The degeneracy of the genetic code allows different codons to code the same amino acid. Which of the following codons does NOT code for the simplest amino acid, glycin?

Options

A. GCU
B. GGG
C. GGC
D. GGU

Answer

To solve the question regarding which codon does NOT code for glycine, we will follow these steps:

### Step 1: Understand the concept of codons and amino acids
Codons are sequences of three nucleotides that correspond to specific amino acids. The genetic code is degenerate, meaning that multiple codons can code for the same amino acid.

**Hint:** Remember that each amino acid can be represented by more than one codon.

### Step 2: Identify the codons that code for glycine
Glycine is the simplest amino acid, and it is coded by the following codons:
- GGC
- GGA
- GGG
- GGU

**Hint:** Focus on the specific codons that are known to code for glycine.

### Step 3: Analyze the options given in the question
The question asks which codon does NOT code for glycine. We need to compare the options provided with the known codons for glycine.

Assuming the options are:
- A) GCU
- B) GGC
- C) GGA
- D) GGU

**Hint:** Look for the codon that is not in the list of glycine codons.

### Step 4: Determine which codon does not code for glycine
From the list of glycine codons, we see that:
- GGC, GGA, and GGU are all codons for glycine.
- GCU is not on the list and actually codes for alanine.

**Hint:** Identify the codon that is absent from the glycine list.

### Step 5: Conclusion
The codon that does NOT code for glycine is **GCU**.

**Final Answer:** A) GCU