3: Quantitative Determinations
- Page ID
- 24746
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- 3.1: Introduction
- Light is a type of energy that travels as a wave-particle. The wavelength of light is the distances between peaks in the waves as light travels. Wavelengths are measured in nanometers (nm) and different wavelengths of light represent differing colors. Light of long wavelengths (infra-red) and very short wavelengths (ultraviolet) are invisible to humans but can be observed by other organisms. As the wavelength decreases, the energy of the light is increased.
- 3.2: Enzymes
- In biological systems, energy is roughly defined as the capacity to do work. Molecules are held together by electrons. Breaking and building these bonds requires an input of energy. The energy needed to initiate such reactions is referred to as activation energy (EA). Catalysts are chemicals that take part in facilitating reactions by reducing the energy of activation. If the activation energy is reduced, the likelihood of a reaction occurring is greatly enhanced.
- 3.3: Exploring Beer's Law (Virtual)
- In this lab, you will use a simulation where you can alter the properties involved in spectrophotometry and examine the Beer-Lambert Law.
- 3.4: Quantitative Detection of Protein (Activity)
- Bovine Serum Albumin (BSA) is a protein that circulates in the blood of cows. Purified BSA can be used with Biuret solution in serial dilutions to generate a Standard Curve. The standard curve will illustrate the relationship between concentration (the dependent variable) and absorbance at 540 nm (the independent variable). We can then use this curve to estimate the concentration of unknown samples. In this lab, you will use a normal spectrophotometer to measure the absorbances at 540 nm.
- 3.5: Quantitative Detection of Proteins (SpectroVis Plus)
- Bovine Serum Albumin (BSA) is a protein that circulates in the blood of cows. Purified BSA can be used with Biuret solution in serial dilutions to generate a Standard Curve. The standard curve will illustrate the relationship between concentration (the dependent variable) and absorbance at 540 nm (the independent variable). We can then use this curve to estimate the concentration of unknown samples. In this lab, you will use a LabQuest spectrophotometer to measure the absorbances at 540 nm.
- 3.6: Enzyme Kinetics (Activity)
- In this activity, you will examine how different factors, such as pH, temperature, and enzyme concentration, affect enzyme activity.
- 3.7: Enzyme Kinetics with Spectrovis
- This exercise uses turnip extract as a source of peroxidase. This turnip extract requires a source of electrons (a reducing agent) in order for the reaction to occur. In this case, a colorless organic compound called guaiacol is used. Guaiacol is oxidized in the process of converting the peroxide and becomes brown. Enzymatic activity can then be traced using a spectrophotometer to measure the amount of brown being formed.