Unit 5 Reflection

In this unit, called "Walking the Dogma" we took a closer look at DNA, the genetic code that is in each and every one of our cells. In the previous unit, we learned that our DNA codes for genetic traits, but we didn't know the specifics of how it did that. DNA stands for deoxyribonucleic acid; it is a double-helix and it is composed of nucleotides. Nucleotides are composed of a 5-carbon sugar (in this case deoxyribose), a nitrogenous base (either Adenine (A), Thymine (T), Cytosine (C), or Guanine (G)), and a phosphate group. The structure of DNA resembles a ladder; the backbone is composed of a phosphate group and a sugar, and the rungs are composed of nitrogenous bases. The double-ringed bases, called purines, bond with the single-ringed bases, called pyrimidines. Adenine and Guanine are purines, while Cytosine and Guanine are pyrimidines. I felt that this part of DNA structure was definitely one of my strengths.

We also learned that DNA is antiparallel meaning that one side runs from 5' to 3' and the other side runs from 3' to 5'. The phosphate group from one nucleotide bonds with the carbon from another. I understand the basic principle of this, but I think that the details of the bonding is a weak point for me.

When we studied the cell cycle, we learned that DNA replicates itself in interphase. In semi-conservative replication, when DNA is unzipped, there are two identical strands, each half of the original. An enzyme called helicase breaks the hydrogen bonds that the nitrogenous bases have with each other. Then another enzyme called DNA Polymerase adds the matching nucleotides to each strand. I feel that I have a clear understanding of this topic. One of the main topics that we studied this unit was protein synthesis. At a 10,000 ft level, the Central Dogma of biology states that genetic information flows from DNA to RNA (transcription) to proteins (translation) to our traits. RNA has uracil instead of thymine, and is single-stranded. It is in some ways similar to a temporary copy of DNA. I felt I was able to understand this process fairly well.

The graphic illustrates the process of how DNA is copied. 

Most of the time, DNA is copied correctly and humans are given the correct proteins that they need to functions. However, sometimes mutations--changes in the DNA, can arise. One type of mutation is a substitution, when one base pair is substituted for another. At its worst, it can change one amino acid, however, sometimes it causes no change at all, resulting in a silent mutation. Another type of mutation is a frameshift mutation, either when a base pair is inserted or deleted, and it cause all the amino acids afterwards to change.

One of the topics that I initially found to be challenging but that I understand now was the ways that genes are regulated. Every cell has the same DNA, and that certain genes have to be turned on or off depending on what type of cell it is.

I have learned much more about DNA and how it is copied and how proteins are made from this unit. From the VARK Questionnaire we took last time, I learnt that I am multimodal, but visual was my highest score. I tried to redraw and memorize diagrams which helped me. Also, I feel that when I try to label unlabeled diagrams for Do Now's in class, I retain the information a lot better.

Protein Synthesis Lab Analysis/Conclusion

In order for the body to make proteins, first the DNA must be transcribed into RNA in the nucleus. It is then converted into messenger RNA (mRNA) and sent out of the nucleus to a ribosome. Instead of thymine (T) though, RNA, single stranded, has the base pair uracil (U). The RNA Polymerase pairs the corresponding nucleotides when it is transcribing DNA into RNA. In the ribosome, the RNA is translated from nucleotide "language" into amino acid "language." The RNA is read three letters at a time, called a codon. Each codon codes for an amino acid. These amino acids are joined together to form a protein.

In the lab we experimented with different kinds of mutations that could potentially occur while DNA is being transcribed into RNA. One example of a mutation we tried is a substitution, where one base pair is substituted for another. This mutation had the littlest effect on the final protein. In the worst possible cases it could change just one amino acid, in many cases it could have no effect. The frameshift mutations had a much greater effect, particularly insertion. Almost all of the amino acids were changed when a base pair was inserted, therefore changing the protein entirely. The mutation is worse if a base pair is inserted at the beginning, because more amino acids are changed. 

I chose an insertion when we were asked to choose our own mutation that would make the greatest difference, therefore the greatest damage to the protein. I chose to insert a G directly after the start codon. Inserting a base pair at the beginning made a huge difference to the protein, because it changed all amino acids in the protein except for Met. My mutation changed the protein the most out of all the ones I tried in the lab. This was because the mutation occurred at the earliest time possible. An insertion also changes the amino acids completely. 

