Enzyme Catalysis Lab

Purpose:
The purpose of this experiment is to understand the functions of enzymes and how pH changes the reaction rate. This can be done by observing the enzyme catalase in the break down of hydrogen peroxide (H2O2) into water (H2O) and oxygen gas (O2), and measuring the amount of oxygen generated and the rate of the enzyme-catalyzed reaction.

Introduction:
Enzymes are proteins that act as catalysts in biochemical reactions; catalysts affect the rate of a chemical reaction. In enzyme-catalyzed reactions, the substrate binds to the active site of the enzyme, and the activation energy of the reaction is lowered so that the produced can be formed more easily. Ways in which enzyme action can be affected include salt concentration, temperature, pH, and activations/inhibitors. 

Methods:
The main point in this lab was to understand enzyme activity. We did this by collecting baseline trials of the rate of reaction of the uncatalyzed reactions. Next we would use the same process to collect data of the catalyzed reactions, after we had added the enzyme Catalase. Then we compared the trials of the two types of reactions to one another and observed what happened to the rate of reaction.

Data:

                     

 

Graphs:


                              



Discussion:

 In this lab, we tested the affect of denaturing enzymes and how that relates to the rate of reaction between two substances.  The substances we tested were catalase,which is an enzyme, and hydrogen peroxide, which is a substrate.  In order to denature the enzyme, we added an acid, H2SO4.  The results we got indicated a direct curve, with a few exceptions.  When aci was added after 90 seconds, there was a slight decrease in rate of decomposition, which did not fillow the trend of increasing rate of reaction.  Also, at 180 seconds, there was a slight decrease as well which did not follow the trend.  This could be caused by a few things.  One, we may have put the acid in slightly too early, which would have caused this decrease.  Two, we may have contaminated the beaker with leftover acid from other experiments and the denaturing could have occurred too early, causing less decomposition to occur.  But, on average, we observed that as an enzyme is left with a substrate for a longer time, more decomposition occurs.  Therefore, length of time the substrate is exposed to the enzyme and amount of decomposition are directly related.  

Conclusion:
We can conclude that concentration of enzymes directly related to rate of decomposition of H2O2.

References:

Campell Biology, 2009

 

 

Diffusion and Osmosis Lab

Purpose

1A: The purpose of this experiment is to understand the nature of selectively permeable membranes. This is accomplished by observing how different molecules such as water, glucose, starch, and iodine interact with a selectively permeable membrane.

1B: The purpose of this experiment is to understand the relationship between solute concentration and the movement of water through a selectively permeable membrane. This can be done by testing the osmosis of water using solutions with different molarities of sucrose.

1C: The purpose of this experiment is to understand water potential and what influences change in water potential. As well as understand the components of the water potential equation and how its used.

1D:  The purpose of this experiment is to understand how to calculate water potential.

1E: The purpose of this experiment is to understand plasmolysis and the effect of concentrated solutions on plant cells. This can be done by putting onion cells in different concentrated solutions.

Introduction

1A: Diffusion is the movement of a solute across a membrane.  Diffusion only occurs when a salute travels down its concentration gradient.  A concentration gradient is the difference in concentration of a solute.  To be more specific, dialysis is the diffusion of a solute across a selectively permeable membrane.  A selectively permeable membrane is a membrane in which only some materials can pass through.  An example of this would be the plasma membrane of a eukaryotic cell.  Water molecules and other small substances are able to pass through a selectively permeable membrane freely, but larger molecules are most likely unable to diffuse

Part 1B: Osmosis is the movement of water through a membrane. An isotonic solution includes two solutions that have the same concentration of solutes, therefore there will be no net charge on the water in either solution. When two solutions have different concentrations of solute, the one with less solute is hypertonic and the one with more solute is hypotonic. When you put these two solutions together separated by a selectively permeable membrane, the water will move from the hypotonic solution to the hypertonic solution.

