genome

Examples of genome in the following topics:

• Genome Reduction

  • Genome reduction is the loss of genome size of a species in comparison to its ancestors.
  • Genome size is the total amount of DNA contained within one copy of a single genome.
  • The opposite or genome reduction also occurs.
  • Genome reduction, also known as genome degradation, is the process by which a genome shrinks relative to its ancestor.
  • A graph show the relative size of genomes, generally more "complex" organisms have larger genomes.

• Annotating Genomes

  • Genome annotation is the identification and understanding of the genetic elements of a sequenced genome.
  • They annotate protein-coding genes and other important genome-encoded features.
  • Once a genome is sequenced, it needs to be annotated to make sense of it.
  • DNA annotation or genome annotation is the process of identifying the locations of genes and all of the coding regions in a genome and determining what those genes do .
  • Genome annotation is the next major challenge for the Human Genome Project, now that the genome sequences of human and several model organisms are largely complete.

• Bacterial Genomes

  • Bacterial genomes are smaller in size (size range from 139 kbp to 13,000 kpb) between species when compared with genomes of eukaryotes.
  • Bacterial genomes are generally smaller and less variant in size between species when compared with genomes of animals and single cell eukaryotes.
  • The relationship between life-styles of bacteria and genome size raises questions as to the mechanisms of bacterial genome evolution.
  • One theory predicts that bacteria have smaller genomes due to a selective pressure on genome size to ensure faster replication.
  • Unlike eukaryotes, bacteria show a strong correlation between genome size and number of functional genes in a genome.

• Viral Genomes

  • The viral genome is the complete genetic complement contained in a DNA or RNA molecule in a virus.
  • An enormous variety of genomic structures can be seen among viral species; as a group, they contain more structural genomic diversity than plants, animals, archaea, or bacteria.
  • The vast majority of viruses have RNA genomes.
  • Plant viruses tend to have single-stranded RNA genomes and bacteriophages tend to have double-stranded DNA genomes.
  • The type of nucleic acid is irrelevant to the shape of the genome.

• Uses of Genome Sequences

  • Genome sequences and expression can be analyzed using DNA microarrays, which can contribute to detection of disease and genetic disorders.
  • Almost one million genotypic abnormalities can be discovered using microarrays, whereas whole-genome sequencing can provide information about all six billion base pairs in the human genome.
  • Although the study of medical applications of genome sequencing is interesting, this discipline tends to dwell on abnormal gene function.
  • Genomics is still in its infancy, although someday it may become routine to use whole-genome sequencing to screen every newborn to detect genetic abnormalities.
  • DNA microarrays can be used to analyze gene expression within the genome.

• Use of Whole-Genome Sequences of Model Organisms

  • The first genome to be completely sequenced was of a bacterial virus, the bacteriophage fx174 (5368 base pairs).
  • Several other organelle and viral genomes were later sequenced.
  • It took this long because it was 60 times bigger than any other genome that had been sequenced at that point.
  • Having entire genomes sequenced aids these research efforts.
  • The process of attaching biological information to gene sequences is called genome annotation.

• Variations in Size and Number of Genes

  • The C-value is another measure of genome size.
  • For example, the predicted size of the human genome is not much larger than the genomes of some invertebrates and plants, and may even be smaller than the Indian rice genome.
  • In prokaryotic genomes, research has shown that there is a significant positive correlation between the C-value of prokaryotes and the amount of genes that compose the genome.
  • In eukaryotic organisms, there is a paradox observed, namely that the number of genes that make up the genome does not correlate with genome size.
  • It is also possible that genomes can shrink due to deletions.

• Biotechnology

  • Relying on the study of DNA, genomics analyzes entire genomes, while biotechnology uses biological agents for technological advancements.
  • Genomics is the study of entire genomes, including the complete set of genes, their nucleotide sequence and organization, and their interactions within a species and with other species.
  • The advances in genomics have been made possible by DNA sequencing technology.
  • The ways in which genomic information can contribute to scientific understanding are varied and quickly growing.
  • In genomics, the DNA of different organisms is compared, enabling scientists to create maps with which to navigate the DNA of different organisms.

• Noncoding DNA

  • For example, over 98% of the human genome is noncoding DNA, while only about 2% of a typical bacterial genome is noncoding DNA.
  • The amount of total genomic DNA varies widely between organisms, and the proportion of coding and noncoding DNA within these genomes varies greatly as well.
  • The pufferfish Takifugu rubripes genome is only about one eighth the size of the human genome, yet seems to have a comparable number of genes; approximately 90% of the Takifugu genome is noncoding DNA.
  • In 2013, a new "record" for most efficient genome was discovered.
  • This 3% has given this plant the title the 'most efficient' genome.

• Whole-Genome Duplication

  • Whole-genome duplication is characterized by an organisms entire genetic information being copied once or multiple times.
  • Genome doubling provides organisms with redundant alleles that can evolve freely with little selection pressure.
  • In 1997, Wolfe & Shields gave evidence for an ancient duplication of the Saccharomyces cerevisiae (Yeast) genome.
  • It was initially noted that this yeast genome contained many individual gene duplications.
  • They found 32 pairs of homologous chromosomal regions, accounting for over half of the yeast's genome.