Noncoding DNA Sequences Research Paper

Improved Essays
The importance of noncoding DNA sequences

Since the completion of Human Genome Project in 2003, it was found that more than 98% of human genome is occupied by noncoding DNA sequences (Genome.gov, 2003), existing between genes and as introns within genes (Figure-1). In genomic, noncoding DNA regions are defined as the sequences of an organism’s DNA, which do not code for proteins. Although it has been known for decades that some of these sequences code for noncoding RNAs that involve in controlling many cellular processes, recently study suggested that many of them are in fact vital in regulating how our genome works (The Encode Project, 2004), while some research proposed that others may have no known biological function for
…show more content…
According to the observation made during the replication of Drosophila melanogaster chromosomes in 1973, the opening of Drosophila’s DNA double helix, known as replication forks (formerly named as eye forms) at a number of different sites were noted (Kriegstein and Hogness, 1974). The creation of replication forks is the result of the formation of replication bubbles. As shown in Figure-4, replication origins are recognized by the origin recognition complex (ORC) to create a replication bubble in late mitosis and early G1 (Leman and Noguchi, 2013, pp. 5-6). Situated at the ends of the replication bubble are replication forks where initiation of DNA replication occurs allowing the replication to proceed in both directions (Figure-4). Similarly, DNA replication in human cells is also initiated at a number of different replication origins on multiple chromosomes simultaneously so that the duration of S phase of the interphase – about 8 hours (Tortora and Derrickson, 2011, pp.96) - is not limited by the total amount of DNA. The form of DNA replication in human is referred to as semi-conservative replication as each of daughter double helix inherited one of the polynucleotide chains of the parent double (Waston and Crick, 1953; Meselson and Stahl, …show more content…
An American geneticist, Hermann J. Muller, was the first to discover the existence of telomere in 1938. He was irradiating Drosophila melanogaster with X-ray to produce mutation at the Drosophila’s chromosomal ends and he observed no mutants with deletions or inversions during the experiment (Muller, 1938). He suggested the presence of a protective cap, known as telomere, at the chromosomal end. It wasn’t a year later; Barbara McClintock - a cytogeneticist from the University of Cornell - proposed another main function of telomeres. While investigating the behaviour of broken chromosomes in maize plants by studying the cytology of x-rayed plants, she observed that when the breakage occurs on one end of a chromosome, fusion of the broken meiotic chromatids does occur. Such consequence result in anaphase bridge configuration termed as the breakage-fusion-bridge (BFB) cycle to ensure cell death (McClintock, 1939).

Non-functional sequences of noncoding DNA include: 1) transposable elements: Class I (retrotransposons) and Class II (DNA transposons and endogenous retroviruses), 2) highly repetitive DNA, 3) introns, 4) pseudogenes, and 5) conserved sequences (McClintock,

Related Documents

  • Superior Essays

    RNA Polymerases

    • 1199 Words
    • 5 Pages

    Griffiths et all. (2002) says that two strands of the double helix of DNA separate and one acts as a temple. They also stated that A pairs with T while and G with C in DNA. However, in RNA A pairs with U and G with C. Since RNA Polymerase (RNAPs) can be found in archaea, bacteria, and eukaryotes there are many different ways to look at what is happening. According to Jun et all.…

    • 1199 Words
    • 5 Pages
    Superior Essays
  • Improved Essays

    The nuclear membrane around the nucleus of the daughter cells disintegrates releasing the chromosome. The meiotic spindles start forming again and the centrioles duplicate. Metaphase II- The pair of sister chromatids arrange themselves in line along the equator of the cell. The centrioles are now present at the opposite ends in each of the daughter cells. The developed meiotic spindle fibers at each end attach onto the centromere present in the sister chromatids of the cell.…

    • 1256 Words
    • 6 Pages
    Improved Essays
  • Superior Essays

    Dna Synthesis

    • 1283 Words
    • 6 Pages

    At this stage, the main objective is unwinding the double-helical structure of the DNA as proposed by Watson and Crick in 1953 and then use both strands as a template to continue the replication process (Weaver, 2012). According to Lodish (2008), it begins with the enzyme helicases steadily unravelling the strands at the replication origins by breaking the hydrogen bonds between the nitrogen bases of the DNA and continue to form a replication fork as it separates the strands into two parental strands (Reece, Reece & Campbell, 2011). During this time, Reece et. al (2011) explain that to prevent the recoiling of the strands, single strand binding protein firmly attached to the free-bound DNA nucleotides, hence inhibiting the formation of hydrogen bonds between the nitrogen bases of the DNA. Subsequently, since the action of unravelling and untwisting the helixes create supercoiling, a torsional pressure along the replication fork, topoisomerase is fully utilized to subdue the supercoiling (Lodish, 2008).…

