Cellular Communication Lab

Purpose:

The purpose of this lab was to see the effect of time on the mating on yeast cells. The dependent variable which was controlled was time. Yeast was kept for 30 minutes, 24 hours, and 48 hours. The independent variable was the number of yeast.

Introduction: 

Cells communicate through signals that can either be local or long-distance. Signal transduction pathway is a series of steps in which a received signal is converted to a specific cellular response. There are 3 stages in cell signaling: reception, transduction, and a response. During reception, a target cell detects a chemical signal when the signaling molecule binds to a receptor protein. There are 3 major types of cell-surface transmembrane receptors: G protein-coupled receptors, receptor tyrosine kinases, and ion channel receptors. During transduction, the receptor protein is changed and the signal is converted to a form that leads to a specific cellular response. The multiple steps in transduction leads to amplification of the signal. 2nd messengers, such as cyclic AMP can also play a role in signal transduction pathways. Finally, the cellular response is triggered by the transducer signal. Cells of the yeast saccharomyces cervisiae, find their mates through chemical signaling and then initiate the mating process. The 2 mating types of yeast, a & alpha, secrete factors that bind to the receptor proteins on the other type of cell. When these factors bind to the receptors, the 2 cells grow toward each other and fuse together. The new a/alpha cell contains all of the genes from both cells.

Methods: 

Yeast was obtained and dropped into three tubes of water. The tubes were labeled with alpha type, A-type and mixed. Different  yeast was added to each tube, and a mix was added to the tube labeled "mixed." A reading was taken right away and yeast cells were counted. After 30 minutes, yeast cells were counted once again to see the reproduction. This was repeated once again after 24 hours and 48 hours. The yeast was  split into three groups: alpha, a-type and mixed.  Single haploid cells, budding haploid cells, shmoos, single zygotes, budding zygotes, and asci's  were the type of cells that were accounted for under the microscope. After each slide was used and counted for, the slides were cleaned in bleach, in order to sterilize and zap the yeast to its death.   

Data:

Graphs:

Alfa type

A type

Mixed type

Discussion:

Trying to count each individual cell was ridiculously difficult. So we divided each slide into quadrants in order to try to effectively get the most accurate count, then we multiplied each quadrant by 4. This still produced inaccurate results because it was very hard to actually get an accurate count of the cells. This is an example of why.

As one can see it is incredibly difficult to count these cells and especially with the given amount of time we had. We simply could not count them fast enough to get an accurate reading. But from our data one can conclude that starting on the initial time the single haploid cells were more numerous than the budding haploid cells, but then the numbers were reversed at about 24 hours. Where there was more budding haploid cells than single haploid cells, but then the numbers of budding cells reduced again probably because of the reduced amount of space to divide and the cells were sending messages saying that they are running out of room and to stop reproducing. That is what can be observed from the Alfa and A types. Where in the mixed culture the number of single haploid cells becomes reduced over time where the number of budding zygotes and asci increase as time passes.

The experiment could have been improved and made more accurate if we had more time to count and been able to easily take pictures of the cells so that they wouldn't be moving and increasing to the difficulty of the counting.

Conclusion:

As one can conclude from the data the a and alfa cultures had a majority of single haploid cells but then as time passed more budding haploid cells were made, but as more time passed the budding haploid cells had begun to recess and at the end there were a majority of single haploid cells. And in the mixed culture as time passes the single haploid cells are reduced and the concentration of of zygotes and asci are raised.

Photosynthesis Lab

Photosynthesis Lab

Purpose: the purpose of this lab is to prove that chlorophyll and chloroplasts are used in the production of oxygen in plants. Denaturation of spinach proteins were tested to show that chloroplasts were no longer useful when denatured. The independent variables were the drops of DPIP which were used to show that chlorophyll was actually functioning. The dependent variables was the light,as in the control sample we were able to completely block off all the light which was supposed to enter the cuvette with a piece of aluminum foil. We were also able to change the state of the spinach by using it either boiled or raw.

