Question

question 10 (1 point)
match the molecule with the most distinctive functional group in its structure.
note that some molecules may have more than one functional group. these
molecules will still have one group that is more identifying (unique) than another.

fatty acid

1. hydroxyl group

nucleotide

1. carboxyl group

monosaccharide

1. amine group

amino acid

1. phosphate group

question 11 (1 point)
which statement about cellulose is true?
it is made of repeating glucose molecules that are flipped every other molecule.
it is largely indigestible by the human body.
it is a polymer made of many repeating monomers joined together.
all the statements are true.

Explanation:

• Fatty acid: Fatty acids have a carboxyl group (\(-COOH\)) which is a key functional group. The carboxyl group gives fatty acids their acidic properties and is crucial for their role in forming lipids (e.g., in esterification reactions to form triglycerides).
• Nucleotide: Nucleotides are composed of a nitrogen - containing base, a pentose sugar, and a phosphate group (\(-PO_{4}^{3 - }\)). The phosphate group is important for the formation of phosphodiester bonds in nucleic acids (like DNA and RNA), which link nucleotides together.
• Monosaccharide: Monosaccharides (such as glucose, fructose) have multiple hydroxyl groups (\(-OH\)). These hydroxyl groups are involved in hydrogen bonding (which affects solubility) and in the formation of glycosidic bonds when monosaccharides combine to form disaccharides or polysaccharides.
• Amino acid: Amino acids have an amine group (\(-NH_{2}\)) and a carboxyl group. While the carboxyl group is also present in fatty acids, the amine group is a distinctive feature that, along with the carboxyl group, allows amino acids to form peptide bonds (through condensation reactions between the amine of one amino acid and the carboxyl of another) to build proteins.

For cellulose:

• Structure: Cellulose is a polysaccharide. It is made up of repeating glucose units. In cellulose, the glucose molecules are linked by \(\beta - 1,4\) - glycosidic bonds, and every other glucose molecule is "flipped" (has an inverted orientation) compared to its adjacent glucose molecule. This gives cellulose a linear and rigid structure.
• Digestibility: Humans lack the enzyme cellulase, which is required to break the \(\beta - 1,4\) - glycosidic bonds in cellulose. So, it is largely indigestible by the human body.
• Polymer nature: By definition, a polymer is a large molecule made up of many repeating monomer units. Since cellulose is made of many glucose (monomer) units joined together, it is a polymer.

Answer:

• Fatty acid: 2. carboxyl group
• Nucleotide: 4. phosphate group
• Monosaccharide: 1. hydroxyl group
• Amino acid: 3. amine group
• For the cellulose question: All the statements are true.