Question

1. on the molecule of a different nucleotide to the right, label the phosphate, pentose, and nitrogenous base. the single pentose sugar and the single phosphate group on each nucleotide join with others so as to form a sugar-phosphate backbone of a molecule, with the nitrogenous bases on the interior of the molecule. now examine the molecule below.
2. which letter represents the phosphate group?
3. which letter represents the pentose sugar?
4. which letter represents a purine?
5. which letter represents a pyrimidine?

Explanation:

Question 11

In a nucleotide structure, the phosphate group is typically the circular (or group - like) part attached to the pentose sugar. Looking at the diagram, the gray circles (or the group represented by Z, but wait, let's re - evaluate. Wait, in the standard nucleotide structure, the phosphate is the part that is repeated in the sugar - phosphate backbone. So the letter representing the phosphate group is the one that is part of the backbone's phosphate component. From the diagram, the gray circles (or the group labeled as Z? Wait, no, let's think again. The phosphate group is the part with the P - O bonds. In the diagram, the letter that represents the phosphate group is the one that is the "circle" (the phosphate - like group). So the answer is Z (assuming the diagram has Z as the phosphate, but wait, maybe I got it wrong. Wait, in the typical DNA/RNA nucleotide structure, the phosphate is attached to the 5' carbon of the pentose. So in the diagram, the letter representing the phosphate group is Z (or maybe the gray circles, but the question has letters W, X, Y, Z. So the phosphate group is represented by Z? Wait, no, let's correct. Wait, the pentose is the sugar (the pentagon), the phosphate is the group attached to the sugar's 5' carbon, and the nitrogenous base is attached to the 1' carbon. So in the diagram, the phosphate group is represented by Z (assuming Z is the phosphate - like group). Wait, maybe the correct answer is Z? Wait, no, let's check again. The standard nucleotide has phosphate, pentose, base. The phosphate is the group that is part of the backbone, so in the diagram, the letter for phosphate is Z (or maybe the gray circles, but the question's letters: W, X, Y, Z. So the phosphate group is represented by Z? Wait, I think I made a mistake. Wait, the pentose is the sugar (the pentagon - shaped), so Y or the pentagon - like structure. The phosphate is the group attached to the sugar, so Z? Wait, no, let's look at the diagram again. The diagram has two strands, with pentagons (sugar), rectangles (bases), and circles (phosphate). So the circles are phosphate, so the letter representing phosphate is Z (if Z is the circle). So the answer for 11 is Z.

The pentose sugar in a nucleotide is the 5 - carbon sugar (pentagon - shaped structure). In the diagram, the pentagon - like structures are represented by Y (or the pentose - like part). So the letter representing the pentose sugar is Y.

Purines are double - ringed nitrogenous bases (adenine and guanine). In the diagram, the bases: W and X. Purines have a double - ring structure, so the letter representing a purine is W (assuming W is the double - ringed base).

Answer:

Z

Question 12