An example of a mutation that occurs in humans is Tay-Sachs disease. It is very rare but depending on the onset can be deadly. The autosomal recessive genetic disorder destroys nerve cells in the brain. Gangliosides are fatty substances which are necessary for development of the brain. Normally, gangliosides are broken down, but people who have Tay-Sachs disease lack the enzyme that breaks them down. This destroys the functioning of the nerve cells. There is a mutation on the Hex A gene that causes Tay-Sachs. 

Human DNA Extraction Lab Conclusion

In this lab, we asked how DNA can be separated from cheek cells in order for it to be seen and studied? We found that in order to extract DNA from cheek cells, three steps must be followed: homogenization, lysis, and precipitation. We accomplished this by homogenizing the cell's tissue with polar liquid. This breaks down the cell membrane and nuclear membrane of the cheek cell. We scraped off some of our cheek cells with our teeth, then swiveled it around in our mouths for 30 seconds. Afterwards we added soap, which was involved in lysis (the disintegration of the cell membrane). We used pineapple juice to break down histones found in DNA that the DNA wraps itself around. This is because pineapple juice, like a few other liquids, has catabolic proteases, enzymes, that help to break down the histones. Then we poured cold isopropanol alchohol onto the test tube and due to the nonpolarity and the polarity of the DNA the DNA became a precipitate and rose to the top of the isopropanol alchohol layer. This data support our claim because in order for DNA inside the nucleus to be seen, first the cell membranes, plasma membranes, and nuclear material must be broken down.

While our hypothesis was supported by our data, there could have been possible errors due to gargling the Gatorade for less than exactly 30 seconds. This would have affected the experiment in that all of the cheek cells would not have been caught in the solution. Also when we left the test tubes in the rack for observation, we did not time the 5 minutes exactly and this may have not allowed the solution to settle enough. I think our group should have used timers for both the gargling of Gatorade and the test tube 5 minute observation to make the experiment more accurate.

This lab was done to demonstrate our understanding of DNA and the process of extracting DNA out of a cell. From this lab I was able to understand how DNA is located in the cell, and that all the membranes that must be broken down differently in order to see the DNA. Based on my experience in this lab, I can apply this same process to extracting DNA from any cells and understand how the process works.

Unit 4 Reflection

This unit focuses on genetics and why individuals have the traits that they have. We started the unit by studying the cell cycle, the way that our body cells formed and the way that many asexually reproducing species reproduce. The cell cycle consists of interphase (the copying of DNA), mitosis (DNA and organelles split), and cytokinesis (the cell officially divides in two). This was one of my strengths; I was able to understand the different phases and the purpose of the cell cycle. We also learnt about asexual and sexual reproduction, and the pros and cons of both. Asexual reproduction yields tons of offspring and is possible without a mate, but there is no genetic variation and the species will not stand the test of time. Sexual reproduction has lots of genetic variation and creates competition for mates, but it requires time and energy and exposes you to parasites. I felt that this topic was fairly straightforward. Meiosis is the process in which gametes (sex cells) are formed. In humans, these are the sperm and egg cells. They are haploid, meaning that they have half the normal number of chromosomes. This is so that during recombination, the new zygote cell will be diploid. I felt strong on this topic. I feel that determining incomplete dominance from codominance as well as looking at dominant and recessive alleles in punnett squares is one of my strengths.

The Law of Segregation and the Law of Independent Assortment are definitely my weak areas. I think that if I try to draw meiosis from memory with the different alleles on each chromosome, I will be able to conceptualize the laws better. I understand the basic definitions, but don't know whether I'll be able to apply them to a specific scenario yet.

I definitely have a better understanding of genetics, punnett squares, and I feel like I am more knowledgeable about why individuals look and are the way they are. I have learnt a lot from doing the infographic; it helped me understand the concepts better when I did research and created my own graphics and diagrams. I would like to learn more about the common human genes that are more complicated than basic dominance and recessiveness. I am also interested in learning more about genetic disorders.

My VARK learning style is multimodal. My scores were visual 7, aural 6, speech/writing 5, kinesthetic 4.  Kinesthetic is my lowest, because I don't tend to learn from simulations as much. These are the scores I would have expected, because diagrams and charts tend to stick in my mind. I will focus on learning and understanding diagrams from the vodcasts and the textbook; during tests I often find myself trying to visualize those.

