elongation

(noun)

the addition of nucleotides to the 3'-end of a growing RNA chain during transcription

Examples of elongation in the following topics:

  • Elongation and Termination in Prokaryotes

    • Transcription elongation begins with the release of the polymerase σ subunit and terminates via the rho protein or via a stable hairpin.
    • The transcription elongation phase begins with the release of the σ subunit from the polymerase.
    • As elongation proceeds, the DNA is continuously unwound ahead of the core enzyme and rewound behind it .
    • Since the base pairing between DNA and RNA is not stable enough to maintain the stability of the mRNA synthesis components, RNA polymerase acts as a stable linker between the DNA template and the nascent RNA strands to ensure that elongation is not interrupted prematurely.
    • During elongation, the prokaryotic RNA polymerase tracks along the DNA template, synthesizes mRNA in the 5' to 3' direction, and unwinds and rewinds the DNA as it is read.

  • Types of Root Systems and Zones of Growth

    • The root tip has three main zones: a zone of cell division, a zone of elongation, and a zone of maturation.
    • The root tip can be divided into three zones: a zone of cell division, a zone of elongation, and a zone of maturation .
    • The zone of elongation is where the newly-formed cells increase in length, thereby lengthening the root.
    • A longitudinal view of the root reveals the zones of cell division, elongation, and maturation.

  • The Mechanism of Protein Synthesis

    • As with mRNA synthesis, protein synthesis can be divided into three phases: initiation, elongation, and termination.
    • The basics of elongation are the same in prokaryotes and eukaryotes.
    • The energy for each step of the ribosome is donated by an elongation factor that hydrolyzes GTP.
    • The elongation factor eEF1 assists in loading the aminoacyl-tRNA, powering the process through the hydrolysis of GTP.
    • The elongation factor eEF2 assists in the translocation, powering the process through the hydrolysis of GTP.

  • Elongation and Termination in Eukaryotes

    • Following the formation of the pre-initiation complex, the polymerase is released from the other transcription factors, and elongation is allowed to proceed with the polymerase synthesizing RNA in the 5' to 3' direction.
    • RNA Polymerase II (RNAPII) transcribes the major share of eukaryotic genes, so this section will mainly focus on how this specific polymerase accomplishes elongation and termination.
    • Although the enzymatic process of elongation is essentially the same in eukaryotes and prokaryotes, the eukaryotic DNA template is more complex.
    • RNA Polymerase II will continue to elongate the newly-synthesized RNA until transcription terminates.
    • Consequently, RNA Polymerase II does not need as many accessory proteins to catalyze the synthesis of new RNA strands during transcription elongation as DNA Polymerase does to catalyze the synthesis of new DNA strands during replication elongation.

  • DNA Replication in Eukaryotes

    • DNA replication in eukaryotes occurs in three stages: initiation, elongation, and termination, which are aided by several enzymes.
    • It occurs in three main stages: initiation, elongation, and termination.
    • During elongation, an enzyme called DNA polymerase adds DNA nucleotides to the 3' end of the newly synthesized polynucleotide strand.
    • An RNA primer is synthesized by primase and is elongated by the DNA polymerase.

  • Binary Fission

    • As the cell elongates, the growing membrane aids in the transport of the chromosomes.
    • After the chromosomes have cleared the midpoint of the elongated cell, cytoplasmic separation begins.

  • The Evolution of Roots in Seedless Plants

    • The root tip can be divided into three zones: a zone of cell division, a zone of elongation, and a zone of maturation and differentiation .
    • The zone of elongation is where the newly-formed cells increase in length, thereby lengthening the root.
    • A longitudinal view of the root reveals the zones of cell division, elongation, and maturation.

  • Blue Light Response

    • Therefore, the chemical signal from the sunlight, which is blue wavelengths of light, was a growth stimulant; the phototropic response involved faster cell elongation on the shaded side than on the illuminated side, causing the plant to bend.
    • Stem cells elongate under the influence of IAA .
    • This overload of auxin next to these cells causes them to start to grow or elongate, tipping the growth of the stem toward the light.

  • Auxins, Cytokinins, and Gibberellins

    • The term auxin is derived from the Greek word auxein, which means "to grow. " Auxins are the main hormones responsible for cell elongation in phototropism and gravitropism.
    • Gibberellins (GAs) are a group of about 125 closely-related plant hormones that stimulate shoot elongation, seed germination, and fruit and flower maturation.
    • Because GAs are produced by the seeds and because fruit development and stem elongation are under GA control, these varieties of grapes would normally produce small fruit in compact clusters.

  • Pancreas

    • The pancreas is an elongated organ that is located between the stomach and the proximal portion of the small intestine .