Understanding Molecular Biology

Understanding Molecular Biology
Molecular Biology - Definition, Engineering, Science, History, Size, Formulas, Geometry: A molecule is defined as a group of atoms (at least two) that are connected to each other very strongly (covalently) in a certain arrangement and are neutral and fairly stable.

Understanding Molecules
Molecules are defined as groups of atoms (at least two) that are connected to each other very strongly (covalently) in a particular arrangement and are neutral and fairly stable. According to this definition, molecules are different from polyatomic ions. In organic chemistry and biochemistry, so organic molecules and biomolecules are filled also considered as molecules.
In the kinetic theory of gases, the term molecule is often used to refer to gases without depending on particle composition. According to this definition, noble gas atoms are considered molecules even though they consist of a single, unattached atom.
Molecules can consist of atoms of the same element (for example, oxygen O2), or can be composed of different elements (for example water H2O). Atoms and complexes connected by non-covalent (for example bound by hydrogen bonds and ionic bonds) are generally not considered as single molecules.

 Molecular biology techniques
 Expression Cloning
One of the basic techniques of molecular biology is expression cloning, which is used for example to study the function of proteins. In this technique, pieces of the DNA coding for the desired protein are transplanted into a plasmid (circular DNA normally found in bacteria; in this technique, plasmids are called expression vectors).
The plasmid which contains the desired piece of DNA can then be inserted into bacterial cells or animal cells. The insertion of DNA into bacterial cells is called transformation, and can be done by various methods, including electroporation, microinjection and chemistry. Insertion of DNA into eukaryotic cells, such as animal cells, is called transfection, and transfection techniques that can be performed include calcium phosphate transfection, liposome transfection, and with commercial reagents. DNA can also be inserted into cells by using a virus (called viral transduction).

Polymerase chain reaction (PCR)
Polymerase chain reaction ("polymerase chain [reaction]", PCR) is a very useful technique for making copies of DNA. PCR allows a small number of certain DNA sequences to be copied (millions of times) to be reproduced (so that they can be analyzed), or modified in certain ways. For example, PCR can be used to add restriction enzyme sites, or to mutate (change) certain bases in DNA. PCR can also be used to detect the presence of certain DNA sequences in a sample.
PCR utilizes the enzyme DNA polymerase which naturally plays a role in DNA propagation in the replication process. However, unlike in living organisms, the PCR process can only copy short fragments of DNA, usually up to 10 kb (kb = kilo base pairs = 1,000 base pairs). The fragment can be a single gene, or only part of a gene.
The PCR process for multiplying DNA involves a series of repetitive temperature cycles, and each cycle consists of three stages. The first stage is denaturation of DNA template (DNA template) at a temperature of 94-96 ° C, namely the separation of DNA double strands into two single strands. After that, a decrease in temperature in the second stage to 45-60 ° C allows annealing or hybridization between the primary oligonucleotide with a single strand of DNA mold.