A student is comparing plant and animal cells under a microscope.

Question

How does the presence of cellulose in plant cells affect their structure and function compared to animal cells?

Answer 1

The presence of cellulose in plant cells significantly influences both their structure and function compared to animal cells. Here are some key points regarding these differences:

Structure:

1. Cell Wall:

   • Plant cells have a rigid cell wall made primarily of cellulose, which provides structural support and determines cell shape. This rigid structure enables plants to maintain turgor pressure, keeping cells turgid and upright.
   • In contrast, animal cells lack a cell wall and instead have a flexible plasma membrane. This allows for a variety of cell shapes but provides less structural support.

2. Turgor Pressure:

   • The presence of a cell wall allows plant cells to resist internal pressure from water (turgor pressure). This pressure is vital for maintaining the integrity and shape of plant tissues.
   • Animal cells can become lysed (burst) if too much water enters due to osmotic pressure, since they lack cell walls to contain the swelling.

3. Shape:

   • Plant cells typically have a fixed geometric shape (often rectangular or box-like) due to the stiffness of the cellulose cell wall.
   • Animal cells can have various shapes and sizes, allowing for a wider range of functions and mobility.

Function:

1. Protection and Support:

   • The cellulose cell wall provides protection against mechanical stress and pathogens. It serves as an additional layer of defense compared to what is typically available to animal cells.
   • Animal cells rely more on their cytoskeleton and extracellular matrix for structural integrity and communication.

2. Growth:

   • Plant cells can grow by expanding their vacuoles, which push against the rigid cell wall, allowing them to increase in size while maintaining structure.
   • Animal cells typically grow more by increasing in volume without a rigid structure to limit their expansion.

3. Photosynthesis:

   • While not directly related to cellulose, plant cells contain chloroplasts that perform photosynthesis, converting sunlight into energy. The structural integrity provided by cellulose allows these cells to position themselves optimally for light exposure.
   • Animal cells do not perform photosynthesis and thus do not need a structure adapted for capturing sunlight.

4. Transport:

   • The cellulose cell wall has pores called plasmodesmata that enable communication and transport of materials between plant cells.
   • Animal cells communicate and transport materials through structures such as gap junctions and direct transport across the plasma membrane.

In summary, the presence of cellulose in plant cells contributes to their rigidity, structural stability, and certain functions, distinguishing them significantly from the more flexible and variable structures found in animal cells.