Cellular Transport Cellular Transport Allawan, Giovanni Allawan, Giovanni B.B. Department of Biology, College of Science, University of the
Department of Biology, College of Science, University of the Philippines Baguio, BaguiPhilippines Baguio, Baguio City 2600, Bengueto City 2600, Benguet
Abstract Abstract
This expe
This experiment examined riment examined the propertiethe properties of a celluls of a cellular membrane whar membrane which were valiich were validated throughdated through different experiments. The procedures were divided into five different experiments, each were associated with different experiments. The procedures were divided into five different experiments, each were associated with the cellular membrane’s properties. The first part of the experiment was specifically designed to determine the the cellular membrane’s properties. The first part of the experiment was specifically designed to determine the structure of the plasma membrane. The membrane was found out to possess certain selectivity in order to structure of the plasma membrane. The membrane was found out to possess certain selectivity in order to control what goes in and out of the
control what goes in and out of the cell; the membrane is also regenerative in nature because even whencell; the membrane is also regenerative in nature because even when pricked or probed with a dissecting needle, the membrane still went back to its original form. The cell pricked or probed with a dissecting needle, the membrane still went back to its original form. The cell membrane is also
membrane is also insoluble in water environment and thus proving its lipid proteins. The insoluble in water environment and thus proving its lipid proteins. The second portion ofsecond portion of the experiment was to prove that there are different transport that occurs within the membrane using dyes, the experiment was to prove that there are different transport that occurs within the membrane using dyes, collodion and yeast suspensions. Utilizing such mixtures helped prove the different transport systems inside collodion and yeast suspensions. Utilizing such mixtures helped prove the different transport systems inside the membrane. It was found out that the membrane has
the membrane. It was found out that the membrane has the capability to diffuse through osmosis certainthe capability to diffuse through osmosis certain molecules in order to achieve equilibrium. The last portion of the experiment was designed to determine the molecules in order to achieve equilibrium. The last portion of the experiment was designed to determine the concentration difference
concentration differences within a s within a semi-permeable membrane. Using the blood cells and NaCl semi-permeable membrane. Using the blood cells and NaCl solutions, itsolutions, it was found o
was found out that the diut that the different concfferent concentrations on entrations on the regionthe regions of the mes of the membrane makes mbrane makes the cell shrivthe cell shrivel orel or burst when exposed to hypertonic, hypotonic or
I. Introduction I. Introduction
The plasma
The plasma membrane is thmembrane is the edge of lie edge of life, the bounfe, the boundary that separatedary that separates the living s the living cell from itcell from itss surroundings. Like all biological membranes, the plasma membrane exhibits selective permeability; that is, surroundings. Like all biological membranes, the plasma membrane exhibits selective permeability; that is, itit allows certain substances to cross it more easily than others (Campbell et al., 2005).
allows certain substances to cross it more easily than others (Campbell et al., 2005). Every cell is surrounded by a cell membrane. The cell
Every cell is surrounded by a cell membrane. The cell membrane protects the cell and helps movemembrane protects the cell and helps move substances and messages in and out of the cell.
substances and messages in and out of the cell. By regulating transport, the membrane helps the cell maintainBy regulating transport, the membrane helps the cell maintain consistency and order.
consistency and order. The lipid layer that form The lipid layer that forms foundation of a cell’s s foundation of a cell’s membrane is actually membrane is actually a bilayer formeda bilayer formed of two phospholipid sheets, a model also
of two phospholipid sheets, a model also known as the fluid mosaic known as the fluid mosaic model (Mason et al., 2015).model (Mason et al., 2015). Cellular membranes contain (1) a
Cellular membranes contain (1) a phospholipphospholipid bilayer, (2) transmembrane proteins, (3) a id bilayer, (2) transmembrane proteins, (3) a supportingsupporting network of internal proteins, (4) cell-surface markers composed of
network of internal proteins, (4) cell-surface markers composed of glycoproteinglycoproteins and glycolipids. The fluids and glycolipids. The fluid mosaic model of the
mosaic model of the membrane and the mosaic composition of proteins floating in the membrane and the mosaic composition of proteins floating in the phospholipid bilayerphospholipid bilayer (Mason et. al., 2015).
