Which of the following statements about genetic code is correct ?

Options

A. It includes 61 codons for amino acids and 3 stop codons
B. Is universal and has 3 bases per codon
C. Some amino acids are coded by multiple codons
D. All of the above

Answer

To determine which of the statements about the genetic code is correct, we will analyze each statement step by step.

### Step 1: Analyze the first statement
- **Statement**: "It includes 61 codons for amino acids and 3 stop codons."
- **Explanation**: The genetic code consists of a total of 64 codons (4^3 combinations of the four nucleotides: A, U, C, G). Out of these, 61 codons specify amino acids, and 3 codons are designated as stop codons. This statement is **correct**.

### Step 2: Analyze the second statement
- **Statement**: "Universal and has 3 bases per codon."
- **Explanation**: The genetic code is indeed universal, meaning it is the same in almost all organisms. Additionally, each codon is made up of 3 nucleotides (triplet code). Therefore, this statement is also **correct**.

### Step 3: Analyze the third statement
- **Statement**: "Some amino acids are coded by multiple codons."
- **Explanation**: This is true; the genetic code is described as degenerate because multiple codons can code for the same amino acid. For example, the amino acid leucine can be coded by six different codons. Thus, this statement is **correct**.

### Step 4: Analyze the fourth statement
- **Statement**: "All of the above."
- **Explanation**: Since the first three statements are correct, this statement is also **correct**.

### Conclusion
Based on the analysis of all statements, the correct answer is **"All of the above."**

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