The cell

Cell is always known as the functional and structural unit of life, it is no wonder that the cell are very fundamental to the living systems of biology as an atom is to chemistry. Currently, our cells is working its best on making our bodies function properly as it should through the method of cell specialization where other cell can help and communicate with one another in order to make a harmony of working system (this phenomenom is called homeostatis).

All each organism are made of cell, which when they are combine together build a tissue that can then be found in each of our organs. But of course, without leaving the unicelullar existing as a single-celled organism, there are organism which consist of other cells functioning together as a multicellular organism. Plants and animals are a multicelluar organism where their organs or bodies is consist of specialized cells in which it cannot survive for so long on their own.

All cells are related by their descent from earlier cells because of the process of evolution in which cell has been modified in many different ways. But although this may be the fact, cells do still shared a common properties.

Prokaryotic Vs. Eukaryotic Cell

Before we identify what is the difference between these two, we must first find a common properties that helps us distinguished between these two.

All cells share certain basic features:

1.) that they are sealed by a selective barrier, called the plasma membrane (or the cell membrane);

2.) Inside them is a jelly-like substance called cytosol (Cytoplasm is different, because it's also consist of other organelles inside of it, meanwhile cytosol is just the core substance of it);

3.) All cell exist with chromosome that helps carry the gene in a form of DNA;

4.) And a ribosome which helps read the instruction of the DNA and then makes a protein out of it.

The major difference that exist is primarily on how both prokaryotic and eukaryotic cell is how they stored their location of the DNA. Cells with their DNA stored in a nucleus and is bounded by a double membrane are Eukaryotic cell. Meanwhile cells that have their DNA stored in a concentrated region without membrane-enclosed which are the nucleoid, are called prokaryotic cells.

A deeper explanation on cytoplasm is that it is a region between the nucleus and the plasma membrane that resides in a eukaryotic cells, and responsible for giving a room to the variety of organelles to specialized and function. However these bounded structures are absen in almost all prokaryotic cells, with an exception that some prokaryotics cell contain regions surrounded by proteins (not membranes) that is within specific reactions take place.

Eukaryotic cells are typically 10-100 µm in diameter, which makes them generally much larger than prokaryotic cells. This is of course proportional to the functionable uses for eukaryotic cell because they are made to handle more of the logistics of carrying out cellular metabolism, on which bring a another gaps between them and prokaryotic cells. Thus, it may be important for us to takes matter on how metabolic requirements impose a defined limit on the size of the eukaryotic cells that is deem functionable for the cell. Larger organisms does not always mean having a larger cells than the smaller one, it could be that they simply have more cells.

The relationship between Nucleus and Ribosome

Nucleus are as simply the storehouse of the cell's DNA which are responsible for providing DNA structure and helps asssembled it to ribosomes in order for the cell to function properly.

It is said that the nucleus contains most of the genes in the eukaryotic cells. (although some genes can be found in mitochondria and chloroplasts.) Averaging about 5 µm in diameter, the nuclear envelope encloses the nucleus which helps seperating it from the cytoplasm. The so called double membrane is consist of a lipid bilayer and are separated by a space of 20-40 nm, but the envelope itself is also perforated by pore structure which at the lip of each pore is the tunnel that is wrapped within the inner and outer membrane of the nuclear envelope. This intricate protein structure are called a pore complex lines that helps plays an important role by regulating the entry and the exit of proteins and RNAs, as well as large complexes of macromolecules.

Within the nucleus, the DNA are able to be stored in such a rigid places and that is due to the fact that DNA are made of chrososomes which are the structure that carry the genetic information. By each chromosomes, it contains one long DNA molecule associated with many proteins and then some of the proteins help coil the DNA strucuture, thus reducing its length and allowing it to fit into the nucleus.

And then there are the nucleolus, which appears as a packed of densely granules with a fibers adjoining part of the chromatin. the nucleolus plays a part on gene expression, first the DNA are writtena and repackaged in a form of mRNA that is then exited to the cytoplasm via the nuclear pores. Thus once it reaches the cytoplasm, ribosomes translate the mRNA's genetic message into a protein synthesis.

Ribosome is a non-organelle component that is responsible for the protein synthesizer, it is made of ribosomal RNAs and protein. It is widely known that ribosomes are divided into two types: Free and bound ribosomes and they are both have identical structure but different locations. Free ribosomes typically roams around and they produce protein within the cytosol, it can be said that they are helpful for the enzymes that catalyze the first steps of sugar breakdown. Bound ribosomes on the other hand are located outside of the endoplasmic reticulum and the nuclear envelope, they generally only made protein that is specific for insertions into membranes, for lysosome packaging, and cell secretion.

The endoplasmic reticulum

The endoplasmic reticulum are probably the closest thing to the nucleus, it's no wonder that the ER are bridge to the nuclear envelope. The ER is consist of membranous tubules and sacs called cisternae which comes from latin "a reservoir for a liquid". The ER also have a space internal room called the ER lumen (cavity) or cisternal space, from the cytosol. Thus it is known that the ER is divided into two: Smooth ER and Rough ER.

The smooth ER comes from the fact that the outer surface lacks ribosomes. It is said that the smooth ER functions in diverse metabolic processes, which vary with cell type. It is responsible for the synthesis of lipids, metabolism of carbohydrates, detoxification of drugs and poisons, and storage of calcium ions. The rough ER comes from outer surface of the membrane which is filled with ribosomes and it can acts as a continuos of the nuclear envelope's outer membrane.

The rough ER acts as a secretion machine in the cell which may helps certain function on the whole system of organ itself. For example, some pancreatic cells synthesize the protein insulin in the ER and then sent the all ready hormones into the bloodstream. We can try to understand the function of the rough ER by looking at the system it provides, as a polypeptide chain grows from a bound ribosome, it forms into a new polypeptide form that is functional enough to enter into the ER lumen through a pore formed by a protein complex. When it has been transformed into a secretory protein called glycoprotein, it then exited out from the ER wrapped in the membranes of vesicles from a specialized region called transitional ER.