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Review for Lab Practical #1 BIOL1406L Dr. Ann M. Davis Lecture Outline • Exam format • Measurement • Scientific method • Spectrophotometry • Acids, bases, and pH • Macromolecules • Microscopy and cytology • Osmosis and diffusion Format of the Lab Practical 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 Requirements for Answers • Spelling must be correct. • Answers must be completely spelled out – no abbreviations! – milligram à full credit – mg à half credit • Answers must be complete. – Reducing sugar à full credit – Sugar à half credit • Numerical answers: – Include the units. – Correctly express with scientific notation when appropriate to do so. 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. Measurement Basic Units of the Metric System • Distance – Basic unit: meter • Volume – Basic unit: liter • Mass – Basic unit: gram • Temperature – Basic unit: degree Celsius http://miazusm.com/icdesign/wp-content/uploads/2010/07/Metric-System-Prefixes.jpg Metric System Prefixes 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) English measurements http://jade.collin.edu/BIOPAGE/faculty/cardenas/1%20measurement_files/frame.htm Metric measurements Measurement of Volume • Volume is cubic units (length x width x depth) • 1 cm3 = 1 cc = 1 ml • Pipettes are Erlenmeyer flasks numbered from the top (0) down • Erlenmeyer flasks and beakers are not accurate! Pipette Graduated cylinder Beaker http://jade.collin.edu/BIOPAGE/faculty/cardenas/1%20measurement_files/frame.htm Measure Volume at the Bottom of the Meniscus http://www.montgomerycollege.edu/Departments/biotp/Metric.html Measurement of Mass • H2O ONLY: 1 cc = 1 ml = 1 g • Mass and weight are not the same! Triple beam balance Electronic scale http://jade.collin.edu/BIOPAGE/faculty/cardenas/1%20measurement_files/frame.htm 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 = 4 oC http://sciencephoto.com/images/download_lo_res.html?id=670013583 Conversion Factors • Example: Convert 6.4 m to cm – 6.4 m x 1 = 6.4 m – 6.4 m x 100 cm = 640 cm 1m • Be careful of your conversion factors! • SHOW YOUR WORK!! Multiple Unit Conversions • Conversion factors can be used in sequence • Ex: Convert 8 in. to mm 2.54 cm = 1 in AND 1 cm = 10 mm 2.54 cm 10 mm 8 in x x = 203.2 mm = 2.03 x 102 mm 1 in 1 cm 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 Important Conversion Factors • Distance • Medical conversions – 1 in = 2.54 cm – 1 kg = 2.21 lbs • Volume – 1 cc = 1 ml – 1 oz = 30 ml – 1 tsp = 5 ml • Mass/weight – 1 kg = 2.21 lbs • Temperature 9 o – oF = C + 32 5 – oC = 5 (oF – 32) 9 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 Scientific Method Overview of the Scientific Method Observation Results Theory/L Hypothesis aw Experiment 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! 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 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 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: 2 + 2 + 3 + 4 + 4 + 4 + 5 + 6 + 10 = 4.44 9 – Median: 2..2..3..4..4..4..5..6..10 à 4 – Range: 10 – 2 = 8 Spectrophotometry Spectrophotometry Measures Absorption of Electromagnetic Radiation http://www.antonine-education.co.uk/physics_gcse/Unit_1/Topic_5/em_spectrum.jpg The Amount of Light Absorption is Related to Concentration • Greater concentration = more molecules • More molecules can absorb more light • Relationship is linear http://www.websters-online-dictionary.org/images/wiki/wikipedia/commons/6/63/Dilution-concentration_simple_example.jpg http://www.pharmainfo.net/files/images/stories/article_images/Various%20UV%20spectrophotometric_Fig2.JPG Introduction to the Spec20 http://iws.collin.edu/jbeck/Spectrophotometryweb/Spectrophotometer.jpg 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 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 Garcia, M. and R. Orr (2011). Biology 1406 & 1408 Lab Manual. Frisco, TX: Collin County Community College District. 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 Preparation of Serial Dilutions 1 ml 1 ml 1 ml 1 ml Original 1 ml H2O 1 ml H2O 1 ml H2O 1 ml H2O 10 mg/ml 5 mg/ml 2.5 mg/ml 1.3 mg/ml 0.6 mg/ml New pipette every time! Mix every time! Acids, Bases, and pH 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- pH is an Expression of the Hydrogen Ion Concentration • Water spontaneously dissociates at a low rate: – H2 O H+ + OH- – [H+] = [OH-] = 10-7 M in pure H2O • pH = -log10[H+] – pH = 7 à Neutral (equal H+ and OH-) – pH < 7 à Acidic (more H+ than OH-) – pH > 7 à Basic (more OH- than H+) + - [H ] and [OH ] Are Inversely Related H+ OH- H+ OH- H + OH- Acid + Base = Neutralization • HCl à H+ + Cl- • NaOH à Na+ + OH- • NaOH + HCl à Na+ + Cl- + OH- + H+ • NaOH + HCl à NaCl + H2O Measurement of pH Using Indicators pH Paper Anthocyanins Extract of red cabbage http://iws.collin.edu/jbeck/AcidsBasesweb/pHpaperandkey2.jpg http://iws.collin.edu/jbeck/AcidsBasesweb/Anthocyaninstandards.JPG 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 http://jade.collin.edu/BIOPAGE/faculty/cardenas/4%20acids_bases_pH_files/frame.htm 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 Comparing Buffering Capacity Solution B Solution A pH 7 10 mL of HCl 10 mL of NaOH 0 mL SOLUTION A IS THE BUFFER http://jade.collin.edu/BIOPAGE/faculty/cardenas/4%20acids_bases_pH_files/frame.htm Macromolecules 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 Classes of Macromolecules • Carbohydrates – Building blocks: Monosaccharides (simple sugars) • Lipids – Building blocks: Fatty acids • Proteins – Building blocks: Amino acids • Nucleic Acids – Building blocks: Nucleotides 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 Carbohydrate Tests Benedict’s Reagent Iodine http://jade.collin.edu/BIOPAGE/faculty/cardenas/5%20macromolecules_files/frame.htm • Tests for reducing sugars • Tests for starch (monosaccharides) (polysaccharide) – Copper sulfate • Heat to 100oC for 3 minutes - + - + Lipids • Building blocks: fatty acids No Detergent Detergent – Saturated – No C – C Added double bonds (solid) – Unsaturated – One or more C – C double bonds Oil (liquid) • Hydrophobic – Cannot Water dissolve in water • Emulsifier – Substance which promotes mixing of lipids and water • Test: Sudan IV http://jade.collin.edu/BIOPAGE/faculty/cardenas/5%20macromolecules_files/frame.htm 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 - + http://jade.collin.edu/BIOPAGE/faculty/cardenas/5%20macromolecules_files/frame.htm Summary of Macromolecule Tests Garcia, M. and R. Orr (2011). Biology 1406 & 1408 Lab Manual. Frisco, TX: Collin County Community College District. Microscopy Parts of the Compound Light Microscope http://academic.pgcc.edu/~kroberts/Lecture/Chapter%204/04-04_CompoundLM_L.jpg Important Concepts in Microscopy • Magnification • Resolving Power • Contrast • Viewing Field – Image orientation – Depth of focus – Size of the field of view – Working distance 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 Image Orientation e http://iws.collin.edu/jbeck/Cellsweb/Letterescopeview.JPG Cytology 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 à 10X à 40X http://www.biologyjunction.com/microscopeuselab_files/image005.jpg Overview of an Animal Cell http://millville.sps.edu/allaccess/divisions/science/jdonnelly/Cell%20Page.htm Human Cheek Cells Cell membrane Cytoplasm Nucleus http://jade.collin.edu/BIOPAGE/faculty/cardenas/7%20microscopy_and%20_cytology_files/frame.htm Overview of a Plant Cell http://millville.sps.edu/allaccess/divisions/science/jdonnelly/Cell%20Page.htm Elodea and Onion Cells Elodea Leaf Onion Epidermis Cell Cell wall wall Central vacuole location Cell membrane Cytoplasm Cell Location of central vacuole Cytoplasm membrane Nucleolus Chloroplasts Nucleus http://jade.collin.edu/BIOPAGE/faculty/cardenas/7%20microscopy_and%20_cytology_files/frame.htm Osmosis and Diffusion Diffusion is Movement Down a Concentration Gradient http://missbakersbiologyclasswiki.wikispaces.com/file/view/diffusion.gif/31772061/diffusion.gif Diffusion Results in a Dynamic Equilibrium http://www.bio.miami.edu/~cmallery/150/memb/c8.7x11.diffusion.jpg Factors Affecting Diffusion • Temperature – Higher temperature à Faster – Lower temperature à Slower • Molecular size – Smaller molecule à Faster – Larger molecule à Slower • Presence of a membrane – Membranes are selectively permeable http://iws.collin.edu/jbeck/Diffusionweb/Page.html Osmosis is the Diffusion of Water Figure 3.19 Osmotic Pressure Can Damage or Kill a Cell (Crenated) http://kentsimmons.uwinnipeg.ca/cm1504/Image130.gif Effects of Osmosis on Red Blood Cells Isotonic Hypotonic Hypertonic http://sciencephoto.com/images/showEnlarged.html/P242457-Red_blood_cells,_isotonic_solution-SPL.jpg?id=802420457 http://sciencephoto.com/images/download_wm_image.html/P242458-Red_blood_cells,_hypertonic_solution-SPL.jpg?id=802420458 http://sciencephoto.com/images/showEnlarged.html/P242456-Red_blood_cells,_hypotonic_solution-SPL.jpg?id=802420456 Effects of Osmosis on Elodea Leaves Isotonic/Hypotonic Hypertonic http://course1.winona.edu/sberg/IMAGES/elodea2.JPG http://course1.winona.edu/sberg/IMAGES/elodeap3.JPG 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%20L ab%20Videos/1406%20Lab%20Videos%20Home.html • Science Den (D202) – Textbooks, microscopes and slides, models, tutoring services
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