Write an essay on one of the topics below - AQA - A-Level Biology - Question 7 - 2017 - Paper 3

Nitrogen-containing substances play a pivotal role in biological systems, forming the backbone of many vital biological molecules.

Importance of Proteins

Proteins are composed of amino acids, which contain nitrogen. They are essential for numerous functions including:

1. Enzymatic Reactions: Proteins function as enzymes, catalyzing biochemical reactions necessary for metabolism.
2. Cell Structure: Structural proteins provide support to cells and tissues.
3. Transport: Proteins like hemoglobin transport oxygen in the blood.

Importance of Nucleic Acids

Nucleic acids such as DNA and RNA are critical for genetic information and expression:

1. DNA Replication: Nitrogenous bases pair through hydrogen bonding, ensuring accurate replication.
2. Protein Synthesis: Messenger RNA (mRNA) is transcribed from DNA and translated into proteins.

Role in Cell Division

Nitrogen-containing substances are vital during cell division:

1. DNA Replication: Ensures each daughter cell inherits the complete set of genetic instructions.
2. Protein Synthesis: Involves the production of proteins required for cell cycle progression.

Immune Response

Nitrogen-containing compounds are involved in the immune response:

1. Antibodies: Proteins that play crucial roles in the recognition and neutralization of pathogens.
2. Cytokines: Signaling proteins that mediate and regulate immunity and inflammation.

Summary

In summary, nitrogen-containing substances are integral to the structure and function of various biological molecules, impacting processes from metabolism to cell division and immune response. Understanding their roles helps in appreciating the complexity of biological systems.