Which of the following best describes the nature of RNA strands?

RNA strands are best described as single-stranded. Unlike DNA, which typically exists as a double helix consisting of two complementary strands that run in opposite directions and are held together by hydrogen bonds between nucleotide bases, RNA is usually found in a single strand. This single-stranded structure allows RNA to fold into complex three-dimensional shapes that are crucial for its various functions, including acting as a template for protein synthesis during translation and as a functional molecule in various cellular processes like catalysis (in the form of ribozymes).

While there are some exceptions, such as certain viruses that may contain double-stranded RNA, the predominant form of RNA in cells is single-stranded. This characteristic plays a significant role in the versatility and functionality of RNA within biological systems, facilitating various functions such as messenger RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA) in the process of gene expression and protein synthesis. Understanding the single-stranded nature of RNA is fundamental in molecular biology and genetics.