Coin Sex Lab Relate and Review

         In this lab we looked at how the probability of having a child with a certain trait was related to actually predicting how many children would actually have that trait. In order to illustrate how genes separate during meiosis, we used coins as props. We determined what possible genotypes we had by looking at our phenotypes; for example if a person had a phenotype of brown hair their genotype could be either BB (homozygous dominant) or Bb. One each side of the coin we wrote one allele (if an individual was heterozygous for brown hair they would write "B" on one side of the coin and "b" on the other.) When we dropped the coins onto the table, it was random which allele landed face side up. This is a simulation of meiosis. When we subsequently paired our coin with our partner's coin to find out the offspring's genotype, we simulated sexual recombination.
         We did a dihybrid cross--we looked at the gene for having brown vs. blonde hair, and the gene for having brown vs. eyes at the same time. We crossed two individuals who were double heterozygous. Their genotypes were BbEe (B=brown hair, b=blonde hair, E=brown eyes, e=blue eyes). The expected phenotypic ratio was 9 brown hair brown eyes: 3 brown hair blue eyes: 3 blonde hair brown eyes: 1 blonde hair blue eyes. Our results were 8 brown hair brown eyes: 3 brown hair blue eyes: 4 blonde hair brown eyes: 1 blonde hair blue eyes. Probability says how likely something is to happen, but the certainty of something actually happening is different. Our results were close to the expected, but slightly different.

Probability is a prediction of the likelihood of an event occurring. If thousands of trials were to be done, the law of averages would ensure that the probability of getting a certain trait was met. However, if a person were to flip a coin 5 times, it is entirely possible that they could flip 10 heads in a row, even though the probability of flipping a head is 50%. Most humans don't have that many offspring compared to other species, and often times probability is inaccurate in predicting offspring's traits.

Genetics can be seen everywhere in our life. Genes are the reason why people have certain traits and the reason why people look the way that they do. I have wondered in the past why some children have completely different traits, such as blonde hair or blue eyes (autosomal inheritance), than their parents do. Now, with the knowledge of punnett squares and different alleles, I can answer that question. Also, knowing how X-linked inheritance works, I can understand why certain people I know are colorblind, even if neither of their parents are.

Genetics Infographic

https://magic.piktochart.com/output/9381881-genetics-infographic

Unit 3 Reflection

Throughout this unit, there were a variety of topics some of which I found to be fairly straightforward, and some which I found difficult. Coming fresh off of the macromolecules unit, I found it helpful to see some of the ways in which carbohydrates, lipids, and proteins are found in cells. Carbohydrates are found in chains around the cell membrane, the cell membrane is made up of phospholipids. Channel proteins as well as proteins made by ribosomes that are found inside the cell.
We also discussed the different parts of a cell; we likened the cell to a factory. There are many organelles that have very specialized jobs: the nucleus holds the DNA that contains instructions for all the cell's activities; the mitochondria are the "powerhouses" and carry out cellular respiration; the ribosomes do protein-synthesis; the ER packages and completes protein-making...etc. I found this topic to be one of my strengths because the different functions of how each organelle works is easy to remember by comparing it to a job in a factory; such as comparing the Golgi Apparatus to a UPS.
We also studied how the cell membrane is selectively permeable, and only some substances can pass through. I felt as though diffusion was definitely one of my strengths: understanding how particles move from a high concentration to a low concentration until equilibrium is reached, at which point particles move back and forth in every direction. I feel as if I have a grasp on the differences between osmosis, diffusion, and facilitated diffusion. Active transport requires energy to be put in from the cell, whereas passive transport does not.

Photosynthesis and respiration were very detailed and went far beyond what I had learnt in the past about them, and in this unit we learnt a lot more about the chemistry behind the basic reactions. Photosynthesis was difficult to understand at first, but with more drawings and with reading the information from multiple sources, I began to grasp it. Inside the mesophyll cells, inside the chloroplasts, photosynthesis occurs. The "photo" part of the reaction happens in the thylakoids of the granum, and the "synthesis" part happens in the stroma of the chloroplast. I feel that I still do not have a full understanding of cellular respiration, although I basically understand that it takes place in the mitochondria and that the three stages are glycolysis, the Krebs cycle, and the electron transport chain. I think with more practice and more re-reading of the topic, I will be able to strengthen this weak area.

