To determine which factors are required for protein synthesis, we will analyze each option provided in the question step by step.
### Step-by-Step Solution:
1. **Initiation Codon (AUG)**:
- The initiation codon is essential for starting the process of translation. It signals the ribosome where to begin synthesizing the protein. Therefore, this factor is required.
- **Hint**: Look for the starting point of translation in the mRNA sequence.
2. **GTP and ATP**:
- Protein synthesis requires energy, which is provided by ATP. Additionally, GTP is involved in the initiation and elongation phases of translation. Both are necessary for the process, so this factor is required.
- **Hint**: Remember that energy is crucial for biochemical reactions, including protein synthesis.
3. **Peptidyl Transferase**:
- Peptidyl transferase is an enzyme found in the ribosome that catalyzes the formation of peptide bonds between amino acids. This is a critical step in protein synthesis, making this factor necessary.
- **Hint**: Consider the role of enzymes in facilitating chemical reactions.
4. **tRNA (Transfer RNA)**:
- tRNA is essential for bringing the correct amino acids to the ribosome based on the codon sequence in mRNA. Each tRNA molecule carries a specific amino acid and has an anticodon that pairs with the mRNA codon. Thus, tRNA is required.
- **Hint**: Think of tRNA as the adapter that translates the genetic code into a protein.
5. **mRNA (Messenger RNA)**:
- mRNA carries the genetic information from DNA and provides the template for the sequence of amino acids in the protein. It is indispensable for protein synthesis.
- **Hint**: mRNA is the blueprint for building proteins.
6. **Amino Acid Activating Enzyme (Aminoacyl-tRNA Synthetase)**:
- This enzyme is responsible for attaching the appropriate amino acid to its corresponding tRNA, a process known as aminoacylation. This step is crucial for ensuring that the correct amino acid is incorporated into the growing polypeptide chain. Therefore, this factor is required.
- **Hint**: Consider how amino acids are prepared for translation.
7. **rRNA (Ribosomal RNA)**:
- rRNA is a key component of ribosomes, which are the sites of protein synthesis. It plays a structural and functional role in the ribosome, making it necessary for the process.
- **Hint**: Remember that ribosomes are made of rRNA and proteins, and they are essential for translating mRNA into protein.
### Conclusion:
All of the factors listed (1. Initiation codon, 2. GTP and ATP, 3. Peptidyl transferase, 4. tRNA, 5. mRNA, 6. Amino acid activating enzyme, 7. rRNA) are required for protein synthesis.
### Correct Combination:
1, 2, 3, 4, 5, 6, 7
