In most of the competitive exams, the Biology segment is regarded as the score booster. It would be a walk in the breeze without any hiccup if learnt well . This article lets you know in detail about the structure of Plant and Animal cell. Questions from this domain are found in various competitive exams. We will also examine and compare the two types of cells, viz Plant Cell & Animal Cell.
It is well known that a cell is the structural and functional unit of life. The cell structure differs according to shape, size and the function to be performed. Since both the Plant cell and the animal cell are eukaryotic cells, they are very similar in structure. For instance, their sizes may range anywhere between 1 to 100 micrometers. As a result both are visible only through a microscope. Most of the cell components like nucleus, plasma membrane, ribosomes, cytoplasm, mitochondria, Golgi apparatus and endoplasmic reticulum are common to both the plant and animal cell. However, the plant cell has a few added organelles like cell wall, chloroplasts and a large vacuole.
Structure of Plant and Animal Cell
Structure of Animal Cell
An animal cell is generally smaller than its plant equivalent. The eukaryotic animal cell has a membrane bound nucleus with the presence of DNA inside the nucleus. Apart from this, various other membrane bound and cellular structures are also present for specific functions. But the animal cell is irregular shaped due to the absence of a cell wall.
A characteristic animal cell consists of the following organelles:
Cell Membrane/Plasma membrane
It is a selectively permeable membrane. That is to say, it permits the entry and exit of some materials in and out of the cell while restricting movement of some others. It is made up of organic molecules such as lipids and proteins. The selective permeability along with the flexibility of the cell membrane enables nutrition (in organisms like amoeba) and exchange of gases by the methods of osmosis and diffusion.
The nucleus is enveloped by a double layered covering called the nuclear membrane. It has pores in it consequently resulting in the exchange of material in and out of the nucleus. Subsequently, it has many sub organelles for a proper cell functioning. The nucleus itself has important functions to play such as cellular reproduction. The chromosomes present in the nucleus contain inheritance information to be passed on from parent to the offspring in the form of DNA (Deoxyribo Nucleic Acid) molecules. Moreover, inside the nucleus is present the nucleolus, which accommodates the proteins and RNA.
|Large in size||Small in size|
|Enveloped by the nuclear membrane.||No enclosing membrane seen.|
|Contains chromosomes.||Chromosomes not present.|
|Rich in DNA.||Rich in RNA.|
However, in prokaryotes due to the absence of a well – defined nuclear membrane, the nuclear region is vaguely established. Such an undefined nuclear region is termed as a nucleoid (only nucleic acids are present).
It is the fluid content present inside the cell membrane which houses other cell organelles. Nonetheless, the fluid present inside the nucleus and is bound by the nuclear membrane, is termed as the nucleoplasm.
It is a large network of membrane bound tubes within the cytoplasm of a cell which is made up of cisternae, tubules and vesicles. It has ribosomes attached to it and is continuous with the nuclear membrane. Most importantly, the ER performs diverse functions including calcium storage, protein synthesis and lipid metabolism. The two types of ER are Rough Endoplasmic Reticulum(REN) and Smooth Endoplasmic Reticulum(SER).
|Ribosomes are present||Ribosomes are absent|
|Made of cisternae and tubules||Made of vesicles and tubules|
|Performs enzyme and protein synthesis||Performs glycogen, lipids and steroids synthesis.|
|Develops from nuclear membrane||Develops from RER|
It consists of a system of membranous vesicles arranged parallel to each other in stacks called cisterns. The function of Golgi Apparatus is to modify, package and dispatch the various material synthesized in the ER throughout the cell. It is often involved in the formation of lysosomes. Furthermore, it is called as Golgi Complex or Golgi.
Often referred to as the ‘Powerhouse of the cell’, mitochondria releases the energy required for the various chemical activities in the form of ATP (Adenosine Tri Phosphate) molecules. Mitochondria is a two-membraned, spherical/rod shaped organelle, in which the outer membrane is porous while the inner membrane is acutely folded. These folds in the membrane accounts for the creation of larger surface area for ATP generating reactions.
Apart from ATP generation, they are capable of generating their own proteins since they possess DNA and ribosomes.
