in vitro

(noun)

any biochemical process done outside of its natural biological environment, such as in a test tube, petri dish, etc. (from the Latin for "in glass")

Related Terms

Examples of in vitro in the following topics:

  • DNA Sequencing Techniques

    • By using a predetermined ratio of deoxyribonucleotides to dideoxynucleotides, it is possible to generate DNA fragments of different sizes when replicating DNA in vitro.
    • A Sanger sequencing reaction is just a modified in vitro DNA replication reaction.
    • Most of the time in a Sanger sequencing reaction, DNA Polymerase will add a proper dNTP to the growing strand it is synthesizing in vitro.
    • If enough template DNAs are included in the reaction mix, each one will have the ddNTP inserted at a different random location, and there will be at least one DNA terminated at each different nucleotide along its length for as long as the in vitro reaction can take place (about 900 nucleotides under optimal conditions.)
    • In shotgun sequencing, multiple copies of the same chromosome are isolated and then fragmented in random locations.

  • Infertility

    • These include diseases (such as sexually-transmitted diseases that can cause scarring of the reproductive tubes in either men or women) or developmental problems frequently related to abnormal hormone levels in one of the individuals.
    • A common type of assisted reproductive technology is in vitro fertilization (IVF) where an egg and sperm are combined outside the body and then placed in the uterus.
    • IVF procedures produce a surplus of fertilized eggs and embryos that can be frozen and stored for future use; the procedures can also result in multiple births.
    • Define infertility and discuss ways in which it can be treated

  • The Energy-Releasing Steps of Glycolysis

    • In the second half of glycolysis, energy is released in the form of 4 ATP molecules and 2 NADH molecules.
    • If oxygen is available in the system, the NADH will be oxidized readily, though indirectly, and the high-energy electrons from the hydrogen released in this process will be used to produce ATP.
    • In the eighth step, the remaining phosphate group in 3-phosphoglycerate moves from the third carbon to the second carbon, producing 2-phosphoglycerate (an isomer of 3-phosphoglycerate).
    • The last step in glycolysis is catalyzed by the enzyme pyruvate kinase (the enzyme in this case is named for the reverse reaction of pyruvate's conversion into PEP) and results in the production of a second ATP molecule by substrate-level phosphorylation and the compound pyruvic acid (or its salt form, pyruvate).
    • Many enzymes in enzymatic pathways are named for the reverse reactions since the enzyme can catalyze both forward and reverse reactions (these may have been described initially by the reverse reaction that takes place in vitro, under non-physiological conditions).

  • Gene rearrangement within genomes

    • This event results in variations of gametes that can produce variation in species.
    • This can result in one chromosome ending up with more DNA and one ending up with less.
    • These types of errors can result in mutations.
    • In both meiotic and mitotic cells, recombination between homologous chromosomes is a common mechanism used in DNA repair.
    • Recombination can be artificially induced in laboratory (in vitro) settings, producing recombinant DNA for purposes including vaccine development.

  • Epigenetic Alterations in Cancer

    • Epigenetic alterations are as important as genetic mutations in a cell's transformation to cancer.
    • In cancer cells, the DNA in the promoter region of silenced genes is methylated on cytosine DNA residues in CpG islands, genomic regions that contain a high frequency of CpG sites, where a cytosine nucleotide occurs next to a guanine nucleotide .
    • When these modifications occur, the gene present in that chromosomal region is silenced.
    • Increasingly, scientists are understanding how these epigenetic changes are altered in cancer.
    • In cancer cells, silencing genes through epigenetic mechanisms is a common occurrence.

  • Cancer and Post-Transcriptional Control

    • Modifications, such as the overexpression of miRNAs, in the post-transcriptional control of a gene can result in cancer.
    • Changes in the post-transcriptional control of a gene can result in cancer.
    • An increase in many miRNAs could dramatically decrease the RNA population leading to a decrease in protein expression.
    • Several studies have demonstrated a change in the miRNA population in specific cancer types.
    • Specific types of miRNAs are only found in cancer cells.

  • Basic Principles of Gas Exchange

    • The concentration of the gas in a liquid is also dependent on the solubility of the gas in the liquid.
    • Too much nitrogen in the bloodstream results in a serious condition that can be fatal if not corrected.
    • Gas molecules establish an equilibrium between those molecules dissolved in liquid and those in air.
    • The composition of air in the atmosphere and in the alveoli differs.
    • The amount of water vapor present in alveolar air is greater than that in atmospheric air (Table 3).

  • Signaling in Yeast

    • Yeasts utilize cell-surface receptors, mating factors, and signaling cascades in order to communicate.
    • The components and processes found in yeast signals are similar to those of cell-surface receptor signals in multicellular organisms.
    • Of the 130 kinase types in yeast, 97 belong to the 55 subfamilies of kinases that are found in other eukaryotic organisms.
    • The only obvious deficiency seen in yeasts is the complete absence of tyrosine kinases.
    • Describe how cell signaling occurs in single-celled organisms such as yeast

  • Varying Rates of Speciation

    • Two patterns are currently observed in the rates of speciation: gradual speciation and punctuated equilibrium.
    • In the gradual speciation model, species diverge gradually over time in small steps.
    • The primary influencing factor on changes in speciation rate is environmental conditions.
    • When a change in the environment takes place, such as a drop in the water level, a small number of organisms are separated from the rest in a brief period of time, essentially forming one large and one tiny population.
    • In (a) gradual speciation, species diverge at a slow, steady pace as traits change incrementally.

  • Lethal Inheritance Patterns

    • An inheritance pattern in which an allele is only lethal in the homozygous form and in which the heterozygote may be normal or have some altered non-lethal phenotype is referred to as recessive lethal.
    • In other instances, the recessive lethal allele might also exhibit a dominant (but not lethal) phenotype in the heterozygote.
    • For instance, the recessive lethal Curly allele in Drosophila affects wing shape in the heterozygote form, but is lethal in the homozygote.
    • Individuals with mutations that result in dominant lethal alleles fail to survive even in the heterozygote form.
    • An example of this in humans is Huntington's disease in which the nervous system gradually wastes away .