In such hypotonic environments, these fish do not drink much water. Instead, they pass a lot of very dilute urine, and they achieve electrolyte balance by active transport of salts through the gills. When they move to a hypertonic marine environment, these fish start drinking sea water; they excrete the excess salts through their gills and their urine, as illustrated in Figure Most marine invertebrates, on the other hand, may be isotonic with sea water osmoconformers.
Their body fluid concentrations conform to changes in seawater concentration. This does not mean that their electrolyte composition is similar to that of sea water. They achieve isotonicity with the sea by storing large concentrations of urea. These animals that secrete urea are called ureotelic animals. TMAO stabilizes proteins in the presence of high urea levels, preventing the disruption of peptide bonds that would occur in other animals exposed to similar levels of urea.
Sharks are cartilaginous fish with a rectal gland to secrete salt and assist in osmoregulation. Dialysis is a medical process of removing wastes and excess water from the blood by diffusion and ultrafiltration. When kidney function fails, dialysis must be done to artificially rid the body of wastes. This is a vital process to keep patients alive. In some cases, the patients undergo artificial dialysis until they are eligible for a kidney transplant.
In others who are not candidates for kidney transplants, dialysis is a life-long necessity. Dialysis technicians typically work in hospitals and clinics. While some roles in this field include equipment development and maintenance, most dialysis technicians work in direct patient care.
Their on-the-job duties, which typically occur under the direct supervision of a registered nurse, focus on providing dialysis treatments. This can include reviewing patient history and current condition, assessing and responding to patient needs before and during treatment, and monitoring the dialysis process. Solute concentrations across a semi-permeable membranes influence the movement of water and solutes across the membrane.
It is the number of solute molecules and not the molecular size that is important in osmosis. Osmoregulation and osmotic balance are important bodily functions, resulting in water and salt balance. Not all solutes can pass through a semi-permeable membrane. Osmosis is the movement of water across the membrane. Osmosis occurs to equalize the number of solute molecules across a semi-permeable membrane by the movement of water to the side of higher solute concentration. Facilitated diffusion utilizes protein channels to move solute molecules from areas of higher to lower concentration while active transport mechanisms are required to move solutes against concentration gradients.
Osmolarity is measured in units of milliequivalents or milliosmoles, both of which take into consideration the number of solute particles and the charge on them. Fish that live in fresh water or saltwater adapt by being osmoregulators or osmoconformers. Skip to content Chapter Osmotic Regulation and Excretion. Need for Osmoregulation. In an isotonic solution, water flows into the cell at the same rate it flows out. When a cell is placed in a hypertonic solution, water actually flows out of the cell into the surrounding solution causing the cells to shrink and lose its turgidity.
Two of the most common substances used to create hypertonic environment for microorganisms and prevent them from growing are salt and sugar.
They are widely applied in food preservation. Table salt sodium chloride is the primary ingredient used in meat curing. 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.
Sugar is used to preserve fruits, either in syrup with fruit such as apples, pears, peaches, apricots, plums or in crystallized form where the preserved material is cooked in sugar to the point of crystallisation and the resultant product is then stored dry. The purpose of sugaring is to create an environment hostile to microbial life and prevent food spoilage.
Neutrophiles are organisms that thrive in neutral pH 7 environments; extromophiles are organisms that thrive in extreme pH environments.
Alkaliphiles are microbes that thrive in alkaline environments with a pH of 9 to 11, such as playa lakes and carbonate-rich soils. Acidophilic organisms are those that thrive under highly acidic conditions usually at pH 2.
Most acidophile organisms have evolved extremely efficient mechanisms to pump protons out of the intracellular space in order to keep the cytoplasm at or near neutral pH.
Therefore, intracellular proteins do not need to develop acid stability through evolution. However, other acidophiles, such as Acetobacter aceti, have an acidified cytoplasm which forces nearly all proteins in the genome to evolve acid stability. An aerobic organism or aerobe is an organism that can survive and grow in an oxygenated environment.
Several varietis of aerobes exist. Obligate aerobes require oxygen for aerobic cellular respiration. In a process known as cellular respiration, these organisms use oxygen to oxidize substrates for example sugars and fats in order to obtain energy. Facultative anaerobes can use oxygen, but also have anaerobic i.
Microaerophiles are organisms that may use oxygen, but only at low concentrations. Aerotolerant organisms can survive in the presence of oxygen, but they are anaerobic because they do not use it as a terminal electron acceptor. Identity of aerobic and anaerobic bacteria : Aerobically different bacteria behave differently when grown in liquid culture: 1 Obligate aerobic bacteria gather at the top of the test tube in order to absorb maximal amount of oxygen. They require oxygen, but at a lower concentration.
An anaerobic organism or anaerobe is any organism that does not require oxygen for growth. It could possibly react negatively and may even die if oxygen is present. For practical purposes there are three categories: obligate anaerobes, which cannot use oxygen for growth and are even harmed by it. Aerotolerant organisms, which cannot use oxygen for growth, but tolerate the presence of it.
And finally, facultative anaerobes, which can grow without oxygen but can utilize oxygen if it is present. Since normal microbial culturing occurs in atmospheric air, which is an aerobic environment, the culturing of anaerobes poses a problem. Therefore, a number of techniques are employed by microbiologists when culturing anaerobic organisms, for example, handling the bacteria in a glovebox filled with nitrogen or the use of other specially-sealed containers.
The GasPak System is an isolated container that achieves an anaerobic environment by the reaction of water with sodium borohydride and sodium bicarbonate tablets to produce hydrogen gas and carbon dioxide. Hydrogen then reacts with oxygen gas on a palladium catalyst to produce more water, thereby removing oxygen gas. Privacy Policy. Skip to main content.
Culturing Microorganisms. Search for:. Other Environmental Growth Factors.
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