directs cell’s activities
Genetic code blueprint
Double helix

61. RNA Ribonucleic acid Needed by DNA to make proteins
Working copy of DNA
Leaves the nucleus