An animal cell is a type of eukaryotic cell that lacks a cell wall and has a true, membrane-bound nucleus along with other cellular organelles. Animal cells are generally smaller than plant cells. Another defining characteristic is its irregular shape. This is due to the absence of a cell wall. But animal cells share other cellular organelles with plant cells as both have evolved from eukaryotic cells.
Structure of Animal Cell
The animal cell comprises the following cell organelles:
- Cell Membrane: A thin semipermeable membrane layer of protein and fats surrounding the cell. Its primary role is to protect the cell from its surrounding. Also, it controls the entry and exit of nutrients and other microscopic entities into the cell.
- Nuclear Membrane: It is a double-membrane structure that surrounds the nucleus.
- Nucleus: It is an organelle that contains several other sub-organelles such as nucleolus, nucleosomes, and chromatins. It also contains DNA and other genetic materials.
- Centrosome: It is a small organelle found near the nucleus which has a thick center with radiating tubules. The centrosomes are where microtubules are produced.
- Lysosome: They are round organelles surrounded by a membrane and comprising digestive enzymes which help in digestion, excretion, and the cell renewal process.
- Cytoplasm: A jelly-like material that contains all the cell organelles, enclosed within the cell membrane. The substance found within the cell nucleus, contained by the nuclear membrane is called the nucleoplasm.
- Golgi Apparatus: A flat, smooth layered, sac-like organelle that is located near the nucleus and involved in manufacturing, storing, packing, and transporting the particles throughout the cell.
- Mitochondrion: They are spherical or rod-shaped organelles with a double membrane. They are the powerhouse of a cell as they play an important role in releasing energy.
- Ribosome: Ribosome is a small organelle made up of RNA-rich cytoplasmic granules, and they are the sites of protein synthesis.
- Endoplasmic Reticulum: This cellular organelle is composed of a thin, winding network of membranous sacs originating from the nucleus.
- Vacuole: A membrane-bound organelle present inside a cell involved in maintaining shape and storing water, food, wastes, etc.
- Nucleopore: Nucleopore is tiny holes present in the nuclear membrane which are involved in the movement of nucleic acids and proteins within the cell.
Types of Animal Cells
There are numerous types of animal cells, each designed to serve specific functions. The most common types of animal cells are:
- Skin Cells: Melanocytes, keratinocytes, Merkel cells, and Langerhans cells.
- Muscle Cells: Myocyte, Myosatellite cells, Tendon cells, Cardiac muscle cells.
- Blood Cells: Leukocytes, erythrocytes, platelet.
- Nerve Cells: Schwann cell, glial cells, etc.
- Fat Cells: Adipocytes.