Lysosomes are membranous sacs filled with digestive enzymes. Often when a cell gets damaged, the lysosomes burst and the enzymes digest its own cell. As a result, the cell kills itself. The lysosomes are aptly called ‘The Suicidal bag of the cell’ for this reason. The digestive enzymes, usually made by the rough endoplasmic reticulum are strong enough to break down all organic matter entering the lysosome. It ,therefore, keeps the cell clean.
Found only in animal cells, it is the major microtubule organizing center. A Centrosome is made up of two micro-tubular rings, called the centrioles. The major functions of a centrosome include providing the structure for the cell and pull apart the chromatids during cell division; hence is involved in cell division.
Structure of Plant Cell
The plant cell is relatively larger and rectangular than the animal cell. When viewed under a microscope both the cells are found to have distinct structural characteristics owing to the respective functions to be performed. In this section, apart from the cell organelles mentioned earlier, the added components of a plant cell are described in detail.
A cell wall is the most distinguishing feature of a plant cell. It is the non- living component which covers the outermost layer of the cell. The major functions of the cell wall include providing shape and support to the cell. Above all, it separates the cell organelles from the outer environment. In short, the cell wall provides a protection to the cell and its organelles. It is arranged is three prominent layers, namely
- The Primary cell wall
- The Middle lamella
- The Secondary cell wall
The Primary cell wall is a thin, less rigid, cellulose – containing layer of the plant cell. The cell growth is permitted in this region of the cell wall. However, it gradually decreases as the cell matures.
The Middle lamella which is made up of pectates of calcium and magnesium, binds the cell walls of two neighboring plants cells. It makes up the outermost layer of cell wall in a mature plant.
The Secondary cell walls, made up of cellulose and lignin, are synthesized in devoted cells like tracheary elements and fibers. As a result, they are exceptionally strong and rigid; thus providing the plant body with the mechanical support it requires.
Exclusively seen in plant cells and in certain algae, Plastids are membrane bound organelle. However, the presence of chlorophyll pigment makes them responsible for the production and storage of food. Based on their specialized functions, plastids are majorly classified into four types.
It contain the chlorophyll pigment for photosynthesis. They are the green plastids.
It contain the carotene pigment responsible for pigment synthesis and storage. It gives distinctive color to fruits and flowers.
These are the chloroplasts that undergo the aging process. for instance, when a leaf is no longer performing photosynthesis, gerontoplasts helps to convert into different organelles.
These are the non-pigmented plastids (colorless). Therefore, it is mostly found in the root of the plant where photosynthesis doesn’t take place. They convert amino acids and fatty acids. Most importantly, they serve as the storage house for starch, lipids and proteins.
It is a large, membrane bound and fluid filled storage sac. In a typical plant cell, the central vacuole may take up to 50-90% of the cell volume. Because of which it is the most prominent cell organelle in most of the plant cells. The animal cell also contain a few small vacuoles. However, they are not prominent as in case of a plant cell. The function and significance of vacuoles differs greatly according to the cell type. Nevertheless it performs storage functions for both nutrients and waste products. Vacuole is surrounded by a cytoplasmic membrane called as the tonoplast. It separates the vacuolar content from the cytoplasm of the cell. The distinguishable categories of vacuoles are as follows:
- Sap vacuole
- Contractile vacuole
- Food vacuole
- Air vacuole
It has a selectively permeable membrane called the tonoplast. Therefore it separates the vacuole from the cytoplasm. The fluid present in the vacuole is called the sap or vacuolar sap. It contains mineral salts, sugars, proteins, aminoacids, etc.
It has a membrane which is extensible and collapsible leading way for diastolic and systolic actions by the vacuole.
It contains digestive enzymes for the digestion of the nutrients. The cytoplasm of the cell receives the digested material from the food vacuole subsequently.
It is often referred to as pseudo vacuole or gas vacuole. Apart from storing gas, it provides buoyancy, mechanical strength and protection from radiation to the cell.
All the major features and differences of a plant cell and animal cell may be listed as in table below.
|Characteristic||Plant cell||Animal cell|
|Shape||Fixed shape||No definite shape|
|Cell wall||Present outside the plasma membrane||Absent.|
|Vacuole||Large vacuole||Small vacuole|
|Golgi Apparatus||Single & complex||Many simpler units|
To sum up, in spite of the differences amongst the various cell types, both the plant and the animal cell structures share undeniable similarities and perform complex processes in identical ways. Entri wishes you a happy learning!