Review for Lab Practical 1

1. Review for Lab Practical #1 BIOL1406L Dr. Ann M. Davis

2. Lecture Outline Exam format Measurement Scientific method Spectrophotometry Acids, bases, and pH Macromolecules Microscopy and cytology Osmosis and diffusion

3. Format of the Lab Practical

4. General Exam Format 24 stations, 50 questions One station per desk 1-3 questions per station 2 minutes per station Entire class rotates as a group YOU MAY NOT MOVE OUT OF TURN! 10 minutes at the end to go back Answer sheet will be provided for you

5. Requirements for Answers Spelling must be correct. Answers must be completely spelled out – no abbreviations! milligram ? full credit mg ? half credit Answers must be complete. Reducing sugar ? full credit Sugar ? half credit Numerical answers: Include the units. Correctly express with scientific notation when appropriate to do so.

6. Rules of the Exam NO notes, notecards, study guides, books, or other aids. Bring only a writing implement. NO cell phones. Turn off and stow in your bag. YOU MAY NOT WORK TOGETHER ON ANY PART OF THIS EXAM! DO NOT discuss the exam outside of class until given permission to do so by the instructor. VIOLATION OF THE CODE OF ACADEMIC ETHICS WILL RESULT IN NO CREDIT.

7. Measurement

8. Basic Units of the Metric System Distance Basic unit: meter Volume Basic unit: liter Mass Basic unit: gram Temperature Basic unit: degree Celsius

9. Metric System Prefixes

10. Measurement of Distance Ruler has English measurements on one side and metric on the other English: Numbered units are inches Metric: Numbered units are centimeters Area = length x width Units are squared (m2)

11. Measurement of Volume Volume is cubic units (length x width x depth) 1 cm3 = 1 cc = 1 ml Pipettes are numbered from the top (0) down Erlenmeyer flasks and beakers are not accurate!

12. Measure Volume at the Bottom of the Meniscus

13. Measurement of Mass H2O ONLY: 1 cc = 1 ml = 1 g Mass and weight are not the same!

14. Measurement of Temperature Celsius scale is set by the boiling and freezing points of water 0oC = Freezing point of water 100oC = Boiling point of water Other common Celsius temperatures Room temperature = 25oC Refrigerator temperature = 4oC

15. Conversion Factors Example: Convert 6.4 m to cm 6.4 m x 1 = 6.4 m 6.4 m x = 640 cm Be careful of your conversion factors! SHOW YOUR WORK!!

16. Multiple Unit Conversions Conversion factors can be used in sequence Ex: Convert 8 in. to mm

17. Conversions Within the Metric System Metric system is base 10 Conversions WITHIN a unit type can move the decimal Use the prefix chart: Example: Convert 6.4 hm to mm Move 2 + 6 decimal places: 640,000,000 mm

18. Important Conversion Factors Distance 1 in = 2.54 cm Volume 1 oz = 30 ml Mass/weight 1 kg = 2.21 lbs Temperature oF = oC + 32 oC = (oF – 32)

19. Rules of Scientific Notation Scientific notation uses powers of 10 to express very large/small numbers Ex: 0.0000000042 L = 4.2 x 10-9 L Move the decimal one position: RIGHT – Subtract 1 from the exponent of 10 LEFT – Add 1 to the exponent of 10 Stop when you have ONE digit in front of the decimal. INCORRECT: 42 x 10-10, 0.42 x 10-8 CORRECT: 4.2 x 10-9

20. Scientific Method

21. Overview of the Scientific Method

22. Experimental Variables Variable – Any condition that could change during an experiment Independent variable – Manipulated by experimenter Dependent variable – Measured by experimenter; expected to DEPEND on the independent variable A good experimental design has only ONE independent variable!

23. Experimental Controls Good experimental design requires proper controls: Positive control – Sample which is known to give a positive result for a test Negative control – Sample which is known to give a negative or zero result for a test

24. Why Do We Use Statistics? Natural world is full of randomness Human mind deals poorly with randomness Statistics tells the likelihood that a result is due to randomness

25. Mean, Median, and Range Mean – Arithmetic average Median – Middle value Range – Difference between smallest and largest value Ex: 2, 2, 3, 4, 4, 4, 5, 6, 10 Mean: = 4.44 Median: 2..2..3..4..4..4..5..6..10 ? 4 Range: 10 – 2 = 8

26. Spectrophotometry

27. Spectrophotometry Measures Absorption of Electromagnetic Radiation

28. The Amount of Light Absorption is Related to Concentration Greater concentration = more molecules More molecules can absorb more light Relationship is linear

29. Introduction to the Spec20

30. Introduction to the Spec20 Digital display Displays selected wavelength and output (Abs or %T) Mode button Selects between Abs and %T modes Sample holder Holds sample for reading Wavelength control knob Changes wavelength 0% T knob Calibrate spectrophotometer for complete blockage of light 100% T knob Calibrate spectrophotometer with blank

31. A Standard Curve is Used to Estimate Concentration of an Unknown Standard - Solution of known concentration Same compound as unknown Standard curve – Graph of absorbances of standards Best fit line through points Same wavelength as the unknown

32. Standard Curves Are Prepared Using Serial Dilutions Serial dilutions – Perform repeated small dilutions to obtain a range of concentrations More accurate Give multiple concentrations Dilutions required are too great to do all at once Cannot measure very small volumes reliably

