1. Chapter 2
Chemistry of Life

2. Biology Biology: The study of life
In order to understand life your must have a basic understanding of chemistry

3. Matter and Energy Matter: anything that occupies spaces and has mass
Everything around us is matter
Element: a pure substance that cannot be broken down into other substances by chemical means
ex. gold, helium, mercury

4. MAtter There are about 25 elements that are essential to life
Four elements make up 96% of living matter
Oxygen, Carbon, Hydrogen and Nitrogen
Trace Elements: elements that make up less than 0.01% of your body mass
Ex. Calcium Phosphorus, potassium and sulfur

5. MAtter

6. Matter
Compounds: a substance containing two or more elements that are chemically combined in a fixed ratio
Ex. H2O
A compounds properties may differ greatly from those of its component elements
Ex. NaCl

7. Atoms Atom: the smallest possible particle of an elements
Atom of all elements are made of even smaller components called sub atomic particles
Proton: a subatomic particle with a single unit of positive charge (+)
Electron: a subatomic particle with a single unit of negative electrical charge (-)
Neutron: a subatomic particle that has a neutral charge ( Think of it like a proton and electron combined)

8. atoms
An atoms protons and neutrons are tightly packed together, forming a central core called the nucleus
Electrons have much less mass than neutrons and protons and continually move about the outside of the nucleus at high speeds
The attraction between the negatively charged electron and positively charged protons keeps the electrons close to the nucleus

9. atoms

10. ElemeNts
An important difference between elements is the number of protons in their nucleus
All atoms of a particular element have the same number of protons
The number of protons is known as the Atomic Number
Ex helium has two protons so it has an atomic number of 2

11. Elements
Left alone atoms generally tend to hold as many protons and electrons.
This creates an atom with an electrically neutral charge because the positive charge of the protons and the negative charge of the electrons cancel each other out
The number of electrons is not always equal to the number of protons, because some elements tend to lose or gain electrons (these atoms are called Ions)

12. Isotopes Some elements have alternative forms called Isotopes
Isotopes have the same number of protons in their atom but a different number of neutrons

13. Radioactive isotopes
Radioactive Isotope: isotope in which the nucleus decays (breaks down) over time, giving off radiation in the form of matter and energy
Ex. carbon-14
Radioactive isotopes have many uses in research and medicine because living cells use radioactive isotopes just as they would use the nonradioactive forms
They are like spies

14. Electron configuration
Electrons differ in the amount of energy they have and the how tightly they are held by the protons in the nucleus
Based in these properties electron are classified into different energy levels
The first and lowest energy level (nearest to the nucleus) can hold 2 electrons
The second level holds 8
If the outermost energy level is not full the element is considered chemically reactive

15. Electron configuration

16. Ions
Ionic Bond: type of chemical bond that occurs when an atom transfers an electron to another atom
Ex. table salt NaCl
Ions: atoms or groups of atoms that have become electrically charged as a result of gaining or losing electrons

17. Covalent Bonds Covalent Bond: forms when two atoms share electrons
Covalent bonds are represented using the element symbols and dots that represent the atoms outermost electrons

18. Bonding Numbers of bonds
The number of bonds an atom can form usually equals the number of additional electrons that will fill its highest energy level.
Ex. a hydrogen atom can accept one additional electron so it can form only one bond
Ex. an oxygen atom can accept 2 additional electrons so its can form up to 2 bonds

19. Molecule Molecule: two or more atoms held together by covalent bonds
Molecules can be modeled in three different ways
Chemical formula: tells you the number and types of atoms
Structural formula: indicates how atoms in a molecule are linked by bonds
Space filling model: shows three dimensional structure of the molecule

20. Chemical Reactions
Chemical reactions: breaking of old chemical bond and the formation of new chemical bonds that result in new substances
The starting materials in a chemical reaction are called the reactants
The ending materials in a chemical reaction are called products

21. Properties of Water All living things are dependent on water
Structure of Water
Two hydrogen atoms attached to an oxygen atom by a covalent bond
What makes oxygen unique is that the oxygen atom hogs all of the electrons
This makes the oxygen more negatively charged than the hydrogen atoms
Polar molecule: a molecule in which opposite ends have electric charges

22. Properties of Water
Because the water molecule is polar the molecules are attracted to each other in a very specific way forming a hydrogen bond
The negative end attracts the positive end

