1. Bacteriophages (phages) are viruses that infect bacterial cells. One application of them is to infect the bacteria on food to kill them so they do not cause human disease. Bacteriophages do not infect human cells.
2. Insulin is a protein made in humans that starts out as a single polypeptide chain and then it is proteolytically cleaved to generate the final product.
3. Maniuplations of genomic sequences using biotechonology allows researchers to make what are called transgenic organisms. Examples include genetically modified food products and organisms, such as mosquitoes, which desired traits.
4. The Polymerase Chain Reaction (PCR) was invented in the late 1980s. It provides a way to amplify DNA sequences (make more of them) starting with very tiny amounts of a target DNA. The process borrows from the mechanism of DNA replication. It requires a target DNA, two primers (one for each strand), 4 dNTPs, and a DNA polymerase (such as Taq DNA Polymerase) that is resistant to denaturation under high temperatures. A cycle of PCR consists of priming the DNA strands, DNA replication, and denaturation. Each cycle of PCR can double the amount of DNA present. After 30 cycles, a theoretical amplification of over 1 billion fold is theoretically possible.
5. DNA fingerprinting is a technique (that uses PCR) that allows one to determine the linkage between a DNA a person. It relies on the fact that some regions of the human genome differ more than others. By amplifying these regions of DNA and analyzing their differences in size of fragments, one can determine with reasonable certainty if a DNA sample matches a person's DNA.
1. Viruses infects cells of all types.
2. Viruses contain nucleic acid (RNA or DNA, single-stranded or double-stranded, depending on the virus) and have a protein coat.
3. The protein coat comes from a gene encoded by the virus and it allows the virus to attach to the cell(s) it infects.
4. Viral infection includes the steps of 1) attachment; 2) injection of the viral nucleic acid; 3) replication and translation of the viral information by the cell; 4) packaging of the viral nucleic acid into coat proteins; and 5) bursting of the cell to release viral particles for more infection.
5. HIV is a retrovirus, meaning it has an RNA genome and an enzyme called reverse transcriptase that converts the viral RNA into double-stranded DNA. HIV has a protein that attaches to CD-4 (a protein found on the membrane of immune system cells)
6. When double stranded viral HIV DNA is made, an enzyme called integrase inserts (attaches) it inside of the host chromosome where it stays. The inserted DNA has a strong promoter that RNA polymerase uses to make more copies of the viral RNA, which continues the cycle.
7. Retroviruses are useful for targeted gene therapy in which a desired gene is inserted into the host chromosome. Lack of specificity of where the gene inserts is of concern, as it has been linked to cancer in some cases.