1C: Water potential is the movement of water in or out of cells. The movement of the water is done by the process of Osmosis (movement of water through a membrane). The two components that make up water potential are pressure potential (physicial pressure) and solute potential. Formula is Water potential = pressure potential + solute potential. The potential of pure water is equal to zero. Water always moves from high to low areas of water potential. Water potential can be a positive or negative value, or it can be zero. Pressure influences the movement of water. With an increase of pressure there will be  more positive value, where on the other hand decrease in pressure there will be a more negative value. As for solute, if there is an increase water potential will be more negative. When water leaves the cell it will shrink, If water is added it will grow. In animal cells too much water will cause the cell to swell or burst. But in plant cells the cell will only grow, this is because of the plant cell which holds the cell together. Once the water potential on the inside of the cell and on the outside of the cell are equal, then it will have reached dynamic equilibrium, where there is no water movement.

1D: Water potential equals the ionization constant plus molar concentration plus the pressure constant plus tempurature (in Kelvin).  Water potential shows water's ability to move from one location to another.  

1E: Plasmolysis is the shrinking of the cytoplasm of a plant cell in response to diffusion of water out of the cell when in a hypertonic solution. In a hypertonic solution, cells lose water because there is a greater concentration of solute outside the cell. In an isotonic solution, there is no net water movement because the solute concentration is the same inside and outside the cell. In a hypotonic solution, the cell gains water because there is a lower solute concentration outside the cell.

Methods

1A: First, we soaked about 20 cm of dialysis tubing in water in order to make it easier to work with.  Then, we we formed a bag out of the tubing and put a solution made of 15% glucose and 1% starch inside of the bag.  We recorded the color of each solution.  We then tested the glucose/starch solution for the presence of glucose.  Next, we filled 3/4 of a cup with iodine solution (Lugol's solution) and filled the rest with water.  We then tested this solution for the presence of glucose.  Next, we put the bag of glucose/starch solution into the cup of iodine/water solution, and proceeded to wait for approximately 30 minutes.  Once the time was up, we recorded the color of each solution and tested for the presence if glucose in each as well.

                                                                                                                 

1B: First, we filled dyalisis tubing with either water or solutions with different molarities of sucrose. We tied off the ends and left room for water to enter. Then, we recorded the weight of each bag and placed each one in a cup of water. We let them sit for 30 minutes and then took each bag out and weighed them. Finally, we calculated the change in mass for each bag.

                                           

1C: First, we poured the five different molarities of sucrose into their designated beakers as well as the distilled water into its own beaker. Next using a cork borer we made 24 potato cylinders (4 per beaker). Then we weighed the potato cylinders 4 at a time and recorded the intial mass. After weighing them we placed the potato cylinders into the beakers (4 per beaker). Following placing the potato cylinders into their beakers, we let them soak in the solution overnight with a sheet of plastic wrap covering the top of the beakers (this prevents evaporation). The day after we took the potatoes out of the beakers, using a paper towel to dab the excess solution off of the cylinders and we weighed them once more to find the final mass. Then we found the percent change in mass (intial mass/final mass).

                                           
 

1D:

1E:  First, put a piece of an onion on a slide and observe it under a microscope.  Sketch a picture of the image.  Then, add several drops of NaCl solution to the slide and record what occurs.  Next, add water to the slide and observe and record what happens.
                           
 

Data

1A

     1B                                 

 

            

                                       

 

                           

1C

                                       

 

 

1E

                              

                                                       

 

                                                                           Flaccid Cells

 

 

Discussion

1A: The change in color from colorless to black/blue in the glucose/starch solution obviously indicates that iodine passed through the membrane, because iodine changes color when it comes into contact with starch.  Beacause we didn't see any color change from red to black/blue in the iodine solution, it must mean that starch was unable to pass through the membrane.  Also, because the iodine tested negative for glucose before the glucose/starch bag was put in, and positive for glucose after it was put in, it must indicate that glucose was able to pass through the membrane into the iodine solution.  All of this information indicates one thing: the dialysis tubing acted as a selectively permeable membrane.  Because glucose was able to pass through the membrane, we must conlude that it is the smallest molecule (besides water) present in this experiment.  Iodine was able to pass through the membrane as well.  Starch however, has to be the largest of the molecules.  It was unable to pass through the dialysis tubing because its size was bigger than that of the pores in the membrane.  Pore size directly affects the diffusion of molecules, then.  If a substance is larger than the pore size, then it will not be able to diffuse across the membrane.  If the molecule is smaller than the pore size, then is will be able to diffuse across the membrane.

