BIO 210 Macromolecules HW PDF

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Lab exercise 5 - Comprehension check 1. Describe the differences and the similarities between monosaccharides, disaccharides, and polysaccharides. Similarities: All of these molecules are carbohydrates. They all have hydroxyl and carbonyl groups. They have a general formula CHO where H is twice as more than C and O. Differences: Monosaccharides consist of only one sugar molecule, it is the monomer subunit and serves as fuel for cells. Disaccharides consist of 2 monosaccharide monomers. Polysaccharides consist of more than two monomers of monosaccharide, their main functions are storage and structure. 2. What is the monomer subunit for carbohydrates? What types of macromolecules can form by linking carbohydrate monomer subunits. Monosaccharide is the monomer subunit for carbohydrates. By linking monosaccharides, disaccharides and polysaccharides can be formed. Polysaccharides are starch, glycogen, cellulose and chitin. 3. Why are carbohydrates important in living organisms? They perform structural and energy storing functions. 4. Why does glucose yield a positive Benedict’s test, but starch does not? Because glucose is a reducing sugar, a monosaccharide that has a free aldehyde group. It reduces the copper sulfate and gives a positive result. Starch is a polysaccharide and is not a reducing sugar. It doesn’t have a free aldehyde or ketone group to react with Benedict's reagent. 5. Name three different monosaccharides and three different disaccharides. What monomer subunits make up the disaccharides that you listed? Monosaccharides: glucose, galactose, fructose Disaccharides: maltose (consists of two monomers of glucose), lactose (consists of glucose and galactose), sucrose (consists of a monomer of glucose and a monomer of fructose) 6. Name three types of polysaccharides found in living organisms. Describe their function and their monomer subunits. Starch - function of storage in plants. Consists of glucose monomers (alpha) Glycogen - function of storage in muscles of animals. Consists of glucose monomers () the chai is branched). Cellulose - structural function in plants. Consists of glucose monomers (beta) 7. You are conducting a qualitative analysis of an unknown solution. A Benedict’s test results in a color change from blue to green. A Barfoed’s test shows no change in color. Lugol’s iodine turns a sample of the solution blue/black. Based on these results, what can you conclude about the contents of the unknown solution? The unknown solution has polysaccharides in it. 8. A solution gives a positive Benedict’s test and a negative Barfoed’s test.How could this happen? The solution doesn’t contain monosaccharides that are reducing sugars, but has di- or polysaccharides that are reducing, which gives a positive Benedict's test (this test shows the presence of reducing sugars, whether it’s a mono-, di- polysaccharide). Barfoed’s

test shows negative because it registers only the presence of monosaccharides. 9. In the Benedict’s and the Barfoed’s tests, why is the boiling time critical? Heat can cause hydrolysis of disaccharides into monosaccharides and the test can give a false positive result for reducing monosaccharides.

Lab exercise 6 - Comprehension Check 1. Sketch and describe the chemical structure of an amino acid. Amino acid consists of a carbon with amino group, carboxyl group and a side chain (known as R group). Amino acids differ by their R groups.

2. What is the difference between an amino acid, a dipeptide, a polypeptide, and a protein? Amino acid acts as a monomer of dipeptides and polypeptides. Dipeptide has two monomers of amino acids, polypeptide has more than more than 2 but less than 50. Protein is the biologically functional molecule that consists of more than 50 amino acids. 3. What is a peptide bond? A peptide bond is a covalent bond that connects amino acid monomers into polypeptides. 4. What are the functions of proteins in living organisms? Proteins have such functions in living organisms as transport, acceleration of chemical reactions, structural, movement, defense, storage, coordination of activities (hormones), response of cell to stimuli 5. What are the functions of lipids in living organisms? Energy storage, signaling and acting as structural components to cell membranes. 6. What chemical property can be used to identify a lipid. They mix poorly with water (if mix at all). 7. Which of the following substances will dissolve Sudan IV? Explain why or why not. (vinegar, margarine, lemonade, heavy cream, skim milk) Margarine and heavy cream will dissolve Sudan IV, because Sudan IV dissolves in hydrophobic substances. Heavy cream and margarine are lipids, and they are hydrophobic. Vinegar, Lemonade, Skim milk will not dissolve Sudan IV because they are hydrophilic. Lab report Carbohydrates

