What is Molecular Biology?

Molecular biology is the science that studies the structure and function of biological macromolecules at the molecular level to clarify the nature of life phenomena. Since the 1950s, molecular biology has been the frontier and growth point of biology. Its main research fields include protein systems, protein-nucleic acid systems (centered on molecular genetics), and protein-lipid systems (ie, biofilms).

In 1953, Watson and Crick proposed that the double-helix structure model of DNA molecules was a sign of the birth of molecular biology.

Chinese name: molecular biology
Foreign name: molecular biology

research content: Proteins, nucleic acids, sugars, lipids, etc.
Related disciplines: Biochemistry, Medical Molecular Biology
Birth time: 1953

Introduction to molecular biology

In 1953, Watson and Crick proposed that the double-helix structure model of DNA molecules was a sign of the birth of molecular biology.

molecular biology

The study of the structure and function of biological macromolecules, especially proteins and nucleic acids, is the basis of molecular biology. The application of modern chemistry and physics theories, technologies, and methods has promoted the study of the structure and function of biological macromolecules, resulting in the vigorous development of molecular biology in the past 30 years.

Molecular biology is closely related to biochemistry and biophysics. The main differences between them are:

Biochemistry and biophysics use chemical and physical methods to study biological problems at different levels such as molecular level, cellular level, overall level, and even the level of groups. And molecular biology focuses on studying the general laws of life activities at the molecular (including multi-molecular systems) level;

At the molecular level, molecular biology focuses on macromolecules, mainly proteins, nucleic acids, lipid systems, and some polysaccharides and their complex systems. The transformation of some small molecules in living organisms is within the scope of biochemistry;

The main purpose of molecular biology research is to clarify at the molecular level the basic characteristics that the entire biological community has in common, that is, the nature of life phenomena; , Chemical phenomena or changes belong to the scope of biophysics or biochemistry.

Molecular Biology Discipline Relationship

Biochemistry is a branch of biology. It is a basic life science that studies the chemical composition, structure, and various chemical changes of life in the process of life. Molecular biology is the science of studying life phenomena at the molecular level. It clarifies the nature of life phenomena by studying the structure, function and biosynthesis of biological molecules.

Scientific research is the driving force for the development of biochemistry and molecular biology. Since 1901, there have been about 550 Nobel Prizes in the field of natural science, of which 200 Nobel Prize winners have involved biochemistry and molecular biology. ^[1]

A brief history of molecular biology development

Molecular biology structure analysis

Structural analysis and research of genetic material have made important contributions in the development of molecular biology. The central content of structural analysis is to explain the physiological functions of cells by elucidating the three-dimensional structure of biomolecules. In 1912, British WH Bragg and WL Bragg established X-ray crystallography to successfully determine the structure of some fairly complex molecules and proteins. Later, Bragg students WT Asbury and JD Bernard conducted preliminary structural analysis of hair, muscle and other fibrin, pepsin, and tobacco mosaic virus, respectively. Their work laid the foundation for the later formation and development of biological macromolecular crystallography. The 1950s was an era when molecular biology emerged as an independent branch of science and developed rapidly. The first is in the analysis of protein structure. In 1951, LC Posen and others proposed an -helix structure, which described a conformation of the peptide chain in the protein molecule. In 1953, F.Sanger completed the determination of the amino acid sequence of insulin by using paper electrophoresis and chromatography technology, setting a precedent for protein sequence analysis. Then JC Kendrew and MF Perutz applied heavy atom isomorph substitution technology and computer technology in X-ray analysis to clarify the three-dimensional structure of whale myoglobin and horse hemoglobin in 1957 and 1959, respectively. In 1965, Chinese scientists synthesized biologically active insulin, first realizing the artificial synthesis of proteins.

Molecular biology explores the mystery of genes

On the other hand, M. Delbrück's group began to explore the mystery of genes by selecting phages as subjects in 1938. Hundreds of the same progeny phage particles were replicated within half an hour after the phage infected the host, so it is an ideal material for graduate students to self-replicate. In 1941, GW Biddle and EL Tatum proposed the "one gene, one enzyme" theory (known as "the first cornerstone of molecular biology"), that is, the function of a gene is to determine the structure of an enzyme, and a gene only determines The structure of an enzyme. But at the time the nature of the genes was unclear. 1944 OT Avery et al.

Protein engineering Transformation phenomenon proves that DNA is genetic material. In 1953, American scientist JD Watson and British scientist FHC Crick proposed the anti-parallel double helix structure of DNA (known as "the second cornerstone of molecular biology"), which opened a new era of molecular biology. The central law proposed by Crick on this basis in 1958 described the flow of genetic information from genes to protein structures. The elucidation of the genetic code reveals how the genetic information is stored in the organism. In 1961, French scientists F. Jacob and J. Mono made the concept of an operon ("the third cornerstone of molecular biology"), explaining the regulation of prokaryotic gene expression. By the mid-1960s, the general nature of DNA self-replication and transcription to produce RNA was basically clear, and the mysteries of genes began to be solved.

