Chapter Questions
Gene Cloning and Editing (12.1-12.5)12.1 Genes can be cloned in recombinant plasmids. Gene cloning is one application of biotechnology, the manipulation of organisms or their components to make useful products. Researchers can manipulate bacterial plasmids so that they contain genes from other organisms. These recombinant DNA plasmids can then be inserted into bacteria. If the recombinant bacteria multiply into a clone, the foreign genes are also duplicated and copies of the gene or its protein product can be harvested.(FIGURE CANNOT COPY)
Enzymes are used to "cut and paste" DNA. Restriction enzymes cut DNA at specific sequences, forming restriction fragments. DNA ligase "pastes" DNA fragments together.
Nucleic acid probes can label specific DNA segments. A short, single-stranded molecule of labeled DNA can tag a desired nucleotide sequence.
Reverse transcriptase can help make genes for cloning. cDNA can be used to identify the genes that are being transcribed by a particular cell at a given moment.
New techniques allow a specific gene to be edited. The CRISPR-Cas9 system allows researchers to target a specific gene in a living cell for removal or editing.
Genetically Modified Organisms (12.6-12.10)Recombinant cells and organisms can mass-produce gene products. Bacteria, yeast, cell cultures, and whole animals can be genetically modified to make products for medical and other uses.
DNA technology has changed the pharmaceutical Industry and medicine. Researchers use DNA technologies to produce drugs, diagnose diseases, and produce vaccines.
Genetically modified organisms are transforming agriculture. A number of important crop plants are genetically modified.
The use of genetically modified organisms raises questions and concerns. Scientists are investigating the potential risks to human and environmental health posed by DNA technologies.
Gene therapy may someday help treat a variety of diseases. Gene therapy, changing a defective gene to a normal one in a living human, shows promise for curing defective genes, but actual successes are rare.
DNA Profiling (12.11-12.15)The analysis of genetic markers can produce a DNA profile. DNA technology-methods for studying and manipulating genetic material-has revolutionized the field of forensics. DNA profiling can determine whether two samples of DNA come from the same individual.
The PCR method is used to amplify DNA sequences. The polymerase chain reaction (PCR) can be used to amplify a DNA sample. The use of specific primers that flank the desired sequence ensures that only a particular subset of the DNA sample will be copied.
12.13 Gel electrophoresis sorts DNA molecules by size.
Short tandem repeat analysis is used for DNA profiling. Short tandem repeats (STRs) are stretches of DNA that contain short nucleotide sequences repeated many times in a row. DNA profiling by STR analysis involves amplifying and quantifying 13 STRs.
DNA profiling has provided evidence in many forensic investigations. The applications of DNA profiling include helping to solve crimes, establishing paternity, and identify victims.
Genomics and Bioinformatics (12.16-12.21)Small segments of DNA can be sequenced directly. Next-and third-generation sequencing machines can quickly determine the sequence of relatively short stretches of DNA.
Genomics is the scientific study of whole genomes. Genomics researchers have sequenced many prokaryotic and eukaryotic genomes. Besides being of interest in their own right, nonhuman genomes can be compared with the human genome.
The Human Genome Project revealed that most of the human genome does not consist of genes. Data from the Human Genome Project revealed that the human genome contains just under 21,000 genes and a huge amount of non coding DNA, much of which consists of repetitive nucleotide sequences.
The whole-genome shotgun method of sequencing a genome can provide a wealth of data quickly. Modern genomic analysis depends upon the whole-genome shotgun method, which Involves sequencing and arranging many small DNA fragments simultaneously.
The field of bioinformatics is expanding our understanding of genomes. Bioinformatics, the use of computational methods to analyze biological data, can be used to analyze large sets of data about DNA sequences and proteins.
Genomes hold clues to human evolution. The comparison of genomic sequences between humans and our nearest evolutionary relatives provides insight into human evolution.