BIO 201 Lab Final Review, Lab 1

what is the concentration of hydrogen ions [H+] in a solution that has a PH of 2?

- 0.01M.

what is the PH of a 1.0M solution of HCl?

- 1.

If you add strong acid to a solution of phosphate buffer at pH 7.0, which form of phosphate in the equilibrium would increase in abundance first? Which would decrease first? If you continued adding acid until there were no longer any changes, which form(s) of phosphate would be present?

- Add acid: H2PO4 -; HPO42- ; H3PO4 - Add base: HPO42- ; H2PO4 -; PO43-

acid dissociation constant Ka equation

- Ka= ([H+][A-])/([HA])

equation for PH and acidity

- PH= -log(H+)

What does PPE stand for? What PPE must be worn in all Cell Biology labs?

- Personal protective equipment. - Lab coat or apron, gloves, goggles or glasses.

What is the positive control in this experiment, and what is its purpose? What is the negative control, and what is its purpose?

- Positive: Phosphate buffer. When no effect is observed, we can conclude that the hypothesis is incorrect only when positive control shows effect. If the pH of the phosphate buffer changes rapidly, there is something wrong with the [HCl], the pH meter, etc. - Negative: Water. Because it is not a buffer, and we should observe drastic changes in pH due to the lack of buffering. If we don't, there is likely something wrong with the HCl or the pH meter.

what is the definition of PH?

- The negative value of the common logarithm (log base 10) of the hydrogen ion concentration (-log[H+]).

State a hypothesis for the experiment(s) we are doing in this lab.

- The pH of the biological solutions will change slowly when acid is added to it. (example)

How do changes in PH affect protein structure?

- pH can change the ionization state of functional groups in proteins. - which can disrupt normal hydrogen and ionic bonding>> and hence affect secondary, tertiary, and/or quaternary structure of protein.

What new equipment will you be using in this lab?

- the PH meter.

standard deviation

- the measure of variability within a dataset.

positive control

- useful when NO effect on the dependent variable is observed. - done by running one or more samples treated with something that is known to cause change in the dependent variable. - if at the end of the experiment you see no change in the dependent variable, you could conclude that your hypothesis was incorrect>> but if your positive control showed no effect, that would indicate that there was a problem with your experiment>> your hypothesis was incorrect from a problem not from the experiment= a false negative, type II error. - positive controls prevent false negatives, type II errors.

negative control

- useful when the effect on the dependent variable is observed. - done by running one or more samples in which the independent variable is fixed at a variable (usually 0), that should not effect the dependent variable. - at the end of the experiment, if the independent variable seems to have had an effect of the dependent variable your hypothesis would be correct.>> but if you see something has effected the negative control as well, you can conclude that the hypothesis was correct due to something else>> so your hypothesis was concluded correct but is intact incorrect= a false positive (type I error). - negative control prevents false positives, type I errors.

what did we do in lab 1?

- we tested how the addition of strong acid alters the PH of water, phosphate buffer, and one biological buffer (yeast extract), potato juice or milk.

sterile technique

- wear the proper personal protective lab equipment (ie. goggles, apron, gloves etc.). - hold the lids of containers with the interior of the lid facing down, while pouring or pipetting from them. - when you can't hold the cap place the interior edge of the cap facing down on a clean paper towel. - use proper pipetting techniques at all times. - close all pipetting boxes when not in use. - wipe surfaces with 70% ethanol before and after procedures involving bacteria, yeast or other microorganisms. - do not handle cell phones, computers etc. in the lab unless required. - do not touch any interior surfaces of anything used to hold solutions or organisms being used in the experiment. - do not touch the tips of any pipette or tube or touch anything to any other surface.

Are there any hazardous materials in this lab?

- yes, HCl.

the scientific method

1. observation (something you have observed in your experiment). 2. question (derived from either an observation or prior knowledge). 3. check accumulated scientific data (make sure your question hasn't already been answered). 4. testable hypothesis (a statement that predicts a measurable outcome). 5. experiment. 6. analysis (comparison of experimental and control samples). 7. conclusion (decision weather or not your hypothesis is correct based on results). 8. communication (results must be communicated with others to receive critical feedback).