Libro ¿Dónde esta el señor astronauta?

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   Sally – 8 marzo, 2025

   Introduction

   Types of Steroids

   Effects and Side Effects

   History and Usage

   # Contents

   ## Steroid
   Steroids are a class of organic compounds characterized by a specific type of chemical structure.

   They are primarily found in animals, plants, fungi, and some bacteria, where
   they play diverse roles in biological processes. Steroids
   have three interconnected rings, with functional groups such as hydroxyl
   or ketone groups attached to the molecule. Their structure is crucial for their activity, enabling them to act as hormones, vitamins, or other bioactive compounds.

   ## Page version status
   This page is based on content from Wikipedia and other reliable sources.

   It has been reviewed and updated by experts in the field.

   For more detailed information, please refer to the original source materials.

   ## Nomenclature
   The nomenclature of steroids refers to the systematic naming of these compounds.
   Steroids are named based on their structural features or
   biological functions. For example, «cholesterol» refers to a
   specific steroid molecule produced in the liver and used in animal cell membranes.

   Other examples include «sex hormones,» such as estrogen and testosterone, which are
   steroidal molecules involved in reproduction and endocrine regulation.

   ## Rings and functional groups
   Steroids have a unique structure with three interconnected rings.
   The core of the steroid framework consists of two cyclohexane rings fused together, forming a bicyclic system.
   Functional groups, such as hydroxyl (-OH) or ketone (C=O) groups, are
   attached to this framework and play a critical role in determining
   the biological activity of the molecule. These functional
   groups can influence steroid behavior, such as their
   affinity for specific receptors or their solubility in different environments.

   ## Naming convention
   The naming convention for steroids follows specific rules that help differentiate between the various types of steroidal molecules.
   The name often includes a prefix derived from the class of compounds (e.g., «sterol» for cholesterol, «keto» for ketone-containing
   sterols). Additional suffixes may indicate modifications or functional groups present on the molecule.
   This system ensures clarity and precision in communication within scientific communities.

   ## Species distribution
   Steroids are distributed across a wide range of species.
   Their presence is not limited to one type of organism, as they can be found in both
   eukaryotes and prokaryotes. For example:
   – **Eukaryotic organisms**: Steroids are abundant in animals, plants, fungi, and single-celled eukaryotes like protozoa.

   – **Prokaryotic organisms**: Sterols, a type of steroid,
   are found in bacterial cell membranes and play a role in maintaining membrane integrity.

   ## Eukaryotic
   In eukaryotic organisms, steroids serve various biological functions.
   For instance:
   – Animals produce a wide variety of steroids, including sex hormones (e.g.,
   estrogen, testosterone) that regulate reproduction and metabolism.

   – Plants synthesize sterols as part of their cell membranes, contributing to the strength and
   structure of these cellular structures.
   – Fungi also produce sterols, such as ergosterol, which is essential for the integrity of fungal cell membranes.

   ## Prokaryotic
   In prokaryotic organisms, sterols are a key component of bacterial cell membranes.
   These sterols help maintain membrane fluidity and flexibility, ensuring that the cell can function under various environmental
   conditions. While sterols are common in bacteria and archaea, they are not typically found in other types of prokaryotes, such
   as viruses.

   ## Fungal
   Fungi produce a variety of sterols, including ergosterol, which is a fundamental component of fungal cell membranes.
   Ergosterol’s structure differs slightly from
   cholesterol, the primary sterol in animals, but it serves similar functions in maintaining membrane integrity and
   facilitating the transport of ions and nutrients across the membrane.

   ## Plant
   In plants, sterols are essential for the
   structural integrity of cellular membranes. Unlike animals, plants do not
   synthesize cholesterol but instead produce a related molecule
   called phytosterol. Phytosterols share some structural similarities with animal sterols but have unique features that make them suited
   to plant biology. These compounds contribute to membrane stability and
   help regulate growth and development in plants.

   ## Animal
   Animals are perhaps the most complex users of steroids, producing a
   vast array of these molecules for various purposes.
   For example:
   – **Sex hormones**: Steroids such as testosterone (male) and estrogen (female) play critical roles in reproduction and sexual differentiation.
   – **Adrenal steroids**: The adrenal glands produce corticosteroids, which
   are involved in stress response and immune function.
   – **Vitamin D**: A steroid molecule derived from cholesterol that
   is essential for bone health and calcium absorption.
   – **Other sterols**: Cholesterol itself is a vital component of
   animal cell membranes and precursor to various hormones and other bioactive compounds.

   ## Types
   Steroids can be categorized based on their function or structure:

   – **By function**: Sex steroids (e.g., estrogen, testosterone), adrenal steroids
   (e.g., cortisol), vitamin D derivatives, and sterols like cholesterol.

   – **By structure**: Intact ring systems, cleaved rings, contracted rings, or expanded rings.