From this unit, I learnt that drawing diagrams (and color coding them) is extremely helpful and is great for really understanding the information. I learnt how to properly focus a microscope and reinforced the do's and don't's of how to use it. I learnt more about the structure and function of cells as well.  I want to learn more in the future about the chemistry behind the Krebs Cycle and the Calvin Cycle. I wonder how the first scientists even imagined that cells could exist, and I think it is fascinating how they designed the microscopes. In order to study, I am going to re-draw the diagrams and look at unlabeled diagrams to try and name all the parts.

Egg Diffusion Lab

In this lab we wanted to further explore how diffusion works, and we wanted to find out how and why a cell's internal environment changes when its external environment changes? We first took two eggs and soaked them in vinegar for 24-48 hours. After this amount of time, the calcium carbonate shell had been dissolved by the acetic acid. After washing and recording the mass and circumference of the eggs, one egg was placed in deionized water and the other was placed in sugar water. We let the eggs sit for 24-48 hours, and then recorded the new circumference and mass.

When the sugar concentration of the solution increased, the mass and circumference of the egg decreased, and the egg began to look shriveled up. The mass of the egg in sugar water decreased on average by 47.25% and the circumference decreased on average by 22.94%. In the egg that was placed in deionized water, the sugar in the macromolecules were the solute inside of the egg and water was the solvent outside. From a desire to reach equilibrium, the solvent wanted to move by diffusion from a low concentration of solute (outside cell) to a high concentration of solute (inside cell). Therefore, the cell gained water and grew. This is an example of a hypertonic solution.

It is desirable for cells to have an equal concentration of solute and solvent inside and outside of the cell. The cell membrane is semi-permeable and does not allow for the solute to leave the cell or enter the cell. The conditions of the cell are only changed by the movement of solvent. This is an example of passive diffusion. The cell expanded when put in vinegar, it shrunk when put in sugar water, and it grew when put in water.
In class we have learned about molecules which move from a high concentration to low concentration when there is an unequal concentration of solute or solvent.

Since cells grow when they are put in water, fresh vegetables in markets will be sprinkled with water to keep them fresh and help them to not shrivel up. Salt is sometimes sprinkled on roads to melt ice because since salt is a solute, the ice (which is water and is a solvent) the solvent will move outside and in order for it to do this it must melt. However, if the salt is sprinkled along the roadside where there are plants, the plants will die. This is because the plant cells will shrink when exposed to too much salt, and when they shrink, they will not function as well.

I would like to see the effect of putting salt on plants in action and other such experiments that illustrate cells shrinking due to too much solvent. Also, I would like to know if the shriveled up egg was placed back in deionized water, how long would it take to be revived?

Data Table for Eggs in Deionized and Sugar Water

Top: Egg that was placed in sugar water
Bottom: Egg that was placed in deionized water

Egg Macromolecules Lab

The egg membrane tested positive for having polysaccharides, lipids, and proteins. When the test tube that contained egg membrane was tested for proteins, and sodium hydroxide with copper sulfate was added, it turned from blue to purple, and we knew that proteins were present. It is logical that proteins would be found in the egg membrane because transfer proteins are used to transport substances back and forth through the cell.
The egg white tested positive for all four macromolecules: monosaccharides, polysaccharides, lipids, and proteins. We added benedicts solution, iodine, Sudan III, and sodium hydroxide mixed with copper sulfate, to see if monosaccharides, polysaccharides, lipids, or proteins respectively, were present. The test tube with benedicts turned from blue to green to orange, the test tube with iodine turned from brown to black, the test tube with Sudan III turned from red to orange. Monosaccharides, polysaccharides, and lipids are needed in the egg white for proper growth and development of the chick (if the egg was fertilized).
The egg yolk tested positive for proteins and lipids. The test tube which had Sudan III added turned from brown to black, which showed that lipids were present. The egg yolk is the actual cell, and lipids were sure to be found in the membrane.

While our hypothesis was supported by our data, there could have been errors due to how much chemical was added into each test tube, and how each part of the egg was separated and put into its own test tube. We might have added too much or too little of each chemical to each sample due to errors in how big each drop was. If one test tube had more chemical than another, it would affect if the egg tested positive for that molecule, or what color it turned. It was also difficult to isolate the egg membrane, and I believe there was still egg white mixed into the test tube when we tested the membrane. Due to these errors, in future experiments I would recommend that we use an instrument to cut the membrane and measure how much chemical we add before we add it.

