Experiment 2: Process in Biochemical Systems
DIALYSIS
1. Test for peptide bonds
Biuret reagent (2mL of 10% NaOH + 5 drops of 0.5% copper sulfate) + dialysis +cellophane
negative result
Broth did not exit cellophane (membrane) because it allows passage of Inorganic molecules (peptide bonds are organic)
another reason could be that proteins are macromolecules, they can’t pass through the semipermeable membrane
2. Test for amino acids
Organic
1mL of 0.2% ninhydrin + 3mL dialysate + heated
negative result
Broth did not exit cellophane (membrane) because it allows passage of Inorganic molecules (amino acids are organic)
if the ninhydrin reacts, blue to purple would be the results
DIFFUSION
Movement of molecules from a HIGH concentration to a LOW concentration
the higher the temperature, the more kinetic energy is produced
Particles move more vigorously, resulting in higher rated of diffusion
Sample 1 (not heated) 30 degrees celsius
with a cooler environment the reagent KMo4 took more time to spread in the water
Sample 2 (heated) 80 degrees celsius
with the help of temperature the reagent diffused much quicker compared to the cooler sample
HYDROLYSIS
compounds break down into smaller molecules upon reacting with water
IODINE - detects presence of starch molecules
Saliva + Iodine (negative)
1% NaCO3 + Iodine
Pancreatin sol. + Iodine
Positive result: Yellow Brown or Blue-Black (presence of starch)
when macaroni is submerged in the substances, the digestive enzymes should breakdown/hydrolyze carbohydrates
LOWERING SURFACE TENSION
Molecules of water are attracted to one another and lowering surface tension means separating H2O molecules
Margarine + 0.5% Na2CO3 (Sodium bicarbonate)
slightly washed away
sodium bicarbonate is not a surfactant, which makes it increase surface tension
Also an inorganic substance increases ST
Positive results:
Margarine + Soap
completely washed away
soap is a surfactant so it lowers surface tension because of its hydrophobic head and hydrophilic tail
emulsion: forms a homogeneous layer