1. The Chemistry of Life Chapter 2

2. Why should we study chemistry in
Biology?
Life depends on chemistry!

3. Life depends on chemistry!
When you eat food or inhale oxygen, your body uses these materials in chemical reactions that keep you alive.
Just as buildings are made from bricks, steel, glass, and wood, living things are made from chemical compounds.
Wouldn’t you want an architect to understand building materials? Same idea applies to geneticists, ecologists, zoologists, botanists, biologists, and etc.

4. Atoms
The study of chemistry begins with the basic unit of matter…the
History
Greeks were first to try to explain chemical reactions
400 BC: thought all matter composed of:
________
_________ first used word “________”, meaning indivisible
Atom

5. Atoms Atoms are composed of 3 main particles: (subatomic particles)
Protons (+)
Neutrons
Electrons (-)

6. Protons and Neutrons
Strong forces bind protons and neutrons together to form the ________, which is at the center of the atom.
Both particles have about the same _______.

7. Electrons
Electrons are negatively charged with about 1/1840 the mass of a _________.
They are in constant________ in the space surrounding the nucleus.

8. Atoms Atoms have _______ numbers of electrons and protons.
Because these subatomic particles have equal but _________ charges, atoms are _________.

10. Elements Elements are the building blocks of all matter.
Elements cannot be __________ into simpler matter.
Group Number:

11. The Elements ____ known elements ____ occur naturally
The ____ elements form a plethora of compounds, just as 26 letters of the alphabet make a seemingly endless number of words.

12. Atomic Number
Counts the number of
_________
in an atom

13. Atomic Number on the Periodic Table11 Na

14. All atoms of an element have the same number of protons11 Na
11 protons
Sodium

15. Atomic Mass Mass of an atom.
Approximately equal to the number of ___________ and ___________
Find number of neutrons by subtracting the number of protons from the mass.

16. The Periodic Table

17. Isotopes
Isotopes are atoms that have the same atomic number but different ______________.
Most elements have two or more isotopes.
Same ________ properties because the electron number does not change.

18. Isotope symbols X A Z
Mass number
Atomic number

19. B Example How many protons does this have?11 5
How many protons does this have?
How many neutrons does this have?
Is the “5” necessary ?

20. More about isotopes:
Some isotopes have ________ nuclei which break down over time.
They are called _________ isotopes
Some radiation is harmful.

21. Radiation can also be useful
Radioactive Dating
Tracers with X-rays
Cancer Treatment
Kill bacteria

22. More About Atomic Structure
The center of the atom is called the ___________.
Electrons live in something called ________.
Shells are areas that surround the center of an atom.
A shell is sometimes called an _________ or ____________________.

23. More About Electrons Every shell can hold only so many electrons
The _________ from the nucleus, the more electrons a shell can hold

24. Valence Electrons The electrons on the ________ edge of the atom
This is where the action is- where _________ takes place
Atoms have no more than __ valence electrons

25. The Octet Rule:
Atoms will combine to form ___________ in order to reach eight electrons in their outer energy level. This is very stable!
Atoms with _________________ tend to lose electrons.
Atoms with ______________ tend to gain electrons.

26. Compound
______ or ______ elements chemically combined in specific proportions
Examples:
Water H2O
_____ NaCl
Sugar C6H12O6
Chemical Formulas are used to represent compounds
Two types of compounds:
______________

27. Ionic Compounds
Form when electrons are _________ from one atom to another.
______ - Atoms with a net charge due to gaining or losing electrons
Gaining electrons gives an ion a _______ charge
Losing electrons gives an ion a _________ charge
**If they have to choose, atoms would rather be stable (with a full “octet”) than neutral.

28. How Does This Happen? Some atoms have a few too many electrons
Some atoms only need a few electrons

29. What do you do if you are a sodium (Na) atom with one extra electron?
Go look for an atom that wants it!

30. Ionic Bonding
Negative ions and positive ions are held together by ionic bond.

31. Ionic compounds form between ______ and ________

32. What If No One Will Give Up An Electron?
Atoms with less than __valence electrons can move close to each other and _______ their electrons
The electrons spend their time around both atoms.
And they lived happily ever after!

33. Covalent Bonds
Formed when a pair of electrons is _______ between two atoms.
Sometimes the atoms share two pairs of electrons and form a ___________, or three pairs of electrons to form a __________.
Structures formed by
covalent bonds are
___________.

34. Covalent compounds form between 2 ________

35. Van der Waals Forces
There are small _________ forces between all atoms
Help to hold molecules to each other
Ex: Gecko

36. 2-2 Water is a Polar Molecule
Polar: Molecule in which electrons are shared _________ between atoms, causing each end of the molecule to have a slight ________
Negative end
Positive end

37. This causes water to be attracted to other polar or charged particles
Water is attracted to _______
Water is attracted to itself, forming hydrogen bonds

38. Hydrogen Bonds In Water Are Responsible For:
__________
Attraction between molecules of different substances
Graduated cylinder
Attraction between molecules of the same substance
Drops of water on a penny
Ex: Surface Tension
Jesus Lizard

39. Types of Chemical Substances
Compounds and Elements are called _____________.
Most matter is neither of these.

40. Mixtures
Mixtures are combinations of substances held together by __________________, not chemical bonds.
Each substance keeps its own properties