This lab was done to demonstrate our understanding of where macromolecules are found in the cell. From this lab, I learned firsthand how phospholipids are found in the membrane, as well as transport proteins and carbohydrate chains (polysaccharides). Based on my experience in this lab, I better understand where the different macromolecules are found.                                            

20 Scientific Questions About the World Around Us

From the article, The 20 Big Questions in Science, the one "big" question that I found very interesting was: Why do we Dream? I thought that it was fascinating that we spend over a third of our lives sleeping and I've always wondered where the sometimes random dreams that I have come from, and what sparks them. There are two possible hypothesis for this question: that dreams are "expressions of unfulfilled wishes," or "random firings of a sleepy brain."

Here are 20 "big questions" of my own:

1. When we look at many animals from the same species, they seem identical to us. Do other species think the same thing of us humans?

2. Roughly when and how did the first human being evolve?

3.  How did scientists come to know so clearly about the structure of the whole universe when space probes nor people have explored that far?

4. Were humans initially intended to consume dairy?

5. Is there scientifically such a thing as a genius? If so, what in their DNA gives them these special qualities?

6. If a child has a physical or mental disability, when in their childhood will signs of this start to show in their behavior?

7. What makes some cancers more life-threatening than others?

8. If a cancer is diagnosed sooner, does that mean that the patient has a greater chance of being cured?

9. If it is said that babies don't have long-term memory, how long will they remember each event that happens to them? How long will it stay in their memory?

10. As time progresses, will people begin to live longer and longer each generation?

11. Why do some genetic disorders develop later in life?

12. Why don't any children remember their infancy?

13. Which continent on the Earth became inhabited first?

14. What is the most common species on the Earth?

15. How are viruses fought by the body, and why do they not require antibiotics?

16. Why are people more likely to be woken up in certain times of their sleep than other times?

17.  Are you more likely to have dreams if you go to bed preoccupied?

18. Does growth happen in spurts?

19. What are some major technological advancements that might happen in our lifetime?

20. Why can't we get vaccinated for common colds?

Identifying Questions and Hypotheses

Is GMO safe?

On the Center for Food Safety, it is explained how scientists have conducted an experiment to test whether or not GMO foods are safe for us to eat. Even though some people (such as GMO seed developers), are saying that these GMO foods are safe to eat, there is no scientific evidence for that. The study proves that there is still valid concern about the safety of genetically engineered foods. The question that the scientists asked in this study was "Is GMO safe?" There has been quite a bit of speculation by scientists that GMO foods are not safe to eat. There has been international recognition that acknowledges the risk posed by GMO's. The scientists conducting this study hypothesize that GMO foods do pose some risk, as engineering foods is very different from conventional breeding. There were also previous aspects that led the scientists to form this hypothesis such as concerns regarding the spread of herbicide weeds, negative health impacts, and increasing the use of herbicide.


Center for Food Safety (Source) 

Unit 2 Reflection

This unit, titled "Chemistry for Biologists" gave us a basic understanding of chemistry as it relates to biology, the study of life. We learnt about the basic structure of all matter, the atom. Exploring deeper into the structure of the atom, we learnt about protons, neutrons, and electrons, where protons and neutrons are roughly equal in mass, but an electron is 1/1840 of the mass! Atoms can bond with each other either in an ionic bond (transfer of electron(s)) or a covalent bond (sharing of electron(s)). I feel strong in this area, and I understand atoms, elements, and how atoms bond with other atoms. We studied "the big 4" macromolecules (giant molecules formed during polymerization): carbohydrates, lipids, proteins, and amino acids. We needed to understand both their structure and function. Carbohydrates look like rings of carbon, hydrogen, and oxygen, and can be either monosaccharides, disaccharides, or polysaccharides, depending on how many of these "rings" are chained together. Proteins are made of amino acids and have four levels of structure: primary, secondary, tertiary, and quaternary. Nucleic acids are formed from nucleotides, which are made up of a nitrogenous base, a 5-carbon sugar, and a phosphate group. I think that the structure of carbohydrates, proteins, and nucleic acids is an area of strength for me, but the structure of lipids is a weak point. I understand lipids are long chains of carbon, hydrogen, and oxygen, but I can't really visualize the general structure. In class, we also discussed and performed experiments about enzymes and how they work best in their optimal pH and temperature.

