In a typical introductory genetics context, how many major types of RNA are commonly emphasized for their roles in gene expression?

• A. Three: mRNA, tRNA, and rRNA
• B. Two: DNA and RNA
• C. Four: mRNA, tRNA, rRNA, and dNTP
• D. Five: mRNA, tRNA, rRNA, snRNA, and lncRNA

Answer: (A)

Verified step by step guidance

1. Step 1: Understand the context of the question, which focuses on the major types of RNA commonly emphasized in introductory genetics for their roles in gene expression.
2. Step 2: Recall that gene expression involves the process of transcribing DNA into RNA and then translating RNA into proteins, where different RNA types have specific functions.
3. Step 3: Identify the three primary RNA types typically highlighted: messenger RNA (mRNA), which carries the genetic code from DNA to ribosomes; transfer RNA (tRNA), which brings amino acids to the ribosome during protein synthesis; and ribosomal RNA (rRNA), which is a structural and catalytic component of ribosomes.
4. Step 4: Recognize that other options include DNA (which is not RNA), dNTP (which are DNA building blocks, not RNA types), and additional RNA types like snRNA and lncRNA, which are important but usually introduced later or considered less central in basic gene expression discussions.
5. Step 5: Conclude that the three major RNA types emphasized in introductory genetics for gene expression are mRNA, tRNA, and rRNA.