All these structures are surrounded by a plasma membrane, similar in composition to that of membranous organelles. The plasma membrane controls the exchange of substances in the cell with the external environment, that is, the food that enters and the waste that is expelled. This membrane surrounds the cytoplasm in which the organelles float in an aqueous medium with all the substances necessary for the chemical reactions to take place so that the cell can live .
An example of a eukaryotic cell is the human cell, with a nucleus inside and with organelles in its cytoplasm.
The nucleus is the characteristic structure of eukaryotic cells. It is made up of a nuclear membrane that surrounds DNA. Genetic information is contained in the structure of DNA. DNA is forming a structure called chromatin, but when the cell is about to divide it condenses to form chromosomes.
The mitochondria are large organelles, surrounded by a double membrane, and are responsible for obtaining the energy needed by the cell through cellular respiration. It uses oxygen to oxidize the organic matter that reaches it, and energy and carbon dioxide (CO2) are released.
The ribosomes are also present in prokaryotes, have the function of producing proteins from the information contained in messenger RNA.DNA is within the nucleus and ribosomes are in the cytoplasm. As the DNA cannot leave the nucleus, the DNA is transcribed into RNA that can cross the nuclear membrane and reach the cytoplasm, where it will be read by the ribosomes that will synthesize the proteins.
The endoplasmic reticulum is made up of sacs, tubules, and vesicles. Two types are distinguished:
- The rough endoplasmic reticulum, named for the appearance it presents when having ribosomes attached to its surface. It is responsible for producing, storing, and transporting proteins.
- The smooth endoplasmic reticulum, which is responsible for lipid production.
The Golgi apparatus is made up of sacs and vesicles from the endoplasmic reticulum. Here, the substances produced in the endoplasmic reticulum are modified and vesicles are generated that will form part of other cellular organelles or will be expelled to the outside.
This topic is also covered in other courses:
- Eukaryotic animal cell (Biology and Geology 1st ESO).
- Animal eukaryotic cell (6th Primary curriculum adaptation).
- Eukaryotic cell (Biology and Geology 4th ESO).
- Eukaryotic animal cell (Biology 2nd Baccalaureate).
- Célula eucariota animal (Biología y Geología 3º ESO) (original page from which this text is translated).
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