Lab 1: Equipment

Question 1

serological pipette instructions

• purpose
• procedure (5)
• what about the markings should you notice on a pipette?
• clean up

Answer 1

• purpose: accurately dispense volumes of liquids
• procedure:
  1. choose the smallest pipette suitable for the volume you intend to deliver
  2. double check you are using the correctly-labeled pipette for the liquid you are dispensing (make your own labels if possible)
  3. attach pipette to a pump/bulb making sure a proper seal is formed
  4. draw the liquid into the pipette slowly; do not allow liquid to enter the pump/bulb; if a blockage occurs release suction until it clears then restart
  5. dispense liquid into receiving container slowly
• markings: fill to 0 and dispense down to 2mL mark means you have dispensed 2 mL
• clean up: return pipette with bulb to where you found it

Question 2

pasteur pipette

• purpose
• procedure (4)
• clean up

Answer 2

• purpose: dispense liquid when accuracy is less important & gently mix by pipetting in and out
  1. double check you’re using the correctly labeled pipette for the liq you’re dispensing
  2. attach pipette to rubber bulb
  3. draw liquid into pipette slowly making sure liquid never enters bulb
  4. dispense slowly
• clean up: dry bulb and return to where you got it from; dispose pasteur pipette into glass disposal container OR return to bottle it was originally attached to

Question 3

preparing wet mounts on glass slides

• purpose
• procedure (4)
• clean up

Answer 3

• purpose: spread sample thin enough between glass slide and cover slip to view under a microscope
  1. place a small drop of sample in middle of glass slide
  2. gently place 1 edge of glass cover slip on the slide so that the cover slip touches your sample
  3. gently lower opposite edge of cover slip using a pencil/ pasteur pipette to avoid forming bubbles under the cover slip
  4. use a tissue to soak up any excess liquid until the cover slip does not move when the slide is tilted
• clean up: dispose slide and cover slip in a glass disposal container found on bench

Question 4

simple chemical test using iodine to test for starch

• purpose
• procedure (3)
• clean up

Answer 4

• purpose: determine if sample contains starch
  1. obtain iodine and a clean dry-spot plate with many depressions on it
  2. add 2-3 drops of your sample to one of the depressions of the spot plate and add 2 drops of iodine solution to the same depression
  3. observe any changes in color. iodine b inds to starch to produce a deep purplish- blue
• clean up: rinse spot plates by turning water onto a slow stream, hold plate at angle to wash (note: iodine leaves stains! be careful)

Question 5

cheesecloth funnel filter

• purpose
• procedure (3)
• note
• clean up

Answer 5

• purpose: filter large solids while allowing liq and small particles to pass through
  1. label a clean test tube and place on tt rack
  2. place funnel ontop of test tube and place a square of cheesecloth on top of funnel
  3. pour sample slowly into middle of cheesecloth and wait for sample to pass through
• note: cheesecloth will absorb ~4.5mL of liquid. keep in mind when pouring homogenate through
• clean up: dispose cheesecloth and contents in garbage, wash funnel and return to bench

Question 6

compound microscope instructions

• purpose (10)
• procedure

Answer 6

• purpose: view objects at 40x, 100x, 400x magnification
  1. rotate lenses until 4x is selected and place slide onto microscope stage
  2. hold metal spring clip on stage aside and set slide so corner of slide sits snug on metal slide holder; release clip so it pushes gently against the opposite corner fo the slide
  3. centre object under lens using stage movement controls
  4. turn light intensity adjustment dial down to ~5 and turn on microscope lamp. move substage condenser all the way up using small adjustment knob on the left. close diaphragm of substage condenser using small black diaphragm lever
  5. use coarse focus knob until you can see object clearly
  6. use fine focus knob and use only right eye to focus object sharply; repeat with left
  7. adjust eye distance until you see 1 image instead of 2 using push and pull crips on outer edge of eyepiece base
  8. rotate to 10x lens without changing focus. now using ONLY the fine focus knob, refocus on the object and centre what you wish to see with the stage movement controls (do not use course focus knob at higher magnifcations)
  9. rotate to 40x objective (never letting lens touch slide/ sample) and refocus with fine focus knob (you may need to increase light intensity by opening diaphragm lever or adjusting light intensity)
  10. always reset the light intensity adjustment to ~5 before turning it off and rotate lens back to 4x before removing slide from stage

Question 7

can you label all the parts on a microscope?

Answer 7

• see lab manual

Question 8

spectrophotometer

• purpose
• procedure (7)
• clean up

Answer 8

• purpose: measure how much light is absorbed by a sample
  1. pipette 2mL of your homogenate into a flash labeled “extract trade in” in exchange for 4mL of pigment extract in a stoppered colorimeter tube
  2. the spectrophotometer should already be turned on. set the wavelength to 470nm with the wavelength knob 4
  3. locate the blank tube
  4. hold the tube by its top only, white the tube with tissue to remove fingerprints
  5. place blank tube into holder under cover 3 and replace cover. then adjust absorbance reading to read zero using knob 2
  6. record absorbance reading
  7. change spectrophotometer to next wavelength using knob 4 and repeat steps 4-6 until all 4 wavelengths have been tested
• clean up: return blank and sample to holder where found and make sure area is tidy; do not dispose of special colorimeter test tubes
• the more light absorbed, the less light observed

Question 9

eppendorf centrifuge

• purpose
• procedure (8)
• clean up

Answer 9

• purpose: separate particles within a mixture into layers according to relative densities by spinning at high speeds with densest particles found at bottom
  1. label 2 clean falcon tubes (with tapered cone shape bottoms)
  2. add a volume of your sample to 1 tube and an equal volume of liquid to the second tube (can be water if only one sample is being spun)
  3. hit power switch
  4. press open and load tubes ensuring they are diagonally balanced
  5. close and wait for it to lock
  6. press speed button repeatedly until it has an rcf value with * before number; when display flashes use arrow buttons to set speed to 1300
  7. press time and set to 10 minutes
  8. press open button to open lid of centrifuge after 10 min
• clean up: rinse extra falcon tubes and leave in container near sink

Question 10

IEC centrifuge

• purpose
• procedure (6)
• clean up

Answer 10

• purpose: separate particles within a mixture into layers according to relative densities
  1. label 2 clean falcon tub es
  2. add sample to 1 tube and an equal volume of liq to second tube
  3. open lid and load making sure it is balanced and speed dial is set to off
  4. close lid set power to on/ timed and set time to 10 min
  5. increase speed dial to white mark to apply 1300x gravitational force (meter should read 1600rpm)
  6. open lid and remove tubes after 10 minutes
• clean up: rinse extra tubes and leave in container by sink

Question 11

Can you label the microscope?

Answer 11

• see google doc

Question 12

review the online tutorial quiz for the microscope

Answer 12

• see canvas