(Mason et. al., 2015). There are two
There are two ways of tranways of transport that ocsport that occur through thcur through the plasma membe plasma membrane. One metrane. One method of tranhod of transportsport is called active transport which r
is called active transport which requires ATP or energy equires ATP or energy to transport substances through the membrane. Theto transport substances through the membrane. The second method is called the passive transport, which does not require the use of ATP or
second method is called the passive transport, which does not require the use of ATP or energy (Sadava et al.,energy (Sadava et al., 2014).
2014). During the passive tranDuring the passive transport, molecules are transported througsport, molecules are transported through the membrane by differences inh the membrane by differences in concentration or pressure betw
concentration or pressure between the inside and outside of the cell. een the inside and outside of the cell. Molecules have a type of energy calledMolecules have a type of energy called thermal energy due
thermal energy due to their constant motion. One result of to their constant motion. One result of this motion is diffusion, the movement ofthis motion is diffusion, the movement of molecules of any substance so that they spread out evenly into the
molecules of any substance so that they spread out evenly into the available space (Campbell et al., 2005).available space (Campbell et al., 2005). Every cell in the
Every cell in the human body uses diffusion as an human body uses diffusion as an important transport process through its selectivelyimportant transport process through its selectively permeable membrane. Facilitated diffusion occurs when molecules are too
permeable membrane. Facilitated diffusion occurs when molecules are too large to penetrate large to penetrate through thethrough the membrane. In this process, the
membrane. In this process, the carrier protein molecules located in carrier protein molecules located in the membrane combine with solutes andthe membrane combine with solutes and transport them down the concentration gradient.
transport them down the concentration gradient.
One of the most important substances that crosses membranes by passive transport is water. One of the most important substances that crosses membranes by passive transport is water. (Campbell et al., 2005). Osmosis is
membrane. The concentration of all solutes in a solution determines the
membrane. The concentration of all solutes in a solution determines the osmotic regulation of the solution. Ifosmotic regulation of the solution. If two solutions have unequal osmotic concentrations, the solution with the higher
two solutions have unequal osmotic concentrations, the solution with the higher concentration is said to beconcentration is said to be hypertonic, and the solution with the
hypertonic, and the solution with the lower concentration is said to be lower concentration is said to be hypotonic. When two solutions havehypotonic. When two solutions have the same osmotic concentration, the solutions are
the same osmotic concentration, the solutions are isotonic (Mason et al., 2015).isotonic (Mason et al., 2015). This expe
This experiment aims to riment aims to validate anvalidate and establish the d establish the structure of tstructure of the plasma memhe plasma membrane as said tbrane as said to be ao be a phospholipid bilayer that contains different proteins. In addition, this experiment also is
phospholipid bilayer that contains different proteins. In addition, this experiment also is geared to know thegeared to know the different transport system insid
different transport system inside the cell and how e the cell and how they are associated with the membranes’ permeability andthey are associated with the membranes’ permeability and tonicity specifically the different phenomenon that happens inside a cell
tonicity specifically the different phenomenon that happens inside a cell membrane.membrane.
II. Materials and
II. Materials and MethodsMethods
A. Structure
A. Structure of the plasmof the plasma membraa membranene
A1. A1.
A 5 ml o
A 5 ml of oil and a f oil and a 5 ml of 5 ml of water were plawater were placed into a tesced into a test tube. The t tube. The water was swater was shaken vigorouhaken vigorously andsly and the observations were recorded. The test tube was again shaken, but this time, the oil and water
the observations were recorded. The test tube was again shaken, but this time, the oil and water were notwere not allowed to settle at the bottom. Afterwards, several drops of the mixture were transferred to a
allowed to settle at the bottom. Afterwards, several drops of the mixture were transferred to a clean glassclean glass slide. The mixture was then examined under the LPO objective for the interphase between oil and water. slide. The mixture was then examined under the LPO objective for the interphase between oil and water.
A2. A2.
