Question

Distinguish between meristem cells and differentiated cells.

Short answer

Meristem cells are undifferentiated cells in plants that exist in regions of active growth such as the tips of roots and shoots, and cambium. They maintain the capability to divide and differentiate into various types of specialized plant cells. These cells are generally smaller in size, have a thin primary cell wall and large nuclei, and fewer organelles. Comparatively, differentiated cells are specialized, having developed specific structures and functions to perform a specific role in the plant. Examples include xylem cells, phloem cells, guard cells, and parenchyma cells. These cells exhibit a more specialized structure based on their role, have thick secondary cell walls, and are found throughout various organs and tissues in the plant where their functions are required.

Step-by-step solution

Define meristem cells

Meristem cells are undifferentiated cells found in the plants, especially in the regions of active growth, such as the tips of roots and shoots, and also in cambium which is between the xylem and phloem. These cells have the ability to divide and differentiate into various types of specialized plant cells.

Define differentiated cells

Differentiated cells are specialized cells that have undergone the process of differentiation, in which they develop specific structures and functions to perform a particular role in the plant. Examples of differentiated plant cells include xylem cells, phloem cells, guard cells, and parenchyma cells.

Compare structure

Meristem cells are generally small, with a thin primary cell wall and large nuclei. They have fewer organelles and small vacuoles compared to differentiated cells. On the other hand, differentiated cells have a more specialized structure depending on their function. For example, xylem cells have thick secondary cell walls for water transport and support, while guard cells have specialized structures to regulate the opening and closing of stomata.

Compare function

The primary function of meristem cells is to actively divide and give rise to new cells that will eventually differentiate and become specialized cells. Differentiated cells, on the other hand, perform specific functions in the plant. For example, xylem cells transport water and minerals, phloem cells transport sugars, and guard cells regulate gas exchange in the leaf.

Compare location

Meristem cells are typically found in areas of active growth in plants, such as the root and shoot tips (apical meristems) and the cambium layer (cambium meristems) which is between the xylem and phloem. Differentiated cells are found throughout the plant, in organs and tissues where their specific functions are needed. To sum up, meristem cells are undifferentiated cells that actively divide and differentiate into various specialized plant cells. They have a simple structure and are found in regions of active growth. Differentiated cells have specialized structures and functions and are located throughout the plant where their roles are required.

Key concepts

Plant Cell Differentiation

Plant cell differentiation is the process by which immature and unspecialized cells, known as meristematic cells, become mature cells with distinct structures and functions. Each plant cell starts its life as a meristematic cell which divides and expands. As these cells develop, they undergo physical and chemical changes tailored to their roles in the plant, such as photosynthesis, support, nutrient storage, or transport.

For instance, a stem cell in the meristem of a young leaf might differentiate into a specialized cell like a palisade parenchyma cell, which is heavily involved in photosynthesis. This process is controlled by genetic expression and influenced by various internal and environmental factors, ensuring that cells develop the right features to work efficiently within the plant's biological systems.

It's crucial for students to recognize that differentiation is directional; once a plant cell has differentiated, it typically cannot revert back to a meristematic state. However, some plants show remarkable plasticity through a process called dedifferentiation, where specialized cells can revert to a meristematic state under certain conditions, a testament to plant adaptability.

Structure of Meristem Cells

The structure of meristem cells is distinctively simple and yet perfectly poised for their primary role in growth and development. These cells, rich in protoplasm, are generally small with a large nucleus that facilitates the rapid cell division necessary for growth. Their primary cell walls are thin and flexible, allowing for expansion as the cells divide.

Meristem cells typically have small vacuoles or none at all, in contrast to differentiated cells that often contain larger central vacuoles. This highlights the meristem's focus on division over storage. The cytoplasm of these cells is dense with the machinery needed for cell division, like centrosomes and spindle fibres, which are absent in differentiated plant cells.

Students should envision the meristems as the plant's cellular 'construction sites' where all cells are initially shaped before being dispatched to different regions of the plant to mature and assume specific roles.

Functions of Differentiated Plant Cells

Once plant cells have differentiated, they take on specialized functions that are integral to the plant's survival and growth. The variety of these functions reflects the amazing diversity of forms and roles that cells can adopt.

Xylem cells, for instance, have toughened walls containing lignin, giving them the strength to support the plant and form efficient water-transporting vessels. Phloem cells, on the other hand, are adapted to transport sugars and other organic nutrients from the leaves to the rest of the plant.

Guard cells, shaped to form stomata pores, play a key role in regulating gas exchange and water release in leaves. Parenchyma cells, perhaps the most versatile, can store nutrients and water, aid in photosynthesis, and help with injury recovery. Students should appreciate these specialized cells as vital components of a well-orchestrated biological system, with each cell type contributing to the plant's overall health and functionality.