1B: Overall, as the molarity of sucrose goes up, the amount of water that diffused into the bag goes up. The bag put into distilled water had the lowest change in mass, because it was isotonic, so water should stay at equillibrium in the two solutions. Then, as the molarity of sucrose went up, more water diffused into the bag because the solution outside of the bag was hypotonic. The solution with 1.0 M sucrose has the highest change in mass because it had the most water diffuse into it. This occurred because of how hypertonic the outside solution was compared to the solution inside the bag. The only error in our data was with the solution of 0.4 sucrose, because it didn't follow the trend; it had a lower change in mass than it should have. Other than that, the trends of our data and the class data are similar, except that our changes in mass of the higher molarity sucrose solutions are significantly higher. The data trend turned out as we expected, because this simulated diffusion in cells, which when placed in a hypotonic solution, take in water.

1C: In our experiement we found that for the distilled water beaker cylinders gained 1.5g of mass with a +17.2% change in mass. At 0.2M sucrose there was a 0.34g gain in mass. As for 0.4-1.0M sucrose solution there was an overall trend of loss in mass and a negative percent change. At 0.4M we recorded a mass change of -1.53g and -16.7% change in mass. The masses would continue to drop from this point on, until we reached a mass change of -3.08g and a percent change of -33.67% for 1.0M sucrose. From less then 0.2M Sucrose we found a postive mass gain. As for 0.4M sucrose and higher molaritites we found a decrease in mass change. This was on behalf of there being enough solute added to the potato cylinders to cause movement of the water from the potatoes. Since water always moves from high water potential to low water potential. Meaning that there was a high water potential within the potatoes and a low potential of water outside of the potatoes. The mass changed because the water was removed from the potatoes, which decreased the mass. When 0.2M or less of sucrose was added there was not enough solute added to change the water potential.

1D: In this experiment, we found water potential.  We determined that if you multiply the ionization constant, molar concentration, pressure constant, and tempurature, then you get water potential.

1E: In this experiment we found that when we added the drops of 15% NaCl the onion cell shrunk in size. This is on behalf of plasmolysis. The 15% NaCl was a hypotonic solution. We learned in lab 1D that water potential always moves from high to low. So in this case the onion cell had more water potential then the NaCl solution. The added drops caused the water with in the cell to vacate, then shrinking the cell in size. When we added a lot of water to the onion the cell increased in size. The onion increased in size because after adding the NaCl the water potential with in the cell was less then the solution the cell was in, making for a hypertonic solution and a turid onion cell. Since water potential once again moves from high to low concentration, once the water that had a higher water potential was added the water poured into the onion cell until it reached equillibrium. If the onion cell had been placed in an isotonic solution the cell would have remained the same size since the solution that the cell was in would have the same water potential. So in summary, when NaCl was added to the onion the cell shrunk in size and lost water, after the water was added to the cell the onion gained water and increased in size.

Conclusion

1A:  Only molecules that are smaller than membrane pore size are able to diffuse through a selectively permeable membrane.  Molecules larger than the pore size of the membrane are unable to diffuse through a selectively permeable membrane.

1B: The more hypertonic the inside solution is, more water diffuses in. An isotonic solution will have little or no change in the amount of water inside.

1C: At 0.2M or above there isn't enough solute to cause a change in water potential. That's why from 0.4-1.0M they lost mass since there was enough solute to cause the water potential to change, causing water to leave the potato, then lowering the mass of the potatoes.

1D: In order to calculate water potential, you multiply ionization constant, molar concentration, pressure constant, an temperature in Kelvin.

1E: When adding NaCl to the onion cell the cell decreased in size, because it was in a hypotonic solution. When adding the water afterwards the onion cell increased in size because it was now in a hypertonic solution. This is on behalf of plasmolysis where water always moves from high to low concentration.

