1. The Chemistry of Life
Chapter 3

2. 3-1: Matter and Substances

3. Atoms
Atom – the smallest unit of matter that can’t be broken down by chemical means
Atoms are made up of three types of particles:
Proton: (+) charged
Neutron: no charge
Electron: (-) charged
Nucleus – consists of protons and neutrons

4. Atoms A proton is about 1000 times larger than an electron
Electron cloud – the region where electrons orbit the nucleus

7. Atoms
Atomic mass =
protons + neutrons
Atomic number - The number of protons in the nucleus of an atom, which determines its place in the periodic table

8. Atoms Atomic Facts - Atomic number Atomic number = protons = electrons
Atomic mass
- Atomic number
# of neutrons
Maximum number of electrons
1st energy level – 2 electrons
2nd energy level – 8 electrons
3rd energy level – 18 electrons

9. Atoms
Element – A substance made up a group of similar atoms that have the same number of protons

10. Atoms
Isotopes – Atoms of an element that have different numbers of neutrons

11. Chemical Bonds
Valence electron – An electron that is found in the outermost shell of an atom
Lewis dot diagrams can be used to show the transfer of valence electrons

12. Polarity Polar – molecules with partial charges on opposite ends
Water is the most abundant compound in organisms

13. 3-3: Carbon Compounds

14. Building Blocks of Cells
The basic units of most biomolecules contain atoms of carbon
Carbon atoms have the ability to form four covalent bonds

15. Carbohydrates Carbohydrates – molecules made of sugars
Sugar – contains carbon, hydrogen, and oxygen in a ratio of 1:2:1
Monosaccharide – a simple sugar
Simple carbohydrates
Ex. - glucose

16. Carbohydrates Disaccharide – two sugars linked together
Oligosaccharide – few sugars linked together
Ex. – Sucrose (table sugar)
Ex. – Lactose (found in milk)

17. Carbohydrates Polysaccharide – Many sugars linked together
Complex carbohydrates
Starch – Consisted of hundreds of glucose units bonded together

18. Carbohydrates Unused glucose in animals is stored as glycogen
Unused glucose in plants is stored as starch

19. Carbohydrates Chitin and cellulose are used to provide support
Chitin is found in shells of crabs, lobsters, and insects
Cellulose is found in cell walls of plants

20. Lipids
Lipids – An organic molecule made up of carbon, hydrogen, and oxygen and will not dissolve in water
Ex. – Fats, phospholipids, steroids, and waxes

21. Lipids
Some steroid molecules include cholesterol and sex hormones (testosterone and estrogen)

22. Lipid Functions
The main purpose of fats is to convert excess food into long-term energy storage units
Phospholipids border cell membranes
Wax covers parts of plants and aquatic birds to repel water

23. Proteins
Protein – composed of chains of amino acids made of carbon, hydrogen, oxygen, and nitrogen
Amino acids – building blocks of proteins
Peptide bond – covalent bond between two amino acids

24. Nucleic Acids Nucleic acid – a long chain of nucleotide units
Nucleotide – a molecule made up of a sugar, phosphate group, and a base
DNA stores genetic information
RNA produces proteins

25. Nucleic Acids
ATP (adenosine triphosphate) – an organic molecule that acts as the main energy source for cell processes

26. 3-4: Energy and Metabolism

27. Chemical Reactions
Reactant – a substance that participates in a chemical reaction
Product – a new substance that is formed in a chemical reaction
S8 + 8 O2  8 SO2

28. Chemical Reactions
Activation energy – the minimum amount of energy required to start a chemical reaction

29. Biological Reactions
Enzyme – a molecule that acts as a catalyst in biochemical reactions

30. Biological Reactions Substrate - the substance acted upon by an enzyme
Active site – the site that attaches to a substrate on an enzyme
Active sites work like a “lock and key”

32. Biological Reactions

33. Biological Reactions Many enzymes are proteins
Denature – Changes in temperature and pH can change a protein’s shape
If an enzyme changes shape, it won’t work well