1. Biology Unit 2
The Chemistry of Life

2. Matter
Something that has mass and takes up space

3. Mass The amount of matter something contains.
This differs greatly from weight!

4. Elements
Substances that can not be broken down into simpler forms of matter
Examples include gold, oxygen, iron, calcium and lead

5. Elements Important for Life
The most important elements for life are carbon (C), hydrogen (H), oxygen (O), nitrogen (N), and phosphorus (P)
Calcium (Ca), Magnesium (Mg), potassium (K), sodium (Na), chlorine (Cl) and iron (Fe) are all needed in lesser amounts

6. Atoms
The simplest particle of an element that still retains the properties of that element

7. Parts of an Atom
The nucleus makes up most of the mass of an atom; it is made of two parts
Protons – the part of a nucleus that has a positive charge
Neutrons – the part of a nucleus that has no charge

8. Parts of an Atom Cont'd
Electrons – negatively charged parts of an atom that orbit at high speeds around the nucleus
Overall, the charge on a normal atom is zero (neutral).

9. Model of an Atom

10. Molecule Two or more atoms chemically bonded together.
Which of the examples to the left is a molecule?

11. Compound Made of atoms of two or more elements.
Which of the examples to the left is a compound?

12. Water
Water is one of the most important compounds to most forms of life, due to its unique chemical properties.

13. Adhesion
Water's ability to stick to other things

14. Cohesion
Water's ability to stick to itself

15. Hydrogen Bonding
The oxygen in water is larger and attracts that electrons shared by the hydrogen unequally.
This causes the oxygen portion to take on a slight negative charge and the hydrogen portion a slight positive one +
H H O _

16. Other Properties of Water
Water has a low freezing point
Water has a high heat capacity (it changes temperature slowly)
Help us remain warm blooded

17. Organic Compounds Usually contain carbon
Usually associated with living creatures
Most are polymers (large molecules made of repeating units)
These polymers are made of small molecules called monomers

18. Dehydration Synthesis
Monomers bond together with the removal of water.

19. Hydrolysis
Monomers are removed with the addition of water.

20. Carbohydrates Made of C, H and O Monomers are called monosaccharides
Examples are sugars, starch and glycogen
Disaccharide – two monosaccharides bonded together
Polysaccharide – many monosaccharides bonded together

21. Lipids Made of C, H and O Monomers are called fatty acids
Examples are fats, oils, waxes, cholesterol, steroids and some hormones

22. Nucleic Acids Made of C, H, O, N and P Monomers are called nucleotides
Example are deoxyribonucleic acid and ribonucleic acid (DNA and RNA)

23. Proteins Made of C, H, O and N Monomers are called amino acids
Enzymes are examples
Polypeptide – many amino acids bonded together

24. Enzymes Enzymes catalyze chemical reactions
This means the reactions happen faster and need less energy to take place
Complex life forms could not live without them
They are not consumed

26. Enzyme Functioning
Enzymes work best at a particular pH, which varies with each enzyme
When temperatures increase, the rate of enzyme activity increases, until 40 degrees C is reached, then the enzyme denatures

27. Enzyme Functioning Continued
Rates of enzyme activity increase as the concentration of substrate increases, until all of the enzymes are active, then increased substrate can not increase reaction rates.

28. Solutions
A mixture of substances that look like one substance and are difficult to separate.

29. Solvent The part of the solution that is present in the largest amount
It dissolves things

30. Solutes Substances present in lesser amounts Can be more than one.
The substances that get dissolved

31. Mixtures
Two or more substances together that do not look like one substance and can usually be easily separated.

32. Suspension A mixture in which one or more substances settle over time.
Ex: Italian dressing

33. Colloid
A mixture in which one substance is found in another, but it doesn’t settle.
Ex: a Jell-o fruit cup

34. Importance of Carbon
The number of outer level or valence electrons determines how an element will react with other elements.
Most elements need to have eight valence electrons in their valence shell to be stable.

35. Importance of Carbon Cont’d
In order to fill its outer electron shell, carbon forms four bonds with other elements
The ability to form four bonds is what allows carbon to make polymers
That’s why earth’s life forms are based upon carbon (organic)