We are aware of the fact that the cell is the structural and fundamental unit of life. It is also the smallest and the most basic biological unit of living organisms. On the basis of the cellular organization, cells are further classified as eukaryotic and prokaryotic. Plant cells and animal cells fall under the eukaryotic category.
Let us have a detailed overview of the animal cell, its types, diagram, and structure.
Animal Cell Definition
“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.”
Explanation
Animal cells range in size from a few microscopic microns to a few millimeters. The largest known animal cell is the ostrich egg, which can stretch over 5.1 inches across and weighs about 1.4 kilograms. This is in stark contrast to the neurons in the human body, which are just 100 microns across.
The shape of animal cells also varies, with some being flat, and others oval or rod-shaped. There are also more intriguing shapes such as curved, spherical, concave, and rectangular. Most of the cells are microscopic in size and can only be seen under the microscope.
As stated before, animal cells are eukaryotic cells with a membrane-bound nucleus. Furthermore, these cells exhibit the presence of DNA inside the nucleus. They also comprise other membrane-bound organelles and cellular structures that carry out specific functions necessary for a cell to function properly.
Animal Cell Diagram
The diagram given below depicts the structural organization of the animal cell. The various cell organelles present in an animal cell are clearly marked in the animal cell diagram provided below.
Though this animal cell diagram is not representative of any one particular type of cell, it provides insight into the primary organelles and the intricate internal structure of most animal cells. Furthermore, it is easy to distinguish between a plant and animal cell diagram just by inspecting the presence or absence of a cell wall.
Animal Cell Structure
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.
A typical animal cell comprises the following cell organelles:
Cell Membrane
A thin semipermeable membrane layer of lipids and proteins surrounds the cell. Its primary role is to protect the cell from its surroundings. Also, it controls the entry and exit of nutrients and other microscopic entities into the cell. For this reason, cell membranes are known as semi-permeable or selectively permeable membranes.
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.
Nuclear Membrane
It is a double-membrane structure that surrounds the nucleus. It is also referred to as the nuclear envelope.
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 that help in digestion, excretion, and in 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
They are small organelles made up of RNA-rich cytoplasmic granules, and they are the sites of protein synthesis.
Endoplasmic Reticulum (ER)
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 is involved in maintaining shape and storing water, food, wastes, etc.
Nucleopore
They are tiny holes present in the nuclear membrane that are involved in the movement of nucleic acids and proteins across the nuclear membrane.
Animal Cell Types
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
Points to Note About Animal Cell
The cell is the structural and functional unit of life. These cells differ in their shapes, sizes and their structure as they have to fulfill specific functions. Plant cells and animal cells share some common features as both are eukaryotic cells.
However, they differ as animals need to adapt to a more active and non-sedentary lifestyle. Furthermore, animals need to acquire their own food, therefore, they do not possess any of the specialized cell organelles such as chloroplasts.
Frequently Asked Questions
Q1 What is an animal cell?
As the name implies, an animal cell is a type of cell that is seen specifically in animal tissues. It is characterized by the absence of a cell wall, with cell organelles enclosed within the cell membrane.
Q2 Name the cell organelle that contains the genetic material of the cell.
Nucleus
Q3 Which cell organelle is responsible for the generation of energy for cellular activities?
Mitochondria
Q4 Name the double-layered membrane responsible for enveloping the nucleus.
Nuclear envelope
Q5 What is the role of lysosomes?
Lysosomes help in digestion, excretion, and cell renewal process.
