Question

Which of the following statements regarding differences between DNA and RNA is FALSE? A. DNA is double stranded, whereas RNA is single stranded. B. DNA uses the nitrogenous base thymine; RNA has uracil. C. The sugar in DNA is deoxyribose; the sugar in RNA is ribose. D. DNA strands replicate in a 5? to 3? direction, whereas RNA is synthesized in a 3? to 5? direction.

Short answer

The false statement is D: DNA strands replicate in a 5? to 3? direction, whereas RNA is synthesized in a 3? to 5? direction.

Step-by-step solution

Understand the Statements

Understand each statement given in the options (A, B, C, D). Identify what is being asked about DNA and RNA.

Recall Characteristics of DNA and RNA

Recall the fundamental differences between DNA and RNA. DNA is typically double-stranded, has thymine as a base, and contains the sugar deoxyribose. RNA is typically single-stranded, contains uracil, and has ribose.

Evaluate Option A

Option A states DNA is double stranded and RNA is single stranded. This is a correct statement based on our recall.

Evaluate Option B

Option B states DNA contains thymine, whereas RNA contains uracil. This is also a correct statement.

Evaluate Option C

Option C states DNA contains deoxyribose and RNA contains ribose. This is another correct statement.

Evaluate Option D

Option D states DNA replicates in the 5? to 3? direction, whereas RNA is synthesized in the 3? to 5? direction. This is incorrect as both DNA replication and RNA synthesis proceed in the 5? to 3? direction.

Conclusion: Identify the False Statement

Based on the evaluation, determine that option D is the false statement.

Key concepts

DNA structure

DNA, or Deoxyribonucleic Acid, is the molecule that carries the genetic instructions for life. It is structured as a double helix, which looks like a twisted ladder. Each 'rung' of this ladder is made up of pairs of nitrogenous bases: adenine (A) pairs with thymine (T), and cytosine (C) pairs with guanine (G).

The backbone of the DNA helix consists of alternating sugar (deoxyribose) and phosphate groups, connected via ester bonds. The double helix structure of DNA is crucial for its stability and its ability to replicate accurately.

The double-stranded nature of DNA allows for complementary base pairing, which is key during DNA replication where each strand serves as a template for a new, complementary strand.

RNA structure

RNA, or Ribonucleic Acid, is typically single-stranded, unlike DNA. It plays multiple roles within cells, such as transferring the genetic code from DNA to the ribosomes for protein synthesis.

RNA's structure includes the sugar ribose, which differs from DNA's deoxyribose by having one more oxygen atom. The nitrogenous bases in RNA also differ slightly from DNA. Instead of thymine (T), RNA contains uracil (U), which pairs with adenine (A). The remaining bases are the same: cytosine (C) and guanine (G).

There are several types of RNA, including messenger RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA), each serving a different function within the cell.

Nucleic acids

Nucleic acids are biomolecules essential for all known forms of life. The two primary types of nucleic acids are DNA and RNA.

The building blocks of nucleic acids are nucleotides, each composed of a phosphate group, a sugar molecule, and a nitrogenous base. Nucleotides link together through phosphodiester bonds to form the long chains of nucleic acids.

These molecules store and transfer genetic information. DNA holds the instructions for building proteins, while RNA translates and carries these instructions to the ribosomes, where proteins are made.

The proper functioning and replication of nucleic acids are critical for growth, development, and cellular function.

Genetic replication

Genetic replication is a vital process by which a cell copies its DNA before cell division. This ensures that each new cell receives an identical set of genetic instructions.

During DNA replication, the double helix unwinds, and each strand serves as a template for a new complementary strand. DNA polymerase is the enzyme that adds new nucleotides in the 5’ to 3’ direction, ensuring accurate base pairing.

RNA synthesis, or transcription, also occurs in the 5’ to 3’ direction. Here, RNA polymerase reads the DNA template and synthesizes a complementary strand of RNA. This RNA then undergoes further processing before it is used in protein synthesis.

Accurate replication is crucial for maintaining genetic integrity and preventing mutations that could lead to diseases.