Introduction:The equation for photosynthesis is 6 CO2 + 6 H2O -> C6H12O6 + 6O2. Photosynthesis has 2 parts: the light reactions and the Calvin cycle. The light reactions occur in the thylakoid membrane, where water is split and oxygen is released and ATP and NADPH are produced. The Calvin cycle takes place in the Stroma and is powered by the ATP and NADPH produced by the light reactions in order to fixed CO2 into sugar. The function of the plant pigments is to absorb light and reflect it to  the reaction centers during the light reactions. The relationship between light intensity and photosynthetic rate is directly proportional so the rate of photosynthesis increases as light intensity increases up until a certain point.  

Methods:  starting off the experiment, each of the cuvettes were filled with a spinach solution, either raw or boiled. DPIP was added to them as well, which was there to be eaten up by the chlorophyll as light reactions would function. If the DPIP was not eaten up and the solution remained blue, the chloroplasts did not function. A control cuvette used to recalibrate the sensor was made the same way as the previous cuvettes with the raw spinach, but it was wrapped in aluminum foil to prevent any sort of light from reaching the chloroplasts. Each of the cuvettes was left in the light for same amount of time, (5,10, and 15 minutes)  and in the sensor for the same amount of time as well. This was to make sure everything was tested equally to provide us with the most accurate results.  

Data:

First Trial

Second Trial

Graphs:

Discussion:

The first trial that we did there was no change in the color because we did not put enough Dpip into the solution because all the Dpip was used up right away and it was impossible to tell the difference over time. So we increased the concentration of the Dpip in order to be able to better see the change in Dpip used. In the experiment one can determine the amount of Dpip used because the translucency in the solution will become closer to 100%. Ans when The Dpip is not used the colorometer will read something less than 100% because the bluish tint will bring down the translucency.

Conclusion:

As the graph shows, the unboiled light and the unboiled dark were the only solutions to significantly increase in the translucency. the unboiled light was as predicted because it would be the only one that the chloroplasts will be using the light to consume the Dpip. And the only logical reason we can think of why the unboiled dark increased in translucency is because during the short time where we took the sleeve off and put it in the colorometer the chloroplasts activated and consumed the Dpip. 

Resources:

Campbell biology ninth edition

Cellular Respiration Lab

Purpose: 

The main objective of this lab was to find out the rate of respiration in dormant seeds, seeds which were germinated, and seeds which were germinated and added to cold water. The temperature was the dependent variable as it was changed from room temperature to ice cold water. The environment, sensor and type of seed used remained the same, making it the independent variable. The main focus was to see the difference temperature makes in the respiration of germinated and non-germinated seeds.

Introduction:

Cellular respiration is a form of aerobic respiration in which glucose is broken down in in order to produce ATP. The general formula for cellular respiration is C6H12O6 + 6O2 --> 6CO2 + 6H2O + energy. This process takes place in the mitochondria. Cellular respiration has 3 stages: glycolysis, citric acid cycle, and oxidative phosphorylation. At each of these stages, ATP is produced. During glycolysis, glucose is broken down into 2 pyruvate molecules. 2 ATP is required to phosphorylase glucose but 4 ATP are produced and 2 NADH. The pyruvate is then oxidized to acetly CoA and then goes on to the citric acid cycle. The citric acid cycle then produces 4 CO2  , 6NADH, 2FADH2 ,and 2 ATP. Finally, in oxidative phosphorylation, the electron transport chain and chemiosmosis are combined together. The total yield for a single molecule of glucose is 30-32 ATP.  Temperature affects the rate of respiration.

Methods:

25 similar pea seeds which were germinated had been counted and picked out along with 25 dormant seeds and 25 glass beads. The glass beads were used as a control group. We first tested the germinated seeds by simply putting them in a container covered with the respiration sensor. Then we had the germinated seeds sit in ice cold water and once again put them in the container covered with the sensor. The same thing was done with the dormant seeds to use as comparison. The glass beads were a control group to act against the dormant and germinated seeds. 

