1
Q
What are serological pipettes used for?
A
To accurately dispense volumes of liquids.
2
Q
5 Procedure Steps
A
- Choose smallest pipette suitable for volume you intend to deliver.
- Double check using correctly labelled pipette to avoid cross contamination.
- Attach pipette to pump or bulb.
- Draw the liquid into the pipette slowly.
- Dispense liquid into receiving container slowly.
3
Q
2 Warnings with serological pipette
A
#'s start with 9 on bottom and count to 0 on top 1mL pipette has #'s for every 0.1 mL and mark for every 0.01mL
4
Q
What are pasteur pipettes used for
A
To dispense liquids when accuracy is less important & gently mix liquid mixtures by pipetting in and out
5
Q
4 step procedure for pasteur pipettes
A
- Double check labels to avoid cross contamination
- Attach pipette to pump or bulb
- Draw liquid into pipette slowly
- Dispense liquid into receiving container slowly
6
Q
Use of wet mounts on glass slide?
A
To spread a sample thin enough to view clearly under a microscope
7
Q
4 step procedure for wet mounts
A
- Place small drop of sample in middle of glass slide
- Gently place one edge of cover slip on slide so that cover slip touches sample
- Gently lower opposite edge of slip using pencil or pasteur pipette to avoid forming bubbles under cover slip
- Use tissue to soak up excess liquid until cover slip does not move when slide is tilted
8
Q
Use of iodine starch test
A
To determine whether a sample contains starch
9
Q
3 step procedure for iodine starch test
A
- Obtain iodine and clean dry spot plate with depressions
- Add 2-3 drops of sample to one depression and add 2 drops of iodine in same depression
- Observe colour changes. Iodine binds with starch to form a purplish-blue colour
10
Q
Use of cheesecloth filter
A
To filter out large solids while allowing liquids and smaller particles to pass through
11
Q
3 step procedure for cheesecloth
A
- Label clean test tube and place in rack
- Place funnel on top of tube, then place cheesecloth on top of funnel
- Pour sample slowly into middle of cheesecloth and wait for sample to pass through into tube
12
Q
Warning for cheesecloth
A
Cloth absorbs 4.5mL of liquid. Make sure sufficient enough homogenate to get enough filtrate despite what is absorbed by cloth
13
Q
What are compound microscopes used for
A
To view objects at 40x, 100x, or 400x magnification
14
Q
10 step procedure for microscope
A
- Rotate objective lens on 4x magnification. Place slide on stage of microscope.
- Hold metal spring clip on stage aside and set slide so that corner of slide sits snugly in metal slide holder. Gently release clip to hold slide in place.
- Move slide using stage movement controls until object centred under lens. Upper dial adjusts up/down, lower dial adjusts left/right
- Turn light intensity adjustment dial down to 5 and turn on microscope lamp. Move substage condenser (under stage_ all the way up using small adjustment knob on left. Close diaphragm of substage condenser using small black diaphragm level.
- Use coarse focus knob to focus object clearly.
- To put both eyepieces in focus, close left eye and focus image in right eye with fine focus until in focus. Close right eye and focus left eyepiece with focusing ring without altering focus knob settings
- Adjust eye distance by pushing or pulling apart eyepieces.
- Do not use coarse focus knob at higher magnifications, can smash lens.
- Reset light intensity to 5 and lens to 4x when done
15
Q
Go pg 21 and Label parts of microscope
A
.
16
Q
What are spectrophotometers used for
A
To measure how much light (of each specific wavelength/colour) is absorbed by a sample. Prism is used to split light to test one wavelength at a time across wide range of possible wavelengths.
17
Q
What are the 4 wavelengths used to test the unknown homogenate in class
A
470 nm blue, 545 nm green, 580 nm yellow, 680 nm red
18
Q
6 steps to use spectrophotometer
A
- Turn on spectrophotometer. Set wavelength to 470 nm blue with wavelength knob 4.
- Locate “blank tube” (colorimeter tube with ethanol in it). Ethanol absorbs light differently at each wavelength, must use blank tube to set spectrophotometer to zero every time change wavelength
- Wipe blank tube with tissue to remove fingerprints.
- Place blank tube in holder under cover 3 and replace cover. Adjust absorbance reading to read zero using knob 2
- Replace blank tube with tube of extract. Record absorbance reading (measure of how much light of particular wavelength is absorbed).
