Osmosis - Nota: 5 PDF

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UNIVERSIDAD DE LA SALLE DEPARTAMENTO DE CIENCIAS BÁSICAS BIOLOGÍA

OSMOSIS

PRESENTED BY:

ROBERTO LUIS MOYA - 40162040 ANDRES CAMILO BERNAL PONARE - 42192012 NICOLÁS POSADA CANCINO - 48201051

PRESENTED TO: PROF. ANDRES PAEZ MARTINEZ

UNIVERSIDAD DE LA SALLE DEPARTAMENTO DE CIENCIAS BÁSICAS BIOLOGÍA

TEAM: GENESIS

UNIVERSITY OF LA SALLE BASIC SCIENCES DEPARTMENT BIOLOGY Osmosis We can define osmosis as a phenomenon of water diffusion through a semi-permeable membrane, which is one that has pores, similar to any filter of molecular size. The size of the pores is so minuscule that it allows small but not large molecules to pass through, usually micron-sized. For example, it lets in water molecules, which are small, but not sugar molecules, which are larger. Direct osmosis: It is the one that occurs in the cells of living beings, in which water enters or leaves through the plasma membrane, allowing a balance with the medium, although in cases

UNIVERSIDAD DE LA SALLE DEPARTAMENTO DE CIENCIAS BÁSICAS BIOLOGÍA

of hypertonic (of enormous concentration of solute) or hypotonic (of minimal concentration of the solute) can cause dehydration or explosion by accumulation of the cell, respectively.

Inverse osmosis: It is an identical mechanism but in the opposite direction, which allows the flow of water or solvent to be from the point of highest concentration to that of the lowest concentration of solute, which is ideal for purification or retention of solute effects. For this to happen, a pressure must be applied that overcomes the natural osmotic pressure (i.e. requires an energy cost).

Importance of osmosis: Osmosis is vital for cellular metabolism, since it is a form of transport of matter between the interior and the exterior of the cell that does not carry any energy expenditure, that is, it is produced passively, without consuming ATP. Furthermore, this principle is fundamental to explain the origin of life, since in the first forms of cellular life there would still be no active metabolic mechanisms.

¿what are the differences between active and passive transport? Active and passive cell transport is the transfer of solutes from one side of the cell membrane to the other. Transport is passive when a metabolic energy source such as ATP is not required, while transport is active when ATP is used as an energy source.

UNIVERSIDAD DE LA SALLE DEPARTAMENTO DE CIENCIAS BÁSICAS BIOLOGÍA

Cell membranes are mainly composed of a lipid bilayer that makes it difficult for certain types of substances to pass through. This barrier function allows the cell to maintain solute concentrations in the cytosol different from the extracellular environment or intracellular compartments.

¿what we mean when we affirm that the interior of the cell is hypertonic with respect to the exterior? Because a hypertonic solution is one that has the highest osmolarity in the external environment, so a cell in said solution loses water (H2O) due to the pressure difference, that is, the osmotic pressure, even dying from dehydration. The outflow of water from the cell continues until the osmotic pressure of the external medium and the cell are equal. Similar phenomena occur when storing food in brine or concentrated sugar syrups.

The animal cell undergoes the phenomenon of creation as a consequence of the outflow of water from the cell ("wrinkling"). In turn, plasmolysis occurs in plant cells: when air leaves the intracellular medium, the protoplasm retracts, producing a space between the plasma membrane and the cell wall.

UNIVERSIDAD DE LA SALLE DEPARTAMENTO DE CIENCIAS BÁSICAS BIOLOGÍA

¿what we mean when we affirm that the interior of the cell is Hypotonic with respect to the exterior? In biology, a hypotonic solution is one that has a lower concentration of solute in the external environment in relation to the interior environment of the cell, that is, in the interior of the cell there is a greater quantity of salt than that found in the medium in which she lives. A cell immersed in a solution with a lower concentration of dissolved materials is in a hypotonic environment; the concentration of water is higher (due to having so few dissolved materials) outside the cell than inside. Under these conditions, water diffuses into the cell, that is, liquid osmosis occurs inside the cell.

A cell in a hypotonic environment swells with water and can explode; When this occurs in the red blood cells, it is called hemolysis. Organisms that live in stream and lake soils inhabit modified rainwater, which is a hypotonic environment. Animal cells undergo the phenomenon of cytolysis, which leads to the destruction of the cell, due to the passage of water into it. On the other hand, in plant cells the turgor pressure phenomenon occurs: when water enters, the cell swells but is not destroyed due to the great resistance of the cell wall.

¿what we mean when we affirm that the interior of the cell is isotonic with respect to the exterior?

UNIVERSIDAD DE LA SALLE DEPARTAMENTO DE CIENCIAS BÁSICAS BIOLOGÍA

If the extracellular fluid has the same concentration of dissolved solutes as the intracellular fluid, the extracellular fluid is said to be isotonic (from the Greek term iso, which means equal to, so etymologically means with equal tension or pressure) and there will be no net flow of water neither inside nor outside the cell. Both the extracellular medium and the interior of the cell have the same osmotic pressure....