Rediscovering Biology - Unit 5 Emerging Infectious Diseases: Animations and Images


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Animations

		Antigenic Shift The influenza virus can mutate through antigenic shift, causing new outbreaks to occur in human populations. View Quicktime Movie

		Bacterial Conjugation Antibiotic resistance genes can be shared between bacteria through a sex pilus. View Quicktime Movie

		Bacterial Transformation Antibiotic resistance genes can be obtained by the uptake of free-floating DNA released from a bacterial cell that has died. View Quicktime Movie

		Dispersal of Malaria and Chloroquine Resistance Comparison of the distribution of the malaria parasite and chloroquine resistance around the world. When the maps are overlaid, it is shown that there is chloroquine resistance nearly everywhere the malaria parasite exists. View Animation Still

		Efflux Pump An efflux pump is a mechanism used by bacteria to eject antibiotics before they can affect the cell. View Quicktime Movie

		Four Gene DNA Vaccine Creating a DNA vaccine for malaria will involve producing antigens from several stages of the parasite's life cycle. View Quicktime Movie

		Influenza Infection Description of how the influenza virus infects a cell and the role of hemagglutinin in the release of RNA from the viral core. View Quicktime Movie

		Malarial Infection Description of the malarial life cycle within the human body. View Quicktime Movie

Images

		Antigenic shift A new form of a virus can arise when multiple viruses infect the same animal cell. Segments of nucleic acid can be exchanged resulting in a novel pathogen.

		Bacterial transformation 1. Naked DNA fragments from disintegrated cells in the area of a potential recipient cell. this cell must be of the correct genus and be in a state of competence, allowing the entry of the DNA fragments. 2. Entry of naked DNA into competent cell. 3. Recombination.

		Distribution of Aedes aegypti and dengue hemorrhagic fever Distribution of the mosquito Aedes aegypti, the vector for dengue/dengue hemorrhagic fever. A mosquito eradication program administered by the Pan American Health Organization ended in 1970.

		Group A Streptococci Electron micrograph of an ultra-thin section of a chain of Group A streptococci. The cell surface fibrils, consisting primarily of M protein, are clearly evident. The bacterial cell wall, to which the fibrils are attached, is also clearly seen as the light-staining region between the fibrils and the dark-staining cell interior. Incipient cell division is also indicated by the nascent septum formation (seen as an indentation of the cell wall) near the cell equator. The streptococcal cell diameter is equal to approximately one micron. (20,000x magnification)

		Hemmagglutinin protein-pH 5 When the influenza virus enters a cell it is engulfed into an endosome. The pH inside the endosome lowers from 7 to 5, causing the hemmagglutinin protein to change shape, open the endosome membrane, and let the viral material into the cell.

		Hemmagglutinin protein-pH 7 When the influenza virus attaches and enters a cell, the hemmagglutinin surface protein is at pH 7. A shape change caused by a lower pH is responsible for the hemmagglutinin to open the endosome and release viral material into the cell.

		Influenza epidemic of 1918

		The life cycle of the malaria parasite Sporozoites are delivered to the human bloodstream from the salivary gland of the Anopheles mosquito when the insect bites. In the liver, the sporozoites multiply and become merozoites. The merozoites enter red blood cells and become trophozoites. Red blood cells rupture and new merozoites, which have developed from the trophozoites, are released. Gametocytes (the sexual stage) are eventually produced. Gametocytes taken up by the mosquito in a blood meal fuse to form zygotes, which give rise to sporozoites.

		Transduction by bacteriophage

		Transposons Transposons facilitate the movement of genes throughout bacterial populations. These jumping genes can move from a chromosomal location to a plasmid. Conjugation allows the resultant plasmid to move readily within the bacterial population.

		Vibrio cholerae Scanning electron microscope image of Vibrio cholerae bacteria, which can infect the digestive system