In just 30 years or so, molecular biology has gone from bold scientific hypotheses to extensive experimental research, thus establishing the theoretical basis of this discipline. Into the 1970s, due to breakthroughs in the study of recombinant DNA, genetic engineering has blossomed in practical applications, and protein engineering to transform the structure of proteins according to human wishes has also become a reality.

Basic content of molecular biology

Molecular biology protein system

The structural unit of a protein is an -amino acid. There are 20 common amino acids. They are arranged in a different order in a variety of proteins that can provide astronomical numbers to the world of life.

Molecular biology protein molecular structure

The organization of protein molecular structure can be divided into 4 main levels. Primary structure, also called chemical structure, is the sequence of amino acids in a molecule. The end-to-end amino acid forms a chain structure through the condensation of amino group and carboxyl group, which is called peptide chain. The local spatial arrangement of the main chain atoms of the peptide chain is a secondary structure. The secondary structure is folded in space to form a tertiary structure. Some protein molecules are assembled from the same or different subunits, and the interrelationship between the subunits is a quaternary structure.

Molecular biology molecular biology research

The special properties and physiological functions of proteins are closely related to the specific structure of their molecules. This is a variety of proteins that can show the molecular basis of various life activities. Studying the relationship between the structure and function of proteins is an important part of molecular biology research.

With the development of structural analysis technology, the chemical structure of several thousand proteins and the three-dimensional structure of several hundred proteins were elucidated in 1962. Since the end of the 1970s, the method of determining the chemical structure of proteins by determining the sequence of complementary DNA has not only improved the efficiency of analysis, but also enabled the analysis of chemical structures of proteins that are difficult to meet the conditions of amino acid sequence analysis.

Discovering and identifying proteins with new functions is still the subject of protein research. For example, the study of proteins related to gene regulation and advanced neural activity has received much attention.

Molecular biology protein-nucleic acid system

The genetic characteristics of an organism are determined primarily by nucleic acids. The genes of most organisms are made up of DNA. A simple virus, such as a lambda phage, is a double-stranded DNA consisting of 46,000 nucleotides in a certain order (because it is a double-stranded DNA, its length is usually calculated in base pairs). The genome of bacteria, such as E. coli, contains 4 × 10 ^ 6 base pairs. The DNA contained in human cell chromosomes is 3 × 10 ^ 9 base pairs.

For genetic information to be expressed in the offspring's life activities, it needs to be copied, transcribed and translated. Replication uses the parental DNA as a template to synthesize daughter DNA molecules. Transcription is based on the nucleotide sequence of DNA to determine the nucleotide sequence in a class of RNA molecules; the latter further determines the amino acid sequence in protein molecules, which is translation. Because this type of RNA plays a role in transmitting information, it is called messenger ribonucleic acid (mRNA). Because there are 4 kinds of nucleotides that make up RNA, but there are 20 kinds of amino acids in proteins, their correspondence relationship is determined by 3 nucleotides connected in a certain order in the mRNA molecule. This is the triad inheritance password.

In the process of expressing its traits, genes interact with nucleic acids and nucleic acids, and nucleic acids and proteins. During DNA replication, the double-stranded helix is disassembled under the action of helicase, and then the DNA polymerase uses the parental DNA strand as a template to replicate the offspring DNA strand. Transcription is catalyzed by RNA polymerase. The translation site Ribonucleoprotein is a complex of nucleic acid and protein. According to the encoding of mRNA, the amino acid is linked into a complete peptide chain under the catalysis of enzyme. Regulatory control of gene expression is also achieved through the interaction of biological macromolecules. For example, the operon on the lactose operon of E. coli controls gene switching by interacting with repressor proteins. The non-histones contained in eukaryotic chromatin play a special role in the regulation of transcription. Under normal circumstances, only 2 to 15% of genes are expressed in eukaryotic cells. This selective transcription and translation is the basis of cell differentiation.

Molecular biology protein-lipid system

Membrane structures commonly found in living organisms are collectively referred to as biofilms. It includes peripheral membranes and organelle membranes with various specific functions in the cells. From the perspective of chemical composition, biofilm is a system composed of lipids and proteins through non-covalent bonds. Many membranes also contain small amounts of carbohydrates and exist as glycoproteins or glycolipids.

