A eukaryotic cell is a cell that contains a nucleus and organelles and is enclosed by a plasma membrane. They include protozoa, fungi, plants, and animals. These organisms are grouped into the biological domain Eukaryota. Eukaryotic cells are larger and more complex than prokaryotic cells, which are found in Archaea and Bacteria, the other two domains of life.
Eukaryotes can reproduce both asexually through mitosis and sexually through meiosis and gamete fusion. In mitosis, one cell divides to produce two genetically identical cells. They act as sex cells. Each gamete has just one set of chromosomes, each a unique mix of the corresponding pair of parental chromosomes resulting from genetic recombination during meiosis.
Characteristics of Eukaryotic Cells
- Eukaryotic cells have the nucleus enclosed within the nuclear membrane.
- The cell has mitochondria.
- Flagella and cilia are the locomotory organs in a eukaryotic cell.
- A cell wall is the outermost layer of the eukaryotic cells.
- The cells divide by a process called mitosis.
- The eukaryotic cells contain a cytoskeletal structure.
- The nucleus contains a single, linear DNA, which carries all the genetic information.
Structure Of Eukaryotic Cell
- Plasma Membrane: The plasma membrane separates the cell from the outside environment. It comprises specific embedded proteins, which help in the exchange of substances in and out of the cell.
- Cell Wall: It is a rigid structure present outside the plant cell. It is, however, absent in animal cells. It provides shape to the cell and helps in cell-to-cell interaction. It is a protective layer that protects the cell from any injury or pathogen attacks.
- Cytoskeleton: The cytoskeleton is present inside the cytoplasm, which consists of microfilaments, microtubules, and fibers to provide perfect shape to the cell, anchor the organelles, and stimulate the cell movement.
- Endoplasmic Reticulum: It is a network of small, tubular structures that divides the cell surface into two parts: luminal and extraluminal.
- Nucleus: The nucleoplasm enclosed within the nucleus contains DNA and proteins. The nuclear envelop consists of two layers- the outer membrane and the inner membrane. Both the membranes are permeable to ions, molecules, and RNA material. Ribosome production also takes place inside the nucleus.
Examples of Eukaryotic Cells
- Plant Cells: Plant cells also contain organelles called chloroplasts which contain the molecule chlorophyll. This important molecule is used in the process of photosynthesis, which is when a plant makes its own energy from sunlight, carbon dioxide, and water.
- Fungal Cells: Some fungi have septa, which are holes that allow organelles and cytoplasm to pass between them. This makes the boundaries between different cells less clear.
- Animal Cells: Animal cells differ from plant cells in that they do not have chloroplasts and have smaller vacuoles instead of a large central vacuole.
- Protozoa: Protozoa are eukaryotic organisms that consist of a single cell. They can move around and eat, and they digest food in vacuoles. Some also have a thin layer called a pellicle, which provides support to the cell membrane.