Learning about the basic chemistry to understand life science was a great experience for me because it helped me understand the science behind many routines we have in our everyday lives. For example, we are told often to eat certain foods because they have protein in them and are good for us. However, before this unit, I did not know how amino acids were broken down and then rearranged to create new proteins.

During this unit, I found enzymes very interesting. I want to learn more about what reactions they speed up in our bodies and why we cannot live without them.

Cheese Lab Conclusion

In the lab in which we researched which conditions and which curdling agents would be optimal for making cheese. We tested four curdling agents: chymosin, rennin, buttermilk, and milk as a control. To see which pH conditions were best, each curdling agent was tested in acidic conditions, basic conditions, and a neutral pH control. In order to find out which temperature conditions were optimal for the enzymes to work best, each curdling agent was also tested in a hot temperature, a cold temperature, and temperature control. We found that chymosin and rennin are the most effective curdling agents, and their optimal conditions are in warm and acidic environments. The lowest curdling time in the experiment was found under acidic and warm conditions, the lowest time being 5 minutes. Under many of the conditions we tested, such as basic and the controls, the only curdling agents which produced curds were chymosin and rennin. Milk did not produce any curds in 35 minutes, our given amount of time, while buttermilk only produced curds in acidic conditions. Rennin is an enzyme which in found in the lining of a baby calf’s stomach, in which the conditions are warm and acidic. This explains why warm and acidic conditions were optimal. This data support our claim because the numbers show that chymosin and rennin produced curds in the least amount of time (5 minutes) in a warm and acidic environment.

While our hypothesis was supported by the data, there could have been errors due to the fact that we checked for curds every 5 minutes. The data shows that under acidic conditions, chymosin, rennin, and buttermilk all curdled in exactly 5 minutes. This is a false conclusion to make because it is highly possible that one or more of the curdling agents curdled before 5 minutes. However, we did not account for this because we only measured time every 5 minutes. This was probably an accuracy error. To avoid this error we could have checked for curds every 2 or 3 minutes instead of 5. Also, there was some error in lack of accuracy in timing. We added the acid, base, and water control to each test tube at slightly different times, and more time had passed still by the time we recorded our initial time and officially started the five minutes. This may have affected the experiment in that the first time we checked for curds, it had probably been more than five minutes. In our data, it shows that buttermilk, rennin, and chymosin all curdled in 5 minutes in the acidic conditions. This may not have actually been true. In the future, it will be better to be more prompt with added the acids and bases and recording the initial time.

This lab was done to demonstrate an understanding of how enzymes work and how they speed up chemical reactions. From this lab I learned that there are clear differences in the results when enzymes are in their optimal conditions, which helps me understand the concept of how enzymes work best in their optimal pH and optimal temperature. Based on my experience in this lab, I now understand that to produce best results, it works well to use as many substrates and enzymes as possible, in their optimal conditions.

	Time to Curdle (minutes)
Curdling Agent:	Chymosin	Rennin	Buttermilk	Milk (control)
Acid	5	5	5
Base	20
pH control	15	10
Cold
Hot	5	5
temp control	10	10

        In the lab, we wanted to find out which carbohydrates tasted the sweetest: monosaccharides, disaccharides, or polysaccharides? Carbohydrates which are monosaccharides and disaccharides have a significantly sweeter taste than carbohydrates which are polysaccharides. Fructose, which definitely stood out as the sweetest carbohydrate, had 180 as its degree of sweetness on a sweetness scale of 0 to 200. We set the sweetness level of sucrose as 100 initially, and then worked around it as we tasted all of the other carbohydrates. We chose fructose to be 180, significantly sweeter than sucrose. Sucrose and fructose, both monosaccharides, tasted sweeter than all the other carbohydrates that were sampled. The lowest numbers on the sweetness scale were both given by polysaccharides: starch and cellulose. Starch and cellulose both had fine, powdery textures, and tasted very bland, without the faintest hint of sweetness. While collecting initial information, we found that sucrose and fructose, the sweetest tasting carbohydrates, are both found in fruit, table sugar, sugar cane; foods which have a sweet taste. Polysaccharides such as starch and cellulose are found in foods such as potatoes and vegetables, which have a bland, non-sweet taste.
   
     Polysaccharides are made up of many monosaccharide rings that are all bonded together. Since a chemical bond is stored energy, if there are more bonds, then there is more energy in that carbohydrate. Therefore, if an organism were to eat a carbohydrate that was a polysaccharide such as starch or cellulose, that organism would benefit from the energy. As humans, we try to eat foods that contain carbohydrates such as starch before a long run because of the amount of energy stored in it. Polysaccharides such as starch would probably be more desirable due to this energy.