The flow mosaic model proposed in 1972 summarizes the basic characteristics of biofilms: its basic skeleton is a lipid bilayer structure. Membrane proteins are divided into epiproteins and embedded proteins. Membrane lipids and membrane proteins are in constant motion.

Biofilms have bilateral asymmetry in structure and function. Take material transport as an example. Some materials can pass through the membrane at high speeds, while others cannot. Elephant kelp can concentrate iodine 30,000 times from seawater. Choice of biofilm

Flow mosaic model of biofilm Sexual permeability makes the pH and ion composition in the cell relatively stable, maintains the ion gradient necessary for nerve and muscle excitement, and ensures the function of cells to concentrate nutrients and eliminate waste.

The energy conversion of a living body is mainly performed on a membrane. The way in which organisms obtain energy is either to use photosynthetic phosphorylation on chloroplast membranes like solar energy using plants; or to use food to carry out oxidative phosphorylation on mitochondrial membranes like animals. Although the energy sources of these two are different, the basic process is very similar, and both of them finally synthesize adenosine triphosphate. For these two mechanisms of energy conversion, the chemical permeation theory proposed by P. Mitchell has gained more and more evidence. The efficiency of the energy released by the organism from the oxidation of food can reach about 70%, and the efficiency of obtaining energy from the combustion of coal or petroleum is usually 20 to 40%, so the study of biodynamics is highly valued. An in-depth understanding and simulation of biofilm energy conversion will contribute to the more efficient use of energy by humans.

Another important function of biofilm is the transmission of information between cells or inside and outside the cell membrane. On the cell surface, a class of proteins called receptors is widely present. Both the effects of hormones and drugs need to be achieved through specific binding to receptor molecules. The distribution of receptor substances on the surface of cancerous cells changed significantly. The surface properties of the cell membrane also have important regulatory effects on cell division and reproduction.

The study of cell surface properties has led to the study of sugars. Research on the structure and function of biological macromolecules such as glycoproteins, proteoglycans, and glycolipids has received increasing attention. From the development trend, the system formed by oligosaccharides and proteins or lipids will become a new and important field of molecular biology research.

Molecular Biology Theory Guide

Significance of theory

The achievements of molecular biology show that the fundamental laws of life activities are uniform in all kinds of organisms. For example, in any organism, its protein and nucleic acid are composed of the same amino acid and nucleotide, respectively. Genetic material, with the exception of some viruses, is DNA and is replicated in all cells by the same biochemical mechanism. The central laws of molecular genetics and the genetic code are, with a few exceptions, universal in most cases.

The achievement of physics proves that all material atoms are composed of a small number of elementary particles according to the same law, which shows that the structure of the material world is highly consistent and reveals the nature of the material world, which has led to the development of the entire physical discipline . At the molecular level, molecular biology reveals a high degree of consistency between the basic structure of the life world and the fundamental laws of life activities, revealing the nature of life phenomena. Just as the study of elementary particles has promoted the development of physics in the past, the concepts and perspectives of molecular biology have penetrated into every branch of basic and applied biology, which has promoted the development of the entire biology and improved it to a brand-new Level.

In the past, biological evolution research mainly relied on morphological and anatomical comparisons between different species to determine kinship. With the development of protein and nucleic acid structure determination methods, comparing the chemical structures of proteins or nucleic acids of different species, we can determine their relationship based on the degree of difference. The phylogenetic tree thus obtained is basically consistent with that obtained by classical methods. Using molecular biology to study classification and evolution has particular advantages. First, the structure of the basic biological macromolecules that make up an organism reflects more essential aspects of life activities. Secondly, according to the degree of structural difference, a quantitative, and therefore more accurate, conception of kinship can be given. Third, for the evolution of microorganisms with very simple morphological structures, only reliable results can be obtained with this method.

The higher-level neural activity of higher animals is an extremely complicated life phenomenon. In the past, it was mostly studied at the cell and even the whole level. The results of in-depth study at the molecular level fully show that the higher-level neural activity is also based on the activity of biological macromolecules. For example, in the process of learning and memory of higher animals, the composition of RNA and proteins in the brain changes significantly, and some drugs that affect the synthesis of proteins by organisms also significantly affect the ability of learning and memory. As another example, the "biological clock" is a well-known biological phenomenon. Chicken experiments have found that there is an important neurotransmitter (5-hydroxytryptamine) and a hormone (melatonin) and an enzyme that controls their changes. The content in the chicken brain changes periodically for 24 hours. . It is this change that forms the material basis of the chicken's "biological clock."

Significance of molecular biology application

Practical significance

In terms of application, the clarification of the principle of biofilm energy conversion will help solve global energy problems. Understanding the enzyme's catalytic principle can more specifically carry out artificial simulation of the enzyme, and design new catalysts widely used in the chemical industry, thus bringing a revolution to the chemical industry.

