Video Transcript
Which of the following correctly describes the structure of an RNA molecule? An RNA molecule is formed of a single strand of nucleotides joined by a sugar–phosphate backbone. An RNA molecule is formed of two strands of amino acids joined by hydrogen bonds that form between the amino groups. An RNA molecule is formed of a single strand of amino acids joined by peptide bonds. An RNA molecule is formed of two strands of nucleotides joined by hydrogen bonds that form between complementary base pairs. Or an RNA molecule is formed when two DNA molecules interact and join together to form a more complex structure.
Let’s first clear the answers from the screen so we have more room to work with. This question is asking us about RNA and its structure. RNA, or ribonucleic acid, is a molecule that plays a central role in the expression of genes. It is similar in structure to DNA except instead of having two strands, as shown here, RNA is usually single stranded. Let’s zoom in to this part of the RNA molecule and get a closer look at its chemical structure. In black is the sugar–phosphate backbone. This is made of a five-carbon sugar, called ribose, and the phosphate group; that’s represented here as a P with a circle around it. A nitrogenous base is attached to the ribose sugar that can be seen here as these different colored boxes.
In RNA, there are four different nitrogenous bases that are usually just expressed as the letter that they start with. There’s adenine, or A for short, guanine, cytosine, and uracil. One of the differences between RNA and DNA is that uracil is present in RNA instead of thiamine in DNA. The basic component or subunit for RNA is called a nucleotide. This includes the phosphate group, the ribose sugar, and the nitrogenous base. These nucleotides can be joined together to form a long polymer. We now have enough information to answer the question, so let’s clear the screen and bring back our answer choices.
The answer that best describes the structure of an RNA molecule is an RNA molecule is formed of a single strand of nucleotides joined by a sugar–phosphate backbone.