A beaker w
A beaker was filled wias filled with milk ath milk and it was heand it was heated to almosted to almost boiling pt boiling point. Aftoint. After the milk er the milk cooled, thecooled, the observations were noted. The skin was removed and
observations were noted. The skin was removed and again, the milk was heated. again, the milk was heated. The process was repeatedThe process was repeated several times.
several times. A3.
A3.
An oil w
An oil was poured intas poured into a petri dish o a petri dish until it is huntil it is half full. A alf full. A drop of egg drop of egg albumen solutialbumen solution was droon was droppedpped into the oil solution. The solution was observed to watch the formation of delicate membrane at the into the oil solution. The solution was observed to watch the formation of delicate membrane at the
protein-lipid interphase. The lab performers wrinkled the membrane by
lipid interphase. The lab performers wrinkled the membrane by gently probing with a dissecting needle andgently probing with a dissecting needle and the membrane was also ruptured using a needle. Lastly, a
the membrane was also ruptured using a needle. Lastly, a small particle of nigrosine was placed on top of thesmall particle of nigrosine was placed on top of the membrane and was gently pushed with a needle through a membrane.
membrane and was gently pushed with a needle through a membrane. B. Selective action of cell membrane
B. Selective action of cell membrane
B1. B1.
One ml of aqueous yeast suspension was placed in each of the
One ml of aqueous yeast suspension was placed in each of the three test tubes labeled 1, 2, and 3.three test tubes labeled 1, 2, and 3. Three drops o
Three drops of congo red f congo red solution wsolution were added. To ere added. To test tube 1test tube 1, four drops o, four drops of 40% fof 40% formalin were armalin were added anddded and were shaken g
were shaken gently. Next, ently. Next, the test tubthe test tube 2 was heate 2 was heated while tesed while test tube 3 stt tube 3 stood as it is. ood as it is. A drop foA drop for eachr each suspension was placed on a glass slide and was observed under the microscope.
suspension was placed on a glass slide and was observed under the microscope. B2.
B2.
A 25 ml
A 25 ml of alkaline of alkaline yeast suspensiyeast suspension was placon was placed into a 10ed into a 100 ml Erlenmey0 ml Erlenmeyer flask. Foer flask. Following thllowing this step,is step, a 25 ml of
a 25 ml of neutral red solution was added and the color was immediately observed within 5 minutes. Next,neutral red solution was added and the color was immediately observed within 5 minutes. Next, the 10 ml mixture was filtered to separate yeast
the 10 ml mixture was filtered to separate yeast cells from the liquid. The color of the cells and thecells from the liquid. The color of the cells and the supernatant fluid were
supernatant fluid were observed.observed. C. Diffusion
C. Diffusion
C1 C1
A pinch of
A pinch of potassium permapotassium permanganate (KMnnganate (KMnO4) and methO4) and methylene blue cylene blue crystals were placrystals were placed in a petried in a petri dish. Subsequently, the spread of the color the color was observed and recorded at
dish. Subsequently, the spread of the color the color was observed and recorded at regular time intervals.regular time intervals. C2
C2
A 3 ml o
A 3 ml of collodion f collodion was placed was placed in a 10 ml in a 10 ml test tube. Ttest tube. The tube was he tube was slowly fillslowly filled and rotated and rotated so that aed so that a thin film forms on the entire inner surfaces. The excess solution was drained out. Subsequently, the tube was thin film forms on the entire inner surfaces. The excess solution was drained out. Subsequently, the tube was placed in an inverted position in a test tube
placed in an inverted position in a test tube rack until the film dried. With the use of knife blade, the edge rack until the film dried. With the use of knife blade, the edge ofof the film was loosen at the mouth of
the outside of the tube
the outside of the tube was rinsed. The collodion was placed in a was rinsed. The collodion was placed in a beaker full of water. Thereafter, a 5 beaker full of water. Thereafter, a 5 ml ofml of 2% iodine solution was added.