We used the Lab Quest to take all the CO2 measurements

The germinated seeds at room temperature

The cup of cold water that the seeds were to be put into

The seeds soaking in the Ice Water

Data:

The rate of respiration for all seeds

Graphs:

The CO2 Graph of the germinated seeds at room temperature

The CO2 Graph of the non-germinated seeds at room temperature

The CO2 Graph of the Germinated seeds after submerged in Ice water

 Combonation of all graphs 

Blue= Germinated at room temp

Purple= Germinated after submerged in ice-water

Green= non-germinated seeds

Red= Glass beads that served as constant

Discussion:

The rate of respiration for the peas at room temperature was .32 ppm/s. The rate of respiration for the peas at the cold temperature was .97 ppm/s. The rate of respiration for the non germinating peas was .05 ppm/s. The average rate of respiration for the peas was .446 ppm/s. The average rate of respiration for the glass beads was .015 ppm/s. The respiration rate was higher for the germinating peas when compared to the respiration rate for the non germinating peas. The temperature of the water also had an effect on the respiration rate of the peas. The peas that were in then cold water had a higher rate of respiration than the peas that were in the water at room temperature

Conclusion:

As shown in the graphs above it is obvious that the germinated seeds produce the most co2, but their co2 production rate decreases after they have been submerged in water. Also it should be noted that the non-germinated seeds barely produced more co2 than the glass beads. So it can be determined that the non-germinated seeds produce little or if not any co2.

 Reasources:

Campbell Biology Ninth Edition

Enzyme Catalysis Lab

Purpose: An enzyme is a protein which speeds up the reaction of a certain biological process. During this lab, the function of an enzyme was tested. Inhibition was also tested. An inhibitor slows down or stops a reaction completely.

Introduction: An enzyme is used to speed up a chemical reaction. This is called a catalyst. a catalyst is needed to raise the activation energy of a material. this material is called the substrate. the substrate will bind to the enzyme in order to activate the reaction and produce the final product. After the product is made the enzyme is not just thrown away or used up, it can be used over and over again, as long as there is substrate for it to act upon. But there are ways that the enzyme can break and fall apart, this is called Denaturing. Once an enzyme becomes denatured it cannot do its job and is therefore useless.  Two very common ways that enzymes become denatured is by a change in ph or a change in temperature. Enzymes like to live in very specific zones. they don't like it too hot or to cold. and if they are out of their comfort zone they will not work as well. and if they get too far out of their comfort zone they will not work at all. This is how enzymes get denatured. Enzymes can only work on a set number of substrates at a time. So if we were to say that one enzyme can only process one substrate every 3 minutes, then after 9 minutes 3 substrates would be made into products. And even if we have 100 substrates to choose from, after 9 minutes only 3 will be made into products. But if we were to add more enzymes into the mix more products can be made. So if there were 2 enzymes after 9 minutes they would have made 6 products, and so on and so forth. I think you get the idea.  Enzymes can only go so fast, and they can only continue  to work as long as there is substrate for them to work with.

Methods: In order to test the ability of an enzyme and an inhibitor, 7 cups were filled with H2O2. Each of these cups had a certain time range the catalase had to be left in there for, ranging from 10 seconds to 360. Catalase in the form of yeast was added in order to start the reaction, and sulfuric acid was added in order to stop the reaction. The solution was then titrated with potassium permanganate until the solution had turned a purple-brown. We knew the solution had ran out of H2O2 once the solution remained a solid purple-brown color.  

Data:

Graphs:

Discussion:

when we titrated for the baseline we found that there was consistently a 3mL reading for the baseline. Then when we found the percent that was spontaneously decomposed in 24 hours of sitting out, we found that there was a  43% difference in the amount that was decomposed. Then when we  titrated the solutions we noticed some interesting things. For instance, the amount of KMno4 that was consumed declined until the time before reaction was 90 sec; then once the tione hit 90 sec the amount consumed stayed the same for the rest of the experiment. this shows that after a min and a half there was no other effect on the amount of KMno4  that would be consumed. Then when we looked at the amount of H2O2 that was used it increased until 90 seconds and then it also leveled off. So It would seem that after 90 seconds the total production of the enzymes will level off.

Conclusion: The rate at which a 1.5% of H2O2 solution decomposes is .22ml of H2O2 per second. After 10 seconds, 2.2ml of the H2O2 was used. A maximum of 2.5 ml of H202 was used during the reaction. After 90 seconds, the H2O2 was no longer used up in the reaction.

Diffusion and Osmosis Lab

Diffusion and Osmosis Lab

Purpose:

1A) In this experiment diffusion of small molecules through dialysis tubing was tested to prove a selectively permeable membrane. The dependent variable consisted of the color and change in starch. The independent variable was the IKI which did not change.

1B) Exercise B shows the relationship between the movement of water through a cell membrane is related to the concentration of a solute. We were trying to see if the differing amount of a solute located inside the cell would change the amount of water that diffused through the cell through osmosis

1C) The purpose of this lab was to determine the water potential of potato cells. This was to be determined by placing potato cores in solutions with different molar concentrations of sucrose and recording the % change in mass of the cores. By finding the molar concentration of sucrose when there is a 0% change in mass, we could then find the molar concentration of the potato cores and then determine its water potential.

1E) The purpose of this lab was to examine the effects that a high concentrated solution would have on diffusion and the cell of an onion. This would be done by placing the onion in

Introduction:

1A)Different cells may have different membranes which control what comes in and what leaves the cell. In this experiment, this was exactly what was tested. Selectively permeability is extremely important to a cell. A cell cannot let anything and everything in. The membrane only allows certain molecules of a certain size in and out.

1B) Two solutions that have the same concentration of solute will be iso tonic. So water will be able to move freely through a selectively permeable membrane but the change in the amount of water in both solutions will stay the same. However if these two solutions have different concentrations of a solute (one being less and one being greater) the change in the amount of water on either side will be different in order to balance out the solution.

 Hypertonic

1C) Water potential is a measurement of the tendency of water to move from one place to another. Water potential is equal to the pressure potential added to the solute potential. Solute potential is the effect of solutes on overall water potential. It is always a negative value and it is inversely related to water potential. An increase in pressure potential also increases the water potential. Water will always move from an area of higher water potential to an area of lower water potential. When the water potential of the cell and the water potential of the liquid are the same, dynamic equilibrium has been reached and there will be no net movement of water. When a cell is placed in an iso tonic solution, the solute concentration of the cell and the solution are equal and there is no net water movement across the plasma membrane. When a cell is placed in a hyper tonic solution, the solute concentration is greater than that inside the cell and the cell loses water. When a cell is placed in a hypo tonic solution, the solution con creation is greater than that inside the cell and the cell gains water.

1E: When placed in a hypertonic solution, the solute concetration is greater than that inside the cell and the cell loses water. When placed in a hypotonic solution, the solute concetration is less than that inside the cell and the cell gains water. When placed in an isotonic solution, the solute concetration is the same as that inside the cell, and there is no net water movement across the plasma membrane. When placed in a hypertonic solution, the cell undergoes plasmolysis and the cytoplasm shrinks and the cellular membrane pulls away from the cell wall.

Methods:

A) In order to stimulate and explain a cells selectively permeable membrane, a piece of dialysis tubing was cut to size and filled With 15% glucose and 1% starch solution. This dialysis tube, now a baggie, was dropped in a cup of IKI. We left the dialysis tube in with the iodine for approximately 30minutes. The bag was then removed and we began observing changes.

B)we filled six dialysis bags with differing amounts of sucrose concentration. These will be our cells with either hypo, Iso, or hyper tonic cells. We then weighed them in order to have their original weight to compare once the test was over. The "cells". We're then submerged inside a cup of water for thirty minutes. After the thirty minutes, the "cells" were weighed again in order to see if there was any difference in the weight. If there was a higher weight that would mean water went into the cell, and if there was a lower weight that would mean that water came out of the cell.

C) For this experiment we cut 24 potato cores and separated them into groups of 4. We weighed each group and recorded it on the date table. Then we placed each group into a cup that contained either 0.0M distilled water, 0.2M sucrose, 0.4M sucrose, 0.6M sucrose, 0.8M sucrose, or 1M sucrose. We then covered the cups and let them sit overnight. The next day we took out the potato cores, blotted them, and then weighed each group and recorded the new weight of the cores on the data table. Then we found the change in mass of the potato cores in each liquid and calculated the % change in mass.

1E) For this lab we observed a piece of an onion under a microscope.  First we put 15% NaCl and then freshwater on the onion and observed the effects of it on the onion cell.