- Change to next wavelength with knob 4 and repeat steps to obtain absorbance reading at that wavelength.
19
Q
2 details about absorbance
A
Absorbance is a logarithmic scale from 0 to infinite so intervals between units not equal. Has no units.
20
Q
What are centrifuges used for
A
Separate particles within mixture into layers according to their relative densities, by spinning at extremely high speeds. Densest particles found at bottom of tube.
21
Q
10 step procedure for centrifuge
A
- Label 2 clean falcon tubes
- Add a volume of sample to one tube and equal volume of liquid to second tube.
- Turn POWER switch on
- Press OPEN button. Place tubes diagonally opposite each other.
- Close lid and wait for lock.
- Press SPEED until reads ref value. Use arrow bottoms to set speed at 1,300.
- Press TIME button and set time to 10 mins.
- Press START.
- After 10 mins press OPEN.
22
Q
Imagine that you need to pipette 5.2 mL of a urine sample into a test tube for analysis. Your lab has clean 10mL, 5mL, and 1mL serological pipettes available. Which Pipette(s) would you use to accurately transfer this volume of urine?
A
10mL
23
Q
A reddish tint to the urine may indicate the presence of blood. Which equipment would you use to test presence of reddish tint in urine?
A
Spectrophotometer
24
Q
Describe one common mistake that students make when using the above equipment
A
Not blanking the machine after each colour test, not wiping the tube of fingerprints
25
Imagine that you are analyzing two ocean water samples for the presence of "red tide" which is caused by high concentrations of red coloured microscopic algae. Choose one piece of lab equipment you would use to accurately compare the concentrations of red tide algae in your two samples.
Spectrophotometer
26
Briefly explain the steps you would take to compare your two samples using this piece of equipment.
- Use spectrophotometer to test the two samples on wavelengths blue, red, green and yellow separately. To test first sample, set machine to 470 nm blue. Take "blank tube" (tube that contains the ethanol) and wipe off all fingerprints. Place blank tube into holder under cover 3 and replace cover. Adjust absorbance reading to read zero using knob 2. Once machine is zeroed, replace with tube of extract, remembering to wipe off fingerprints with this tube as well. Record absorbance reading at this wavelength. This is a measure of how much light this particular wavelength has absorbed. Change machine to next wavelength with knob 4 and repeat steps.
27
Imagine you have already focused on a specimen at 100x magnification. Describe in detail the steps you would take to view the sample at 400x magnification
Rotate to 40x magnification. Refocus using fine focus knob. More powerful lens capture less light, increase light intensity by either opening diaphragm level on substage condenser or adjusting light intensity.
28
A simple way to determine dehydration level is by observing how clear your urine is. Imagine you want to compare the clarity of several urine samples using a spectrophotometer. Describe the steps you would take to prepare a spectrophotometer for this measurement.
z
29
Name two tools that you can use to separate some of the components of your unknown homogenate for further analysis
Cheesecloth and centrifuge
30
Which of these tools do you think is the better choice? Two reasons for answer
Centrifuge. Cheesecloth absorbed 4.5 mL of your homogenate, if you do not have enough volume you won't have any left to test. Cheesecloth is less accurate as it only filters out large solids, certain midsized particles can still pass. Centrifuges separates the homogenate into layers relative to their densities, you will get a more precise measurement and able to test different particles accurately.
31
What kind of sln was the egg held in overnight
Glucose
32
Is the membrane of this decalcified egg permeable to the solutes of that solution
No
33
Describe what would have happened to the egg if the permeability was opposite to what you wrote in part B.
Interior of egg is hypertonic to sln, therefore water moves in and egg swells up
34
What structural component of the RBC membrane might solute X pass through?
Phospholipids
35
Name one additional variable (besides molecular weight and polarity) that can affect the RBC membrane permeability to solutes, in general
Size of particle?*
36
Point out 2 major mistakes in the following experiment and clearly explain how each mistake can result or misleading results: The researchers prepared two test tube with 2mL of 0.3M Urea solution in each tube. In the treatment tube, they added 0.01 mL of 0.3 HCl (to make it more acidic). In the control tube, they added 0.01mL of distilled water. They then added one drop of bovine blood to each tube simultaneously, shook them immediately, and timed how long it took for the bold text placed behind the tubes to be visible through the mixture.