2% iodine solution was added. D. Osmosis
D. Osmosis
A water moun
A water mount of a Bt of a Boat of moseoat of moses was views was viewed under the ed under the microscope. Tmicroscope. Then, the dihen, the distilled water stilled water waswas drained out using filter paper. Thereafter, a 0.5% NaCl was added to the side
drained out using filter paper. Thereafter, a 0.5% NaCl was added to the side of the cover slip. The changesof the cover slip. The changes in size of the cell were
in size of the cell were observed. Subsequently, anoobserved. Subsequently, another water mount of a boat ther water mount of a boat of moses was prepared andof moses was prepared and was viewed
was viewed under the microunder the microscope. The dscope. The distilled water istilled water was also drainwas also drained out. Finalled out. Finally, a drop oy, a drop of 1.0% Nf 1.0% NaCl wasaCl was placed on the side of the cover slip.
placed on the side of the cover slip.
E. Hemolysis and crenation of the red
E. Hemolysis and crenation of the red blood cellblood cell
With the use
With the use of a sterile of a sterile cotton soakcotton soaked in 70ed in 70% alcohol, a % alcohol, a finger was clfinger was cleaned. Afterwareaned. Afterwards, the fingds, the fingerer was pricked u
was pricked using a sterile sing a sterile disposable disposable blood lancet. A blood lancet. A drop of bdrop of blood from lood from the finger the finger was added to was added to a drop ofa drop of 0.9% NaCl on a clean glass slide. Another drop of blood was added to
0.9% NaCl on a clean glass slide. Another drop of blood was added to a drop of distilled water on the slide. a drop of distilled water on the slide. AA cover slip was secured
cover slip was secured and was examined under the and was examined under the microscope. The observations were recorded.microscope. The observations were recorded. Afterwards, a
Afterwards, a drop of 10drop of 10% NaCl w% NaCl was added to onas added to one edge of e edge of the cover slithe cover slide glass of de glass of the slide withe slide with sodiumth sodium chloride and a piece of blotting paper to the
III. Results and Discussion III. Results and Discussion
A. Structure
A. Structure of the plasmof the plasma membraa membranene
A1. A1.
The structure
The structure of the plasof the plasma membrane was ma membrane was observed thobserved through the mixrough the mixture of oil ture of oil and water. In thand water. In thee experiment, it was evident that the mixing of the water and oil resulted to
experiment, it was evident that the mixing of the water and oil resulted to oil globules on top of the water.oil globules on top of the water. Furthermore, it was also observed that there is a
Furthermore, it was also observed that there is a significant barrier that separates oil and water since thesesignificant barrier that separates oil and water since these substance are immiscible even when shaken vigorously. This happens because the
substance are immiscible even when shaken vigorously. This happens because the oil is less oil is less dense than that ofdense than that of the water resulting the oil to settle towards the upper portion of the
the water resulting the oil to settle towards the upper portion of the mixture.mixture.
According to
According to Mason (20Mason (2015), the ph15), the phosphate grouposphate groups of lipis of lipids in the plads in the plasma membrane asma membrane are charged andre charged and other molecules attached to them are also charged or polar. The strongly polar
other molecules attached to them are also charged or polar. The strongly polar phosphate end is hydrophilicphosphate end is hydrophilic while the fat
while the fatty acid end ity acid end is strongly ns strongly nonpolar and honpolar and hydrophobic. Aydrophobic. As for the exs for the experiment, oiperiment, oil is hydrophol is hydrophobicbic region whereas the water
region whereas the water is the hydrophilic region of the is the hydrophilic region of the phospholipid bilayer of the cell membrane.phospholipid bilayer of the cell membrane. Hydrophilic molecules dissol
Hydrophilic molecules dissolve easily with water ve easily with water because they carry because they carry charged groups or uncharged polarcharged groups or uncharged polar groups that can
groups that can form either favorable interactions between hydrogen bonds with water molecules (Rabago etform either favorable interactions between hydrogen bonds with water molecules (Rabago et Figure 1.
al., 2003). In contrast, the nonpolar interior of a
al., 2003). In contrast, the nonpolar interior of a lipid bilayer impedes the passage of any water-soluble polarlipid bilayer impedes the passage of any water-soluble polar or charged substances through the bilayer, just as a
or charged substances through the bilayer, just as a layer of oil impedes the passage of a layer of oil impedes the passage of a drop of water (Masondrop of water (Mason et al., 2003). In
et al., 2003). In connection,connection,a lipid bilayer is stable because water’s affinity for a lipid bilayer is stable because water’s affinity for hydrohydrogen bonding never stopsgen bonding never stops (Mason et al., 2015).
