Eukaryotic cells are those cells that have a well-defined nucleus and organelles (also called organelles) covered by membranes. These cells are typical of multicellular organisms such as animals, plants, fungi and algae with the exception of cyanobacteria.
Unicellular organisms such as protozoa and amoebas are also eukaryotic cells. The characteristics of the eukaryotic cell make them very different from prokaryotic cells.
The structure of the eukaryotic cell is characterized by its multicompartmentality since it has different compartments in the form of organelles where the different functions of the cell occur.
The eukaryotic cell has great complexity since a large number of metabolic processes occur inside it, such as cellular respiration, protein synthesis, carbohydrates, DNA duplication… which allow the cell to perform functions such as obtaining energy and division. cell phone among others.
Its organization and functioning are complex and are the subject of study of cell biology.
Eukaryotic cell structure
The cell membrane, as already explained, gives shape to the eukaryotic cell. Its function, in addition to giving shape to the cell, is also to regulate the exchange of substances with the outside world. You can learn more in this post.
The cytoplasm is the space between the plasma membrane and the nucleus and is where the nucleus, the organelles (or organelles) and the cytoskeleton are located. In the cytoplasm is the cytosol, which is the substance that makes up the internal environment and where a large number of the metabolic processes of cells occur.
Characteristics of eukaryotic cells
Some characteristics of eukaryotic cells are:
- Has a diameter of between 10-100 micrometers
- It has a cell nucleus which is bounded by a nuclear membrane or what is called a nucleus.
- Eukaryotic cells move using cilia and flagella which are composed of the protein tubulin. The structure of the flagella in these cells is more complex than the flagella in prokaryotic cells.
- Has a number of organelles enclosed by a cell membrane, including mitochondria, endoplasmic reticulum, Golgi bodies, lysosomes, and sometimes chloroplasts.
- DNA is stored in the nucleus
- The structural components of eukaryotic cell walls are phospholipids.
Organelles of the eukaryotic cell
The eukaryotic cell in turn can be divided into animal and plant eukaryote. Both are different and you can find more information in this post.
The main characteristic of the eukaryotic cell is that they have a nucleus. It is a membranous structure that surrounds the cell’s genetic material and protects it. The nuclear envelope is also called the karyotheque or nuclear membrane, which is different from the membrane that surrounds the outside of the cell.
The nucleus has an internal environment called the nucleoplasm that contains the chromosomes where the DNA is located and the nucleolus, which is a structure that helps in the synthesis of proteins.
Another important organelle of eukaryotic cells is the endoplasmic or endoplasmic reticulum. It is a network of channels and membranous sacs found in the cytoplasm and which in turn has two parts: the smooth and rough endoplasmic reticulum.
The smooth endoplasmic reticulum (SRE) is the part where lipid synthesis occurs. The rough endoplasmic reticulum (RER) is where protein synthesis takes place. The rough part is due to the presence of ribosomes.
Ribosomes are the key organelles for protein synthesis since they are responsible for translating messenger RNA into proteins. Its importance is vital.
Another important organelle of eukaryotic cells is the Golgi apparatus, which is a series of membranous compartments that help in the modification and transport of proteins and lipids to their final destinations from the endoplasmic reticulum. The Golgi apparatus also helps in the formation of lysosomes and the synthesis of carbohydrates.
Lysosomes and peroxisomes
Lysosomes are organelles that come from the Golgi apparatus that contain enzymes that allow them to fulfill their function, which is to degrade substances that come from the external environment such as food, bacteria, viruses… or from the internal environment such as degraded structures of the cell. Its function is cellular digestion.
Eukaryotic cells also have mitochondria. In this post we explain mitochondria in detail. They are organelles that are the main source of energy production of the cell, we could say that they are the battery of the cell thanks to the oxidative phosphorylation that takes place in them. Mitochondria contain their own strand of DNA and their own translation machinery.
Chloroplasts are organelles that are only present in the plant cell and are where photosynthesis takes place. They are similar to mitochondria and also contain their own DNA strand and their own translation machinery.
Another important characteristic of eukaryotic cells is the presence of cytoskeleton, a structure that helps maintain the shape and structure of the cell and facilitate the movement of the cell and organelles within the cell. The cytoskeleton is composed of microtubules and intermediate filaments and is key to carrying out cell division.
Another important characteristic of eukaryotic cells is the presence of cilia. Cilia can fulfill different functions such as movement but also the uptake of substances or molecules, as happens in poriferae where the cilia direct suspended food into the interior of the sponge.
Flagella are not present in all cells, they are filaments that are responsible for giving momentum to the cell so that it can move.
Functions of the eukaryotic cell
Nutrition and obtaining energy
Many metabolic processes are carried out inside eukaryotic cells, such as cellular respiration and photosynthesis, to obtain energy and produce molecules necessary for their survival.
Provide structure and support
In both animals and plants, cells can be bone cells, muscle cells or form part of stems, roots or leaves to form the structures or skeletons of the organisms.
Reproduction and growth
The cell is responsible for duplicating DNA molecules for subsequent cell division that allows them to proliferate and divide to grow and reproduce. For this, it develops all the stages of mitosis and meiosis for this purpose.
Protection of genetic material
Cells develop mechanisms to protect DNA. These mechanisms can be metabolic processes such as DNA repair, the development of proteins such as chaperones that protect DNA against heat shock, or complex structures such as the nucleus.
Defense against external attacks
There are cells whose function is to defend the body against infections and other attacks, also macrophages and others are defensive structures to protect in the case of animals.
Control, coordination and response to changes in the external or internal environment
Cells also fulfill the function of responding to external stimuli and also of coordination, as is the case of neurons for motor coordination. Other forms of response to external or internal changes are those that occur thanks to the cells that make up the organs of the endocrine system.