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Assertion : The sugar phosphatebackone o...

Assertion : The sugar phosphatebackone of two chains in DNA double helix show anti-parallel polarity.
Reason : The phosphodiester bonds in one strand go from a 3' cardon of one nucleotide to a 5, carbon of adjacent nucleotide, whereas those in complementary strand go vice versa.

A

If both assertion and reason are true and reason is the correct explanation of assertion

B

If both assertion and reason are true but reason is not the correct explanation of assertion

C

If assertion is true but reason is false

D

if both assertion and reason are false.

Text Solution

AI Generated Solution

The correct Answer is:
### Step-by-Step Solution: 1. **Understanding the Assertion**: The assertion states that the sugar-phosphate backbone of the two chains in the DNA double helix shows anti-parallel polarity. This means that the two strands of DNA run in opposite directions. 2. **Understanding the Reason**: The reason given explains how the phosphodiester bonds are formed in the DNA strands. It states that in one strand, the phosphodiester bonds connect the 3' carbon of one nucleotide to the 5' carbon of the adjacent nucleotide. In the complementary strand, the bonds go in the opposite direction, connecting the 5' carbon of one nucleotide to the 3' carbon of the adjacent nucleotide. 3. **Analyzing the Structure of DNA**: The backbone of DNA is composed of alternating deoxyribose sugars and phosphate groups. The phosphate group is attached to the 5' carbon of one sugar and the 3' carbon of the next sugar, forming a phosphodiester bond. 4. **Identifying the Directionality**: In one strand, the directionality is from the 5' end to the 3' end, while in the complementary strand, the directionality is from the 3' end to the 5' end. This is what is meant by anti-parallel. 5. **Conclusion**: Both the assertion and the reason are correct. The reason correctly explains why the sugar-phosphate backbone of the DNA strands is anti-parallel. Therefore, the correct answer is that both the assertion and the reason are true, and the reason is the correct explanation for the assertion. ### Final Answer: Both the assertion and the reason are correct, and the reason is the correct explanation for the assertion. ---
### Step-by-Step Solution: 1. **Understanding the Assertion**: The assertion states that the sugar-phosphate backbone of the two chains in the DNA double helix shows anti-parallel polarity. This means that the two strands of DNA run in opposite directions. 2. **Understanding the Reason**: The reason given explains how the phosphodiester bonds are formed in the DNA strands. It states that in one strand, the phosphodiester bonds connect the 3' carbon of one nucleotide to the 5' carbon of the adjacent nucleotide. In the complementary strand, the bonds go in the opposite direction, connecting the 5' carbon of one nucleotide to the 3' carbon of the adjacent nucleotide. 3. **Analyzing the Structure of DNA**: The backbone of DNA is composed of alternating deoxyribose sugars and phosphate groups. The phosphate group is attached to the 5' carbon of one sugar and the 3' carbon of the next sugar, forming a phosphodiester bond. ...
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