23. Properties of Water
Hydrogen Bond: type of weak attraction between the hydrogen atom of one molecule and a slightly negative atom with in another molecule
Hydrogen bonds are very weak
These hydrogen bonds make water have some very unique properties

24. Properties of Water The Unique Properties of Water
Cohesion: the tendency of molecules of the same kind to stick to one another
Water has a much stronger cohesion than other liquids
Adhesion: the type or attraction that occurs between unlike molecules
ex. water sticks to glass
Adhesion and cohesion are very important properties of water to life on Earth

25. Properties of Water Temperature
Because of the hydrogen bonds water has a much greater resistance to temperature change
Ex. getting water to boil
Temperature: a measure of the average energy of random motion of the particles in a substance

26. Properties of Water Low density of ice
Density is the amount of matter in a given volume
In most substances the solid state is more dense than the liquid state
But in water the solid form is much less dense than the liquid
This is why ice floats on water

27. Properties of Water Water has the ability to dissolve other substances
Solution: a uniform mixture of two or more substances
Ex. when you dissolve salt into water
Solvent: the substance that dissolves the other substance and is present in the greater amount
Ex water
Solute: the substance that is dissolved and is present in the lesser amount
Ex. Salt

28. Carbon Based Molecules
Remember that an atoms bonding ability is related to the number of electrons in the outermost energy level
Carbon has four electrons in the outermost energy level which means that it has the ability the form up to four bonds with other atoms
Carbon atoms can form bonds with one or more other carbon atoms producing many different carbons skeletons
Organic Molecules: carbon based molecules
Inorganic Molecules: non-carbon based molecules
Hydrocarbons: organic molecules that are composed of only hydrogen and carbon
In addition to hydrogen atoms oxygen and nitrogen are also common

29. Carbon Based Molecules

30. Carbon Based Molecules
Functional Group: a group of atoms within a molecule that interacts in predictable ways with other molecules
Hydrophilic: attracts water
an example of a hydrophilic functional group is the hydroxyl group

31. Monomers and Polymers Monomers and Polymers
Polymers: long chains or molecules that your cells link together
Monomers: the smaller units that make up polymers
Polymers can form long straight chains or the chains can fold over one other
A living organisms has thousands of different polymers that help the organisms perform different functions
These thousands of polymers are made up of only 50 different kinds of monomers

32. Monomers and Polymers Building and Breaking Polymers
Organisms not only build polymers they also have to break them down
Ex. many of the molecules in your food are polymers. Your body must breaks down these molecules in order for it to use
Each time a monomer is added to a chain a water molecule is released
This is called a dehydration reaction because it involves removing a water molecule
De- (remove) Hydro- (water)

33. Building and breaking polymers
Dehydration Reaction
Hydrolysis Reaction
Hydro-water
Lysis- to break

34. Carbohydrates
Life’s large molecules are classified into four main categories: carbohydrates, lipids, proteins and nucleic acids
Carbohydrates: organic compound made up of sugar molecules.
Sugars contain the elements carbon, hydrogen and oxygen in the ratio of 1 carbon: 2 hydrogen: 1 Oxygen
Most sugars have a carbon skeleton with a ring shape

35. Carbohydrates Monosaccharides
Monosaccharides contain just one sugar unit
Ex Glucose, fructose and Galactose
Sugar molecules are the main food supply for cellular work
Very similar to how a car uses gasoline

36. Carbohydrates Disaccharides
Double sugars made from monosaccharides by using a dehydration reaction
Sucrose which consists of a glucose molecule linked to a fructose molecule

37. Carbohydrates Polysaccharides (complex carbohydrates)
Long polymer chains made up of simple sugar monomers
Ex. Starch is a polysaccharide made entirely of glucose molecules
Starch is found in plant cells
Starch chains branch and coil up into loop
Animal cell do not contain starch they contain glycogen
Glycogen is a polysaccharide that helps animals store excess sugar

38. Carbohydrates
Some polysaccharides in plants serve as building materials
Ex. Cellulose- protects cells and stiffens the plant
Cellulose is also made of glucose molecules (like glycogen and starch)
Most animals, including people cannot digest cellulose because they lack the molecule necessary to break the bonds between the glucose molecules in cellulose
But some organisms like cows and termites can break down cellulose and use it for nutrients because they have microorganisms in their digestive tracts that are able to break down the cellulose

