Difference Between Plant and Animal Cells

Main Difference – Plant vs Animal Cells

Plant cells and animal cells are two types of eukaryotic cells. Thus, both these cell types are composed of membrane-bound organelles like nucleus, mitochondria and endoplasmic reticulum. Both cell types contain 80S ribosomes for protein synthesis. Plant cells exhibit a fixed, rectangular shape due to the presence of a cell wall. Their cell wall is mainly composed of cellulose. On the contrary, animal cells have a round, irregular shape due to the absence of a cell wall. The key difference between plant and animal cells is that plant cells are composed of cell walls and chloroplasts whereas animal cells lack cell walls and chloroplasts. 

This article studies, 

1. What are Plant Cells
      – Structure and Characteristics
2. What are Animal Cells
      – Structure and Characteristics
3. What is the difference between Plant and Animal Cells

What are Plant Cells

Plant cells belong to the kingdom: Plantae. One of the characteristic features in plant cells is the cellulose cell wall they bear. Plant cell wall is mainly composed of different compounds such as cellulose, hemicellulose, pectin and lignin. These compounds are secreted by protoplast in the cell membrane. The cell wall provides the shape to form tissues of the plant and plays a vital role in intercellular communication, in addition to providing protection. The cell wall helps to form plant-microbe interactions. Plasmodesmata is a specialized cell-to-cell communication pathway that is created through the pores in the primary cell wall. Plasmalemma and endoplasmic reticulum of the adjacent cells are continuous through the plasmodesmata. 

On the other hand, plant cells consist of a large, central vacuole. The membrane of the vacuole is called the tonoplast. Water-filled vacuole maintains cell’s turgor and helps to control the movement of molecules between the cytosol and the sap. Ultimately, the vacuole stores digested waste proteins and organelles and other useful material.

Another major characteristic in plant cells is their ability to produce carbohydrates from carbon dioxide and water with the aid of sunlight. This process is called photosynthesis. Chlorophyll is the green-colored pigment which absorbs the sun light. It occurs in plastids identified as chloroplast.

On the other hand, amylplasts are another plastid type which is specialized for the storage of starch. Elaioplasts are specialized for the storage of fat. Pigments are synthesized and stored in chromoplasts. Plastids are composed of their own genomes with about 100 to 120 unique genes in it. Plastids are thought to be originated from prokaryotic endosymbionts found in early ancestor eukaryotes.  

Figure 1: Generalized Plant Cell

What are Animal Cells

Multicellular cells belonging to the kingdom: animalia are referred to as animal cells. Approximately 210 distinct cell types can be found in adult human body. They have various functions like production of enzymes, hormones and production of energy. Animal cells are smaller in size compared to plant cells. They are irregular in shape due to the lack of a cell wall. The outer boundary of an animal cell is the plasma membrane which is considered as semi-permeable. Semi-permeable membranes only allow selected molecules to move across it. Plasma membrane is composed of phospholipids containing polor heads and non-polor tails. It is described by the lipid bi-layer model. Animal cells also lack a large vacuole as well as plastids. They contain structures like cilia, centrioles, flagella and lysosomes. Lysosomes store digestive enzymes.

Figure 2: Generalized Animal Cell

Difference Between Plant and Animal Cells

Cell Wall

Plant Cells: Plant cells are composed of a cell wall made up of cellulose.

Animal Cells: Animal cells don’t possess a cell wall. Thus, animal cells can change the shape of the cell often.

Size of the Cell

Plant Cells: Plant cells are usually larger in size.

Animal Cells: Animal cells are comparatively smaller in size.

Shape

Plant Cells: Animal cells have a rectangular, fixed shape.

Animal Cells: Plant cells have a round, irregular shape.

Vacuole

Plant Cells: They have one or more, comparatively very smaller vacuoles.

Animal Cells: They have one, large, central vacuole taking 90% of cell volume.

Centrioles

Plant Cells: Centrioles are present in lower forms of plants.

Animal Cells: Centrioles are present in all animals.

Cholroplast

Plant Cells: Plant cells are composed of chloroplast to produce their own food. Hence, plant cells are autotophs.

Animal Cells: Animals cells do not contain chloroplast. Hence, animal cells are heterotrophs.

Lysosomes

Plant Cells: They don’t have lysosomes.

Animal Cells: They consist of lysosomes in the cytoplasm.

Glyoxysomes

Plant Cells: They are composed of glyoxysomes.

Animal Cells: They don’t have glyoxysomes.

Junctions

Plant Cells: They are composed of plasmodesmata as cell junctions.

Animal Cells: Tight junctions and desmosomes are present as junctions.

Food Reservation

Plant Cells: They reserve food in the form of starch.

Animal Cells: They reserve food in the form of glycogen.

Amino Acid and Coenzyme Synthesis

Plant Cells: Plant cells synthesize all required amino acids, coenzymes and vitamins by themselves.

Animal Cells: Animal cells are unable to synthesize all amino acids, coenzymes and vitamins required by them.

Spindle Formation

Plant Cells: Spindle formation is anastral.

Animal Cells: Spindle formation is amphiastral.

Cell Burst

Plant Cells: Plant cells do not burst under hypotonic conditions due to the presence of cell wall.

Animal Cells: Animal cells will burst under hypotonic conditions.

Conclusion

The basic structure of plant and animal cells are comparatively the same. Animal cells are smaller than plant cells. They also consist of an irregular shape. Therefore animal cells can act as transporters. The most common example is red blood cells in human circular system. On the other hand, plant cells contain plastids called chloroplast for photosynthesis. But, animal cells do not contain chloroplasts. Thus, plant cells are considered as autotrophs whereas the animal cells are considered as heterotrophs. This is the main difference between plant and animal cells.

Reference:
1. “Plant cell”. Wikipedia, the free encyclopedia, 2017. Accessed 22 Feb 2017
2. “Plant Cell Anatomy”. Encharnted Learning, 2016. Accessed 22 Feb 2017
3. “Animal Cell Structure”. MOLECULAR EXPRESSIONS, 2015. Accessed 22 Feb 2017
4. “Animal cell”. TutorVista.com, 2017. Accessed 22 Feb 2017

Image Courtesy:
1. “Simple diagram of plant cell (en).svg”. By domdomegg – Own work (CC-By-4.0) via Commons Wikimedia
2. “0312 Animal Cell and Components.jpg”. By OpenStex –  (CC-BY-4.0) via Commons Wikimedia