Question

9. Which of the following statements about the building blocks of polymers is true? a. When looking at the complete structure of a nucleotide you can always tell whether it is considered a ribo-nucleotide or a deoxyribo-nucleotide. b. When looking at a glucose monomer (in linear form), you can always tell which polymer of glucose (a starch or cellulose) it will be incorporated into. c. When looking at a single amino acid, you can always tell whether it will be the last amino acid in a polypeptide chain. d. When looking at a nitrogenous base, you can always tell if it will be incorporated into a doublestranded nucleic acid or a single-stranded nucleic acid. e. There is more than one correct answer

Answer 1

When looking at the complete structure of a nucleotide you can always tell whether it is considered a ribo-nucleotide or a deoxyribo-nucleotide.

Ribonucleotides and deoxyribonucleotides differ in the 2’ carbon group of the ribose ring. Ribonucleotides have hydroxyl group at the 2’ carbon while deoxyribonucleotides don’t have. So, by just looking at the complete structure of a nucleotide, we can tell whether it is a ribonucleotide or deoxyribonucleotide.

Other options are wrong.

b. When looking at a glucose monomer (in linear form), you can always tell which polymer of glucose (a starch or cellulose) it will be incorporated into.

Glucose is present as α-glucose in starch and β-glucose in cellulose. These two forms are anomers formed only in the cyclic ring (Haworth projection) form NOT in the linear form. So, by just looking at linear form of glucose we CANNOT tell whether it’s polymer.

c. When looking at a single amino acid, you can always tell whether it will be the last amino acid in a polypeptide chain.

We CANNOT tell whether an amino acid is the last amino acid of the polymer, by looking at it.

d. When looking at a nitrogenous base, you can always tell if it will be incorporated into a double stranded nucleic acid or a single-stranded nucleic acid.

Nitrogenous bases are present in both double stranded nucleic acids or single-stranded nucleic acids.