33. Preparation of Serial Dilutions

34. Acids, Bases, and pH

35. Strong vs Weak Acid/Base Strong acid/base Complete dissociation in water Ex: HCl H+ + Cl- Weak acid/base Incomplete dissociation in water Ex: HOAc H+ + OAc-

36. pH is an Expression of the Hydrogen Ion Concentration Water spontaneously dissociates at a low rate: H2O H+ + OH- [H+] = [OH-] = 10-7 M in pure H2O pH = -log10[H+] pH = 7 ? Neutral (equal H+ and OH-) pH < 7 ? Acidic (more H+ than OH-) pH > 7 ? Basic (more OH- than H+)

37. [H+] and [OH-] Are Inversely Related

38. Acid + Base = Neutralization HCl ? H+ + Cl- NaOH ? Na+ + OH- NaOH + HCl ? Na+ + Cl- + OH- + H+ NaOH + HCl ? NaCl + H2O

39. Measurement of pH Using Indicators

40. Measurement of pH Using a pH Meter pH meter must be calibrated before first use Rinse with dH2O before and after each use Allow number to stabilize before reading

41. What is a Buffer? Solution of: Weak acid (ex. HOAc) Conjugate base of weak acid (ex. OAc-) Resists large changes in pH Weak acid absorbs small amounts of strong base Conjugate base absorbs small amounts of strong acid Buffering range – Range of pH where a buffer resists large changes in pH

42. Comparing Buffering Capacity

43. Macromolecules

44. Macromolecules are the Chemical Compounds of Life Polymer – Chain of monomers Monomer – Building blocks for macromolecules Covalently linked in chains Chains can be wound up to form 3-D structures

45. Classes of Macromolecules Carbohydrates Building blocks: Monosaccharides (simple sugars) Lipids Building blocks: Fatty acids Proteins Building blocks: Amino acids Nucleic Acids Building blocks: Nucleotides

46. Carbohydrates Building blocks: monosaccharides C:H:O = 1:2:1 Monosaccharides can be linked together: Disaccharide = 2 monosaccharides joined by covalent bond (ex. Sucrose = glucose + fructose) Polysaccharide = many monosaccharides joined by covalent bonds in sequence (ex. starch, glycogen, cellulose) Reducing sugar – Sugar with free carbonyl Predominantly monosaccharides

47. Carbohydrate Tests Benedict’s Reagent Tests for reducing sugars (monosaccharides) Copper sulfate Heat to 100oC for 3 minutes Iodine Tests for starch (polysaccharide)

48. Lipids Building blocks: fatty acids Saturated – No C – C double bonds (solid) Unsaturated – One or more C – C double bonds (liquid) Hydrophobic – Cannot dissolve in water Emulsifier – Substance which promotes mixing of lipids and water Test: Sudan IV

49. Proteins Building block: amino acids 20 different types Linked by peptide bond Multiple levels of 3-D structure Perform many structural and catalytic functions in living cells Test: Biuret reagent Copper sulfate NaOH

50. Summary of Macromolecule Tests

51. Microscopy

52. Parts of the Compound Light Microscope

53. Important Concepts in Microscopy Magnification Resolving Power Contrast Viewing Field Image orientation Depth of focus Size of the field of view Working distance

54. Considerations for the Viewing Field Orientation – Image is rotated 180o Depth of focus – How much thickness of the sample is in focus Smaller as magnification increases Field of view – How much area of the slide is seen Smaller as magnification increases Working distance – How far the objective lens is from the slide Smaller as magnification increases

55. Image Orientation

56. Cytology

57. Preparation of a Wet Mount Drop of water on slide Transfer specimen into drop Place one edge of coverslip against drop Gently lower coverslip over drop 4X ? 10X ? 40X

58. Overview of an Animal Cell

59. Human Cheek Cells

60. Overview of a Plant Cell

61. Elodea and Onion Cells Elodea Leaf Onion Epidermis

62. Osmosis and Diffusion

63. Diffusion is Movement Down a Concentration Gradient

64. Diffusion Results in a Dynamic Equilibrium

65. Factors Affecting Diffusion Temperature Higher temperature ? Faster Lower temperature ? Slower Molecular size Smaller molecule ? Faster Larger molecule ? Slower Presence of a membrane Membranes are selectively permeable

66. Osmosis is the Diffusion of Water

67. Osmotic Pressure Can Damage or Kill a Cell

68. Effects of Osmosis on Red Blood Cells

69. Effects of Osmosis on Elodea Leaves Isotonic/Hypotonic Hypertonic

70. For More Review… Collin College Biology Department – BIOL1406/1408 Lab Tutorial Pages: http://iws.collin.edu/jbeck/Lab%20Study.htm Collin College Biology Department – BIOL1406/1408 Lab Practical Review Guides: http://jade.collin.edu/BIOPAGE/faculty/cardenas/review%20pictures%20for%20practical.html Dr. Mark Garcia – Video Reviews: http://iws.collin.edu/mgarcia/1406%20Lab/1406%20Lab%20Videos/1406%20Lab%20Videos%20Home.html Science Den (D202) Textbooks, microscopes and slides, models, tutoring services