Читать книгу Molecular Mechanisms of Photosynthesis - Robert E. Blankenship - Страница 37

Plants are the most complex of all photosynthetic organisms (Taiz et al., 2018). The simplest plants are the bryophytes, including the mosses, liverworts, and hornworts. They are in many ways like algae and do not have true roots or leaves, or a vascular (liquid‐transporting) system. They do not produce hard tissues for support. The vascular plants include the ferns and the seed plants. The ferns reproduce by means of spores, and have roots, leaves, and vascular tissues, as well as woody tissues for mechanical support. The seed plants reproduce by means of seeds and also contain roots and leaves, as well as vascular and woody tissues. The seed plants are divided into two groups: gymnosperms and angiosperms. Gymnosperms are the more primitive group and include coniferous trees. Angiosperms, also known as flowering plants, make up the vast majority of the species of plants around us.

Remarkably, the basic structure of the photosynthetic membrane and the mechanism of photosynthesis are generally similar in all oxygenic photosynthetic organisms. Some cells include novel antenna complexes, and certain regulatory mechanisms are clearly more sophisticated as one moves from cyanobacteria to algae to higher plants. However, the same basic principles and complexes are found throughout this wide range of organisms. It seems that nature perfected the ability to carry out photosynthesis several billion years ago and has not made major alterations since then. Even the anoxygenic photosynthetic bacteria, while clearly much more primitive than oxygenic forms, carry out photosynthesis using the same basic physical principles. As we proceed, we will examine each of these groups, comparing and contrasting them, trying to find common principles, and pointing out significant differences where they occur.