Micro Exam ch 8
Terms in this set (33)
is the use of microorganisms to make practical products such as bread, wine, paper, and antibiotics
recombinant DNA technology
Modifying the genome of the organism by natural processes for a variety of practical purposes
as recombinant DNA technology which is used
To eliminate undesirable phenotypic traits in humans, animals, plants, and microbes
•To combine beneficial traits of two or more organisms to create valuable new organisms
•To create organisms that synthesize products that humans need.
are chemical and physical agents used to create changes in a microbe's genome to effect desired changes in the microbe's phenotype. For example, researchers exposed the fungus Penicillium to mutagenic agents and then selected strains that produce greater amounts of penicillin.
The Use of Reverse Transcriptase to Synthesize cDNA
Reverse transcriptase is an enzyme that transcribes DNA nucleotides from an RNA template. Genetic researchers use it to make complementary DNA (cDNA), so called because it is complementary to an RNA template. Since eukaryotic cDNA lacks noncoding sequences, scientists can insert it into prokaryotic cells, making it possible for the prokaryotes to produce eukaryotic proteins such as human growth factor, insulin, and blood-clotting factors.
Synthetic Nucleic Acids
are synthesized with the help of the machine by supplying nucleotides and other required agents like ligases.
They are used for creating genes for specific protein, to create DNA and RNA probes, to elucidate the genetic code and to synthesize antisense nucleic acid molecule.
are enzymes used by bacterial cells to protect against phages by cutting phage DNA into nonfunctional pieces. Scientists use restriction enzymes to cut DNA
Scientists use restriction enzymes to cut DNA at locations with specific and usually palindromic nucleotide sequences
are carriers of genes. In recombinant DNA technology, a vector is a small DNA molecule (such as a viral genome, transposon, or plasmid) that carries a particular gene and a recognizable gene marker into a cell so that the cell will develop a new phenotype—for example, the ability to synthesize growth hormone.
Vectors must be small enough to manipulate in the laboratory, be able to survive inside cells, contain a recognizable genetic marker, and provide the required genetic elements.
is a collection of bacterial or phage clones, each of which carries a fragment (typically a single gene) of an organism's genome. Genetic researchers create each of the clones in a gene library by using restriction enzymes to generate fragments of the DNA of interest and then ligase to synthesize recombinant vectors. They insert the vectors into bacterial cells, which are then grown on culture media.
Multiplying DNA in vitro
The Polymerase Chain Reaction (PCR)
polymerase chain reaction (PCR)
is a technique by which scientists produce a large number of identical molecules of DNA in vitro. PCR is a repetitive process that alternately separates and replicates the two strands of DNA.
about 940C, separation of the two strands of DNA
about 650C,addition of nucleotide mixture followed by cooling
about 720C, heating to increase the rate of replication
repetition of the cycle
With each repetition of the cycle, the number of DNA molecules increases exponentially. After 30 cycles in a few hours, PCR produces over a billion copies of the original DNA molecule.
researchers use to find clones containing the DNA of interest. They then isolate and culture cells that have the desired radioactive or fluorescent marker.
a technique for separating molecules (including fragments of nucleic acids) by size, shape, and electrical charge. The technique involves drawing DNA molecules, which have an overall negative charge, through a semisolid gel by an electric current toward the positive electrode within an electrophoresis chamber. Smaller DNA fragments move faster and farther than larger ones. In genetic engineering, scientists use the technique to isolate fragments of DNA molecules that can then be inserted into vectors, multiplied by PCR, or preserved in a gene library.
technique begins with the procedures of gel electrophoresis just described, but allows researchers to stabilize specific DNA sequences and then localize them using DNA dyes or probes. The Southern blot is used for genetic fingerprinting, diagnosis of infectious disease, and other purposes.
consist of molecules of single-stranded DNA that have been immobilized on glass slides, silicon chips, or nylon membranes. Single strands of fluorescently labeled DNA in a sample washed over an array adhere only to locations on the array where there are complementary DNA sequences. DNA microarrays can be used in a number of ways including monitoring gene expression, diagnosing infection, and identifying organisms in an environmental sample.
uses an electrical current to puncture microscopic holes through a cell's cytoplasmic membrane so that DNA can enter. Thick cell walls are first removed enzymatically to form protoplasts. (Protoplasts are cell without cell wall)
is a process in which the cytoplasmic membranes of protoplasts encountering each other fuse to form a recombinant cell.
is a process in which scientists use a gene gun to inject a cell with a tungsten or gold bead coated with DNA. In microinjection, a glass micropipette is used.
is the sequencing, analysis, and comparison of genomes
involves locating genes on a nucleic acid molecule, frequently by using DNA probes to identify restriction fragments or clones containing the gene of interest.
Scientists have inserted genes for insulin and other proteins into bacteria and yeast cells so that the cells synthesize these proteins in vast quantities. Genetically engineered proteins are safer and less expensive than proteins isolated from donated blood or from animals.
Scientists synthesize subunit vaccines—which use a portion of a pathogen rather than the pathogen itself—by introducing genes for a pathogen's polypeptides into vectors. When the vectors, or the polypeptides they produce, are injected into a human, the body's immune system is exposed to and reacts against relatively harmless antigens instead of the potentially harmful pathogen. Vaccine for hepatitis B is an example for subunit vaccine.
Genetic mutations cause some diseases such as inherited forms of breast cancer and Huntington's disease. In genetic screening, laboratory technicians use DNA microarrays to screen a patient's blood or other tissues for these genetic mutations before the patient shows any sign of the disease
Medical laboratory technicians and forensic investigators use gel electrophoresis and Southern blotting for so-called genetic fingerprinting or DNA fingerprinting, to identify individuals or organisms by their unique DNA sequences. The technique is used in paternity investigations, crime scene forensics, diagnostic microbiology, and epidemiology
In gene therapy, missing or defective genes are replaced with normal genes, in theory curing the genetic disease. For example, patients have been successfully treated for severe combined immunodeficiency disease (SCID). Unfortunately, gene therapy has also caused patient deaths, because some patients' immune systems have hyper responded to the presence of the vectors.
Clinical microbiologists now use PCR, fluorescent genetic probes, and DNA microarrays in diagnostic applications such as examining patient specimens for sequences unique to certain pathogens
In xenotransplants involving recombinant DNA technology, human genes are inserted into animals to produce cells, tissues, or organs that are then introduced into the human body.
Recombinant DNA technology has been applied to the realm of agriculture to produce transgenic organisms, recombinant plants and animals that have been altered for specific purposes by the addition of genes from other organisms. Agricultural uses of recombinant DNA technology include advances in herbicide resistance, salt tolerance, freeze resistance, and pest resistance, as well as improvements in nutritional value and yield.
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