Agenda • Turn in Pre-lab #4: Macromolecules • Hand back Microworlds • Lab Quiz #3 (pH) MICROWORLDS HINTS • Field Sizes – – – – 40X = 5mm 100X = 2mm 400x = 0.5mm = 500μm 1000x = 0.2mm = 200μm • State what you’re estimating the size of • Label at least 2 structures – – – – More than 2 gives you a safety cushion Animal cells don’t have a cell wall! Bacteria don’t have a nucleus! You can’t see & label most cells parts with 4x obj. Microworlds • Graded entries are in the grade book as a score out of 20 points. • Remaining entries will be out of 50 points. • You do NOT need to turn in the graded entries on the final due date. Testing for Macromolecules • Testing for the presence of – Carbohydrates – Lipids – Proteins – NOT nucleic acids Testing for Carbohydrates • Monomer = monosaccharides – Glucose – Fructose • Disaccharide – Lactose = glucose + galactose – Sucrose = glucose + fructose • Polysaccharide – Starch (plants) – Glycogen (animals) Testing for Reducing Carbohydrates • BENEDICT’S REAGENT tests for the presence of any monosaccharide and some disaccharides Testing for Carbohydrates • BENEDICT’S REAGENT tests for the presence of any monosaccharide and some disaccharides • Does not detect all sugars (sucrose) • Dispose of Benedict’s waste in appropriate container Testing for Carbohydrates Detects Reducing Sugars Monosaccharides Testing for Carbohydrates • Boiling water bath (with boiling chips) – PLEASE NOTE THAT BOILING WATER IS HOT – Wear goggles – solutions can boil out of tubes • TUBE 1 = Glucose (positive control) • TUBE 2 = negative control (?) • Heat for 5 minutes and observe Testing for Carbohydrates • IODINE REAGENT tests for the presence of starch (what do we know about starch? Testing for Carbohydrates • TUBE 1 = Starch solution from potato (positive control) • TUBE 2 = negative control (?) • Add 3-4 drops iodine and observe • NOTE: Iodine stains badly Testing for Lipids • PAPER TEST – paper will become translucent in the presence of lipids (think KFC napkins) • Do early so it has a chance to dry (will take 15 minutes at least) Testing for Proteins • BIURET REAGENT reacts with proteins to give a light purple color Testing for Proteins • TUBE 1 = Egg Albumen (positive control) • TUBE 2 = negative control (?) • Add 1mL (about two droppers FULL) of Biuret • Dispose of Biuret’s waste in appropriate container Testing for Macromolecules in Food – OTHERS • If liquid, test just like before • If solid, mince up 1 cm3 and mix with 10mL distilled water • Test with: – Benedict’s (reducing sugar) – Iodine (starch) – Paper (lipid) – Biuret (protein) Safety Precautions • Wear GOGGLES at all times when there are people working with hazardous chemicals (Biuret’s and Benedict’s Solutions) • Wash your test tubes BEFORE you start – this lab gets cross-contaminated OFTEN • Wash out all test tubes using test tube brush when you’re done, get the goo out! Put tubes away upside-down in drawer to drain • Make sure your tray is returned to its original position & looks neat and clean up the food table! No food scraps lying around. • Attendance points today, but a penalty if you leave a mess!