1.cell membrane

The cell membrane is a double layer of phospholipid molecules.

Every cell in the body is enclosed by a cell (Plasma) membrane. The cell membrane separates the material outside the cell, extracellular, from the material inside the cell, intracellular. It maintains the integrity of a cell and controls passage of materials into and out of the cell. All materials within a cell must have access to the cell membrane (the cell’s boundary) for the needed exchange.

The cell membrane is a double layer of phospholipid molecules. Proteins in the cell membrane provide structural support, form channels for passage of materials, act as receptor sites, function as carrier molecules, and provide identification markers.

endoplasmic reticulum

The endoplasmic reticulum (ER) is a continuous membrane system that forms a series of flattened sacs within the cytoplasm of eukaryotic cells. All eukaryotic cells contain an ER. In animal cells, the ER usually constitutes more than half of the membranous content of the cell. The endoplasmic reticulum(ER) was discovered by Keith R. Porter and Thomson in 1945.

it forms an interconnected network of flattened, membrane-enclosed sacs known as cisternae (in the RER), and tubular structures in the SER. The membranes of the ER are continuous with the outer nuclear membrane.

There are two types of endoplasmic reticulum: rough endoplasmic reticulum (rough ER) and smooth endoplasmic reticulum (smooth ER). Both types are present in plant and animal cells.

What are the differences between the two types of endoplasmic reticulum?

The most basic difference between RER and SER is the presence of ribosomes. When ribosomes attach to the surface of an ER, it gives a characteristic rough appearance; hence it is called Rough ER. On the other hand, a smooth ER does not have ribosomes on its surface. It possesses ribosomes attached to its membrane.

ribosome

A ribosome is an intercellular structure made of both RNA and protein, and it is the site of protein synthesis in the cell. The ribosome reads the messenger RNA (mRNA) sequence and translates that genetic code into a specified string of amino acids, which grow into long chains that fold to form proteins.

What is a nickname for ribosome?

The ribosome has earned the nickname “mother of all molecules” for good reason. Three RNA molecules and more than 50 proteins come together to make this biological machine, one of the largest complexes in the cell.

Ribosomes are the sites in a cell in which protein synthesis takes place. Cells have many ribosomes, and the exact number depends on how active a particular cell is in synthesizing proteins. For example, rapidly growing cells usually have a large number of ribosomes 

functions of ribosome

The important ribosome function includes:

1. It assembles amino acids to form proteins that are essential to carry out cellular functions.
2. The DNA produces mRNA by the process of DNA transcription.
3. The mRNA is synthesized in the nucleus and transported to the cytoplasm for the process of protein synthesis.
4. The ribosomal subunits in the cytoplasm are bound around mRNA polymers. The tRNA then synthesizes proteins.
5. Ribosomes are the site of protein synthesis.
6. The proteins synthesized in the cytoplasm are utilized in the cytoplasm itself, the proteins synthesized by bound ribosomes are transported outside the cell.