1. They only tested one tube for each sample. Need to make replicates for each treatment and control group. Makes results more reliable and convincing.
1. They did not duplicate the experiment. Need to duplicate to show that the results were consistent and due to some other variable.
37
The cell membranes of red blood cells are more permeable to Solute X than Solute Y. Describe an experiment that you could perform to test hypothesis. (Describe 2 treatment groups, dependent variable, and how you will replicate your results)
***
| Perform experiment once more to make sure results are consistent and not due to some other variable.
38
Where does translation take place in a eukaryotic cell?
Outside nucleus on ribosomes
39
In which direction is the mRNA moving, relative to the ribosome, as translation continues
Left
40
Describe pyrimidine base features
6 membered rings, with 2 nitrogens and 4 carbons. Cytosine, thymine, uracil
41
Describe purine base features
9 membered rings, with 4 nitrogens, 5 carbons. Adenine, guanine.
42
What enzyme is responsible for transcribing the information from DNA onto RNA?
RNA polymerase
43
Where does this enzyme begin transcription (name the location on the DNA gene where the first mRNA nucleotide is added)
The Promotor
44
What does each little black line represent? (i.e. what is it that moved along the gel during electrophoresis)
*
45
If you take two blood samples from one individual and found the DNA fingerprint for both samples, will they look the same? (Assume no mutation occurred)
Yes
46
Name two DNA technology that are useful for investigating a crime scene
DNA fingerprinting with restriction endonuclease and gel electrophoresis *
47
Example how two tools can be useful for catching murders
*
48
What is a confounding factor
*
49
What is a negative control
*
50
Determine what a cell membrane is permeable and impermeable to when given description of what happened to the cell in specific solutions
*
51
Given the results from an experiment involving solutions separated by a semipermeable membrane, identify the relatively hypertonic, hypotonic or isotonic solutions
In semi permeable membrane, if solution is hypertonic to the cell then the cell will shrivel since water moves out of cell. If solutions hypotonic to cell, cell will swell and possibly burst since water moves into cell. If isotonic solution the cell will stay the same.
52
Explain why RBCs will lyse in 0.3M solutions when the RBC membrane is permeable to the solute in that 0.3M solution
Since the membrane is permeable to the solute in the solution, the solute will diffuse through the membrane into the cell. This makes the inside of the cell hypertonic to the outside of the cell and water will move in by osmosis, causing the RBCs to lyse.
53
Predict how permeable the RBC membrane would be to specific solutes when given info on the solutes polarity hydrophilicity or distribution coefficient.
The higher the distribution coefficient, the more permeable the cell is to the solute. The more non polar a solute is, the more permeable it is to the RBC membrane. The more hydrophobic the solute is, the more permeable the solute is to the RBC membrane.
54
Predict whether a particular solute will cross a cell membrane through the phospholipid bilayer or through a transport protein, based on its polar, hydrophilicity, or distribution coefficient
If a solute is non polar, it will pass through the membrane's phospholipid bilayer. If a solute is polar, it will pass through a transport protein. If a solute is hydrophobic, it will pass through the membrane's phospholipid bilayer. If a solute is hydrophilic, it will pass through a transport protein. If a solute's distribution coefficient is high, is will pass through the phospholipid bilayer. If the distribution coefficient is low, it will pass through a transport protein.
55
Given description of mixtures of solutions and RBCs, predict which mixture will have a shorter lysis time & justify prediction
*
56
Given results of experiment with RBCs mixed with different 0.3M solutions, draw reasonable conclusions from these results
*
57
Point out mistakes made in methods of an experiment and explain how those mistakes might lead to misleading results
*No control group, no negative control, replicating tubes, replicating entire experiment, only manipulating dependent variable
58
Predict the direction in which solutes and/or water will move, when given a description of the permeability of a membrane, and the solutions found on either side of that membrane. Defend these predictions in terms of diffusion and osmosis
*
59
Prepare a wet mounted slide view with 40x objective and calculate total magnification
Total magnification on 40x lens is 400x.
60
Draw what a RBC all look like when placed in a specific solution
*
61
Design proper negative controls for an experiment, and explain why they are necessary
*
