DNA vs. RNA - Online Tutor, Practice Problems & Exam Prep

RNA

Hi. In this video, we're going to be talking about DNA versus RNA. So for most of this, you're going to know, but we're just going to review some of the ways in which RNA differs from DNA. One way is that RNA contains the base uracil instead of thymine. Also, RNAs are commonly found as single-stranded polymers compared to the DNA, which is double-stranded. Now, this isn't entirely true; there are double-stranded RNAs, of course, but they're more commonly found as single-stranded sequences. RNAs have a really unique ability as they can form these complex three-dimensional structures, whereas DNA usually only forms as a double helix. A couple of these structures include hairpins, which are very small, just 5 to 10 nucleotides, pairing with each other. And then there's also the larger stem-loops, which can be larger than 10 nucleotides. And then, a really cool activity is that these 3D RNA molecules have certain catalytic activities. We term these RNAs ribozymes because they are essentially RNA enzymes, and DNAs do not do this at all. So whereas the DNA is typically seen as a double helix. When we're really looking at RNA, this is how you're going to see it. This is actually, if you're interested, a TR RNA molecule or transfer RNA molecule. You don't need to know that. Just know that it has a 3D structure with loops that interact and bind together, and this RNA can carry out different catalytic activities, whereas DNA would not be able to. So, let's move on.

Which of the following is not a property of RNA?

• A. Contains the base Uracil instead of Thymine
• B. RNA can form 3D structures with complex functions
• C. RNA is commonly found as a double helix
• D. RNA can act as enzymes

Which of the following differences between RNA and DNA is not true?

• A. RNA has Uracil, DNA has Thymine
• B. RNA is single stranded, DNA is double stranded
• C. RNA can act as an enzyme, DNA cannot act as an enzyme
• D. RNA contains the base cytosine, DNA contains the base Uracil

Here’s what students ask on this topic:

What are the main differences between DNA and RNA?

DNA and RNA differ in several key ways. DNA contains the base thymine, while RNA contains uracil. DNA is typically double-stranded, forming a double helix, whereas RNA is usually single-stranded, allowing it to form complex three-dimensional structures like hairpins and stem loops. Additionally, RNA can perform catalytic activities as ribozymes, which DNA cannot do. These differences are crucial for their roles in cellular functions, with DNA primarily storing genetic information and RNA playing various roles in protein synthesis and gene regulation.

Why does RNA use uracil instead of thymine?

RNA uses uracil instead of thymine due to evolutionary and structural reasons. Uracil is energetically less expensive to produce than thymine. Additionally, the presence of uracil in RNA helps distinguish it from DNA, which uses thymine. This distinction is important for the cell's machinery to recognize and process RNA and DNA differently, ensuring proper functioning of processes like transcription and translation.

What are ribozymes and how do they function?

Ribozymes are RNA molecules with catalytic activity, functioning similarly to protein enzymes. They can catalyze various biochemical reactions, such as cleaving RNA strands or forming peptide bonds during protein synthesis. Ribozymes achieve this through their complex three-dimensional structures, which allow them to bind specific substrates and facilitate chemical reactions. This unique ability of RNA to act as both genetic material and a catalyst highlights its versatility in cellular processes.

How do the structures of RNA and DNA affect their functions?

The structures of RNA and DNA significantly influence their functions. DNA's double-stranded helix provides stability, making it ideal for long-term storage of genetic information. In contrast, RNA's single-stranded nature allows it to fold into complex three-dimensional shapes, enabling diverse functions such as catalysis (ribozymes), protein synthesis (mRNA and tRNA), and gene regulation. These structural differences are essential for the distinct roles each molecule plays in the cell.

What roles do mRNA and tRNA play in protein synthesis?

mRNA (messenger RNA) and tRNA (transfer RNA) are crucial for protein synthesis. mRNA carries the genetic code from DNA to the ribosome, where it serves as a template for assembling amino acids into proteins. tRNA, on the other hand, brings the appropriate amino acids to the ribosome, matching its anticodon with the codon on the mRNA. This ensures that the amino acids are added in the correct sequence, allowing the synthesis of functional proteins.