(Mason et al., 2015). A2.
A2.
After allow
After allowing the milk ing the milk to cool, to cool, it is observit is observed that the heed that the heating of thating of the milk resulted e milk resulted to skin foto skin formationrmation as seen in the Figure 2.1. According to Ballam (2015), the skin formed after heating the milk was due to as seen in the Figure 2.1. According to Ballam (2015), the skin formed after heating the milk was due to thethe loss of solids that the milk undergoes as it is
loss of solids that the milk undergoes as it is being heated. The milk can be associated with plasma membranebeing heated. The milk can be associated with plasma membrane because of its
because of its regenerative property, wherein, it has the regenerative property, wherein, it has the ability to replace substantial portions of themselvesability to replace substantial portions of themselves (Marshal et al., 2018).
(Marshal et al., 2018).
Milk provides an intriguing system for examining how mass transport
Milk provides an intriguing system for examining how mass transport can drive morphologicalcan drive morphological change:
change:upon heating a pot of liquid milk, a upon heating a pot of liquid milk, a milk ‘skin’ forms within minutes as proteins in solution denaturemilk ‘skin’ forms within minutes as proteins in solution denature and are driven to the air
and are driven to the air – – liquid interface where they aggregate to form a thin, poroelastic film (Evans et al.,liquid interface where they aggregate to form a thin, poroelastic film (Evans et al., 2016).
2016).
Figure 2.
A3. A3.
The formatio
The formation of a delin of a delicate membrane at cate membrane at the protein-lthe protein-lipid interphaipid interphase is observse is observed by placined by placing a dropg a drop of egg albumen into a half-filled oil perti dish. The interphase between the egg albumen and the lipids of egg albumen into a half-filled oil perti dish. The interphase between the egg albumen and the lipids represents the phospholipid laye
represents the phospholipid layer of a r of a plasma membrane. When the nigrosine dye was added on top of theplasma membrane. When the nigrosine dye was added on top of the membrane, the egg albumen and oil only served as a
membrane, the egg albumen and oil only served as a transport channel through whictransport channel through which the nigrosine wash the nigrosine was diffused.
diffused.
In addition, even when the membrane
In addition, even when the membrane is poked and probed with is poked and probed with dissecting needle, the membranedissecting needle, the membrane healed itself and absorbed the nigrosine dye, this is due to the
healed itself and absorbed the nigrosine dye, this is due to the capability of the egg-oil interphase to repaircapability of the egg-oil interphase to repair itself and in order to protect the
itself and in order to protect the cell from its surroundings. (Urry et al., 2017).cell from its surroundings. (Urry et al., 2017).
B. Selective action of cell membranes B. Selective action of cell membranes
B1. B1.
Test tubes 1
Test tubes 1, 2 and 3 , 2 and 3 showed diffshowed different results. erent results. For the test tuFor the test tube 1, the cbe 1, the color remained olor remained the same. Thithe same. Thiss indicates that the cells in that solution did not accept the dye.
indicates that the cells in that solution did not accept the dye. This is due to the stabilizing property ofThis is due to the stabilizing property of Figure 3.
formalin (Fox et al., 1985). In addition, formalin prohibits the entrance of
formalin (Fox et al., 1985). In addition, formalin prohibits the entrance of the Congo red solution thusthe Congo red solution thus reducing the pigmentation.
reducing the pigmentation. Among the
Among the three test tubethree test tubes, it was seen s, it was seen that the tethat the test tube 2 st tube 2 which was hwhich was heated near boeated near boiling point iling point hadhad the most stained cells followed by test tube 1. This happened because the solution was exposed to heat which the most stained cells followed by test tube 1. This happened because the solution was exposed to heat which causes the membrane to disrupt and eventually denatured of the yeast and
causes the membrane to disrupt and eventually denatured of the yeast and which in turn blocks the cellularwhich in turn blocks the cellular activities inside the cell.
activities inside the cell. Test tube 3
Test tube 3 on the othon the other hand can uner hand can undergo active tdergo active transport because ransport because the yeast can fathe yeast can facilitate activcilitate activee transport thus, making the solution less pigmented since it
transport thus, making the solution less pigmented since it allows the exit of some allows the exit of some pigments.pigments.