References

Campbell Biology, 9th Edition

Diffusion and Osmosis Lab, College Board

 

 

 

 

Grace's Restoration Reflection

I wasn't sure what to expect when I arrived at the Glacial Park Restoration Center. As soon as we got out of the bus and stepped into the building I witnessed a stuffed coyote. I thought to myself jokingly, "so is this what we're going to restoring?" I thought it was so funny, I had to take a picture with it. I was also surprised with one thing. The place had wi-fi. I honestly thought that in a this large field, 

there would not be any internet connection. It was a funny thought. 
    When we walked out of the building, we listened to the ecologist speaking about what we were going to do for the rest of the day and what the motto is at the center. He stated that the point of ecological restoration is to speed up the process of restoring what nature would restore in a much longer time span because humans are degrading faster the nature can reproduce. Therefore, we were there to help restore nature quicker. 
    After walking the a beautiful and mesmerizing field of ups and downs, we split up into groups, and I was in the group to remove invasive species in the forest. At first, I couldn't tell the difference between what was hurting the trees and what was helping it. I decided to just cut down everything but the big oak trees. I hope for the most part, that helped out the trees. Although it took a lot of physical labor,
 I had a lot of fun. When our group had finished, I 
truly saw the difference we made. Before the forest
 was very dull and the trees were barely getting 
sunlight. Now the forest was incredibly open and the
 sun was blazing. I felt really good. I felt like I really
 did something to help nature and the ecosystem. 
After taking some pictures, we moved on to the 
next site.

 


At this next stop, I saw a couple of shrubs planted in a field. Our job was to water them. They did not get water from nature in over a week, so it was our job to help speed up the process. Everyone got a gallon of water and found a dry plant to fill up. After this, we planted acorns. That was my favorite part. We learned about how squirrels find these acorns and disperse them around the forest. Without knowing, these two species shared a relationship. But for some reason, the squirrels did not come to this area, so oak trees were scarce. As our job to restore, we planted a thousand acorns in the field, one by one. I had to take my time digging up a hole and planting one specific acorn at a time, but I felt like I contributed more. I was just imagining that it would be my acorn that I planted to grow and become a huge oak tree. I really enjoyed it. 

 
After finishing up at this site, we were on our way to the bus. I could not stop thinking about how much I learned at this field trip. It was a give and take relationship. I was helping to restore nature, while nature was teaching me. I honestly felt great afterwards, and learned a lot from this experience!  

My Restore the Forest Team! =) 

Marley's Restoration Reflection

During this field trip, we got to experience restoration ecology. The point of ecological restoration is to speed up the process of restoring a degraded area. We went out in the field and removed invasive plants that weren't native to the area. The non native plants were taking over, and weren't allowing the native plants to grow. By removing these invasive plants, we made room for the native plants to grow. We then went on to water new, but native, trees that were brought into the area. We also spread seeds in the same area to help the native plants grow.

This field trip exposed me to something I had never heard of before, and I'm glad I got to experience it. I think restoration ecology is amazing because humans are slowly ruining the environment, and this helps to restore some of the damage. Some of the many benefits of restoration ecology include improving biodiversity, improving ecosystem productivity, improved water quality, and increased carbon storage. All of these things are included in restoring natural ecosystems. After experiencing everything during this trip, I would love to get more involved with restoration ecology.

Morgan's Restoration Reflection

Start of the trip!

At the start of the trip we would learn that buckthorn and a few other species weren't native to the environment. They were brought into this enivronment by people. The ecologist that we worked with would then tell us that this whole area we were in over 3500 acres used to be farm land. The agriculture that would take place before the conservationists took charge of the land had ruined the ecosystems that previously existed. Not to mention that the distruction of the habitats for the animals that lived in the area pushed all the animals away. It was only up until recently that some of the old inhabitants would come back to their previous homes. Like the badgers that had recently returned to the area. The most important thing that was learned from this part of the trip waas that if you restore the environment that the organisms that lived there before it was ruined would return.

 

The next part of the trip was probably the most fun and exciting! We would be removing the plants that were not native to the area. We were making room for those native plants that didn't stand a chance with the over populus non-native plants. In our group we would cut down 4 trees and a large amount of brush that covered the forrest floor. All while leaving the multiple oaks alone. We also created a burn pile because many priaires need fires to grow. This would also kill anything that wasn't naturally occurring since the non-natives wouldn't be able to tolerate the fire.

The next thing that we did on our trip was watering the hill & burr oak sapplings. Since we haven't had very much rain in the past few days it was vital that we gave the sapplings water. We poured about 2 gallons of water on each tree.

