Question

if every group in the class starts with the same 20,000 x g supernatant, by the time different groups have done the 40-65% ammonium sulfate cut, their results usually vary greatly. what are likely reasons for this variance?

Answer 1

Variability in results from a 40-65% ammonium sulfate cut can stem from measurement precision, temperature control, mixing efficiency, centrifugation variability, and human error. Ensuring strict control over experimental conditions can help minimize these variations.

Step-by-step explanation:

When different groups perform a 40-65% ammonium sulfate cut from the same starting 20,000 x g supernatant, variations in their results are commonly observed. These variations can be attributed to several factors:

• Measurement precision: Small differences in measuring the weight or volume of ammonium sulfate can lead to significant changes in the salt concentration and thus affect protein precipitation.
• Temperature control: Variations in temperature during the process can impact the solubility of proteins, as cooler temperatures generally enhance protein precipitation by ammonium sulfate.
• Mixing efficiency: Uneven mixing can result in an inconsistent distribution of the ammonium sulfate, leading to varied protein precipitation across different samples.
• Centrifugation variability: Differences in centrifuge performance, such as slight speed fluctuations or imbalanced rotors, can affect the sedimentation of the precipitated proteins.
• Human error: Mistakes made during the experimental process, including timing and handling of samples, can contribute to variance.

All of these factors are possible causes of the observed variability between groups. It's essential to control the experimental conditions as tightly as possible to minimize this variance and obtain more consistent results.