Unit 2 Reflection

        Unit two encompassed macromolecules such as carbohydrates, lipids, proteins, and nucleic acids, as well as molecular properties. Carbohydrates are saccharides, atoms of carbon, hydrogen, and oxygen formed into rings. Lipids include phospholipids that make up cell membranes, as well as fatty acids in food that can be saturated or unsaturated. Proteins include enzymes, which facilitate the chemical reactions of substrates into products, and structural proteins, which make up different parts of the body. Nucleic acids are composed of nucleotides, which combine at the bases and phosphate groups to form long chains of DNA or RNA, and also include ATP, which is broken down to acquire energy. In addition, polar molecules such as water have properties like cohesion and adhesion, which allow them to be attracted to other molecules of the same or different substance. These properties allow water to be very useful in making solutions, usually as the solvent. Another type of mixture that water is often found in is a suspension, such as blood or cytosol, where undissolved materials fail to settle out. This attraction is called a hydrogen bond, where oppositely charged regions attract; other bonds include ionic bonds, in which atoms gain or lose an electron, and covalent bond, in which electrons are shared.

Nucleic acids include DNA, or deoxyribonucleic acid

        We also completed a number of different labs in this unit, including the sweetness lab and the cheese lab. These experiments provided further insight into various topics, showing how a higher number of rings leads to less sweet sugar, and how a hot, acidic chymosin solution gave the optimal environment for cheese curdling in milk, respectively. The sweetness lab was mostly a success, aside from a subjective analysis providing slightly contrasting results, but the cheese lab data was skewed by having to clean up early, and some groups not incubating the samples for the full length of time. This led to a somewhat longer curdling time, but the results were still conclusive. In general, however, the labs proved a success in supporting certain concepts and hypotheses and grantng insight, aside from the minor setbacks due to user error.

The sweetness lab compared the sweetnesses of different saccharides

        All in all, I attained from this unit an abundance of both information and experience, and I look forward to learning more in-depth about the processes and makeup of enzymes and ATP, and finding out the nuances and complex aspects of how our body functions.

Sweetness Lab

        In the sweetness lab, we looked at the sweetness of different sugars, including sucrose, galactose, maltose, lactose, and starch: we found that in general, monosaccharides were the sweetest and polysaccharides were the most bland. This was supported by our high ratings (with 100 being the base sweetness of sucrose) of 150 and 70 for glucose and fructose, respectively, and our low ratings of 0 for starch and cellulose; monosaccharides averaged about an 83.3 on our scale, disaccharides a 45, and polysaccharides a 0. This data supports our claim, as the differences between the different sugar types were both significant and consistent. The carbohydrate structures of the different sugars likely affected their sweetness; our results also supported this, with the monosaccharides with the least rings and bonds being much sweeter than the polysaccharides with the most.

The sugar samples in order of sweetness

The different sugars tested

       As with any experiment, the sweetness lab results were not without flaws or inconsistencies. The testers often gave different ratings for the samples, which probably resulted from various taste sensitivities of the testers or slightly varying samples. In addition, as subjective ratings made up most of the experiment, many testers likely had contrasting impressions of the sweetness of the sugars. Even the amounts of sugar in each sample were arbitrary, which could have led to a skewed perception. According to the U.S. National Library of Medicine, taste is linked to smell, and different taste buds on the tongue have varying degrees of sensitivity to different tastes. This could have further influenced testers to record contrasting results. All in all, the sweetness of different sugars are affected by many factors, some of which are very difficult to control.

Sweetness lab results

Biology Collage

Jean Fading Lab

       In this lab, we asked what concentration of bleach would be best to fade the color out of new denim material; we found that about a 25% concentration was most effective, as the 25%-bleach-soaked-denim had less fabric damage but still yielded a reasonable amount of fading. We rated those jean samples an average of 2 out of 10 for fabric damage, and an average of 3 out of 10 for color removal. A Chlorox article claims about a 5.9% concentration of bleach being effective, but their more concentrated and potent bleach solution would mean this would be somewhat higher with generic bleach. This data supports our claim because the final concentrations are comparable to an extent. (especially taking into account some possible errors below)

The varied effects of different concentrations of bleach on denim

        The data partly supports the expected results, but yielded a higher successful percentage of bleach due to the partial submerging of the fabric. This incomplete submerging was a result of the small petri dishes and stacking of the fabric, and would have made a higher concentration of bleach necessary with the limited contact. The jeans stacking together covered some area that would ideally also be in contact with the bleach. Also, not all of the denim was submerged, because the petri dishes were insufficient in height; another centimeter of height would probably be more effective. For future executions of this lab, a larger container (with more solution) and a simple separation of the fabric samples would help the denim be more fully submerged and show a more accurate representation of the effects of the bleach concentration on the jean pieces.

Results show significant variation across different jean samples

        This lab was done to demonstrate the proper execution of the scientific method and the process that must be undergone in an experiment. We learned how a proper hypothesis is formed, and also how different variables and constants are utilized in an experiment. This helped me understand and experience firsthand the correct procedure of a scientific experiment. Furthermore, based on my experience from this lab, I now understand how 25% is an effective percentage of bleach to use with jean fading.

25% bleach, 75% water: the optimal concentration for jean fading