Problem 10 - Biology: Science for Life with Physiology

Question

RNA and DNA are similar because _________ . A. they are both double-stranded helices; B. uracil is found in both of them; \(\mathrm{C}\). both contain the sugar deoxyribose; D. both are made up of nucleotides consisting of a sugar, a phosphate, and a base

Step-by-Step Solution

Answer

D. both are made up of nucleotides consisting of a sugar, a phosphate, and a base.

Step 1: Identify Key Components

RNA and DNA are nucleic acids that form the genetic material in organisms. They differ in several aspects, including structure, sugar content, and bases present, but also share some common features.

Step 2: Eliminate Incorrect Options

Evaluate each answer choice based on what you know about RNA and DNA. A common feature of RNA and DNA is that they are both made up of nucleotides. However, they differ in being single (RNA) or double-stranded (DNA), the type of sugar (ribose in RNA and deoxyribose in DNA), and containing uracil (only in RNA).

Step 3: Identify the Correct Feature

Both RNA and DNA are made of nucleotides which consist of a sugar, a phosphate group, and a nitrogenous base. This common structural feature matches option D.

Step 4: Verify with Explanation

Option D is correct because both RNA and DNA have this basic nucleotide structure. The other options are incorrect based on known distinct differences: RNA is single-stranded with ribose sugar and contains uracil, whereas DNA is double-stranded with deoxyribose sugar and contains thymine.

Key Concepts

Nucleotides

Nucleotides are the basic building blocks of nucleic acids, which are essential for storing and transmitting genetic information in living organisms. These small molecules each consist of three distinct parts:

• A sugar molecule, which is either ribose (in RNA) or deoxyribose (in DNA)
• A phosphate group that forms the backbone by linking the sugars together
• A nitrogenous base that can be either adenine (A), thymine (T - in DNA), cytosine (C), guanine (G), or uracil (U - in RNA)

Both DNA and RNA are composed of these nucleotides but differ in their sugar components and bases. In DNA, thymine pairs with adenine, whereas in RNA, uracil takes the place of thymine. This fundamental structure allows DNA and RNA to encode the genetic instructions necessary for life.

Genetic Material

The genetic material in an organism refers to DNA and, in some cases, RNA. These molecules are crucial for storing and conveying the instructions that govern the biological processes in an organism. DNA, or deoxyribonucleic acid, is responsible for storing long-term genetic information. It resides primarily in the cell nucleus and has the famous double-helix structure.

RNA, or ribonucleic acid, typically serves to transfer and execute the instructions found in DNA. RNA can exist in many forms, including messenger RNA (mRNA), which carries genetic information to the ribosomes where proteins are made; ribosomal RNA (rRNA), which forms a part of the ribosome; and transfer RNA (tRNA), which helps incorporate amino acids into growing protein chains. Though RNA often works as a mediator in genetic expression, it never replaces the fundamental long-term storage role of DNA.

Nucleic Acids

Nucleic acids are large biomolecules that play a crucial role in cellular function and evolution. There are two primary types: DNA (deoxyribonucleic acid) and RNA (ribonucleic acid). These molecules act as the blueprint of biological entities, each fulfilling unique yet interrelated roles.

DNA holds the genetic blueprint and fulfills a storage role. Its unique feature is the double helix, where two strands wind around each other stabilized by hydrogen bonds between complementary bases (adenine with thymine, and guanine with cytosine).

RNA, on the other hand, is typically single-stranded and performs multiple roles depending on its type—whether it's mRNA, tRNA, or rRNA. Importantly, nucleic acids enable the storage, replication, and expression of genetic information, which are essential processes for growth, development, and reproduction in all living organisms. Understanding nucleic acids and their functional differences provides insight into the complex biology of life.