Chapter 19
Virus- infectious particle consisting of nucleic acid packaged in a protein coat. Most scientists consider viruses non-living because they cannot reproduce or carry out metabolic activities outside of a host cell. Viruses are classified as either DNA or RNA viruses. (Either molecule can be single or double stranded).
Capsids- the protein shell enclosing the virus. Vary in size and shape
Host Range- the number of species that a virus can infect. Virus enters host cell and releases its DNA, which codes for viral proteins which assemble into new virus particles.
Lytic Cycle- viral cycle that results in the death of the host cell. Virulent Phage- replicates only by the lytic cycle. Restriction Enzymes- identify foreign DNA and cut it up- restricting its ability to infect the bacterium.
Lysogenic Cycle- allows replication of the phage genome without destroying the host. Temperate Phages- capable of using lytic and lysogenic cycle.
Explain the major differences between the lytic and lysogenic cycles. What is a capsid? How are restriction enzymes a beneficial defense against viruses?
Retroviruses- (class VI)- contain 2 molecules of single-stranded RNA. Have the most complicated replication. Equipped with enzyme called reverse transcriptase which transcribes an RNA template into DNA. Provirus- viral DNA integrated into animal cell.
Vaccine- harmless derivative of pathogen that stimulates immune system to mount a defense against the harmful pathogen, if encountered. Epidemic- general outbreak Pandemic- a global epidemic Prions- infectious proteins- most likely transmitted in food.
The manipulation of organisms or their components to make useful products.
Genetic Engineering- the direct manipulation of genes for practical purposes. Recombinant DNA- DNA molecules formed when segments of DNA from two different sources- often different species- are combined in vitro.
Plasmid- small circular DNA molecule that replicate separately from bacterial chromosome. Gene Cloning- production of multiple copies of a single gene. Used to amplify a particular gene or produce a specific protein.
Fig. 20-2 Bacterium 1 Gene inserted into plasmid Cell containing gene of interest Bacterial chromosome Plasmid Recombinant DNA (plasmid) 2 Gene of interest Plasmid put into bacterial cell DNA of chromosome Recombinant bacterium 3 Host cell grown in culture to form a clone of cells containing the cloned gene of interest Gene of Interest Protein expressed by gene of interest Copies of gene Protein harvested Basic research on gene 4 Basic research and various applications Basic research on protein Gene for pest resistance inserted into plants Gene used to alter bacteria for cleaning up toxic waste Protein dissolves blood clots in heart attack therapy Human growth hormone treats stunted growth
Restriction Enzymescut DNA molecules at specific locations. Protect DNA by cutting up foreign DNA from other organisms or phages. Sticky Ends- single stranded end of restriction fragment. DNA Ligase- seal sticky ends together.
Gel Electrophoresis- a technique for separating nucleic acids or proteins on the basis of their size and electrical charge. Produces a DNA fingerprint or genetic profile.
Polymerase Chain Reaction (PCR)- DNA is amplified and copied many times in a test tube.
What determines how the DNA fragments separate in gel electrophoresis? What happens in PCR (polymerase chain reaction)? What do restriction enzymes do?
DNA Microarray Assays- detects and measures expression of genes
Totipotent- a cell that can give rise to all the specialized types of the organism. (plants)
Nuclear Transplantationremoves the nucleus from an unfertilized egg and replaces it with the nucleus of a differentiated cell.
Stem Cellsunspecialized cells that reproduce indefinitely and can differentiate into specialized cells of one or more types. Embryonic stem cells are considered pluripotent, because they are capable of differentiating into many cell types.
Gene Therapyintroducing genes into an afflicted individual for therapeutic purposes.
in vitro Totipotent Pluripotent Stem cell Gene therapy Transgenic Genetic profile Genetically modified
On a sheet of paper, respond to the question posed at the end of this morning s reading: Would you eat meat that came from a cloned animal? Also, how do you feel about genetically modified agricultural products? Do you think they are a good thing, and could eliminate some world hunger problems or do you worry that they have been treated with too many antibiotics and are a potential health threat? Provide any additional comments you wish.