Figure 4.1.
Figure 4.1. Aqueous yeast Aqueous yeast suspension witsuspension withh 40% formalin and congro red solution. 40% formalin and congro red solution.
Figure 4.3.
Figure 4.3. Aqueous yeast Aqueous yeast suspension witsuspension withh congo red solution.
congo red solution.
Figure 4.2.
Figure 4.2. Heated aqueous yeast suspensionHeated aqueous yeast suspension with congo red solution.
B2. B2.
The internal
The internal environment environment of yeast ceof yeast cells is slightly lls is slightly acidic, wiacidic, with pH betweth pH between 5.5 to en 5.5 to 6.0 (Ev6.0 (Evans et al.,ans et al., 2017). As soon as the 25 ml of neutral red
2017). As soon as the 25 ml of neutral red solution was mixed with 25 ml of alkaline yeast suspension, thesolution was mixed with 25 ml of alkaline yeast suspension, the color of the mixture turned dark red. This was
color of the mixture turned dark red. This was due to the diffusion of the neutral red solution into the cells,due to the diffusion of the neutral red solution into the cells, because neutral red solution is red in
because neutral red solution is red in acidic conditions and turns yellow in a pH of about 8.0 (Evans et al.,acidic conditions and turns yellow in a pH of about 8.0 (Evans et al., 2017)).
2017)).
As an evid
As an evidence that the ence that the neutral red soneutral red solution was dilution was diffused into ffused into the cell, the the cell, the filtered yeast celfiltered yeast cellsls containing the dye had a little or no
containing the dye had a little or no change when it comes to color. Since the yeast are change when it comes to color. Since the yeast are very acidic, even invery acidic, even in basic solutions, it undergoes diffusion until the
basic solutions, it undergoes diffusion until the whole solution reaches the state of whole solution reaches the state of equilibrium (Mason et al.,equilibrium (Mason et al., 2015). Additionall
2015). Additionally, the alkaline solution went to y, the alkaline solution went to back its original solution as back its original solution as soon as it was soon as it was filtered.filtered. C. Diffusion
C. Diffusion
C1. C1.
In the experiment, the diameters
In the experiment, the diameters of potassium permanganate (KMnO4) and methylene blue grewof potassium permanganate (KMnO4) and methylene blue grew wider over ti
wider over time. It is obme. It is observed that foserved that for approximately r approximately every 2 minuteevery 2 minutes, the potass, the potassium permanganatsium permanganate grew ae grew a lager diameter compared to methylene blue as seen in
lager diameter compared to methylene blue as seen in Figure 6.1 and 6.2.Figure 6.1 and 6.2. Figure 5.
According to
According to Chang (199Chang (1998), the size o8), the size or the molecular wr the molecular weight of a ceight of a certain substance can ertain substance can affect theaffect the diffusion rate. Heavier molecules move slower, therefore they diffuse more
diffusion rate. Heavier molecules move slower, therefore they diffuse more slowly. The reverse is true slowly. The reverse is true forfor lighter molecules. Potassium permanganate has a molecular weight of
lighter molecules. Potassium permanganate has a molecular weight of 158 g/mol, while methylene blue has a158 g/mol, while methylene blue has a molecular weight of 374 g/mol. Because of the size of the particle, heavier substances find it hard to move molecular weight of 374 g/mol. Because of the size of the particle, heavier substances find it hard to move from one place to
from one place to another and thus require more another and thus require more concentration gradient (Chang, 1998concentration gradient (Chang, 1998).).
C2. C2.