1. Benedict’s Test for Reducing Sugar a. A boiling water bath was set up using a 600 mL beaker filled two-thirds with water. b. 1mL of different solutions was added to the test tubes (water, glucose, fructose, maltose, lactose, sucrose, starch, Karo syrop, Potato juice, Onion juice, White bread, Apple and unknown solution). c. 5mL of Benedict's reagent was added to each tube. d. The test tubes were placed into the boiling water bath for 5 minutes, then they were taken out and allowed to cool down. e. The observations in color change were recorded in the table below. 2. Barfoed’s Test a. A boiling water bath was set up using a 600 mL beaker filled two-thirds with water. b. 1mL of different solutions was added to the test tubes (water, glucose, fructose, maltose, lactose, sucrose, starch, Karo syrup, Potato juice, Onion juice, White bread, Apple and unknown solution). c. 3mL of Barfoed's reagent was added to each tube. d. The test tubes were placed into the boiling water bath for 2 minutes, then they were taken out and allowed to cool down. e. The observations in color change were recorded in the table below. 3. Iodine Test a. 5 drops of starch solution was added to one well. b. 3 drops of iodine solution was added, and it turned blue-black color. c. 5 drops of the remaining solutions were added to other wells separately, and 3 drops of iodine were added to each well. d. The observations in color change were recorded in the table below.

Samples

Benedict Test (color)

Barfoed’s Test (precipitate - y/n)

Iodine Test (blue-black- y/n)

blue

no

no

Glucose

red/orange

yes

no

Fructose

orange

yes

no

Maltose

orange

no

no

Lactose

orange

no

no

Sucrose

blue

no

no

Water

Starch

blue

no

yes

Karo Syrup

red

yes

no

Potato Juice

blue

yes

no

Onion Juice

orange

yes

no

White Bread

green

yes

no

Apple

orange

yes

yes (black)

Unknown Solution

orange

no

no

Lipids

1. Sudan IV Test a. 1mL of water was added to test tube 1, 1mL of oil - to test tube 2, 1 ml of water and 1mL of oil were added to test tube 3. b. A few grains of Sudan IV were added to each test tube. The test tubes were shaken and allowed to sit for one minute. c. Observations were recorded in the table below. d. 1 mL of white bread mixture was added to test tubes 4 and 5. 1mL of water was added to test tube 4. 1 mL of oil was added to tube 5. e. 1mL of unknown solution was added to test tube 6 and 7. 1mL of water was added to test tube 6. 1 mL of oil was added to tube 7. f. A few grains of Sudan IV were added to each test tube. The test tubes were shaken and allowed to sit for one minute. g. Observations were recorded in the table below.

Test Tube

Samples

Observations

1

Oil only

Sudan grains dissolved

2

Water only

Sudan grains didn't dissolve

3

Oil plus water

Sudan dissolved in the layer with oil

4

White bread plus water

Sudan grains didn't dissolve

5

White bread plus oil

Sudan dissolved in the layer with oil

6

Unknown plus water

Sudan grains didn't dissolve

7

Unknown plus oil

Sudan dissolved in the layer with oil

2. Grease Spot Test a. A drop of water was applied to a paper towel, and a drop of oil to another area of the paper towel. b. A drop of white bread solution and a drop of unknown lipid solution were applied to different paper towel areas. c. All the spots were allowed to dry and the observations were recorded in the table below.

Samples

Observations

Oil

translucent

Water

not translucent

White Bread

not translucent

Unknown

not translucent

Proteins

Biuret Test a. 1 mL of various solutions were added to 6 test tubes (water, egg albumen, histidine, trypsin, gelatin solution, unknown protein solution). b. 2 mL of Biuret reagent was added to each test tube. c. Test tubes were allowed to sit for 5 minutes. d. Color change observations and results were recorded in the table below.

Test Tube

Sample

Color of Solution

Protein? (yes/no)

1

Water

Light blue

no

2

Egg albumen

Purple

yes

3

Hestidin

Light blue

no

4

Trypsin

Light blue

no

5

Dilute gelatin

Violet

yes

6

Unknown protein

Light blue

no...