Question

The pair in which both species have iron is (a) nitrogenase, cytochromes (b) carboxypeptidase, haemoglobin (c) haemocyanin, nitrogenase (d) haemoglobin cytochromes

Short answer

Options (a) and (d) are correct, as both pairs contain iron.

Step-by-step solution

Understanding the Problem

We need to identify a pair of biological molecules, referred to as 'species', in which both members contain iron. The options provided are different pairs of biological molecules.

Analyze Each Option

Let's break down each option to check for iron presence: 1. **Nitrogenase**: Contains iron; it's an iron-sulfur enzyme. **Cytochromes**: Contain iron; they are heme proteins. 2. **Carboxypeptidase**: Contains zinc, not iron. **Haemoglobin**: Contains iron; it has an iron-containing heme group. 3. **Haemocyanin**: Contains copper, not iron. **Nitrogenase**: Contains iron. 4. **Haemoglobin**: Contains iron. **Cytochromes**: Contain iron.

Identify Correct Pair

From our analysis: - Option (a) Both nitrogenase and cytochromes contain iron. - Option (b) Carboxypeptidase does not contain iron. - Option (c) Haemocyanin does not contain iron. - Option (d) Both haemoglobin and cytochromes contain iron. Options (a) and (d) both consist of pairs that have iron.

Select the Correct Answers

Based on the analysis, the pairs that contain iron in both species are: - Option (a) nitrogenase, cytochromes - Option (d) haemoglobin, cytochromes

Key concepts

Iron-containing enzymes

Iron-containing enzymes play crucial roles in a range of biological systems. They act as catalysts, speeding up chemical reactions in cells. A good example is nitrogenase, an enzyme that facilitates the conversion of nitrogen gas from the atmosphere into ammonia. Iron is present in nitrogenase as part of an iron-sulfur cluster, which is essential for its activity. Another common class of iron-containing enzymes is cytochromes, which are involved in electron transport chains. These are vital in cellular respiration, helping cells to produce energy efficiently. Without iron, these enzymes would not function effectively, hindering biological processes necessary for life. This makes iron a critical element in enzyme function.

Heme proteins

Heme proteins are a group of proteins that contain an iron atom embedded in a heme group. The heme group is a complex ring-like structure that helps the protein in carrying out its functions. A familiar example of a heme protein is hemoglobin, which transports oxygen in the blood. The iron in the heme group binds to oxygen molecules, allowing hemoglobin to carry them through the bloodstream to cells. Another example is the cytochrome proteins found in the mitochondria. They play a key role in the process of energy production within cells through the electron transport chain. The presence of iron within the heme group is what allows these proteins to bind with gases like oxygen or transfer electrons, which is fundamental to their function.

Iron-sulfur clusters

Iron-sulfur clusters are assemblies of iron and sulfur atoms found in a wide variety of enzymes. These clusters are fundamental in facilitating electron transfers because they can easily gain and lose electrons. They are integral to enzymes like nitrogenase and play essential roles in metabolic pathways. The structure typically involves iron atoms coordinated with sulfur from cysteine amino acids in proteins. This arrangement provides stability and enables efficient electron transfer. Iron-sulfur clusters are also used in enzymes associated with DNA repair, energy production, and biosynthesis processes, showcasing their versatility and importance within biological systems.

Biological molecules with metal ions

Inorganic metal ions are found in various biological molecules and are crucial for the molecules' stability and function. These metal ions, such as iron, zinc, or copper, often act as cofactors, assisting in biochemical reactions. For instance, the enzyme carboxypeptidase contains zinc which is essential for its role in protein digestion. In contrast, hemoglobin relies on iron to carry oxygen. Each metal ion has unique properties that enable these biological molecules to perform specific functions. Through the selective incorporation of metal ions, organisms can conduct numerous biochemical processes, which underscores the significance of metal ions in maintaining life. Understanding these roles provides insight into how complex and efficient biological systems can be.