Question

Kinetin, a modified form of adenine was discovered from (a) autoclaved herring sperm DNA (b) coconut milk (c) corn kernel (d) fungus.

Short answer

Kinetin was discovered from (a) autoclaved herring sperm DNA.

Step-by-step solution

Identifying the source of Kinetin

To solve this exercise, it is necessary to recall or research the original source from which kinetin was discovered. Kinetin, which is a type of cytokinin, was first isolated from the DNA of herring sperm. Therefore, the task is to match the correct option with this information.

Choosing the correct option

After identifying that kinetin was discovered in the DNA of herring sperm, look at the given options and choose the one that matches this description. In the provided options, (a) autoclaved herring sperm DNA is the correct source of kinetin.

Key concepts

Cytokinins

Cytokinins are a class of plant hormones that play a pivotal role in various plant growth processes, including cell division, shoot and root development, and the delay of senescence, which is the aging process in plants. The discovery of cytokinins was a significant milestone in plant biology. They were first isolated from herring sperm DNA, which surprisingly contributed to the understanding of plant growth. These hormones function by stimulating plant cell division and growth, leading to the formation of new tissues, hence they are named after 'cytokinesis', the process of cytoplasm division in cell division.

As part of plant hormone regulation, cytokinins work in concert with other hormones like auxins and gibberellins to fine-tune plant development. They are essential for tissue culture, where small plant tissue fragments can be used to regenerate whole plants, primarily due to the action of cytokinins in stimulating cell division.

Herring Sperm DNA

Herring sperm DNA is an unlikely but historically significant source for the discovery of plant hormones, specifically kinetin. It is not something that comes to mind when thinking about plant growth, but it was the DNA from herring sperm that led to the isolation of the first cytokinin. The process involved autoclaving the herring sperm DNA, which means it was subjected to high temperature and pressure in a steam environment. This process allowed the breakdown of DNA into smaller components, one of which was kinetin. Kinetin, although naturally occurring in plants, was thus first identified from an animal source, which highlights the surprising intersections between different biological domains.

Since that serendipitous discovery, the role of DNA in encoding and regulating the development of organisms has been far better understood. Moreover, it showcases the importance of cross-disciplinary research and how studies on one type of organism can yield results pertinent to another.

Plant Hormones

Plant hormones, also known as phytohormones, are chemical messengers that influence a wide array of plant functions. They are integral to the life of plants, controlling processes from seed germination to flowering, fruiting, and even death. These hormones include auxins, gibberellins, cytokinins, ethylene, and abscisic acid, each with specific roles in plant development and stress responses.

For instance, auxins are involved in the elongation of plant cells and are key players in the phototropic (growth towards light) and gravitropic (growth in response to gravity) responses of plants. Gibberellins are vital for seed germination and stem elongation, while abscisic acid plays an essential role in seed dormancy and helps plants to withstand drought. Ethylene is unique as it is a gaseous hormone and it influences fruit ripening and leaf abscission. Understanding plant hormones is not only crucial for botany and agriculture, but it also has practical applications in food production and environmental sustainability.