Question

Match the following: List I List II 1\. Nucleic acid A I D.N.A. B 2\. Uracil \(\quad\) B Hormones 3\. Thymine C I Polynucleotides D R \(\begin{array}{lll}\text { 4. Double helix structure } & \text { D R.N.A }\end{array}\) The correct matching is 1 2 3 4 (a) \(\mathrm{C}\) D \(\mathrm{A}\) A (b) C A \(\mathrm{A}\) D a \(B\) (c) C t. \(\mathrm{D}\) A (d) \(\mathrm{C}\) \(\mathrm{B}\) D C

Short answer

Option (c): C D A A.

Step-by-step solution

Analyzing List I

Understand that List I consists of terms related to nucleic acids and other molecular biology concepts. These terms are: 1. Nucleic acid 2. Uracil 3. Thymine 4. Double helix structure.

Analyzing List II

List II contains descriptors or categories where each term from List I can belong: A. Proteins B. Hormones C. Polynucleotides D. R.N.A.

Matching 'Nucleic acid' from List I

The term 'Nucleic acid' is a macromolecule composed of polynucleotide chains. Therefore, it matches with C, Polynucleotides.

Matching 'Uracil' from List I

Uracil is a component found in RNA, not DNA. Therefore, 'Uracil' matches with D, R.N.A.

Matching 'Thymine' from List I

Thymine is one of the four bases in DNA, but it is not present in RNA. This matches it with term A, as it is not directly given in List II as an option. However, based on choices, it should be A, Polynucleotides.

Matching 'Double helix structure' from List I

The double helix is the well-known structure of DNA, but since DNA is a polynucleotide, this matches with A, Polynucleotides, and D, DNA, commonly known separately in context.

Determining the Correct Answer

Reconcile the determined matches with the choices: 1: C 2: D 3: A 4: A This corresponds to option (c): C D A A.

Key concepts

Uracil and RNA

Uracil is one of the four nucleotide bases in RNA, replacing thymine, which appears in DNA. This difference between RNA and DNA is crucial for their differing functionalities. Uracil forms a base pair with adenine during the transcription process.

Its presence in RNA allows it to be more flexible and reactive. RNA doesn't need the same stability as DNA because it is usually transient and single-stranded.

Here are some important points to remember about uracil and RNA:

• The structure of uracil is simpler compared to thymine, lacking a methyl group.
• Uracil helps prevent possible errors in the genetic code by staying specific to RNA.
• It plays a critical role in protein synthesis through processes like transcription and translation.

Understanding the unique role of uracil in RNA provides insight into how genetic information is expressed and utilized within cells.

Thymine and DNA

Thymine is one of the four nucleotide bases in DNA, paired specifically with adenine. This complementary pairing is crucial for the DNA's stability and function. Unlike uracil, thymine includes a methyl group at its 5-carbon position, which makes it more stable.

The presence of thymine ensures the integrity of the genetic information stored within DNA molecules.

Key aspects of thymine in DNA include:

• Thymine is paired with adenine through two hydrogen bonds, playing a vital role in the DNA structure's stability.
• It protects the DNA from being randomly altered by helping maintain the DNA ladder's rigidity.
• The presence of thymine helps in the accurate replication of DNA.

These features highlight the importance of thymine to the structural and functional integrity of DNA.

Double Helix Structure

The double helix structure is one of the most iconic representations of DNA. Composed of two strands that coil around each other with base pairs joined by hydrogen bonds, it forms the pivotal structure of DNA molecules.

This shape allows for the compact storage of genetic information, as well as its faithful transmission during cell division.

Some characteristics of the double helix structure include:

• The double helix has major and minor grooves that provide accessibility for proteins that regulate genetic information.
• The structure is stabilized by a sugar-phosphate backbone linked by covalent bonds, while base pairs bind via hydrogen bonds.
• This arrangement enables the two strands to separate during replication, ensuring that each daughter cell receives an accurate copy of DNA.

Understanding the double helix structure is essential for comprehending how DNA functions as a hereditary material.