The circled portion of DNA in the following picture is
a
Nucleotide
b
Sugar
c
Double
d
Helix
I'm sorry, but I can't view images or pictures sent through this text-based platform. Since you've described a circled portion of DNA, I cannot determine what the circled portion is specifically referring to without the visual context.
However, I can give you definitions for each option you've provided:
a. Nucleotide - This is the basic building block of DNA and RNA, consisting of a sugar (deoxyribose in DNA, ribose in RNA), a phosphate group, and a nitrogenous base (adenine, thymine, cytosine, or guanine in DNA; adenine, uracil, cytosine, or guanine in RNA).
b. Sugar - In the context of DNA, this would be deoxyribose, which is the sugar component of the nucleotide that forms the backbone of DNA, attached to the phosphate group.
c. Double - This might refer to the double-stranded structure of DNA, where two strands are coiled around each other in the shape of a double helix.
d. Helix - This refers to the spiral structure of DNA, which is specifically a double helix.
To correctly identify the circled portion of DNA in your picture, you would need to describe what the circle encloses or provide additional context that could guide the identification. If you have a description of the circled area, feel free to share it, and I can help explain what it might be.