The next part was where we planted a bunch of acorns. The acorns that squirrels plant yearly are the natural way of planting oak trees. So forgetting where you acorn is isn't as bad as the squirrel in Ice Age makes it out to be! We planted each acorn about an inch under the surface one by one. Unless you felt a bit lazy then there might have been a few more then one per hole. 

I felt that this was probably one of the best field trips because you could really embrace the nature nd help the environment at the same time! Not to mention you can tell people that you saved the planet for the day! Plus how many people can say they got to use a huge bow saw to cut down trees on a field trip? Only down fall was when I thought I was going to fall down the giant hill that you felt like you could never see the top off. 

Katie's Restoration Post

     Before we started studying ecology, I didn't really think about it that much.  I kind of thought that you just left an area alone in order to restore it to what it used to be.  But there's really cool science involved in restoration ecology.  I think it's totally fascinating how the introduction of one single species can completely change the environment-for better or worse.  During our field trip, the ecologist explained how new species like honeysuckle and buckthorn invaded the area and overtook the landscape. If I was just looking at the land, it would look pretty good to me because there was lots of thriving vegetation.  But, all that vegetation that isn't indigenous to the area has created a landscape that may not be able to support all the organisms it was once able to support.  Recently at Glacial Park,  badgers have been reintroduced to the area because of the restoration projects taking place.  It's pretty cool to see the benefits of the restoration in the past few years.  

Here's what we did on the field trip:

- Watered young tree seedlings that were recently planted

- Planted acorns 

- Scattered savannah grass seeds to make an landscape suitable for several different kinds of plant life

- de-forested an area of honeysuckle and buckthorn in order to restore the natural landscape 

                                  

                                 

                                                            Here's a "before" picture

                                  

                                                            Here's an "after" picture

                 

                                  

      

                                This is where we watered recently planted trees and spread seed

     There's no doubt that restoration ecology has numerous benefits.  Bt what are the downsides?  One question  I definitely have is this: what exactly are the goals of restoration ecologists?  They want to restore the land back to what it was before people changed it, but how "natural" is the landscape supposed to be? The only domesticated animal indigenous to the Americas is the llama, so does that mean that other domesticated animals shouldn't be a part of the landscape's population?  That's a completely extreme example, but in a science like restoration ecology, it might be hard to set specific goals.

   The benefits of restoration ecology are obvious.  It's definitely important for nature's future, and its important for people's future as well.  I'm just glad we got to be a part of it.

Acids and Bases Lab

Purpose:

   The purpose of this lab experiment was to see which substance was the most resistant to differences in pH levels by adding drops of acid and base solution. We were trying to find the best buffer from our substances.

Introduction:

   Acids and bases are formed when water dissociates into a hydroxide (OH-) and hydronium  (H+) ions.  The dissociation occurs because of the polar nature of water.  Water naturally will share electrons unequally between its hydrogen and oxygen atoms.  Sometimes, the electrons will be shared so unequally that the electrons will leave one of the hydrogen atoms and attach to another hydrogen and an oxygen.  That's where hydronium and hydroxide ions are formed.  Acids denote a substance that has an abundance of hydronium ions, and bases have an abundance of hydroxide ions.

     pH is a measure of the quantity of hydronium.  More specifically, it's defined by the negative log of the hydronium concentration.   The pH scale gives people an accurate way of categorizing a substance as an acid or a base.  The substances are placed on one of fourteen points, the lower the number, the more acidic the substance is. If a substance has an H+ concentration of 10 to the negative 7, then it would have a pH of 7.  Likewise, if it had a hydronium concentration of 10 to the negative 13, it would have a pH of 1.  Water is considered neutral with a pH of 7. 

     Buffers are compounds that prevent a substance from becoming too acidic or basic.  They function by either providing H+ ions when a substance becomes too basic, or accepting H+ ions when becoming too acidic.  Buffers are especially important in preserving life.  For example, blood needs to be at about a pH of 7.2.  If it varies too much, biological processes could cease to function.  If it would become too acidic, then a buffer would accept H+ ions from blood.

 Methods:

     First, we tested the pH of water with two separate Vernier probes in two separate beakers.  Then, we gradually added both an acid and a base to different beakers containing the water.  Periodically, we collected the pH of both the acid and base waters.  Next, we tested the pH of an antacid solution and a salt solution and repeated the same steps we took to test the pH of water. 