It is said that a
It is said that a cell’s membrane are selectively permeable, and substances do not cross the barriercell’s membrane are selectively permeable, and substances do not cross the barrier indiscriminately (Urry et al., 2017). The results in this experiment can be associated with that of the
indiscriminately (Urry et al., 2017). The results in this experiment can be associated with that of the membrane’s property, which is semi
membrane’s property, which is semi-permeability. As soon as the -permeability. As soon as the mixture of collodion and iodine wasmixture of collodion and iodine was suspended into a beaker with water, the color of the solution in the bag
suspended into a beaker with water, the color of the solution in the bag turned into a bluish-black color. Thisturned into a bluish-black color. This is because the iodine was able to penetrate
is because the iodine was able to penetrate through the membrane into the bag.through the membrane into the bag.
On the other hand, the solution in the beaker turned yellowish which indicates that starch did not On the other hand, the solution in the beaker turned yellowish which indicates that starch did not pass through the membrane into the beaker. The results of the experiment can further be attributed to the pass through the membrane into the beaker. The results of the experiment can further be attributed to the study of Razos (2018). In his experiment, he concluded that the collodion can be compared to cell
study of Razos (2018). In his experiment, he concluded that the collodion can be compared to cell membrane’s permeability. The collodion only allows smaller molecules to
membrane’s permeability. The collodion only allows smaller molecules to pass through it like pass through it like iodine, smalliodine, small enough to pass freely through the membrane and at the same
enough to pass freely through the membrane and at the same time prohibiting the entrance of the starchtime prohibiting the entrance of the starch Figure 6.1.
Figure 6.1.Potassium permanganate and methylene blue asPotassium permanganate and methylene blue as soon as it placed in a petri dish.
soon as it placed in a petri dish.
Figure 6.2.
Figure 6.2.Potassium permanganate andPotassium permanganate and methylene blue after approximately 2
since it has larger
since it has larger molecules. Furthermore, the starch turned to bluish-black color because the molecules. Furthermore, the starch turned to bluish-black color because the iodine was ableiodine was able to diffuse from a
to diffuse from a higher concentration outside the collodion bag.higher concentration outside the collodion bag.
D. Osmosis D. Osmosis
As stated b
As stated by Mason (20y Mason (2015), o15), osmosis is thsmosis is the diffusion e diffusion of water acof water across a membrane ross a membrane toward a higtoward a higherher solute concentration (p 104-105). This concept can be associated when the
solute concentration (p 104-105). This concept can be associated when the four specimens in the four specimens in the experimentexperiment are compared.
are compared. When the
When the water mount iwater mount is placed in s placed in a slide with da slide with distilled wistilled water, it is obseater, it is observed that cell rved that cell divisions idivisions insidenside the specimen are more compact compared to the cell
the specimen are more compact compared to the cell boundaries with water mount and NaCl solution asboundaries with water mount and NaCl solution as shown in (Figure 8.1 and 8.3). This is because the cells observed are hypotonic which means the outside of shown in (Figure 8.1 and 8.3). This is because the cells observed are hypotonic which means the outside of the cell is less concentrated. So in order
the cell is less concentrated. So in order for the cell to reach a for the cell to reach a state of equilibrium, it had to gain water. Thestate of equilibrium, it had to gain water. The cells swelled as water
cells swelled as water enters by osmosis. However, the relatively inelastic cell wall will enters by osmosis. However, the relatively inelastic cell wall will expand only so muchexpand only so much before it exerts a back pressure on the
before it exerts a back pressure on the cell, called turgor pressure that opposes further water uptake (Urry etcell, called turgor pressure that opposes further water uptake (Urry et al., 2017).
al., 2017).
Figure 7.
In contrast, the specimens as shown in
In contrast, the specimens as shown in Figure 8.2 and 8.4 showed spaces in between the cells. Figure 8.2 and 8.4 showed spaces in between the cells. This isThis is due to the exposure of the specimen to a
due to the exposure of the specimen to a hypertonic solutiohypertonic solution, which in this case is the NaCl. n, which in this case is the NaCl. The cell lostThe cell lost water to its su
water to its surroundings anrroundings and shrinks and shrinks and as the cell d as the cell shrivel, its shrivel, its plasma membranplasma membrane pulls away e pulls away from the celfrom the celll wall at multip
wall at multiple places. Thle places. This phenomenois phenomenon is also cn is also called plasmolyalled plasmolysis (Urry et al.sis (Urry et al., 2017)., 2017).
