osmotic environment

(noun)

environment with controlled net movement of molecules from a region of high solvent concentration to a region of low solvent concentration through a permeable membrane.

Examples of osmotic environment in the following topics:

  • Mycoplasmas and Other Cell-Wall-Deficient Bacteria

    • Cell walls are unnecessary here because the cells only live in the controlled osmotic environment of other cells.
    • Similarly, they have no need for genes encoding many different pathways for various carbon, nitrogen and energy sources, since their intracellular environment is completely predictable.
    • Because of the absence of cell walls, Mycoplasma have a spherical shape and are quickly killed if placed in an environment with very high or very low salt concentrations.
    • L-forms have varied shapes and are sensitive to osmotic shock .

  • Osmoregulators and Osmoconformers

    • Aquatic organisms with various salt tolerances adapt to their environments through osmoregulation and osmoconformation.
    • These fish are incapable of osmotic regulation in the alternate habitat.
    • They evolved osmoregulatory mechanisms to survive in a variety of aquatic environments.
    • Sharks are "ureotelic" animals that secrete urea to maintain osmotic balance.
    • Salmon physiology responds to freshwater and seawater to maintain osmotic balance

  • Osmotic Pressure

    • It is also defined as the minimum pressure needed to nullify osmosis.The phenomenon of osmotic pressure arises from the tendency of a pure solvent to move through a semi-permeable membrane and into a solution containing a solute to which the membrane is impermeable.
    • Two of the most common substances used to create hypertonic environment for microorganisms and prevent them from growing are salt and sugar.
    • Removal of water and addition of salt to meat creates a solute-rich environment where osmotic pressure draws water out of microorganisms, thereby retarding their growth.
    • The purpose of sugaring is to create an environment hostile to microbial life and prevent food spoilage.

  • Introduction to Osmoregulation

    • The cell loses water, which moves outside to the hypertonic or "high salt" environment.
    • The process of excretion helps the body maintain osmotic balance.
    • Cells placed in a hypertonic environment tend to shrink due to loss of water.
    • In a hypotonic environment, cells tend to swell due to intake of water.
    • The blood maintains an isotonic environment so that cells neither shrink nor swell.

  • Nonthermophilic Crenarchaeota

    • Nonthermophilic Crenarchaeota can be extreme halophiles living in highly salty environments.
    • Crenarchaeota can be extreme halophiles, and include organisms living in highly salty environments (for example, halococcus).
    • Rhodopsin protein and other proteins serve to protect Halococcus from the extreme salinities of the environment.
    • To do this they use a solute, which is either found in their cell structure or is drawn from the external environment.
    • Special chlorine pumps allow the organisms to retain chloride to maintain osmotic balance with the salinity of their habitat.

  • Osmoregulation

    • Tonicity is the ability of a solution to exert an osmotic pressure upon a membrane.
    • In a hypotonic environment, water enters a cell, and the cell swells.
    • Fish, however, must spend approximately five percent of their metabolic energy maintaining osmotic homeostasis.
    • Freshwater fish live in an environment that is hypotonic to their cells.
    • This protein is too large to pass easily through plasma membranes and is a major factor in controlling the osmotic pressures applied to tissues.

  • Malpighian Tubules of Insects

    • They are lined with microvilli for reabsorption and maintenance of osmotic balance.
    • The secretion of ions alters the osmotic pressure, which draws water, electrolytes, and nitrogenous waste (uric acid) into the tubules.
    • Water and electrolytes are reabsorbed when these organisms are faced with low-water environments and uric acid is precipitated and excreted as a thick paste or powder.
    • By not dissolving wastes in water, these organisms are able to conserve water; this is especially important for life in dry environments.
    • Explain how insects use malpighian tubules to excrete wastes and maintain osmotic balance

  • Developmental Changes in Fluids

    • Given that, it is imperative that the in uterine environment be optimal for proper fetal development.
    • The hypothalamic-neurohypophysial system plays a fundamental role in the maintenance of body fluid homeostasis by secreting arginine vasopressin (AVP) and oxytocin (OT) in response to a variety of signals, including osmotic and non-osmotic stimuli.

  • Freshwater Environments

    • Fresh water creates a hypotonic environment for aquatic organisms.
    • Although most aquatic organisms have a limited ability to regulate their osmotic balance and therefore can only live within a narrow range of salinity, diadromous fish have the ability to migrate between fresh water and saline water bodies.

  • Extremophiles and Biofilms

    • Almost all prokaryotes have a cell wall: a protective structure that allows them to survive in both hyper- and hypo-osmotic conditions.
    • Extremophiles have been found in all kinds of environments: the depth of the oceans, hot springs, the Arctic and the Antarctic, in very dry places, deep inside earth, in harsh chemical environments, and in high radiation environments, just to mention a few .
    • One example of a very harsh environment is the Dead Sea, a hypersaline basin that is located between Jordan and Israel.
    • Hypersaline environments are essentially concentrated seawater.
    • Discuss the distinguishing features of extremophiles and the environments that produce biofilms