BIO 208L Study Guide - Midterm Guide: Photon, Sodium Azide, Thermodynamics
LAB 1 - Equipment & Procedures
Learning Objectives:
Become familiar with lab equipment and safety rules
Make solutions
Use the pH meter
Design a simple experiment
Collect/Analyze data using Excel
Pre Lab
1) liquid solution- liquid with one or more substances dissolved in it
2) Buffers- substances that minimize changes in the [H+] and [OH-] ions. Buffer solutions
usually contain mixtures of weak acids and their conjugate base, which can combine
reversibly with [H+] ions. Reduce changes in pH.
3) Dilution Series-- a set of solutions, each containing the same components, but with one of
the components(component of interest) present at a different concentration in each
solution
● Parallel Dilutions
○ consists of a series of solutions where all are made from the original solution
○ Conveniently prepared when the set of solutions is to contain the component
of interest over no more than 100-fold range of concentration
○ Often varied in a linear fashion Ex: .01, .03, .05
● Serial Dilutions
○ Prepared when the set of dilutions range over at least two orders of
magnitude
○ Ex: ½, ¼, ⅛
○ common dilution factor
Pre Lab Questions:
1. Using the formula weight of Tris (FW = 121.1), how much (to the nearest 0.01 g) is needed
to prepare 50 mL of a 0.50 M solution?
121.1(g Tris) x .5(moles Tris) x 50 mL = 3.0275 (g of .5M Tris)
mol Tris 1000mL
3.03 g
2. What is the definition of pH?
negative log of Concentration of H+ ions in a solution; measure of a
solutions [H+] concentration and indirectly, it’s acidity.
3. Considering that micropipetters are most accurate when delivering volumes of 50-100% of
their total capacity, which micropipetter(s) would you choose to MOST ACCURATELY
dispense a volume of 125µL?
P200
4. Where do you place used glass 10-mL pipets?
The pipet wash container located at the back of the room, tip down.
Clicker Questions:
1. Many pieces of measuring glassware used to store liquids have no covers or lids. How
will you ensure that there is no spillage during mixing?
Answer: Stretch a piece of Parafilm and invert the solution
2. Which of the following statements below best describes Tris?
Answer: A compound that maintains the pH of a solution between 7.0 and 9.0
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3. What is the dilution volume required to prepare a working solution of 1M sucrose of
25mL final volume from a stock solution of 2.5M solution?
C1V1 = C2V2
(2.5M) (xmL) = (1M)(25mL)
Answer: 10mL
4. Which one of the following would most accurately measure a 200-mL volume of liquid?
Answer: 250mL graduated cylinder
5. The standard deviation of a set of measured values is a measure of:
● how tightly the values cluster around the mean or target value (PRECISION)
● Accuracy determined by percent error
● Precision determined by standard deviation
Items Frequently Used in the Cellular and Molecular Laboratory
Equipments
Function
Picture
Top-loading
balance
Measures the weight in 0.00g;
Should tare before use-- taring is a
procedure whereby the balance is set to
zero immediately prior to the addition of
the substance whose weight is to be
determined
Squeeze bottle
contains dH2O; rinsing purposes
Graduated
cylinder
Measures volume in mL, more precise
and accurate than beaker and flask
Measure from the bottom of the
meniscus-- when viewed straight on, the
bottom of the meniscus should be level
Erlenmeyer flask
Measures volume in mL, less precise and
accurate compared to graduated cylinder
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Beaker
Measures volume in mL, the least precise
and accurate out of the graduated
cylinder and Erlenmeyer flask
Blow-out pipet
Measures 10 mL of volume only
When delivering to a tube or other
container, one would normally touch the
inside surface of the receiving container
to ensure the transfer of any adhering
liquid.
Pipet pump
facilitates accurate delivery of controlled
volumes from the pipet
Test tube
Used to add small amount of solutions
Automatic
micropipetters
range of use should not go beyond max
or min values indicated, three types
P10 (0.5-10 microliters),
P200 (20-200 microliters),
P1000 (100-1000 microliters).
Parafilm
Used to cover lidless containers; never
use it to cover volatile organic solvent
because the solvent will dissolve the
parafilm and contaminate the solution
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Document Summary
Become familiar with lab equipment and safety rules. Collect/analyze data using excel: liquid solution- liquid with one or more substances dissolved in it, buffers- substances that minimize changes in the [h+] and [oh-] ions. Buffer solutions usually contain mixtures of weak acids and their conjugate base, which can combine reversibly with [h+] ions. Reduce changes in ph: dilution series-- a set of solutions, each containing the same components, but with one of the components(component of interest) present at a different concentration in each solution. Consists of a series of solutions where all are made from the original solution. Conveniently prepared when the set of solutions is to contain the component of interest over no more than 100-fold range of concentration. Often varied in a linear fashion ex: . 01, . 03, . 05. Prepared when the set of dilutions range over at least two orders of magnitude.
