Mutagens

A friend insists that all mutagens are dangerous. How would you respond?

A scientist comes to you with a drug that can transform all toxic substances into non-toxic substances and wants you to invest in his company.

A scientist comes to you with a drug that can transform all toxic substances into non-toxic substances and wants you to invest in his company. Would you invest? Why

Calculate the minimum number of amino acids necessary for one segment of alpha-helix to traverse the membrane completely. for Bacteriorhodopsin MW 26,000

Under some environmental conditions the halophile Halobacterium halobium synthesizes a membrane protein (MW 26,000) bacteriorhodopsin, which is purple because it contains retinal. Molecules of this protein aggregate into purple patches in the cell membrane. Bacteriorhodopsin acts as a light activated proton pump that provi ...continues

Agarose gel electrophoresis

When digested DNA is analysed using agarose gel electrophoresis the total size of fragments sometimes does not add up to the size of the original DNA molecule. How can this be explained and how can this be seen in ethidium bromide stained agarose gels?

Calculate the number of glucose molecules within a single cell & calculate the molar concentration of hexokinase.

Mycoplasmas are the smallest living cells. They are spherical and have a diameter of about 0.33 μm (radius of mycoplasmas = 0.165 μm)a. (a)Glucose is the major energy source of mycoplasma cells. Its concentration within such cells is 0.1 mM. Calculate the number of glucose molecules within a single cell. (b) The fi ...continues

Given their approximate diameters, calculate the approximate number of hapatocytes (diameter 20 ìm), bacteria (diameter 1 ìm), virus (diameter 10 nm)

Question: Given their approximate diameters, calculate the approximate number of a. hepatocytes (diameter 20 micrometers) radius=10 micrometers, b. bacteria (diameter 1 micrometers) radius=0.5 micrometers, and c. virus particles (diameter 10 nm, radius=5 nm=.005 micrometers) that can be placed in a single layer, on ...continues

Buffers - calculate the relative proportions of weak acid and conjugate base under the following conditions

For any buffer system, calculate the relative proportions of weak acid and conjugate base under the following conditions: 1. pH=pKa -2 2. pH=pKa -1 3. pH=pKa 4. pH=pKa +1 5. pH=pKa +2 Under which of these conditions (1-5) would the solution be an effective buffer. why?

Amount of a substance

Calculation of amount of phenol red in micrograms present in 3ml of the solution, you will need to use the following data: the concentration of the unknown 5.0 micromoles, volume = 3ml, MW of phenol red = 376.4g.

Concentration/Photometry - Using a spectrophotometer set at 400 nm, an absorbance reading of 0.050 was obtained for a solution of p-nitrophenol at pH 6.5.

Using a spectrophotometer set at 400 nm, an absorbance reading of 0.050 was obtained for a solution of p-nitrophenol at pH 6.5. The molar extinction coefficient of p-nitrophenol 21500 M-1cm-1 and the pka for p-nitrophenol is 7. What is the total concentration of p-nitrophenol in the experimental solution.

Obliogmycin

The addition of oligomycin to mitochrondria markedly drecreased both the rate of electron transfer from NADH to oxygen and the rate of ATP formation. The susbequent addition of DNP leads to an increase in the rate of electron transfer without changing the rate of ATP formation. What does oligomycin inhibit and what is the mech ...continues