Question

A FASTA file begins with which symbol to indicate a header line?

• A. #
• B. @
• C. >
• D. $

Hint:

Remember the difference: \[ \boxed{\texttt{>} \rightarrow \text{FASTA Header}} \] \[ \boxed{\texttt{@} \rightarrow \text{FASTQ Header}} \] FASTA stores only sequence information, whereas FASTQ stores both sequence and quality scores.

Answer 1

The Correct Option is C

Concept: FASTA is one of the most commonly used file formats in bioinformatics for storing DNA, RNA, or protein sequences. Each sequence in a FASTA file begins with a header line that starts with the greater-than symbol (>). The header is followed by one or more lines containing the nucleotide or amino acid sequence.
• FASTA format is simple and universally accepted.
• The header provides information such as sequence ID, gene name, or description.
• The actual biological sequence is written immediately below the header.
• Multiple sequences can be stored in the same FASTA file.

Step 1: Understand the FASTA file format.
A typical FASTA file appears as: \[ \begin{array}{l} \texttt{>Sequence\_1} \\ \texttt{ATGCGTAGCTAGCTAG} \\ \texttt{CGATCGATCGATCG} \end{array} \] Here,
• The first line beginning with > is the header.
• The remaining lines contain the DNA or protein sequence.

Step 2: Eliminate the incorrect options.

• # is generally used for comments in programming languages.
• @ is commonly used in FASTQ files but not FASTA files.
• $ has no role in FASTA formatting.
• Only the symbol > indicates the header line.

Step 3: Choose the correct option.
Therefore, \[ \boxed{Option (C) is the correct answer. \]