Full credit:EYE OF SCIENCE / SCIENCE PHOTO LIBRARY
T-bacteriophages on E.coli. Coloured Transmission Electron Micrograph (TEM) of T-bacteriophage viruses attacking a bacterial cell of Escherichia coli. Seven virus particles are seen (blue), each with a head and a tail. Four of these are "sitting" on the brown bacterial cell and small blue "tails" of genetic material (DNA) are seen being injected into the bacterium. T-bacterio- phages are parasites of bacterial cells. The virus attaches itself to the cell's wall and, using it's tail as a syringe, injects it's own DNA into the bacterium. The virus DNA then takes over the bacterial cell, forcing it to produce more viruses. Magnification: x63,000 at 5x7cm size. |
Full credit:EYE OF SCIENCE / SCIENCE PHOTO LIBRARY
T-bacteriophages on E.coli. Coloured Scanning Electron Micrograph (SEM) of T-bacteriophage viruses attacking a bacterial cell of Escherichia coli. Dozens of blue-coloured viruses are seen around the cell, each having a head and tail. T- bacteriophages are specific parasites of E. coli bacteria. The virus attaches itself to the cell wall of the E. coli cell using it's tail. The elongated tail is a contractile sheath which acts like a syringe to squirt the contents of the head, the DNA genetic material, into the host cell. Viral DNA commandeers the genetic machinery of the cell, forcing it to reproduce more bacteriophages. Magnification: x18,000 at 6x6cm size. |

Full credit: LEE D. SIMON / SCIENCE PHOTO LIBRARY
T2 bacteriophage viruses. Coloured transmission electron micrograph (TEM) of T2 bacteriophage viruses (red) attacking an Escherichia coli bacterium. Each phage consists of a large DNA- containing head and a tail composed of a central sheath with several fibres. The fibres attach to the host cell surface, and the phage DNA is injected into the cell through the sheath. It instructs the host to build copies of the phage (progeny, in cell). Destroying the host's DNA releases nucleotide building blocks, from which phage DNA is synthesised. It is then packaged in the progeny, which are released when the host bursts. Magnification: x64,000 at 6x9cm size. |