   Although every person tasted the same carbohydrates, they gave different ratings on the sweetness scale. Everyone would have tasted the carbohydrates in a unique way because their taste buds taste different substances differently. Also, taste is something that is extremely subjective, and prone to observer bias, so the numbers would have certainly varied. There might have also been error of the taster due to whether they accurately remembered the sweetness of each carbohydrate. Even though the ratings varied, the overall trend was the same. Most people found that polysaccharides tasted less sweet than the monosaccharides and disaccharides.

    According to NCBI, for any food that we eat or drink, there are taste receptors in the taste buds on the mucous membrane that test the taste of food. Chemical substances from the food are recognized by the sensory cells. According to Popular science, people who have a lot of papillae on their tongue taste certain flavors stronger than others who have less papillae. The chemicals on our tongue that trigger recognition of the five senses vary between people, causing them to taste foods slightly differently. This may have caused some of the varying ratings in our sweetness lab.

Biology Collage

Bleaching Jeans in Various Concentrations of Bleach

In this lab we wanted to find out which concentration of bleach would be best for fading the color out of new denim jeans in ten minutes without causing any damage to the fabric material. We found an overall trend: the higher the concentration of bleach we used, the more faded the jeans would become. Each bleached denim square was rated on a scale of 1 to 10 (10 being completely white and 1 being no color change). The jean squares, which had been soaked in the petri dish containing 100% bleach, had an average of 7.3 on the “color removal scale”. This was the highest average among all the denim squares soaked in varying concentrations of bleach; 50% bleach, 25% bleach, 12.5% bleach, 0% percent bleach (100% water which was used as a control). There was a very visible change in the jeans left in the 100% bleach; most of the darker blue coloring was no longer seen after about two minutes into the bleaching process. It is widely known that bleach is a chemical used to “whiten” or removal color from something, and our experiment confirmed this fact. After the denim squares were soaked in water, the jeans in 100% bleach appeared very faded with little original blue color and had a yellowish tinge as well. In the other bleach solutions, some of the jeans appeared vaguely lighter, and some had no noticeable change at all. The amount the jean squares were faded on the “color removal scale” decreased as the concentration of the bleach decreased. The 50% solution jeans had an average of 5, the 25% bleach soaked jeans had an average of 1.3, followed by 0.6 in the 12.5% bleach. The condition of the jeans was damaged very little in this experiment; the fabric damage reaching a high of 1.3 in the 100% and 50% bleach, and a low of 1 in the 25% and 12.5% bleach. This data support our claim because it is evident from our results that the highest concentration of bleach produced the most faded jeans, which was the desired outcome.

While our hypothesis was supported by our data, there could have been errors due to our mistake in sometimes failing to keep all the constants the same. Possible error may have resulted from the many different pairs of jeans that we used to cut out the denim squares. Each pair of jeans has a unique shade of blue; some jeans that we used in our lab were a very dark wash, and some were a lighter wash. This definitely affected our judgment in how faded each denim square was. The method that we used for analyzing and measuring the results of the experiment is especially prone to observer bias, since the average color removal results were solely dependent on subjective judgment. Due to these errors, in future experiments I would recommend using the same pair of jeans when cutting out the 5x5 cm squares of denim to ensure that each square started out being the same shade. I would also suggest using a scale of 1 to 5 scale instead of a 1 to 10, and clearly defining what would constitute a 1, 2, 3, 4, and 5 to reduce observer bias and make the experiment more repeatable.

This lab was done to demonstrate knowledge of the scientific method; to show that we understood the six different steps and could write a proper hypothesis. From this lab I got an opportunity to practice the scientific method that we learnt in class, and the experiment helped me better understand how to be precise while doing labs as well as being extra cautious while working with chemicals such as bleach. Based on the experience I’ve had with this lab, I now know how to apply the accuracy and careful following of the procedure to other labs in the future. I have also learnt the correct way to form and write a hypothesis in all future labs; using if...then… form and putting the assumptions in the if… part of the hypothesis.

Concentration (% bleach)	Average Color Removal (scale 1 to 10)	Average Fabric Damage (scale 1 to 10)
100	7.3	1.3
50	5	1.3
25	1.3	1
12.5	0.6	1
0	0	0