The Nature of Science

1. The Nature of Science Biology is the study of the living world

2. Scientific Method is the process scientists use to gather information and test hypothesis • A hypothesis is a proposed scientific explanation for a set of observations • A hypothesis must be testable

3. A theory is a well-tested explanation that unifies a broad range of observations (hypotheses) • A theory may be revised or replaced as science advances

4. Designing an Experiment • An experiment starts with observations • Observations lead to asking a question and proposing a hypothesis • A hypothesis is tested using a controlled experiment • Data is the information collected; results are recorded and analyzed • A conclusion is drawn and the hypothesis is either supported or disproven

6. Qualitative Datadescribes data (color, age, shape, etc)

7. Quantitative Datacounts numerical data

8. Controlled Experiment • Independent Variable – this is what the scientist changes across groups in an experiment

9. Dependent Variable – this is what changes as a result of the independent variable and is consequently measured

10. In a controlled experiment only ONE variable is changed at a time and all other variables are kept unchanged, or controlled.

11. Major Molecules of Life • Macromolecules – giant molecules found in living cells; made from thousands of smaller molecules.

12. Dehydration synthesis is the process that removes a H2O molecule from two reactants to create bonds forming a single molecule from two or more by removing H2O

13. Hydrolysis is the process of adding a H2O molecule to a reactant to break bonds forming two separate molecules by adding H2O to a single molecule.

14. Amonosaccharide– • -Mono = “one or single” • -saccharide= “sugar” • building block of all carbohydrates • Main energy storing molecules of living things =

15. Carbohydrates • Living things use carbohydrates as their main source of energy • Plants use carbohydrates for structural purposes • Carbohydrates are sugars and starches

16. Single sugar molecules are called monosaccharides • Monosaccharides include glucose and fructose

17. Large macromolecules formed from many monosaccharides are known as polysaccharides in a process called polymerization. • Poly = “many” • saccharide = “sugar” • macro = “very large”

18. POLYSACCHARIDE • Polysaccharides include: starches and cellulose

19. Monosaccharide

20. Polysaccharide

21. Lipids • Lipids are not soluble in water • Fats, oils, and waxes are lipids • Lipids can be used to store energy • Lipids are important parts of waterproof coverings (like skin) and biological membranes

22. Lipids are formed from a glycerol molecule and several fatty acids

23. LIPIDS Examples: fats, phospholipids, steroids

24. Saturated fats join carbon to carbon with a single bond. • Unsaturated fats join at least one carbon atom to another carbon atom with a double bond. • Polyunsaturated fats have more than one carbon to carbon double bond.

26. FATS: • Saturated: solid at room temp. (butter) • Unsaturated: oils at room temp. (olive oil) • PHOSPHOLIPIDS: • found in the cell membrane • STEROIDS: • estrogen, testosterone, cholesterol

27. Fats– used for cell membranes - used to store energy

28. Nucleic Acids • Nucleic acids store and transmit genetic information • The individual molecules in nucleic acids are called nucleotides and are made of a sugar, a phosphate group, and a nitrogenous base • The two kinds of nucleic acids are DNA and RNA • The order of the individual nucleotides in a DNA or RNA molecule determine the traits in an organism

30. Proteins • There are 20different amino acids found on our planet • Amino acids are the building blocks of proteins • Different combinations of amino acids form different proteins • Each protein has a specific role or job in an organism

31. Some proteins control the rate of reactions and regulate cell processes • Some proteins are used to form bones and muscles • Some proteins transport substances into or out of cells and fight disease

32. Just like any tool, a protein’s function is determined by its shape.

33. AMINO ACIDS • There are 20 total amino acids that comprise proteins http://www.medterms.com/script/main/art.asp?articlekey=2222 • Ex: Phenylalanine: essential for physical and intellectual growth. Tyrosine is made from phenylalanine.

34. Chemical Reactions and Enzymes • A chemical reaction is a process that changes one set of chemicals into another set of chemicals • Reactant: the chemicals entering the reaction • Product: the chemicals made from the reaction

35. Many chemical reactions require energy in order for them to occur; humans eat food in order to supply energy for these chemical reactions

36. Energy needed to start a chemical reaction is called activation energy. • A catalyst is a substance that speeds up the rate of a chemical reaction. Activation Energy w/o Catalyst Activation Energy with catalyst

37. Enzymes are proteins that act as biological catalysts in chemical reactions that occur in cells. • Enzymes are tools; they are NOT part of the chemical reaction and are the same after the reaction as they were before the reaction. • Enzymes lower the activation energies, allowing the chemical reaction to occur without needing so much energy to get started.

38. The reactants of enzyme-catalyzed reactions are called substrates. • Enzymes provide a site where reactions can be brought together to react; reducing the activation energy • Enzymes can be turned off or on by certain proteins in cells. • Enzymes can be affected by pH and temperature

39. Enzymes are very specific to a particular substrate; they will only “fit” that particular molecule

40. ENZYME EXAMPLE • Phenynalaninehydroxylase breaks down phenylalanine into tyrosine which helps break it down. Without the enzyme build up of this amino acid would cause too much toxin in the brain.

41. ENZYME EXAMPLE • Lactase is the enzyme that breaks down lactose in the body. Lactose is a major type of sugar found in milk. • Salivary amylase is the enzyme that breaks down food in your mouth before it enters your digestive tract.

42. Interactive Enzyme Animations for Students • Click below http://www.lewport.wnyric.org/jwanamaker/animations/Enzyme%20activity.html

43. Online Indicator Lab http://www.okc.cc.ok.us/biologylabs/Documents/Organic%20Compounds/Organic%20Compounds.htm