nucleotide

Examples of nucleotide in the following topics:

• Nucleotide and Nonnucleotide Reverse Transcriptase Inhibitors

  • They mimic, respectively, nucleosides or nucleotides but lack a free hydroxyl group at the 3' end.
  • Nucleoside and nucleotide inhibitors are also called competitive substrate inhibitors.
  • Non-nucleotide inhibitors are non-competitive inhibitorsof reverse transcriptase.
  • The mechanisms for resistance against the nucleoside (nucleotide) inhibitors are two.
  • Resistance to the non-nucleotide inhibitors is caused by mutations in the inhibitor binding site of the enzyme.

• DNA Sequencing Based on Sanger Dideoxynucleotides

  • Sanger sequencing is based on the incorporation and detection of labeled ddNTPs as terminal nucleotides in DNA amplification.
  • This method is based on amplification of the DNA fragment to be sequenced by DNA polymerase and incorporation of modified nucleotides - specifically, dideoxynucleotides (ddNTPs).
  • The classical chain-termination method requires a single-stranded DNA template, a DNA primer, a DNA polymerase, normal deoxynucleotidetriphosphates (dNTPs), and modified nucleotides (dideoxyNTPs) that terminate DNA strand elongation .
  • These chain-terminating nucleotides lack a 3'-OH group required for the formation of a phosphodiester bond between two nucleotides, causing DNA polymerase to cease extension of DNA when a ddNTP is incorporated.
  • Technical variations of chain-termination sequencing include tagging with nucleotides containing radioactive phosphorus for radiolabelling, or using a primer labeled at the 5' end with a fluorescent dye.

• Purine and Pyrimidine Synthesis

  • Unlike pyrimidines, purines are biologically synthesized as nucleotides and in particular as ribotides.
  • Purines are biologically synthesized as nucleotides and in particular as ribotides; i.e., bases attached to ribose 5-phosphate.
  • This is the only mitochondrial step in nucleotide rings biosynthesis.
  • This acts to balance the relative amounts of purine and pyrimidine nucleotides.
  • A purine is a nucleotide (a nucleoside + phosphate group) that is amine based and planar, aromatic, and heterocyclic.

• The Phosphorus Cycle

  • Phosphorus, important for creating nucleotides and ATP, is assimilated by plants, then released through decomposition when they die.
  • Phosphorus is an important element for living things because it is neccesary for nucleotides and ATP.

• Antiviral DNA Synthesis Inhibitors

  • However, the nucleoside analogue lacks free 3' end needed for the addition of the next nucleotide .
  • This prevents the incorporation of the next nucleotide and terminates the elongation of the DNA chain.
  • After administration, the molecule gets activated by phosphorylation both by viral and host cell kinases and the resulting nucleotide incorporated into the newly synthesized DNA resulting in premature chain termination.
  • Acyclovir does not contain a sugar molecule with a 3'-OH group and will interrupt the synthesis of a newly synthesized nucleotide chain if added to it.

• The Deltaproteobacteria

  • The myxobacteria have very large genomes, relative to other bacteria, e.g. 9–10 million nucleotides.
  • Sorangium cellulosum has the largest known (as of 2008) bacterial genome, at 13.0 million nucleotides.

• Nanoarchaeum and Aciduliprofundum

  • Its genome is only 490,885 nucleotides long; the smallest non-viral genome ever sequenced next to that of Candidatus Carsonella ruddii.
  • N. equitans genome consists of a single circular chromosome, and lacks almost all genes required for synthesis of amino acids, nucleotides, cofactors, and lipids, but encodes everything needed for repair and replication. 95% of its DNA encodes for proteins for stable RNA molecules.
  • Nanoarchaeum cannot synthesize most nucleotides, amino acids, lipids, and cofactors.

• DNA Analysis Using Genetic Probes and PCR

  • Genetic probes are based on the detection of unique nucleotide sequences with the DNA or RNA of a microorganism.
  • Once such a unique nucleotide sequence, which may represent a portion of a virulence gene or of chromosomal DNA, is found, it is isolated and inserted into a cloning vector (plasmid), which is then transformed into Escherichia coli to produce multiple copies of the probe.
  • Describe how genetic probes can be used to detect unique nucleotide sequences within the DNA or RNA or a microorganism

• Slipped-Strand Mispairing

  • The short repeat sequences are 1 to 7 nucleotides and can be homogeneous or heterogeneous repetitive DNA sequences.
  • Start (ATG) is the start codon in which the ribosome initiates translation of nucleotide sequence into amino acids, and (-10 -35) is the promoter which is the binding site for the RNAP to initiate transcription of DNA into RNA.

• Primer Extension Analysis

  • This technique requires a radiolabelled primer (usually 20 to 50 nucleotides in length) which is complementary to a region near the 3' end of the gene.
  • In one, the modified nucleotide cannot be recognized by the polymerase or reverse transcriptase; in such cases, the chain ends at the site of modification.