The Effect Of Temperature On Permeable Membranes Biology Essay

The purpose of this experiment was to find what consequence an addition in the surrounding temperature has on the selectively permeable membranes of works cells, e.g. , ruddy chou ( Lane, 2010a ) .The cell membrane is the fluid-mosaic theoretical account.

The proteins are embedded in the cell membrane. The lipid exists as a phospholipid bilayer signifier. The hydrophobic which mean H2O detesting parts of the lipid molecule face the interior while the hydrophilic which mean H2O loving parts face either the cytol or extracellular aqueous environment. The protein molecules are of two types in the membrane.

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Internal proteins are embedded in the phospholipid bilayer which enhance the membrane ‘s form, supplying passageways for the motion of substances through the membrane while the peripheral proteins are attach to the surface of membrane and are easier to pull out ( Losos, Manson and Singer, 2008 ) The intent of a cell membrane is to command what enters and exits the cell. It acts as a selective barrier between the internal and external fluid that means the cell membrane to be selectively permeable. This procedure supplies the cell with utile stuff and removes waste merchandises. Normally, this is done by active or inactive transit. The inactive transit allows substances to travel from high concentration to low concentration without energy required. The active transit carries substances such as ions and glucose from low concentration to the high concentration, necessitating energy and a bearer to back up ( Losos, Manson and Singer, 2008 ) .

Figure 2 ( Adapted from Garland, 2004 ) shows the procedure of transit through the cell membraneFigure 2: Transportation system through the Membrane ( Adapted from Garland, 2004 )Certain conditions can damage the cell membrane. For case, high temperature leads to violent hits that can destruct a membrane. There is a hypothesis that an addition in temperature denatures the membrane and causes the substances within the membrane to leak out ( Answers, 2010 ) . The high temperature can do the cell membrane more permeable and let it to be more prone to escape.Red chous are used as a theoretical account to look into how the temperature affects the selectively permeable membranes. Red cabbages contain a big saddle horse of a water-soluble ruddy pigment called anthocyanin, which is located in the vacuole and unable to go through through the tonoplast membrane.

If these cells are affected by alterations in temperature, the unity of the cell membrane becomes damaged. As a consequence, anthocyanin which as antioxiants and protects cell from oxidative harm can leak out of the cells and into the encompassing H2O. The extent of harm to the cell membrane is straight associated to the strength of ruddy colour and it would look in the H2O environing the ruddy chou ( Manhattan, 2009 ) .



7 trial tubingsTest tubing rackCork bore bitScalpelTileSmall beakerMounted needleLarge beakerThermometerBurner( Lane, 2010b )First, a foliage of ruddy chou tissues was cut into 42 phonograph record of the same size ( about 1mm broad ) by a cork bore bit. 42 ruddy chou phonograph record were placed in a little beaker and were washed.

7 trial tubings were labelled 30a„? , 40a„? , 50a„? , 60a„? , 70a„? , 80a„? and 100a„? . The first two trial tubings which labelled 30a„? , 40a„? and about 6 cm3 cold H2O was added utilizing a measurement cylinder. The staying trial tubings had 6 cm3 cold H2O added to each. Meanwhile, a H2O bath was prepared utilizing a big beaker, tripod and gauze.

The 7 trial tubings with 6 cm3 H2O were heated in the H2O bath. A thermometer was placed into each trial tubing to mensurate the temperature. 6 ruddy chou phonograph record were impaled on a mounted acerate leaf with infinite between each phonograph record.

When the H2O inside the trial tubing labelled 30a„? reached 30a„? temperature, the burner was removed and 6 phonograph record on the acerate leaf was placed in the trial tubing for precisely 1 min so the trial tubing was removed from the H2O bath. The discs were left in this tubing.When the H2O inside the trial tubing labelled 40a„? reached 40a„? temperature, the above process was repeated. The trial tubing labelled 50a„? reached the temperature. All the processs were restarted harmonizing to the usher. To all the trial tubings were added 6 cm3 cold H2O and a H2O bath was prepared utilizing a big beaker, tripod.

When the H2O was heated gently to 30a„? , the burner was removed and the 6 ruddy chou phonograph record on an impaled acerate leaf were placed in the H2O bath for precisely 1 minute. The phonograph record was pushed off and dropped into the trial tubing labelled 30a„? . The process was repeated for the other tubings. From 40 & A ; deg ; to 90 & A ; deg ; C, all the processs in ain H2O bath.