   ## Rings and functional groups
   The number and arrangement of rings in the steroid framework influence its biological activity.
   For example:
   – **Intact ring system**: Steroids with all three rings intact often retain their basic
   structural features, allowing them to interact with
   specific receptors and perform normal cellular functions.

   – **Cleaved rings**: Modified steroids where one or more rings have been broken or altered can result
   in compounds with different properties. These derivatives may
   be more effective at targeting specific cellular pathways or receptors.

   – **Contracted rings**: Steroids with one ring contracted into a smaller, often five-membered structure are common in certain hormones and signaling
   molecules.
   – **Expanded rings**: Some steroid derivatives have additional carbons added to the ring system, altering their
   shape and function.

   ## Biological significance
   Steroids are biologically significant compounds with diverse roles in organisms.
   They serve as signaling molecules, hormone precursors, and
   structural components of cell membranes. For example:
   – **Signaling**: Steroids can act as hormones, transmitting signals within and between cells to regulate gene expression and cellular activity.

   – **Vitamin D**: A steroid derivative that is essential
   for bone health and calcium absorption.
   – **Cholesterol**: A major component of animal
   cell membranes, which also serves as a precursor for sex hormones and other
   steroidal molecules.

   ## Biosynthesis and metabolism
   The biosynthesis of steroids involves complex biochemical pathways that convert simple precursors into highly structured molecules.
   The two primary pathways for steroid synthesis are the Mevalonate pathway (also known as the cholesterol biosynthesis pathway) and the alternative pathways, such as the reverse transport of sterols in cells.

   ### Mevalonate pathway
   The Mevalonate pathway is a series of enzymatic reactions that
   convert acetyl-CoA into mevalonic acid, which serves as a precursor for the synthesis of cholesterol and other steroids.
   This pathway is active in most animals and plays a critical role in maintaining cellular health and
   homeostasis.

   ### Steroidogenesis
   Steroidogenesis refers to the process by which sterols are synthesized and modified into biologically active molecules.
   For example, cholesterol can be converted into vitamin D in sunlight, or transformed into
   sex hormones like estrogen and testosterone. This process is tightly regulated by the body to ensure
   that steroid levels remain within a healthy range.

   ### Alternative pathways
   In addition to the Mevalonate pathway, alternative pathways for
   steroid biosynthesis exist, particularly in certain tissues and
   organisms. These pathways may involve different precursors or unique enzymatic modifications, allowing for
   the production of specialized sterols tailored to specific biological needs.

   ### Catabolism and excretion
   Once steroids have fulfilled their biological function, they
   are broken down by enzymes known as steroid sulfatases and sulfotransferases.
   This process, known as catabolism, converts the steroids into inactive metabolites that can be safely excreted from the body.
   The excretion of sterols is a critical step in maintaining homeostasis and preventing the buildup
   of potentially harmful levels of these molecules.

   ## Isolation, structure determination, and methods of analysis
   The isolation and structural determination of steroids are essential for understanding their biological roles and developing
   new therapies. Techniques such as chromatography, mass spectrometry,
   and nuclear magnetic resonance (NMR) spectroscopy are commonly used to isolate and analyze steroidal compounds.
   These methods allow researchers to identify unknown steroids or study the
   structure of known molecules in detail.

   ## Chemical synthesis
   The chemical synthesis of steroids involves the use
   of organic chemistry techniques to construct these molecules from simpler precursors.

   While natural methods dominate in biological contexts, synthetic approaches have been developed
   for the purposes of research and drug development.
   Synthesis can be challenging due to the complexity of
   the steroid framework, but advanced methodologies have
   made it possible to create sterols with specific structural modifications.

   ### Precursors
   The synthesis of steroids begins with precursors such as mevalonic acid or isopentenyl pyrophosphate (IPP), which are derived from
   acetyl-CoA. These compounds undergo a series of enzymatic reactions to produce the steroid nucleus, the core structure of all sterols.

   ### Semisynthesis
   Semisynthesis involves the chemical manipulation of naturally occurring steroids or their derivatives to create new molecules with desired properties.

   This approach is particularly useful for modifying existing
   sterols to enhance their biological activity or improve their
   pharmacokinetics.

   ### Total synthesis
   Total synthesis refers to the de novo construction of steroids from non-steroidal precursors, without relying on natural sources.

   This method is often used in drug discovery to create molecules with therapeutic potential.
   The challenge lies in replicating the complex structure and biological activity of naturally occurring sterols.

   ## Research awards
   Over the years, significant research has been conducted into the chemistry, biology,
   and applications of steroids. Notable scientists
   in this field have received awards for their contributions to understanding steroid metabolism,
   biosynthesis, and function. These achievements have led to advancements in fields such
   as medicine, nutrition, and pharmacology.

   ## See also
   – **Lipid metabolism**
   – **Endocrinology**
   – **Biochemistry**

   ## References
   This article is based on publicly available information and does not constitute medical advice.
   Always consult a healthcare professional for medical concerns or before
   starting any new treatment regimen.

   Check out my blog people who use steroids