Plant vs. Animal Cells: Discover the Structures That Make Each Unique

Every living thing is made of cells, and you have already explored how cells organize into systems in Cells to Systems: Hierarchical Organization of Life. Now you will zoom in to compare two major cell types: plant cells and animal cells.

Both plant and animal cells are eukaryotic cells, meaning they have a membrane-bound nucleus. However, they have important structural differences that reflect how each organism survives plants make their own food using sunlight, while animals consume food for energy.

When you look at a plant cell, you will notice three structures that animal cells do not have.

The cell wall is a rigid outer layer made of cellulose that surrounds the cell membrane. It gives plant cells their fixed, rectangular, box-like shape and provides structural support. Because animal cells lack a cell wall, they have flexible, rounded, and irregular shapes instead.

Inside the plant cell, you will find chloroplasts green organelles that contain a pigment called chlorophyll. Chlorophyll absorbs sunlight and powers photosynthesis, the process that converts sunlight, water, and carbon dioxide into glucose. This is why plant cells appear green and why plants can make their own food.

Plant cells also have a large central vacuole that stores water, nutrients, and waste products. This vacuole creates turgor pressure, keeping the plant firm and upright. When a plant loses water, the vacuole shrinks and the plant wilts.

Animal cells have centrioles, organelles that help organize cell division. Most plant cells do not have centrioles. Animal cells also have only small, scattered vacuoles rather than one large central vacuole.

Because animal cells have no rigid cell wall, their flexible cell membrane allows them to take on many different shapes suited to their specific jobs such as the flat shape of skin cells or the long shape of nerve cells.

Despite their differences, plant and animal cells share several essential organelles.

The nucleus acts as the control center of the cell, holding DNA organized into chromosomes that direct all cell activities. The cell membrane is selectively permeable, meaning it allows needed substances in and keeps harmful ones out. Mitochondria are called the "powerhouse of the cell" because they carry out cellular respiration, converting glucose and oxygen into ATP energy a process that happens in both plant and animal cells.

Plant Cell: A type of eukaryotic cell found in plants that contains a cell wall, chloroplasts, and a large central vacuole in addition to organelles shared with animal cells.

Animal Cell: A type of eukaryotic cell found in animals that has a flexible cell membrane, small vacuoles, and centrioles, but no cell wall or chloroplasts.

Eukaryotic Cell: A cell that has a membrane-bound nucleus containing its DNA. Both plant and animal cells are eukaryotic cells.

Chloroplast: An organelle found only in plant cells that contains chlorophyll and is responsible for photosynthesis. Chloroplasts are what make plant cells appear green.

Chlorophyll: The green pigment inside chloroplasts that absorbs sunlight energy to power photosynthesis. Chlorophyll is what gives plants their green color.

Photosynthesis: The process by which plant cells use chloroplasts to convert sunlight, water, and carbon dioxide into glucose and oxygen. Animal cells cannot perform photosynthesis.

Cell Wall: A rigid outer layer found only in plant cells, made primarily of cellulose. It gives plant cells their box-like shape and provides structural support.

Cellulose: A tough, complex carbohydrate made of long chains of glucose molecules that forms the main structural material of the plant cell wall.

Cell Membrane: A thin, flexible, selectively permeable layer that surrounds all cells both plant and animal and controls what substances enter and exit the cell.

Selectively Permeable: A property of the cell membrane that means it allows some substances to pass through while blocking others, helping the cell maintain a stable internal environment.

Nucleus: The membrane-bound organelle found in both plant and animal cells that contains DNA organized into chromosomes and acts as the control center of the cell.

Mitochondria: Organelles found in both plant and animal cells that carry out cellular respiration, converting glucose and oxygen into ATP energy. They are often called the "powerhouse of the cell."

Cellular Respiration: The process carried out by mitochondria in which glucose and oxygen are broken down to release usable energy in the form of ATP. This occurs in both plant and animal cells.

ATP: Adenosine triphosphate the usable energy currency of the cell, produced by mitochondria during cellular respiration.

Vacuole: An organelle that stores water, nutrients, and waste products. Plant cells have one large central vacuole; animal cells have only small, scattered vacuoles.

Central Vacuole: The large storage organelle unique to plant cells that holds water and creates turgor pressure to keep the plant firm. When it loses water, the plant wilts.

Turgor Pressure: The pressure created by water inside the central vacuole pushing against the cell wall, which keeps plant cells firm and upright.

Cytoplasm: The jelly-like fluid that fills the interior of a cell and surrounds all the organelles, excluding the nucleus. It is found in both plant and animal cells.

Ribosomes: Tiny organelles found in both plant and animal cells that build proteins by linking amino acids together using instructions from the nucleus's DNA.

Centrioles: Organelles found in animal cells that help organize the spindle fibers during cell division. Most plant cells do not have centrioles.

When you examine a cell under a microscope, you can identify whether it is a plant or animal cell by looking for key structures. If you see a rigid outer wall, green organelles, and a large central space, you are looking at a plant cell. If the cell has a rounded, irregular shape with no green organelles and no outer wall, it is most likely an animal cell.

You can also connect this knowledge to Cell Components: Organelles and Functions to deepen your understanding of what each organelle does, and to Cell Functions: Transport and Energy Production to see how these structures work together to keep cells alive.

Remember: both cell types share the nucleus, cell membrane, mitochondria, ribosomes, and cytoplasm but only plant cells have chloroplasts, a cell wall, and a large central vacuole, while only animal cells have centrioles.

Before exploring plant and animal cell types, you should be familiar with Cells to Systems: Hierarchical Organization of Life, which shows you how individual cells build up into tissues, organs, and organ systems. Understanding that foundation helps you appreciate why cell structure matters so much.

You should also review Basic Principles: Fundamental Concepts of Cells to make sure you understand what cells are and why they are the basic unit of life before comparing plant and animal cell structures.

Your study of plant and animal cell types connects to many other important science concepts. Here is how each related topic links to what you are learning:

Basic Principles: Fundamental Concepts of Cells You will use the foundational ideas about what cells are and how they function as the starting point for comparing plant and animal cell structures.

Cell Components: Organelles and Functions You will explore each organelle in greater detail here, building directly on the structures you identify when comparing plant and animal cells.

Cell Functions: Transport and Energy Production You will discover how the organelles in plant and animal cells work together to move materials and produce energy, extending what you learn about mitochondria and cell membranes.

Taxonomy Systems: Kingdoms and Classification Criteria You will see how the differences between plant and animal cells relate to how scientists classify all living things into kingdoms.

Species Diversity: Biodiversity Measurements You will understand how the variety of cell types across species contributes to the incredible biodiversity of life on Earth.

Evidence of Change: Fossil Record and Similarities You will explore how similarities in cell structure across species provide evidence of shared ancestry and evolutionary change.

Natural Selection: Adaptation and Survival You will connect the structural differences between plant and animal cells to how each organism has adapted to survive in its environment.

Comparative Biology: Anatomical and Genetic Evidence This subsequent topic builds on your understanding of cell structure to compare anatomy and genetics across different species.

Adaptation: Environmental Pressures You will apply your knowledge of cell structure to understand how environmental pressures drive adaptations at the cellular level.

Genetic Variation: Sources of Diversity You will explore how the nucleus and DNA in plant and animal cells are the source of genetic variation and diversity in living things.