Figure 8.1.
Figure 8.1.Water mount of boat of mosesWater mount of boat of moses using distilled water.
using distilled water.
Figure 8.4.
Figure 8.4.Water mount of boat of mosesWater mount of boat of moses exposed to 1.0% NaCl
exposed to 1.0% NaCl Figure 8.3.
Figure 8.3. Second water mount of boat ofSecond water mount of boat of moses using distilled water.
moses using distilled water.
Figure 8.2.
Figure 8.2. Water mount of boat of mosesWater mount of boat of moses exposed to 0.5% NaCl
E. Hemolysis and crenation of the red
E. Hemolysis and crenation of the red blood cellblood cell
The first
The first glass slide, wglass slide, which contaihich contains a drop ons a drop of blood wif blood with 0.9% th 0.9% NaCl are expoNaCl are exposed in an ised in an isotonicsotonic environment where there will be no
environment where there will be no net movement of water across net movement of water across the plasma membrane. Water diffusesthe plasma membrane. Water diffuses across the membrane but at the same
across the membrane but at the same rate in both directions (Urry et al., rate in both directions (Urry et al., 2017). In the experiment, the first2017). In the experiment, the first slide is in isotonic condition because the blood cells have almost the same levels of solute to solvent ratio as slide is in isotonic condition because the blood cells have almost the same levels of solute to solvent ratio as the NaCl solution thus no collapsing or bursting happened because the volume is stable. The blood cells the NaCl solution thus no collapsing or bursting happened because the volume is stable. The blood cells retained their normal size and shape.
retained their normal size and shape.
In the next step, the blood cells were submerged to the water thus
In the next step, the blood cells were submerged to the water thus putting the cell in a hypotonicputting the cell in a hypotonic environment since there are more solvent than solute in the environment. Supposedly, as the water enters the environment since there are more solvent than solute in the environment. Supposedly, as the water enters the cell from a hypotonic solution, the cell should have collapsed due to pressure applied to the plasma
cell from a hypotonic solution, the cell should have collapsed due to pressure applied to the plasma
membrane allowing the escape of the hemoglobin found in the blood cells, also called hemolysis (Urry et al., membrane allowing the escape of the hemoglobin found in the blood cells, also called hemolysis (Urry et al., 2017) However, in the experiment, the cells seemed
2017) However, in the experiment, the cells seemed to be round. The to be round. The result showed otherwise probablyresult showed otherwise probably because the cell membrane is enclosed by a
because the cell membrane is enclosed by a lipid bilayer which then is responsible for the slowing of thelipid bilayer which then is responsible for the slowing of the movement of water across the
movement of water across the membrane.membrane.
For the final slide, the blood cells were added to
For the final slide, the blood cells were added to 10% NaCl which has a higher concentration of salt.10% NaCl which has a higher concentration of salt. The exposure
The exposure of the blof the blood cell to ood cell to 10% NaCl 10% NaCl caused a hypertonicaused a hypertonic environmenc environment to the t to the cell. This icell. This is because thes because the solute is more concentrated than the solvent in the environment inside the cell. In a hypertonic solution, the solute is more concentrated than the solvent in the environment inside the cell. In a hypertonic solution, the cells shrivelled due to the exit of the water
cells shrivelled due to the exit of the water from the cell (Urry, et al., 2017). As observed in the experiment,from the cell (Urry, et al., 2017). As observed in the experiment, the cells lost
the cells lost their round shape which indicates that their round shape which indicates that cells in a cells in a hypertonic environment did underwent osmotichypertonic environment did underwent osmotic pressure.
pressure.
Figure 9.2.
Figure 9.2.Blood cells in Blood cells in distilled water.distilled water. Figure 9.3.Figure 9.3.Blood cells with 10% NaCl.Blood cells with 10% NaCl. Figure 9.1.
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