Comparing plant and animal cells | Year 7 Biology (Cambridge) PDF Download

Introduction

Animal and plant cells share many similarities since they are both eukaryotic cells, meaning they have a membrane-bound nucleus. However, there are also key differences between them. This chapter explores the similarities and differences between animal and plant cells, along with their structures and functions.

Similarities Between Animal and Plant Cells

Membrane-Bound Organelles

Both animal and plant cells have membrane-bound organelles, including:

• Cytoplasm: The fluid inside the cell that contains organelles.
• Cell Membrane: A semi-permeable barrier that controls what enters and exits the cell.
• Nucleus: Contains the cell’s genetic information.
• Mitochondria: Known as the powerhouses of the cell, they convert glucose into ATP (energy).
• Rough and Smooth Endoplasmic Reticulum (ER): The rough ER is covered with ribosomes and helps produce proteins, while the smooth ER makes lipids.
• Golgi Apparatus: Modifies and packages proteins.
• Peroxisomes: Break down waste products.

Key Differences Between Animal and Plant Cells

• Cell Wall
  • Plant Cells: Have a rigid cell wall made of cellulose that provides additional stability and protection, giving plant cells a fixed, angular shape.
  • Animal Cells: Do not have a cell wall and are more round and irregular in shape.
• Energy Production
  • Plant Cells: Are autotrophs, meaning they produce their own food through photosynthesis using chloroplasts. Chloroplasts contain chlorophyll, which captures light energy.
  • Animal Cells: Are heterotrophs, meaning they consume other organisms for food. They obtain sugar from their diet and break it down for energy.
• Vacuoles
  • Plant Cells: Have a large central vacuole that can occupy up to 90% of the cell’s volume, storing nutrients, degrading waste substances, and filling up space.
  • Animal Cells: Have smaller vacuoles that are more numerous and do not occupy as much space as the central vacuole in plant cells.

Specialized Structures

• Chloroplasts
  • Plant Cells: Contain chloroplasts for photosynthesis, where sunlight is converted into sugar, which is then used to produce energy.
  • Animal Cells: Lack chloroplasts because they do not perform photosynthesis.
• Centrioles and Cytoskeleton
  • Animal Cells: Have centrioles that help in cell division and microtubule organization. Animal cells also have a well-defined cytoskeleton for structural support.
  • Plant Cells: Do not have centrioles but have multiple small nucleation sites for microtubule organization.
• Flagella and Cilia
  • Plant Cells: Only reproductive cells (gametes) may have flagella.
  • Animal Cells: Sperm cells have flagella for movement. Many animal cells have cilia, which are used to move debris and mucus in the respiratory system and help sperm move towards the egg in the reproductive system.
• Lysosomes
  • Animal Cells: Clearly defined lysosomes that contain enzymes to break down biomolecules and are involved in processes like secretion and cell signaling.
  • Plant Cells: The presence of lysosomes is debated, but they have vacuoles that perform similar functions.
• Plasmodesmata and Gap Junctions
  • Plant Cells: Have plasmodesmata, channels that connect two plant cells and allow communication.
  • Animal Cells: Have gap junctions, similar channels that connect the cytoplasm of adjacent cells for communication.

Examples

• Mitochondria in Animal and Plant Cells:
  • Function: Convert glucose into ATP.
  • Example: Muscle cells in animals have more mitochondria due to higher energy needs.
• Chloroplasts in Plant Cells:
  • Function: Perform photosynthesis.
  • Example: Leaves of plants contain many chloroplasts to capture sunlight efficiently.
• Cell Wall in Plant Cells:
  • Function: Provides structure and protection.
  • Example: The cell wall allows plants like trees to stand upright and grow tall.
• Vacuoles in Plant Cells:
  • Function: Store nutrients and waste products.
  • Example: The large central vacuole in plant cells helps maintain turgor pressure, keeping the plant rigid.

Conclusion

Animal and plant cells have many common structures and functions, reflecting their shared eukaryotic nature. However, they also have distinct features that reflect their different roles in living organisms. Understanding these similarities and differences helps in comprehending the complexity and functionality of cells.