Unit 2 Reflection

Coming into Unit 2 in biology, we applied what we learned in Unit 1, to set-up our experiments with implementing the scientific method. We not only learned about the living things that were introduced in Unit 1, but we looked more into those living things, learning not only what those living things are, but what makes up them, such as the individual molecules. In this unit we looked at the Big 4 macromolecules.

The first one was carbohydrates, that are either monosaccharides, disaccharides, and polysaccharides that are represented by the number of rings they have. The carbohydrates are one of the most important molecules because it is the main energy source for the consumer and it is how the producers store their energy.

The next molecule we focused on were lipids, which are just long chains of fatty acids, either saturated fats or unsaturated fats, that are used for energy storage, making cell membranes, and hormones.

Another type of molecule that we learned about were nucleic acids, made up of thousands and thousands of nucleotide. Nucleotides bond to make either 2 strands, called DNA, or 1 strand, RNA. It tells us who we are, as it contains the information, such as characteristics inherited from generations and generations past.

The last type molecule that we learned about were proteins, which are just made up of amino acids. Proteins, the 2 types are structural proteins and enzymes, are one of the most necessary molecules because it is used to support the body, help cells communicate, speed up chemical reactions, and channel proteins.

Towards the end of this unit, we really focused on enzymes, one of the types of proteins. We did a virtual lab explaining what enzymes were and how they worked, and we did a lab where we made cheese, where we learned the applications for enzymes. We learned that in an enzyme 3 very important parts are the substrate, active site, and product. The substrate is the molecule the enzyme works on. Active site is where the substrate attaches to the enzyme. The product is what the enzyme produces. In the cheese lab that we did to understand the applications of enzymes, we learned which enzyme made the reactions faster and which conditions made the protein not denature.

This unit was one that not only taught me about what makes up living things, but I grew as a student and scientist through the labs we did. I learned about time management, specifically through the labs we did, because through the different labs we realized that only if we all worked well and efficiently could we finish the lab on time. Another one of the skills I practiced was perseverance, because I couldn’t and wasn’t able to give up when I was trying to learn the building blocks of life.

Although the unit is over, I still want to learn about DNA, something mentioned in this unit. To me, DNA is the most interesting part of humans and biology because it tells us who we are. DNA can usually tell you if you have a specific disease or not. It can tell you what characteristics from your parents or your long lost relatives you inherited. DNA is one of the most important, I think, parts of biology, and I am very interested in learning and understanding how DNA might or does play a role in the common cold.

Sweetness Lab

In this lab, we asked the question, “How does the structure of a carbohydrate affect its taste regarding sweetness?” We found that the monosaccharides were the sweetest, disaccharides were not as sweet, and polysaccharides were the most bland. In our experiment, the monosaccharides that we tested were galactose, fructose, and glucose. The disaccharides were sucrose, maltose, and lactose, and the polysaccharides were cellulose and starch. In the experiment, sucrose was given a rating of 100 in regards to its degree of sweetness, glucose was given a 120, fructose was given a 150, galactose was given a 130, maltose was given a 70, lactose was given a 30, starch was given a 5, and cellulose was given a 2. These results could have come from the research that monosaccharides, since they have just one sugar unit, are sweeter than the polysaccharides or disaccharides with multiple. In addition, monosaccharides are more used and found in sweet foods. This data supported our claim because the monosaccharides that we tasted proved to be sweeter than the disaccharides and polysaccharides that we tasted.

The carbohydrate structure affected how they are used by cells and organisms because since monosaccharides have only 1 ring, they are used in foods. Since disaccharides have 2 rings they are used for energy. Since polysaccharides have 3 or more rings, they are many used to store energy and is used for photosynthesis and is found in cell walls.

In this experiment, not all testers gave each sample the same rating. The testers could have not drank water in between each test, meaning that the sugar could’ve tasted sweeter or more bland than it was supposed to. Everyone has different taste buds, so one sugar would have tasted different for another person. Also the spoons could have been contaminated when tasting the different sugars, mixing many different tastes and therefore giving false results.

According to Dr. Robert Margolskee, what causes humans to taste sweetness is the receptor proteins on the taste cells in the taste buds getting stimulated by something sweet. After it gets stimulated, a signal is sent to the centers of the nervous system that respond to sweetness, causing humans to taste sweet. But what causes people to rank the sweetness of the same samples differently because of tasting the sweetness differently is that a person might have more taste buds and therefore more taste cells or they might respond to the sweet signal differently.

This lab’s main focus was to learn about how the structure of a carbohydrate can affect its taste, and how it ultimately affects the cell or organism.

http://www.npr.org/2011/03/11/134459338/Getting-a-Sense-of-How-We-Taste-Sweetness (Dr. Robert Margolskee’s interview)

Biology Characteristics of Life

Jean Lab

In this lab, we asked the question what concentration of bleach is best to fade the color out of new denim material in 10 minutes without visible damage to the fabric. We found that a higher concentration of 100% took out the most amount of color on the jeans but damaged the fabric the most, because when we ranked the color removal and the fabric damage on a scale of 10, the average for the color removal was a 7 and a 4 for a the fabric damage. But with the smallest concentration of 0%, we found that there was no damage to the jeans and no color was taken out, as the average for both the color removal and the fabric damage was 0. However with the 25% concentration of bleach, the highest amount of color was taken out without any visible damage to the fabric, as the average for the color removal was a 4 and there was no fabric damage. These results could be supported by knowledge about the properties of bleach saying that bleach breaks down pigments and gets the color of the clothes as close as possible to white because 100% of bleach broke down many of the pigments and removed most of the color of the jeans, and the lower concentrations broke down fewer of the pigments and took out only a little of the color.

While our hypothesis was supported by our data, there could have been a few errors that affected our experiment. While doing the experiment, the times that we left the bleached jeans out before dousing it in water were not controlled and varied between each concentration. Also, the water we used as our negative control became contaminated, because when measuring the water in the graduated cylinder, the water got contaminated with bleach because before pouring the water in the graduated cylinder, we had poured the 100% concentration, the 50% concentration, the 25% concentration, and the 12.5% concentration of bleach. In the future, to not repeat the mistakes made that could have had a slight effect on our experiment, almost invalidating it, we could have one person designated to keep track of the timings making sure everything is controlled. Also, regarding the error of contaminating the water, we should have done the experiment starting with 0% and ending with the 100% concentration rather than the other way around like what we did during the experiment.

This purpose of the lab was to familiarize ourselves and demonstrate our knowledge of the scientific method through an experiment. Through this lab, we learned where we were at in the scientific method, meaning we learned what we were good at and what we weren’t good at. We learned that we were able to follow instructions but need to pay attention more on making the experiment controlled. Based on my experience from this lab, I know the scientific method and am able to use it properly in an experiment.