genetics

• Genes are segments of DNA that contain instructions for building proteins, which are the building blocks of life.
• The basic process of transformation involves the introduction of DNA into bacterial cells through a vector such as a plasmid.
• Bacterial division and culture in the lab are important aspects of gene mapping in bacteria.
• The F factor plays a crucial role in conjugation.
• The terms F + and F - are used in conjugation.
• Conjugation was determined to occur through experiments that involved the determination of the role of the F factor in bacterial cells.
• The basic molecular mechanism of conjugation involves the transfer of DNA from the donor to the recipient through a conjugation pillus.
• F’ plasmids are made in the cell.
• Conjugation involves various outcomes, as determined by the pairing of the bacterial cells.
• The recipient is crossed to a prototrophic strain with the genotype phe + met + ara +.
• The table below shows the selected marker and gives cotransduction frequencies for the unselected marker.
• Identify the compounds present in each of the selective media.
• Use the cotransduction data to determine the order of the genes.
• Selected marker: phe + met + ara + met + 4 - 7.
• Unselected marker: phe - 2,51.
• Cotransduction frequencies for the unselected marker: met +, phe + -, ara + 68, 5 -.
• Bacterial conjugation, transformation, and transduction are different processes that involve the transfer of genetic material from a donor bacterial cell to a recipient cell.
• Bacteria lack membrane-bound organelles, replicate very fast, can be grown in liquid or on solid plates, and their DNA is a single circular chromosome packaged into a nucleoid.
• Bacterial DNA contains extrachromosomal DNA on plasmids, has high copy plasmids that replicate autonomously and low copy plasmids that cannot replicate autonomously.
• Bacterial cell division involves division by binary fission, DNA replication, chromosome separation, cell contents division, asexual reproduction, and the two daughter cells are identical to each other and then mother cell.
• Genetic transfer occurs by three processes: conjugation, transformation, and transduction.
• Each method involves a one-way transfer of genetic material from a donor bacterial cell to a recipient cell.
• Transferred DNA may be an extrachromosomal plasmid or a portion of the bacterial chromosome.
• Plasmids transferred to recipient cells may bring new genes that alter the growth of the recipients, or a second copy of genes already present in the recipient.
• Transformation is the uptake of DNA from the environment.
• Hfr Strain Genes Transferred Hfr1 oriT serR leuY asnB serC tyrT fumC Hfr2 oriT nadB proL fumC tyrT serC asnB Hfr3 oriT tyrT fumC proL nadB leuU cysE Hfr4 oriT serR pheR cysE leuU nadB proL
• Conjugation is the transfer of replicated DNA from a donor to a recipient.
• Transformation is the uptake of DNA from the environment.
• Transduction is the transfer of DNA from one bacterium to another by a viral vector (bacteriophage).
• The lytic cycle is a six-step process that leads to lysis of the host cell: Attachment of the phage to the host cell, Injection of the phage chromosome into the host, followed by circularization of the phage chromosome, Replication of phage DNA using host proteins and enzymes, Transcription and translation of phage genes, and subsequent production of heads, sheaths, and tail fibers for assembly of progeny phage, Packaging of phage chromosomes into phage heads, Lysis of the host cell, and release of progeny phage particles.
• Some bacteriophages (temperate phages) have an alternate, temporary life cycle involving integration of the phage chromosome into the bacterial chromosome, this is called the lysogenic cycle; integration is called lysogeny.
• Lysogeny can persist for many bacterial cell cycles, but eventually comes to an end, and the lytic cycle is triggered.
• Steps of the Lysogenic Cycle: Attachment of the phage particle to the host cell, Injection of the phage DNA into the host, followed by phage-chromosome circularization, Integration of the phage chromosome into the host chromosome at a specific DNA sequence found in both chromosomes, Excision of the prophage in response to an environmental signal, through a reversal of the site-specific integration, Resumption of the lytic cycle, beginning with phage-chromosome replication.
• Bacteriophage kill bacteria when cell lysis is triggered, this cell death forms clear patches or plaques (clearings) on a lawn of bacteria.
• Generalized transducing phage package DNA into their heads based on size not content, can package bacterial chromosomal DNA fragments by mistake, Bacteria that are “infected” with a transducing phage will not lyse because they only received bacterial DNA not phage DNA.
• Conjugation is the physical transfer of DNA from one bacterial cell to another through a conjugation pillus.
• Once the DNA is gone, it can't be recovered.
• The phage genome replicates so it can make progeny phages.
• During replication, mistakes can be made.
• Revertible mutants, also known as point mutations, can spontaneously be converted to wild-type.