Data:

   

 Water

pH

 Number of Drops

 

 Salt

pH

Number of Drops

Antacid

pH 

 Number of Drops

Discussion:
     We tested the solutions of water, antacid and salt to see which would be the best at maintaing a consistent pH level when an acid (HCl) or base (NaOH) was added (best buffer).

Water (pH of 7)
(we had a reading of 6.9 pH for our water)

Acid added to water
-starting at a pH of 6.90 acids general trend was a decrease in pH for how much HCl was added. The largest change in pH occurred when we added 10 drops. At this point we observed a 1.55 drop in pH. The pH of the water dropped from 6.9 to 5.35. Through out the rest of the trial the pH would decrease at a rate being cut in half after every trial (ex 0.4 to 0.2 decrease to 0.1). At the end of the trials the pH ranged from 6.9 to 3.12. That's a change of 3.78 pH.


Base added to water
-starting with a pH of 6.90, we added a base to water to find that there was a general trend that was an increase of pH by no specific rate for how much NaOH was added. The largest increase of pH would be after adding 15 drops of base, here the pH increased by 2.26 (8.02 to 10.28). By the end of all the trials the pH ranged from 6.9 to 11.51  which is a difference of 4.61 in pH.

Salt (pH of about 6.5)

Our results for salt showed that without adding any other substances, salt would be between 6.25 and 6.5 on the pH scale.

Adding acid to Salt
 -After adding 5 drops of acid we observed a very slight increase of approximately 0.3 in pH of the acid beaker. For the next set of 5 drops there was relatively no change but it did go down to 6.18. On the contrary, once we hit the 15 drop mark, acid had a much larger change in pH. The salt beaker that was having acid added to it had a change in pH from 6.18 to 4.60. After the acid beaker reached 4.60 it would decrease in pH by increments of 0.2-0.3 for the remainder of the trials. The general trend here was a decrease in pH for how much HCl was added.


Adding a base to Salt
- For this trial there is a strange pH level in the first trial before we added any drops of the base. We had a reading of 9.25 pH, but in the acid portion of the same trial we had a reading for uncontaminated salt of 6.63. We should have this same number if we had done this trial correctly. We did have some human error (we spilled our first beaker and had to start over). I think the reason we had such a high pH at the beginning was maybe we didn't clean the beaker out well enough to get rid of the extra NaOH. Other than that the solution increased at recognizable rate of about 0.4 to 0.5 drop of pH. General trend was an increase for amount of NaOH added.


Antacid (pH of about 6.7)

Adding Acid to Antacid
- We had a starting reading of a pH 6.7. In this trial adding the acid wouldn't really effect the antacid solution. It would not fluctuate much at all. The largest change in pH was between trials of 5 & 10 drops, where the pH would go from 5.98 to 6.10. The highest the pH would be at 6.7 pH and lowest at 5.62 pH. The range of difference in pH was a modest 1.08. The general trend was that the solutions pH wouldn't really change that much at all no matter how much HCl was added.

Adding Base to Antacid
- This trial was another one where we experienced a strange reading in the unchanged solution. We got a reading of 9.11 for the 0 drops added trial. This unfortunately was another trial that we happened to knock over the beaker and spill the contents of the beaker everywhere. I think we go this reading because there was left over NaOH in the beaker. We should have gotten the 6.7 pH that we did in the acid portion. The biggest increase in pH came when the pH jumped from 9.11 to 9.89 a change of 0.78 pH. General trend was an increase of pH for the more NaOH added.

** Antacid is the most resistant to change in pH, which makes it the best buffer out of the three.

Did our findings add up to our hypothesis?

-Despite our human error in two of our trials our expectations were meet in this experiment! We had predicted that we would see a general trend when acid is added to a solution that the pH would decrease and if a base is added then the pH would increase. Although we were unsure which solution would be the best buffer.

Conclusion:

The best buffer we found to be was antacid although our data may have been skewed from spilling the basic substance twice, linearly the antacid was most resistant to the changes in pH level.

References: 
http://www.chemistry.wustl.edu/~edudev/LabTutorials/Buffer/Buffer.html