39. Carbohydrates

40. Carbohydrates
Almost all carbohydrates are hydrophilic because there are many hydroxyl found on them
This means that monosaccharides and disaccharides dissolve easily in water
On the other hand cellulose and some forms of starch are such large molecules that they do not dissolve in water

41. Lipids Characteristics of lipids Uses of lipids
Lipids are water avoiding
Hydrophobic: meaning water fearing
Uses of lipids
They can act as a boundary that surrounds and contains the watery contents in your cell
They can also store energy in your body

42. Lipids
Fats
Fat consists of a three-carbon backbone called glycerol attached to three fatty acids
Fatty acids contain long hydrocarbon chains
Some fats are solid at room temperature
Some fats are oil and liquids at room temperature
Unsaturated Fat

43. Lipids Saturated Fats Unsaturated Fats
A fat in which all three fatty acid chains contain the maximum possible number of hydrogen atoms
All the carbon atoms in the fatty acid chains form single bonds with each other, and the rest of their bonds are with hydrogen atoms.
Saturated fats are solid at room temperature
Unsaturated Fats
Contains less than the maximum number of hydrogen atoms in one or more of its fatty acid chains, because some of its carbon atoms are double bonded to each other
Usually liquids at room temperature

44. Lipids
Steroids
A lipid molecule in which the carbon skeleton forms four fused rings
While all steroids have the core of four rings, they differ in the kinds of functional groups that are attached to the rings
Steroids can circulate in your body as chemical signals
Ex. estrogen and testosterone

45. Lipids Maybe the best known steroid is cholesterol
It is an essential molecule found in the membranes that surround your cells
It is also the starting point from which your body produces other steroids

46. proteins Function of Proteins
Protein is a polymer constructed from a set of just 20 monomers known as amino acids
Proteins are responsible for almost al of the day to day functioning of organisms
Proteins form the structures that make up fur, hair, muscles and provide long term nutrient storage
Proteins also have other functions including acting as signals and conveying messages from one cell to another

47. Proteins
Amino Acids
Each amino acid monomer consists of a central carbon atom bonded to four partners
Three of the central carbon partners are the same in all amino acids
One partner is a hydrogen atom
One partner is a carboxyl group
One partner is an amino group
What is different in each amino acid is the side group
The side group is responsible for the particular function of the amino acid

48. Proteins Building a Protein
Cells create proteins by linking amino acids together into a chain called a Polypeptide
Each link is created by a dehydration reaction between the amino group of one amino acid and the carboxyl group of the next amino acid in the chain
There are an enormous variety of proteins that your body can create because there are many different orders the amino acids can go in
Think of amino acids as letters in an alphabet and the polypeptides are the words that you can make from the alphabet

49. Proteins

50. Proteins Protein Shape
A protein in a simple form of an amino acid linked together cannot function properly
A functional protein consists of one or more polypeptides precisely twisted, folded and coiled into a unique shape
An unfavorable change in temperature, pH, or some other quality of the environment can cause the protein to unravel and lose it normal shape
This is called the denaturation of the protein

51. Activation energy
To start a chemical reaction, it is first necessary to weaken chemical bonds in the reactant molecules
To weaken the chemical bonds you usually need energy
This energy is called activation energy because it activates the reactants and triggers a chemical reaction

52. Activation Energy
One way to provide activation energy is to heat a mixture of molecules
The hotter the molecules the more they will collide and the more likely the bonds in those molecules will break
In cells however to provide the activation energy you cannot heat the cell because it will kill it
You instead use what is called a Catalyst: a compound that speeds up chemical reactions
The main catalyst in chemical reactions are proteins called enzymes

53. Enzymes
Enzymes provide a way for reactions to occur at the cell’s normal temperature
An enzyme does not provide the activation energy it lowers the activation energy
Each type of enzyme catalyzes a specific kind of chemical reaction

54. Enzymes
The reason that enzymes only catalyze one type of reaction is because of its shape.
It is sort of like how a key fits into a lock
Substrate: a specific reactant acted upon by an enzyme
The substrate fits into a particular region of the enzyme called the active site

55. Enzymes

56. Nucleic Acids
Polymers that are made up of monomers called nucleotides.
There are two types of nucleic acids
DNA and RNA
Nucleotides contain three parts
A sugar
A phosphate group
A nitrogen base