For 100a„? the phonograph record, needle were placed in other ‘s H2O bath with the temperature at 100a„? for 1 minute, so the phonograph record were pushed off and dropped into the trial tubing labelled 100a„? . The phonograph record in the trial tubing were left for 20 proceedingss and so the tubings were shaken and compared.


Temperature /a„?Observation30The 6 ruddy chou phonograph record were still violet and unchanged the H2O was still colorless.40The colors of the 6 ruddy chou phonograph record were remained and unchanged purple and the H2O was still clear.50The colors of 6 ruddy chou phonograph record were a small bleached and the H2O became a small purple.60The colors of 6 ruddy chou phonograph record were faded lighter purple more than 50a„? and the coloring material of H2O changed from colourless into light purple.

70The colors of 6 ruddy chou phonograph record were faded more than 60a„? and the coloring material of H2O changed from transparent into a light blue.80The colors of 6 ruddy chou phonograph record were really faded than 70a„? and the coloring material of H2O changed from transparent into a light viridity.100The colors of 6 ruddy chou discs changed from purple into white and the coloring material of H2O was strongly changed from transparent into green.Table 1: Heating the Red Cabbage Discs


Table 1 shows clearly that an addition temperature on the ruddy chou fades the purple of these phonograph records and they become more and more bleached while the coloring material of the environing H2O inside the trial tubing becomes darker and darker.

This phenomenon purple-blue-green consequence from that the ruddy chou dies have permeable membranes losing the permeableness of their cell membranes. If the temperature goes against what the membranes can defy, the permeableness of membranes additions as the protein becomes denatured, the lipid parts of membranes liquefies and the proteins create holes in the cloth, and the membranes fall apart. The high temperature produces an addition in kinetic energy that makes atoms in the protein to vibrate and travel more breaking H and ionic bonds in protein molecules and altering the 3D form of the system. These proteins are unable to interpret substances in and out of the membrane. All the factors lead to the anthocyanin leaking out of the membranes bring forthing a coloring material in the H2O environing the ruddy chou cells ( Erik, 2002 ) . The consequences of look intoing the consequence of temperature on permeable membranes are mostly as predicted.There were several variables that controlled this experiment to do certain the consequences were comparable.

The first major key variable was the size of ruddy chou phonograph record. The ruddy chou tissue was cut into phonograph record which were used to guarantee truth by increasing preciseness in the volume of H2O. The cylinders should be same for all experiments because the volume of H2O affected the concentration of the pigment. The 2nd variable was leting adequate clip ( 20 proceedingss ) for coloring material to be seen. All the trial tubing should be left the same and adequate clip for observations after seting the ruddy chou phonograph record into the trial tubing. Time altered the consequence of the experiment ; some tubings had a longer consequence than others, more of the pigments in the ruddy chou cells will leak out and the pigments in the encompassing H2O. All the stuff should be washed really exhaustively after cutting.

This procedure made the experiment more extremely accurate, because utilizing H2O to rinse the stuff meant that drosss were minimised.Possible mistakes may hold arisen during this experiment. First, the process at the beginning of the experiment was non right followed harmonizing to the instructions ( Lane, 2010c ) . For case, 6 cm3 cold H2O was measured non accurate, the ruddy chou foliage did non rinse under running H2O and utilizing another H2O bath which resulted from the direction had non been read carefully and earnestly. Second, the phenomenons purple-blue-green in this trial was a small different from the theory that as the temperature increases, the coloring material of the environing H2O will go darker ( Lane, 2010d ) . This may stem from much of the ruddy pigment get awaying from the phonograph record while heating the ruddy chou in the beaker. The consequence of the higher temperature may hold affected this more as a batch of the pigment has already leaked out into the beaker. Another ground may be the concentration of pigment taking to alter the stableness of the pigment molecule.

Third, the clip was non sufficient for reiterating the experiment, which made the consequences less accurate.A future experiment should be improved in follow ways. The direction should be read carefully and exhaustively, so the experiment can travel on logical. Second, the temperature should be checked at the start of when the ruddy chou was put in the H2O and at the terminal of the last minute utilizing a thermometer to keep the temperature of the het H2O.

Third, a tintometer should be provided to mensurate the sum of light absorbed by solution of each reaction temperature. The higher concentration of anthocyanin means a higher reading on the tintometer. Fourthly, the experiment should be repeated more times to do certain the consequences were non obtained by opportunity or by external factors. In add-on, the consequence of ice chest temperature even under 0a„? could be tested to detect if the membrane is broken down in a similar manner.


It can be concluded that as the temperature was increased, more of the ruddy pigment leaked out of the permeable membrane. The permeableness of the membrane in ruddy chous can be damaged by high temperature.


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