Site Selection

Examples of Site Selection in the following topics:

• Building a better future

  • The USGBC has developed a rating and certifi cation system titled Leadership in Energy and Environmental Design (LEED) to recognize the efficiency performance of buildings (as well as healthcare systems and labs) in five key areas: sustainable site development, water savings, energy efficiency, materials selection, and indoor environmental quality.

• Hosts for Cloning Vectors

  • Alternatively, if replication of the DNA in different species is desired (for example transfer of DNA from bacteria to plants), then a multiple host range vector (also termed shuttle vector) may be selected.
  • Whatever combination of host and vector are used, the vector almost always contains four DNA segments that are critically important to its function and experimental utility--(1) an origin of DNA replication is necessary for the vector (and recombinant sequences linked to it) to replicate inside the host organism, (2) one or more unique restriction endonuclease recognition sites that serves as sites where foreign DNA may be introduced, (3) a selectable genetic marker gene that can be used to enable the survival of cells that have taken up vector sequences, and (4) an additional gene that can be used for screening which cells contain foreign DNA.

• Shuttle Vectors and Expression Vectors

  • Expression vectors are used for molecular biology techniques such as site-directed mutagenesis.
  • One of the most common types of shuttle vectors is the yeast shuttle vector that contains components allowing for the replication and selection in both E. coli cells and yeast cells.
  • The E. coli component of a yeast shuttle vector includes an origin of replication and a selectable marker, such as an antibiotic resistance like beta lactamase.
  • The yeast component of a yeast shuttle vector includes an autonomously replicating sequence (ARS), a yeast centromere (CEN), and a yeast selectable marker.
  • Please note the presence of a multiple cloning site, a promoter, a repressor, and a selectable marker.

• Mutation

  • Site-directed mutagenesis, also called site-specific mutagenesis or oligonucleotide-directed mutagenesis, is a molecular biology technique often used in biomolecular engineering in which a mutation is created at a defined site in a DNA molecule.
  • The copied gene contains the mutated site.
  • Finally, mutants are selected.
  • The mutants may also be counter-selected due to presence of a mismatch repair system which favors the methylated template DNA.
  • In this experiment, random mutations were introduced into the virus by site-directed mutagenesis.

• Maturation of T Cells

  • As these cells leave the thymus, they travel to sites that contain secondary lymphoid tissue, such as the lymph nodes or tonsils, where antigen presentation will occur to facilitate the development of antigen specific adaptive immunity.
  • Positive selection "selects for" T cells capable of interacting with MHC.
  • A thymocyte's differentiation into helper or cytotoxic versions is also determined during positive selection.
  • Double-positive cells (CD4+/CD8+) that are positively selected on MHC class II molecules will eventually become CD4+ helper T cells, while cells positively selected on MHC class I molecules mature into CD8+ cytotoxic T cells.
  • The potentially autoimmune cells are removed by the process of negative selection.

• Carbon-Carbon Bond Formation

  • With the exception of Friedel-Crafts alkylation, these reactions all give products having one or more functional groups at or adjacent to the bonding sites.
  • Control of regio and stereo-selectivity in the formation of reactive intermediates.
  • A good example of the first enhancement is the extraordinary selective control that is now possible for the aldol reaction.
  • Unfortunately, the dehydration of the terminal 3º-alcohol (last step) was less selective and gave appreciable amounts of the gem.
  • This acid is attached to a chiral auxiliary before undergoing a selective aldol reaction with the chiral aldehyde shown at the bottom right.

• Clonal Selection and B-Cell Differentiation

  • B Cells develop in way that is similar but different to T cells, and undergo clonal selection
  • This is a form of positive selection.
  • They are also tested for autoreactivity through negative selection.
  • B Cell Activation refers to the differentiation and clonal expansion of B cells.When the B cell receptor on the cell surface matches its cognate antigen present in the body, the B cell proliferates and secretes a free form of those receptors (antibodies) in the body with identical binding sites as the ones on the original cell surface.
  • Following the initial infection, random mutations during clonal selection could have produced memory B cells that can more easily bind to antigens than the original B cells could.

• Sampling from a population

  • In general, we always seek to randomly select a sample from a population.
  • The most basic type of random selection is equivalent to how raffles are conducted.
  • The selected names would represent a random sample of 100 graduates.
  • Or perhaps her selection would be well-representative of the population.
  • For this reason, we suspect there is a negative bias in product ratings on sites like Amazon.

• Role of the Media Specialist in Resource-Based Learning

  • The media specialists play a crucial role in resource-based learning, beginning with the selection and acquisition of curriculum-supported materials.
  • Hartman must teach students how to efficiently use the various components of the site in order to maximize its potential.

• Recombinant DNA Technology

  • The cloning vector is treated with a restriction endonuclease to cleave the DNA at the site where foreign DNA will be inserted.
  • The restriction enzyme is chosen to generate a configuration at the cleavage site that is compatible with that at the ends of the foreign DNA.
  • Most modern vectors contain a variety of convenient cleavage sites that are unique within the vector molecule (so that the vector can only be cleaved at a single site) and is located within a gene (frequently beta-galactosidase) whose inactivation can be used to distinguish recombinant from non-recombinant organisms at a later step in the process.
  • Vector molecules with dephosphorylated ends are unable to replicate, and replication can only be restored if foreign DNA is integrated into the cleavage site.
  • When bacterial cells are used as host organisms, the selectable marker is usually a gene that confers resistance to an antibiotic that would otherwise kill the cells, typically ampicillin.