41. Mixtures may be either:
____________
________
____________

42. Solutions Have small particles
Are ___________ (not the same as colorless)
Do not separate
Water solutions are very common in biological systems
Examples: salt water, kool-aid, air, brass, vinegar

43. Suspensions Have very________ particles
Settle out (separates into layers)
Examples: blood platelets, muddy water, calamine lotion, oil & water, Italian salad dressing

44. pH Scale Measures concentration of __________ ions in a solution
Ranges from 0 to 14
7 is _______
0-7 have more hydrogen ions (H+) and are _______
7-14 have more hydroxide ions (OH-) and are _______

45. Acids, Bases, and pH Water molecules form ions
H2O H OH-
Water hydrogen ion hydroxide ion
Very few ions are formed in pure water, but there are equal numbers of hydrogen and hydroxide ions
Water is neutral!

46. pH of common substances

47. pH and Homeostasis
Maintaining a pH between 6.5 and 7.5 is important in cells
Dissolved compounds called _______ control pH
________

48. Organic Compounds

50. Organic Compounds Make up most of living organisms
Contain bonds between two or more _______ atoms
Carbon can easily bond with up to __ other elements
4 valence electrons = 4 covalent bonds

51. Organic Compounds
Carbon atom is versatile, can be “__________” of long chains or rings
Organic molecules can be extremely large and complex; these are called ________________

52. Macromolecule “______ molecules”
Formed by a process called _________________
Large compounds (________) are built by joining smaller ones (__________) together

53. Organic Compounds Four main types of organic macromolecules:
______________
_______
__________

54. Carbohydrates Made of Carbon, Hydrogen, & Oxygen
Main energy source for living things
Breakdown of sugars supplies immediate _______ for cell activities
Extra sugar is stored as complex carbs called __________

55. Carbohydrates Single sugar molecules are called _________________
Examples:
_________ – in many plant and animal tissues, most common monosaccharide
________ – in many fruits
galactose – component of milk

56. Carbohydrates
Large molecules of many monosaccharide are _______________
Examples:
__________ – animals use to store excess sugar
plant starch – plants use to store excess sugar
__________ – fibers that give plants their rigidity & strength

58. Lipids
Store more energy than carbohydrates because the chains are longer
Ex: Fats, oils, waxes
Won’t dissolve in water

59. Lipids
Important parts of biological membranes and __________ coverings
__________ are lipids that act as chemical messengers

60. Lipids Many lipids are made from a glycerol combined with ____________
If all carbons have single bonds, lipid is ___________
Ex: butter, lard, animal fat (usually solid at room temperature)
If any carbons have double or triple bonds, lipid is ________________
Ex: vegetable oil, fish oil, peanut oil (usually liquid at room temperature)

62. Proteins Contain C, H, O, plus ________
Formed from _______________ joined together
More than ___ amino acids can be joined in any order or number to make countless proteins (think of how many words can be made from 26 letters!)

63. Proteins
Chains are folded and twisted giving each protein a ______________
______________ forces and __________ bonds help maintain protein’s shape
_________ of protein is important to its function!

64. Proteins Provide structure Aid chemical activities in your body
Ex: _______- makes up your skin, muscles & bones
Aid chemical activities in your body
Ex: ________- work to speed up rxns in your body
Transport substances into or out of cells
Help fight diseases

66. Nucleic Acids Contain C, H, O, N plus ____________
Formed by bonding of individual units called __________
Nucleic Acid
nucleotide

67. Nucleic Acids Store and transmit hereditary information
Ex: (deoxyribonucleic acid)
_____(ribonucleic acid)

69. Chemical Reactions
When one set of chemicals changes into another set of chemicals, a ________________ occurs
Bonds are either ________ or _________ (or both!)

70. Chemical Equations 2H2O Represent a reaction
Give the types and amounts of substances that react and form
_________ _________
2H2 + O2
“yields”
“yields”
2H2O

71. Evidence of a Chemical Reaction
Formation of a _________ (a solid substance separated from a liquid)
_____ is evolved (seen by bubbles forming in a liquid)
Change in ______ or light energy

72. Energy Transfer
Much of the energy organisms need is provided by _____ (food)
Undergoes a series of chemical reactions in which energy is released (___________________)
The net release of free energy is called an __________ (exothermic) reaction

73. Reactions that involve a net absorption of free energy are called ______________ (endothermic) reactions
_____________ is an example
Most reactions in living organisms are endergonic; therefore living organisms require a __________ source of energy

74. Most chemical reactions require ________ to begin
The amount of energy needed to start the reaction is called ______________________

75. Enzymes
Some chemical reactions are slow or have activation energies that are too high to make them practical for living tissue
These chemical reactions are made possible by ____________

76. Catalyst Substance that speeds up the rate of chemical reactions
Work by lowering a reaction’s __________________

77. Enzymes Mostly _________. Biological catalysts
_______ up reactions in cells
Very specific
Named for the reaction is catalyzes
Names always end in ________

78. Substrates The __________ of enzyme catalyzed reactions
The _________ of the enzyme and the substrate have complementary shapes
Fit like a lock and key.

79. Regulation of enzyme activity
Enzymes are affected by any variable that affects chemical reactions
____
____________
_______________