Molecular Biology: Nucleic Acids, DNA, RNA, and Protein Synthesis

Posted on Jan 20, 2025 in Biology

Molecular Biology: Unraveling Life’s Blueprint

Molecular biology is the science that studies the structure, function, and other aspects of nucleic acids and other macromolecules present in cells. It is a discipline related to biochemistry and genetics.

Nucleic Acids: The Building Blocks of Life

Nucleic acids are organic macromolecules involved in all the processes of storage and expression of genetic information.

Composition and types of nucleic acids:

• Phosphate group
• Carbohydrate
• Nitrogenous base

Nucleic Acid Structure and Functions

In DNA nucleotide bonding, adenine always bonds with thymine (A-T), and guanine with cytosine (G-C). In RNA nucleotide bonding, the bases follow the same pattern except for adenine, which bonds with uracil (A-U).

DNA: The Master Molecule

DNA is found in the cell nuclei of eukaryotes and in the cytoplasm of prokaryotes. Its key functions are:

1. Store genetic information
2. Transmit this hereditary information
3. Control the processes of genetic information expression via transcription and translation

Central Dogma of Molecular Biology:

Replication (DNA) > Transcription (RNA) > Translation (Protein)

DNA Replication: Copying the Code

DNA Replication is the process by which DNA builds a complementary copy of itself. It takes place in the S phase of the cell cycle, in the nucleus of eukaryotic cells or the cytoplasm of prokaryotic cells.

DNA Replication Process

Three phases:

1. Unwinding and separating the double helix
2. Building new chains
3. Correcting errors

Biological Importance of DNA Replication

Replication makes an exact copy of the DNA molecule, with its unique sequence of nucleotides. This ensures that the daughter cells conserve the parent cell’s genetic information.

Gene: The Unit of Heredity

A gene is a biologically significant segment of DNA. In other words, it is the basic unit of genetic information. Each gene has a specific number of nucleotides.

Transcription: DNA to RNA

Transcription is the process by which a chain of mRNA is built from a fragment of DNA. It takes place in the nucleus of eukaryotic cells and in the cytoplasm of prokaryotic cells.

Translation: RNA to Protein

Translation is the process by which proteins are built from mRNA with the help of tRNA and ribosomes. It takes place in the cell cytoplasm.

Genetic Code: The Language of Life

The genetic code is the “dictionary” that matches the language of nucleotides in the mRNA with the language of amino acids in proteins.

Mutation: A Change in the Code

A mutation is a change in the DNA, which usually has effects on the expression of genetic information.

Biotechnology: Applying Molecular Biology

Biotechnology is the set of techniques that use living organisms or their substances to create products for human use.

Directionality in Molecular Processes

Question: DNA replication is bidirectional, while transcription and translation are unidirectional. How would you explain the difference?

Answer: In DNA replication, we have two strands being copied simultaneously in opposite directions, leading to bidirectionality. In RNA transcription and protein translation, we have only one strand being processed, resulting in unidirectionality.

Central Tenet of Molecular Biology

Question: What is the central tenet of molecular biology?

Answer: Replication (DNA) > Transcription (RNA) > Translation (Protein)

Classifying Molecular Processes

Classify the following terms according to the process they belong to: