Review for Lab Practical _1 - Collin College.ppt

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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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