Dictionary > Steroid

Steroid

Definition
noun, plural: steroids
Any of the group of fat-soluble organic compounds containing four rings arranged in a particular molecular configuration, produced either naturally (i.e. from the sterols lanosterol and cycloartenol) or synthetically
Supplement
A steroid refers to any of the group of natural and synthetic hormones or lipids containing a hydrogenated cyclopentanoperhydrophenanthrene ring system. Steroids occur naturally and have various physiological effects. Many of them occur as a cell membrane component. Others may serve as signaling molecule. Natural steroids are produced by the cell from the sterols, such as lanosterol and cycloartenol. Lanosterols are the source of steroids in animals and fungi. Cycloartenol are the source of steroids in plants. The core of a steroid is basically made up of 17 carbon atoms bonded in four rings. The rings A, B, and C are six-member cyclohexane rings and the ring D is a five-member cyclopentane ring. Hundreds of steroids occur naturally and they vary by the functional groups bound to the core.
In animals, the steroids include those found in vertebrates and insects. Steroids in vertebrates, including humans, are exemplified by cholesterol and steroid hormones. Steroid hormones include sex hormones (e.g. androgens, estrogens, and progesterones), corticosteroids (e.g. glucocorticoids and mineralocorticoids), and anabolic steroids. In insects, ecdysteroids and ecdysterones are steroids involved in molting.
Certain steroids are produced synthetically and are used in medicine. For example, prednisone, prednisolone, methylprednisolone and dexamethasone are used for the treatment of leukemia. They may also be used to suppress graft rejection and graft-versus-host disease after a bone marrow transplant. Nevertheless, taking these therapeutic steroids has side effects, e.g. increased risk of infection and moon face.
In plants, the steroids are exemplified by steroidal alkaloids, phytosterols, and brassinosteroids. In fungi, the steroids include the ergosterols, which are analogous to the cholesterol in the cell membrane of animals.
Word origin: ster(ol) + oid
See also:

Related term(s):

  • corticosteroid
  • D-homosteroid
  • Gonadal steroid
  • Saturated steroid 6 alpha-hydroxylase
  • Sex steroid
  • Sex steroid-binding globulin
  • Steroid 11 beta-monooxygenase
  • Steroid 11-alpha-hydroxylase
  • Steroid facies
  • Steroid hormone
  • Steroid receptor
  • Steroid sulfatase deficiency
  • Related form(s):

    • steroidal (adjective, of, relating to, or pertaining to a steroid)


    You will also like...

    Still Water Animals
    Still Water Animals

    Animals living in aquatic habitats have diversified and evolved through time. They eventually occupy ecological niches a..

    Schematic diagram of DNA replication
    DNA Structure & DNA Replication

    DNA is a double helix structure comprised of nucleotides. A nucleotide, in turn, is made up of phosphate molecule, deoxy..

    green plant cells
    Plant Cells vs. Animal Cells

    Plant cells have plastids essential in photosynthesis. They also have an additional layer called cell wall on their cell..

    An artistic depiction of Dunkleosteus fish
    Fish

    The sea was teeming with life. Eventually, through reproduction and continued variation, fish came about. There are over..

    Genetic engineering
    Genetic Engineering Advantages & Disadvantages

    This tutorial presents the benefits and the possible adverse eventualities of genetic engineering. Know more about this ..

    Growth Patterns
    Growth Patterns

    This tutorial describes the sigmoid curve, annual plant growth, tree growth, human growth, and insect growth as the grow..