BIOL 3120 Cell Biology Lab 1 pH & Buffers PDF

BIOL 3120 (Cell Biology Lab) Lab1 pH & Buffers Rubaia Tasmin Email: [email protected] Lab safety guidelines: Protect yourself & others Wear gloves & lab coats at all times Use safety goggles when needed Manage biohazardous waste Don’t throw needles/ broken glasswa...

BIOL 3120 (Cell Biology Lab) Lab1 pH & Buffers Rubaia Tasmin Email: [email protected] Lab safety guidelines: Protect yourself & others Wear gloves & lab coats at all times Use safety goggles when needed Manage biohazardous waste Don’t throw needles/ broken glassware into normal trash You should throw away used gloves into normal trash 2 Important Lab Policies: Attendance & participation MANDATORY Notify the TA in advance when missing a lab- NO MAKE-UP labs Read the lab manual before the scheduled lab Course grade: Exams & Quizzes, Lab Clean-up, Lab reports, Group Assignment Report/ Presentation 3 Are you doing the pipetting correctly? https://www.youtube.com/watch?v=TFXX8yCWjMo Quick exercise before beginning today’s lab!! https://www.wikilectures.eu/images/a/ab/Pipetting_positions.jpg 4 Are you doing the pipetting correctly? Question 1: Question 2: Step 1- Add 850µl using Step 1 - Add 720µl using P1000 P1000 Step 2 - Remove 24µl using P200 Step 2- Remove 150µl Step 3 - Add 4.5µl using P10 using P200 Final volume should be 700.5µl Step 3- Add 8.5µl using P10 Final volume should be Question 3: 708.5µl Step 1 - Pipette 830µl using P1000 Step 2 – Remove 45µl using P200 5 Step 3 – Add 6.6µl using P10 What is pH? “p” means “-log” Hydrogen ion/proton concentration of a solution Measured on a scale from 0 to 14 pH= -log[H+] pOH= -log[OH-] pH + pOH=14 Importance of pH: Proper functioning of cell Enzymatic reactions, solubility of substances https://www.sciencenewsforstudents.org/article/scientists-say-ph 6  What is a Buffer? Any substance that resist changes in pH of a solution pKa = -log10Ka where Ka is acid dissociation constant A lower pKa value = stronger acid (lower value indicates the acid more fully dissociates in water) Importance of Buffers: Appropriate environment when cell/organelle is removed from its actual home 7 What you have to do? 1. Power up → Calibrate the pH meter with pH 7.0 solution (Press Cal) 2. Measure the pH of 0.05M HCl and 0.05M NaOH 3. Titration of an amino acid (glycine) with NaOH # Follow the procedure in the lab manual and answer the questions in your lab report. Determining pH with a pH meter 1. Always rinse the probe with distilled water 2. Pat dry with Kimwipe. Do not rub the probe! 3. Insert the probe into the solution 8 https://www.m-s-c.org/wp-content/uploads/2017/06/maxresdefault.jpg Titration curve for Glycine Step1 : Loss of H+ from COOH group Step2 : Loss of H+ from NH3+  At 50 % titration, the glycine exists as a zwitterion. This is the isoelectric point pI. At this point, pH=pI. pI=½(pK1+pK2) Titration of amino acid. Shown here is the titration curve of0.1M glycine at 25°C. The shaded boxes, centered about pk1 and pK2, indica the regions of greatest buffering power. https://biochemden.com/titration-curve-of-glycine/ 9 Lab report format: File name for your lab report submission- BIOL3120_Section_Lastname_Firstname_ LabN​ 1. Introduction: Principal of the lab, main concept, purpose of the experiment. 2. Materials: All the chemicals used along with concentration, and instruments used. 3. Methods: Brief method/ protocol. 4. Results: Tables, calculations, graphs etc. 5. Discussion/conclusion: What improvements can you make? How can you justify the results? What is your conclusion? 6. Lab manual questions & underlined questions Times New Roman, 12 pt, Single-spaced, 1" margins. Complete sentences and paragraphs; correct grammar. # Send me the Word document by email: [email protected]  Should be YOUR OWN WORK  Must submit by the beginning of next scheduled laboratory  Computer graphs recommended! 10