a sample of badly polluted water from the Chicago River
blood serum from a mouse infected with a protozoan parasite
a sample of contaminated tap water
none of the above
The correct answer is (d), none of the above. This is actually a sample from the aerobic treatment of waste water at the Stickney wastewater treatment plant in Stickney, Ill., which is the largest wastewater treatment plant in the world. The community of organisms shown here (including masses of bacteria as well as both single celled and multicellular eukaryotic organisms) cleans wastewater by converting the organic carbon and nitrogen compounds that enter the plant via the sewer system into new cells, carbon dioxide, and nitrate.
The biochemical pathway below traces out:
The pathway by which certain microbes can remove organic sulfur from petroleum
The initial steps in the biochemical synthesis of steroid hormones
The initial steps in the biochemical degradation of cholesterol
none of the above
The correct answer is (a). The presence of organic compounds containing sulfur in petroleum is a major health and environmental problem. The greater the amount of such compounds that remain in fossil fuels, the greater the amount of sulfur oxides are produced and released to the environment. These sulfur oxides can be health hazards as well as result in acid rain. A number of bacteria have been isolated and studied that have the ability to remove the sulfur from one of the most common of these organic sulfur containing compounds (dibenzothiophene or “DBT”). The biochemical pathway by which this occurs is shown above, in which the sulfur is removed as sulfate and the carbon-carbon bonds, and thus the fuel value, of the product are left intact.
The picture below is:
an artist’s conception of the details of the structure of a cell membrane
an X-ray crystallographic analysis of a small portion of the structure of the hemoglobin form the bacterium Vitreoscilla
a three-dimensional depiction of how lactic acid is produced in muscle during strenuous activity
none of the above
Image permission: Ratakonda, S., A. Anand, K. L. Dikshit, B. C. Stark, and A. J. Howard, “Crystallographic structure determination of B10 mutants of Vitreoscilla hemoglobin: role of Tyr29 (B10) in the structure of the ligand binding site,” Acta Crystallograr. Sect. F: Struct. Biol. and Cryst. Comm. 69, 215-222 (2013).
The actual answer is (b). X-ray crystallography is an important technique by which the most intimate details of the structures of biological molecules, including proteins, can be determined. The outer edges of the shapes shown above represent the outer edges of the electron clouds of a number of atoms in a small portion of a particular bacterial hemoglobin. The discovery of hemoglobins in bacteria has been an unexpected but very important advance in understanding how bacteria that infect humans try to escape the immune system, and has also contributed significantly to advances in biological production of dozens of important compounds.
Colorectal cancer is the third leading cause of cancer-related deaths in the United States. The following pictures show micrographs of two different clinical colon biopsy samples. Which one of these pictures shows colon cancer?
Image B is from the colon cancer biopsy. As tumors progress and become more aggressive the normal tissue structure is lost. Image B shows a Grade 2 colon tumor. Image A is from a biopsy from a healthy colon.
Mitochondria are the power engines for cells. What will mitochondria do when the cells are placed under starvation conditions? The following pictures are from “immunostaining” of individual mammalian cells grown in cell culture (mitochondria stained green; actin stained red; and nucleus stained blue).
Mitochondria will elongate during starvation conditions. Cell A has been grown under normal culture conditions; Cell B has been grown under starvation conditions and shows elongated mitochondria (see also the insets in each of images A and B).
A DNA sequence is a string of nucleotides, which can be represented as a string of letters on a computer. Uncompressed, each letter requires one byte. How much RAM (Random Access Memory) would be required to load a sequencing dataset sufficient to cover the human genome at a 50X depth?
The human genome is estimated at three billion base pairs. A total of 150 billion nucleotides will be required to provide a sequencing depth of 50X. Without any compression algorithm applied, at least 150 gigabytes of RAM will be required to load this dataset into memory. This is before performing any analysis. Computers capable of handling high-throughput sequencing datasets are often equipped with terabytes of RAM!
Parasitism is often facilitated by the gain of new functions, sometimes by turning one’s metabolism against itself. What is the main mechanism by which pathogens can acquire new functions from foreign sources?
Horizontal/lateral gene transfer is the process by which an organism can acquire genes from unrelated organisms. The newly acquired genetic material, however, must be expressed, translated, and properly folded to retain its function. Localization is also vital, as the new product must be targeted to the proper region(s) of the cell(s).
Land plant photosynthesis uses the red portion of the light spectrum. In contrast, the photosynthetic apparatus of most algae is optimized towards the blueish, shorter wavelength portion of the spectrum. Why?
Shorter wavelengths travel deeper into water. Organisms whose photosynthesis have been optimized towards the orange/red portion of the spectrum would be restricted to shallow waters.
Studying biochemistry at IIT helped me understand how to think for myself. My professors and classes required me to do more than just regurgitate information. Instead, they pushed me to analyze information, identify trends, and determine conclusions that I could support. These abilities translate into all fields of work, and as a healthcare consultant, I know that the skills I developed at IIT are invaluable to my success.”