Xenotransplantation, or heterologous transplant is the transplantation of living cells, tissues or organs from one species to another. Such cells, tissues or organs are called xenografts or xenotransplants. In the event that a person is very badly burned or injured and is lacking large areas of skin, xenografts are used to temporarily repair the affected areas. Xenograft is a surgical graft of tissue from one species to an unlike species (or genus or family). A graft from a baboon to a human is a xenograft. The prefix "xeno-" means foreign. It comes from the Greek word "xenos" meaning stranger, guest, or host.

As one PCR cycle, doubles the number of ds DNA. So, after each PCR cycle the initial number of ds DNA gets multiplied by 2 successively. So, after 10 PCR cycle the number of resulting DNA will be 2¹⁰*4 ds DNA

An easier and more accurate method to determine the microbial count is the plate method , where a food sample is placed on a culture medium plate. After an appropriate incubation period, you can count the number of colonies that have formed on the culture medium plate. A viable cell count allows one to identify the number of actively growing/dividing cells in a sample. The plate count method or spread plate relies on bacteria growing a colony on a nutrient medium. The colony becomes visible to the naked eye and the number of colonies on a plate can be counted.

Sequencing DNA means determining the order of the four chemical building blocks - called "bases" - that make up the DNA molecule. ... For example, scientists can use sequence information to determine which stretches of DNA contain genes and which stretches carry regulatory instructions, turning genes on or off. Sequencing technology has vastly improved in recent years.  The Human Genome Project was aided by several 'breakthrough' technological developments, including Sanger DNA sequencing and its automation, DNA-based genetic markers, large-insert cloning systems and the polymerase chain reaction.

A computer program can be used to check an unknown DNA sequence for ORFs. The program transcribes each DNA strand into its complementary RNA sequence and then translates the RNA sequence into an amino acid sequence. Each DNA strand can be read in three different reading frames. Sequencing DNA means determining the order of the four chemical building blocks - called "bases" - that make up the DNA molecule. The sequence tells scientists the kind of genetic information that is carried in a particular DNA segment.

A contig--from the word "contiguous"--is a series of overlapping DNA sequences used to make a physical map that reconstructs the original DNA sequence of a chromosome or a region of a chromosome. A contig can also refer to one of the DNA sequences used in making such a map. Generally, contigs are suspected to be part of the same chromosome in that their end sequences overlap. ... Comparisons of base sequence data with other organisms indicate conservation of a considerable number of sequences.

The LEU2 gene codes for an enzyme which is needed for the synthesis of the amino acid leucine. Yeast cells having this plasmid can grow on a medium lacking leucine and hence can be selected over cells not containing the plasmid.

P1 Phage Derived Artificial Chromosome:  
They can carry large amounts (about 100–300 kb) of other sequences for a variety of bioengineering purposes. It is one type of vector used to clone DNA fragments (100- to 300-kb insert size; average, 150 kb) in E. Coli. A vector containing foreign DNA is termed recombinant DNA. The four major types of vectors are plasmids, viral vectors, cosmids, and artificial chromosomes. Of these, the most commonly used vectors are plasmids. Common to all engineered vectors are an origin of replication, a multicloning site, and a selectable marker.

A bioreactor refers to any manufactured device or system that supports a biologically active environment. In one case, a bioreactor is a vessel in which a chemical process is carried out which involves organisms or biochemically active substances derived from such organisms.  The main function of a properly designed bioreactor is to provide a controlled environment to achieve optimal growth and/or product formation in the particular cell system employed.

Mass spectrometry (MS) is an analytical technique that measures the mass-to-charge ratio of ions. ... These spectra are used to determine the elemental or isotopic signature of a sample, the masses of particles and of molecules, and to elucidate the chemical identity or structure of molecules and other chemical compounds. A mass spectrometer produces charged particles (ions) from the chemical substances that are to be analyzed. The mass spectrometer then uses electric and magnetic fields to measure the mass ("weight") of the charged particles.

Sanger Sequencing Steps

The Sanger sequencing method consists of 6 steps:
(1) The double-stranded DNA (dsDNA) is denatured into two single-stranded DNA (ssDNA).
(2) A primer that corresponds to one end of the sequence is attached.
(3) Four polymerase solutions with four types of dNTPs but only one type of ddNTP are added.
(4) The DNA synthesis reaction initiates and the chain extends until a termination nucleotide is randomly incorporated.
(5) The resulting DNA fragments are denatured into ssDNA.
(6) The denatured fragments are separated by gel electrophoresis and the sequence is determined.

The genome of a cell is continuously damaged, which is inevitable because DNA damage often arises as a result of normal cellular processes. ... The result is double-strand breaks (DSBs) in the chromosome. A DSB can also be caused by environmental exposure to irradiation, other chemical agents, or ultraviolet light (UV). A double-strand DNA break (DSB) occurs or arises when both strands of the DNA duplex are severed, often as the result of ionizing radiation.

Site-directed mutagenesis (SDM) is a method to create specific, targeted changes in double stranded plasmid DNA. There are many reasons to make specific DNA alterations (insertions, deletions and substitutions), including: To study changes in protein activity that occur as a result of the DNA manipulation. Site-directed mutagenesis is one of the most important laboratory techniques for creating DNA libraries by introducing mutations into DNA sequences. There are numerous methods for achieving site-directed mutagenesis, but with decreasing costs of oligonucleotide synthesis, artificial gene synthesis is now occasionally used as an alternative to site-directed mutagenesis. Since 2013, the development of the CRISPR/Cas9 technology, based on a prokaryotic viral defense system, has also allowed for the editing of the genome, and mutagenesis may be performed in vivo with relative ease

Herceptin works by attaching itself to the HER2 receptors on the surface of breast cancer cells and blocking them from receiving growth signals. By blocking the signals, Herceptin can slow or stop the growth of the breast cancer. Herceptin is an example of an immune targeted therapy. Herceptin is an intravenous drug that is part of a chemotherapy regimen that is used to prevent recurrence of breast cancer, and for the treatment breast cancer that has spread beyond the breast (metastasized). It belongs to a class of drugs called monoclonal antibodies.