Question

Identify the linkage in backbone of single strand of DNA ?

• A. Base- phosphate -sugar
• B. Phosphate -base -sugar
• C. Sugar -phosphate- base
• D. Phosphate -sugar-phosphate

Hint:

The backbone alternates sugar and phosphate; the phosphate links two sugars.

Answer 1

The Correct Option is D

Step 1: Parts:
Base attaches to sugar at C1'. Phosphate attaches at C5' and bridges to the next sugar at C3'.

Step 2: Chain:
Repeating units run phosphate, sugar, phosphate, sugar. The bases stick out sideways.

Step 3: Result:
The linkage in the backbone is phosphate - sugar - phosphate, option (D).

Final Answer:
Backbone is phosphate-sugar-phosphate. \[ \boxed{\text{(D) }\text{Phosphate-sugar-phosphate}} \]