All parts of the animal cell and their functions
The animal cell is the building block of all animal structures. It is a type of eukaryotic cell, which is characterized by having a nucleus where the genetic material is enclosed in the form of deoxyribonucleic acid or DNA.
The animal cell has different parts with specific functions, as shown in the following table:
|
Parts of the animal cell |
Function |
|---|---|
| plasma membrane | Protects the interior of the cell |
| Core | synthesizes DNA and RNA |
| Cytoplasm | Allows movement of molecules and organelles |
| Endoplasmic reticulum | Assemble and process proteins |
| Ribosome | synthesize proteins |
| Golgi apparatus | Stores and distributes proteins and lipids form vesicles |
| Mitochondria |
Synthesizes ATP (biological energy molecule) oxidizes fatty acids |
| lysosome | Digests material ingested by the cell |
| peroxisome | oxidizes fatty acids Synthesizes myelin lipids Remove hydrogen peroxide |
| centrosome | Organize and assemble microtubules |
| cytoskeleton | Provides structure and support to the cell Allows cell movement |
Next, each of the parts of the animal cell and what they are used for are described.
plasma membrane
The plasma membrane or cell membrane is the outermost part of the cell that limits and closes its content, separating the extracellular environment from the cell interior. Its structure is fluid and dynamic, made up of a double layer of lipids, mainly phospholipids and cholesterol, and proteins.
One-third of the cell's proteins are found in the plasma membrane. These are responsible for perceiving external conditions or signals and sending that information inside, so that the cell can respond to the stimulus. Other proteins allow the passage of elements such as sodium and calcium, so that the cell can carry out its activities.
The cytoskeleton is attached to the plasma membrane, in order to maintain the shape of the cell and the movement of intracellular structures.
Core
The nucleus is the part of the cell where the genome or genetic information such as deoxyribonucleic acid (DNA) is concentrated. It contains the functions of DNA and ribonucleic acid (RNA) synthesis, cell division and control of cellular activities.
The nucleus can be distinguished thanks to the nuclear envelope, formed by two membranes with holes or nuclear pores. During cell division, the nuclear envelope disappears until new cells are formed and is rebuilt.
In the nucleus, chromatin can also be distinguished, which is nothing more than DNA attached and packaged to nuclear proteins.
Inside the nucleus is the nucleolus, present in all animal cells, except those that have lost their nucleus, such as red blood cells. The main function of the nucleolus is the production of ribosomes. In growing or cancer cells, the nucleolus increases in size.
Cytoplasm
The cytoplasm is the space that surrounds the nucleus to the membrane. Submerged within the cytoplasm are the cell's organelles and the microtubule skeleton.
The cytoplasm is composed of:
- the cytosol: the semi-gelatinous internal fluid where nutrients and waste are dissolved.
- inclusions: are insoluble particles in the cytosol, such as glycogen and fat granules.
- organelles: are "small organs" formed by membrane with specific functions, such as mitochondria and lysosomes.
- protein fibers: formed by polymers of small proteins, they include actin microfilaments and tubulin microtubules.
Endoplasmic reticulum
The endoplasmic reticulum is the largest organelle in the cell. It is a constantly changing membrane structure. Participates in the modifications that proteins and lipids have during their synthesis and after they are synthesized. It also has a role in cellular calcium homeostasis.
The endoplasmic reticulum can be divided into:
- The rough endoplasmic reticulum: is a continuation of the nuclear envelope. It consists of stacked sacs of membranes with attached ribosomes, giving it a rough appearance. Participates in the synthesis of proteins, transfer and folding of the same.
- The smooth endoplasmic reticulum: is devoid of ribosomes and participates in the synthesis of lipids. Cells such as those that synthesize steroid hormones and liver cells have a large amount of smooth endoplasmic reticulum.
Ribosome
Ribosomes are small dense granules of RNA and protein. Its main function is the synthesis of proteins following the directions of the DNA.
There are free ribosomes in the cytoplasm and ribosomes attached to the membrane of other organelles, for example, the endoplasmic reticulum. Some free ribosomes form groups of 10 to 20 forming polyribosomes.
Golgi apparatus
The Golgi apparatus or Golgi complex consists of a series of stacked curved sacs that are continuous with the endoplasmic reticulum. It is responsible for receiving the proteins synthesized in the rough endoplasmic reticulum, modifying them and packing them into vesicles for their transport to the sites where their function is required.
Mitochondria
The mitochondria is a double membrane organelle, the outer mitochondrial membrane and the inner mitochondrial membrane, which delimits the matrix. It is responsible for the production of adenosine triphosphate or ATP, the cell's energy molecule. In addition, the mitochondria regulate the cell cycle and apoptosis.
Muscle cells form long networks of mitochondria for rapid and coordinated energy production. In the neuron, the mitochondria in the postsynaptic dendrites are larger and more interconnected.
lysosome
Lysosomes are a heterogeneous group of vesicles of different sizes and contents. Their main function is the digestion of the external or internal material of the cell, for which they are considered a kind of "cellular stomach". It does this thanks to several enzymes that degrade proteins, carbohydrates, lipids and nucleic acids.
Lysosomal enzymes are produced in the endoplasmic reticulum, mature in the Golgi apparatus, and transported to the cytoplasm in small vesicles, known as primary lysosomes. Mature lysosomes fuse and divide, making them a dynamic compartment.
Lysosomes exist in all animal cells except the red blood cell. Endocytosed or autophagocytosed degradation of materials takes place within lysosomes which have a Acidic pH between 4 and 5. After the enclosed material has been degraded, the lysosomes enter a state of "repose".
peroxisome
The peroxisome is a membranous organelle that participates in oxidative metabolism. In mammals, abundant peroxisomes are found in liver and kidney cells.
Peroxisomes participate in the oxidation of fatty acids, in the synthesis of myelin lipids, and in the removal of hydrogen peroxide from cells.
When peroxisomes malfunction or do not exist, a disease called Zellweger syndrome occurs.
centrosome
The centrosome is a nonmembranous organelle that serves as the organizing center for microtubules. Facilitates cell motility, polarity, shape maintenance, cell division, vesicle transport. In the interphase or phase of the cell where it is not dividing, the centrosome is close to the nucleus.
The centrosome of a mammalian animal cell consists of a protein scaffold surrounding a pair of cylindrical centrioles.
You may also be interested in seeing mitosis and meiosis.
cytoskeleton
The cytoskeleton is a flexible three-dimensional structure made up of protein filaments. Depending on the thickness of the filament, they are classified into microfilaments (7 nanometers (nm)), intermediate filaments (10 nm), and microtubules (25 nm).
The cytoskeleton maintains the shape of the cell, allows the movement of cilia and flagella, and participates in the intracellular transport of organelles.
You may also be interested in seeing animal and plant cell.
References
Goodman, S. R. (2019). Cell (biology). AccessScience. Retrieved January 25, 2022, from https://doi.org/10.1036/1097-8542.116000
Hettema, E., Gould, S. (2017). Organelle formation from scratch. Nature 542: 174–175. https://doi.org/10.1038/nature21496
Islinger M, Voelkl A, Fahimi D, Schrader M. (2018). The peroxisome: an update on mysteries 2.0. Histochemistry and Cell Biology 150:443. https://doi.org/10.1007/s00418-018-1722-5
Kurz, T., Terman, A., Gustafsson, B., Brunk, U.T. (2008). Lysosomes in iron metabolism, aging and apoptosis. Histochemistry and Cell Biology 129: 389
