Lab 2: The Chemistry of Life

  1. Nitrogen fixation is a natural process by which inert or unreactive forms of nitrogen are transformed into usable nitrogen. Why is this process important to life?

Nitrogen fixation as a process is significant to life in the sense that it converts the unreactive form of the inert gases into usable form. The conversion produces nitrates and nitrates which are used as nutrients by plants. The plants in turn use the nutrients to manufacture of proteins which are useful for human being. The proteins are useful for the formation of body cells

  1. Given what you have learned about the hydrogen bonding shared between nucleic acids in DNA, which pair is more stable under increasing heat: adenine and thymine, or cytosine and guanine? Explain why.

Hydrogen bonding in cytosine and guanine are more stable under increasing heat rather temperatures. This is because of the presence of three hydrogen bonds which means more heat is required to break them down. Thymine and adenine have only two hydrogen bonds.

  1. Which of the following is not an organic molecule; Methane (CH4), Fructose(C6H12O6), Rosane (C20H36), or Ammonia (NH3)? How do you know?

Ammonia is not an organic molecule since it does not contain carbon as part of the component.

Experiment 1: Testing for Proteins

Data Tables and Post-Lab Assessment

Table 1: A Priori Predictions

Sample

Initial Color

Final Color

Is Protein Present?

1. Albumin Solution

Extremely pale yellow

Yellowish purple

yes

2. Gelatin Solution

Light yellow (almost clear)

Lavender

No

3. Glucose

Clear

Clear blue

No

4. Water

Clear

Clear blue

No

5. Unknown

Milky White

Cloudy sky blue

No

Sample

Initial Color

Final Color

Is Protein Present?

1. Albumin Solution

Yellow

Purple

Yes

2. Gelatin Solution

Dark yellow

Purple on Top

Yes

3. Glucose

Clear

Dark

No

4. Water

Blue

Blue

No

5. Unknown

Foggy

Clear

No

Table 2: Testing for Proteins Results

Post-Lab Questions

  1. Write a statement to explain the molecular composition of the unknown solution based on the results obtained during testing with each reagent.

The molecular composition is mostly water, due to the absence of changes. Protein is thus not represented.

  1. How did your a priori predictions from Table 1 compare to your actual results in Table 2? If there were any inconsistencies, explain why this occurred. My predictions were close to the actual results. Glucose and water barely turned blue.
  1. Identify the positive and negative controls used in this experiment. Explain how each of these controls are used, and why they are necessary to validate the experimental results.

The positive control was the egg white solution (albumin solution). It was necessary because white egg has albumin, a vital source of protein. The negative control experiment would be water. This is because water does not have proteins; we therefore did not expect any color change.

This was significant for control tests and allowed comparison to be able to establish that protein was present

  1. Identify two regions which proteins are vital components in the human body. Why are they important to these regions? Formation of cells and the growth of body tissues in the human body.
  1. Diet and nutrition are closely linked to the study of biomolecules. Describe one method by which you could monitor your food intake to ensure the cells in your body have the materials necessary to function. I could use nutrition meal clocking app on my wrist watch to help me monitor food intake. I would remain committed to this method to ensure that I take all the diets required for growth and sustenance of the body

Experiment 2: Testing for Reducing Sugars

Data Tables and Post-Lab Assessment

Table 3: Testing for Reducing Sugars Results

Sample

Initial Color

Final Color

Reducing Sugar Present

1 – Potato

White

Green

Yes

2 – Onion

White

Yellow

Yes

3 – Glucose Solution

Clear

Orange

Yes

4 – Water

Clear

Clear

None

5 – Unknown

Clear

Light Blue

None

Post-Lab Questions

  1. What can you conclude about the molecular make-up of potatoes and onions based on the two tests you performed? Why might these foods contain these substance(s)?

Both onion and potato contain starch that is a polymer of glucose. They store sugar in the form of starch as opposed to other plants which store sugar in other forms.

  1. What results would you expect if you tested ribose, a monosaccharide, with Benedict’s solution? Biuret solution? If Ribose is tested using Benedict’s solution, a positive response is expected since it is a monosaccharide and thus contain glucose. When testing a monosaccharide with Biuret solution, a negative response is expected since monosaccharides do not have peptide bonds

Experiment 3: What Household Substances are Acidic or Basic?

Data Tables and Post-Lab Assessment

Table 4: pH Values of Common Household Substances

Substance

pH Prediction

Test Strip Color and pH

Acetic Acid (Vinegar)

Acidic

Yellow, 4

Sodium Bicarbonate Solution (Baking Soda)

Basic

Green, 8

Milk

Basic

Green/Yellow, 7

Rubbing alcohol

Acidic

Yellow, 5

Wine

Acidic

Yellow, 4

Mr. Clean

Acidic

Green, 9

Post-Lab Questions

  1. What is the purpose of determining the pH of the acetic acid and the sodium bicarbonate solution before testing the other household substances?

This was to establish control experiments. This would help to know what to expect while testing other household substances. If the expectations were met, then we would know that the test went well.

  1. Compare and contrast acids and bases in terms of their H+ ion and OH ion concentrations.

Hydrogen ions (H+) are produced from dissociated acids while Hydroxyl (OH-) from bases. Addition of more acids results into more concentration of hydrogen ions. On the hand, addition of more bases and the dissociation thereof, results into more concentration of hydroxyl ions to the solution thus making it more basic.

  1. Name two acids and two bases you often use.

The two acids I use regularly are vinegar and lemon juice while bases are bleach and soapy detergent.

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