Data:

1A

1B

1C

Graphs

1C

Discussion:

1A) Starting off, the baggie contained 15% glucose and 1% starch and the solution was colorless. The baggie was then added to a solution of water and IKI which was a dark yellow color. After sitting for 30minutes, the solution inside the baggie was a dark blue color and the solution in the cup was still a dark yellow. This clearly explains concept of a semi permeable membrane. As we predicted, the starch in the baggie would react with the IKI as in passed through the semi permeable membrane of the baggie. To prove that it was only the starch that reacted to the IKI, we tested and realized that both at the beginning and at the end of the experiment the glucose remained the same.  This was done with glucose testing strips. At the beginning the glucose tested at 15 inside the baggie and 30 on the outside. At the end, we dipped the glucose testing strip once again and it tested at the same as in the beginning. The results matched our predictions, as we said glucose molecules are too big to get through the selectively permeable membrane, but since the starch molecules are a lot smaller they would make it through

1B) After we pulled the bags out of the water and weighed them we noticed that the bag with just distiller water weighed the same as when we put it in originally. This was expected because it is just water , so no extra water needed to be added or removed to create a balance inside the cell. But then as the molar it you'd sucrose inside the cell increased so did the % change in mass. The more concentration of sucrose inside the bag the more amount of water went into the cell. The amount of water that was let in steadily increased as the molar it's went up. Starting with only a 2% increase in mass at .2M of sucrose, alluded way to a 10% mass increase in the 1.0M of sucrose. This experiment clearly showed how a hypo tonic cell will tend to take in more water in order to equalize itself with the concentration on the outside. The experiment did exactly what we thought it would, we thought that the higher the molarity, the more water the cell would take in, in order to equalize the outside.

1C) As the potato cores were placed in solutions with higher molar concentrations of sucrose, the % change in mass of the cores became more negative. When the potato cores were placed in 0.0M distilled water or 0.2M sucrose, the potato cores' mass increased and the % change in mass was positive. This means that the cores were placed in a hypo tonic solution and they gained water and mass. When the cores were placed in .4M sucrose, .6M sucrose, .8M sucrose, or 1M sucrose, the potato cores' mass decreased and the % change in mass was negative. This was because the cores were in a hyper tonic solution and they lost water and mass. Looking at the graph of the data, you can see that somewhere between .2M sucrose and .4M sucrose, the % change in mass would've been 0% and the molar concentration of sucrose would equal the molar concentration of the potato cores. This means that water potential of the water with that molar concentration would equal the water potential of the potato tissue. This concentration is approximately .23M sucrose. An inconsistency in the data is at .8M sucrose. The % change in mass should've followed the trend and been more than the % change in mass of .6M sucrose but instead it was less. A better way to improve results and get more accurate results would be to have a way to dry all the potato cores the same way so that some wouldn't lose more water than others.

1E) When the 15% NaCl was added to the onion, the cell was in a hypertonic solution and the cell underwent plasmolysis and lost water. However when freshwater was added to the onion, it was in a hypotonic solution and the onion cell gained water.

Conclusion:

1A) Selectively permeable membranes are extremely important in a cells life. They play a huge role in keeping the cell safe and satisfied.  This was proven in this experiment after the starch in the dialysis baggie reacted with the IKI on the outside, which shows us how the difference in size of starch and glucose played an important role in getting through the selectively permeable membrane.  

1B) All in all this experiment showed that an iso tonic solution will cause a cell to take in no extra water, but a hypo tonic solution will cause the cell to take on water in order for the inside and outside of the cell to reach an equilibrium.

1C) The molar concentration of sucrose at which its water potential is equal to the water potential of the potato tissue is approximately .23M sucrose. At this concetration, the solution has a water potential of -5.29 bars (.1M = -2.3 bars). Although the solute concetration of the potato tissue and the solution aren't equal, the pressure potential of the potato cells equals out the solute potential of the potato so that both water potentials are equal. Since there is no net movement of water at this concetration, this means that the water potential of the potato cells is equal to the water potential of the liquid. Therefore, the potato cores have a water potential of -5.29 bars.

1E) When the NaCl was placed on the onion cell it experienced plasmolysis. It then gained back water when it was placed in freshwater.