    • 1283 Words
    • 6 Pages
    Superior Essays
  • Great Essays

    Prokaryotic Cell Biology

    • 1728 Words
    • 7 Pages

    In laymen terms, the genetic material from the egg and sperm are combined to create daughter cells with a complete complement of chromosomes. The first stage of meiosis is called Interphase. This is when the chromosomes are duplicated in preparation for the division. The next 4 stages are referred to as meiosis I. Prophase I is when the homologous chromosomes pair up and exchange segments. Metaphase I is when the pairs of chromosomes line up along the spindle.…

    • 1728 Words
    • 7 Pages
    Great Essays
  • Superior Essays

    Lagging strands are created by the production of small DNA fragments called Okazaki fragments that are eventually joined together. Both types of organisms also begin new DNA strands with a small primer of RNA. (Taylor, 2017) Differences Differences between prokaryotic and eukaryotic DNA replication are largely related to contrasts in size and complexity of the DNA and cells of these organisms. The average eukaryotic cell has 25 times more DNA than a prokaryotic cell (Diffen, 2007). Location: Since Prokaryotes do not have membrane-bound organelles, it preserves its DNA in the cytoplasm where the replication takes place as well.…

    • 1021 Words
    • 5 Pages
    Superior Essays
  • Improved Essays

    The cell duplicates perfectly, with the same DNA. During this phase, the chromosomes align, separate, and are moved to the opposite ends of the cell, forming two identical cells (OpenStax, 2013). Within this phase, there are five sub-phases called prophase, prometaphase, metaphase, anaphase, and telophase. An example of mitosis would be the regrowth of human skin. All cells undergo a stage where they prepare to duplicate and that is known as the interphase stage.…

    • 723 Words
    • 3 Pages
    Improved Essays
  • Decent Essays

    Recombination and mutation are the motivation of evolution. Recombination is critical for repairing DNA lesions and for chromosomal pairing, and exchange during meiosis (Krejci et al. 2012). Recombination does not occur uniformly on the chromosomes of eukaryotes. Meiotic recombination in well studied yeast revealed that non-uniformity of recombination was observed when the frame of reference is an entire chromosome, multigene region and a pair of genes or a small region upstream of a gene (Lichten and Goldman 1995).…

    • 991 Words
    • 4 Pages
    Decent Essays
  • Superior Essays

    In Today’s Science article titled The Origami of DNA it was about how Genome is organized in looping. Genetic material stored in the nucleus in a compressed way that let on amounts of data to be stored in bitty places. Society had very clear perspective on how genomes were stored until recent times. Researchers have found approach that helps find the grouping of the human genome in three dimensions. Researchers discovered much of the genome was package into loops.…

    • 802 Words
    • 4 Pages
    Superior Essays
  • Improved Essays

    (2014) conducted GWAS of 282 soybean breeding lines for resistance to SCN HG Type 0 using the USLP 1.0 SNP arrays (Hyten et al. 2010). The authors detected a significant association between markers and the known gene regions but no novel regions were detected. Han et al. (2015) identified 19 association signals significantly related to resistance to SCN HG Types 0 (race 3) and 1.2.3.5.7 (race 4) as well as over 130 new sources of SCN resistance.…

    • 742 Words
    • 3 Pages
    Improved Essays
  • Improved Essays

    Parvovirus Research Paper

    • 1461 Words
    • 6 Pages

    FPV is in the family Parvoviridae, which contains 26 species of virus that infect a broad host range, covering species from invertebrates to humans. Parvoviruses are small single stranded DNA viruses enveloped by a T=1 non-enveloped capsid protein. Replication of these viruses can only occur when the host cell is in S-phase of its mitotic cycle (15). FPV has a very small linear genome that is only 5 kilobases in length (4). The virus’s genome has specific sequences, similar to a TATA boxes, that initiate transcription of major virus specific mRNA.…

    • 1461 Words
    • 6 Pages
    Improved Essays

Related Topics