Genetic Engineering Molecular biology also played a huge role in biotechnology. The success of recombinant DNA technology in 1973 paved the way for the development of genetic engineering. Since the 1980s, genetic engineering technology has been used to introduce some genes from higher animals into single-celled organisms, and fermentative methods are used to produce interferons, multiple peptide hormones and vaccines. The further development of genetic engineering will provide a fundamental solution for the targeted breeding of animal, plant and microbial elite species and the effective control and treatment of some human genetic diseases.

From the perspective of gene regulation, research on cell carcinomatosis has also made a lot of progress. Molecular biology will make an important contribution to the ultimate human conquest of cancer.

Molecular biology related applications

Molecular biology paternity test

In recent years, the progress of human genome research has been changing rapidly, and molecular biology technology has also been continuously improved. With the continuous penetration of genome research into various disciplines, the progress of these disciplines has reached unprecedented heights. In forensic science, the detection of STR and single nucleotide (SNP) sites is the core of second- and third-generation DNA analysis technologies, and it is a successor to RFLPs (restriction fragment length polymorphism) and VNTRs (variable number). Tandem repeat sequence polymorphism). The cutting edge of punishment

megabace dna analysis system In biotechnology, DNA analysis provides a scientific, reliable and fast means for forensic medical evidence testing, making the physical evidence identification transition from individual exclusion to a level that can be made the same. DNA testing can directly identify crimes, homicides, rape and homicides, The detection of major and difficult cases such as corpse fragmentation and rape-induced pregnancy cases provide accurate and reliable evidence. With the development and application of DNA technology, the detection of DNA marker system will become an important means and way to solve the case. This method is very mature as a paternity test, and it is also recognized as the best method in the world.

Molecular biology and human development

Molecular biology, as a comprehensive science of modern science, is not only reflected in pure scientific value; more importantly, its development is related to all aspects of human beings. Molecular biology can be divided into two types: macromolecular biology and electronic biology. The above-mentioned application in criminal investigation and the content including but not limited to personal identification and identification of male and female infants are generally practical uses of macromolecular content. Electronic biological biology explains the basic elements and composition of life from the perspective of small molecules and atoms that are more detailed than large molecules. It has more unsolved puzzles and broader scientific prospects. Cloning technology is basically just an entry-level application of this topic. It can be imagined that with the deepening of research and the further development of physics in the future. Human beings have the potential to become "Gods" who create alternative creatures.

Molecular biology genetically modified food

Genetically Modified Foods (GMF) is the use of modern molecular biology technology to transfer the genes of certain organisms to other species, transforming the genetic material of the organism to make it more accessible to people in terms of shape, nutritional quality, and consumption quality. Needed goal shift. Foods produced by using genetically modified organisms as direct food or as raw materials are "genetically modified foods". It can increase the yield per unit area of crops; it can reduce production costs; it can enhance the ability of crops to resist insect pests and viruses by transgenic technology; improve the storability of agricultural products, extend the shelf life, and meet the increasing needs of people's living standards; The development time is greatly shortened; it can get rid of the influence of seasons and climate, and it can be supplied at low cost in four seasons; it breaks the boundaries of species, continuously cultivates new species, and produces foods that are beneficial to human health. ^[2]

Molecular Biology Yang Qisheng Books

Title: Molecular Biology

Author: Yang Qi Health

Editor-in-chief: Zou Xiaoning

Publisher: Zhejiang University Press

Release date: 2006-07-07

ISBN: 7-308-03628-6

Molecular biology is a discipline that studies and explains the structure and function of biological macromolecules. It is an important branch of contemporary biological science and a rapidly developing basic discipline. In the preparation of this book, reference was made to excellent teaching materials at home and abroad, and based on the "Basics of Molecular Biology" written in 1994, the strengths of the original framework were maintained, and years of teaching practice were used to expand and rewrite.

molecular biology The book starts with the structure of proteins, nucleic acids, genes, and genomes, and along the main line of the central law, explains the interactions and functions of biological macromolecules in replication, transcription, translation, information transmission, and gene expression regulation. When writing, it focused on the basic concepts and theories of molecular biology, tried to make the narrative as accurate as possible, and better reflected the development trend of molecular biology. The book is divided into 12 chapters, including protein molecular structure, nucleic acid structure, genes and genomes, biological macromolecular interactions, genetic engineering principles, DNA replication, gene transcription, post-transcription processing, protein biosynthesis and post-translation processing, cells Information transmission, regulation of prokaryotic gene expression, regulation of eukaryotic gene expression. Through the study of this book, students can understand the current overview of molecular biology, basic ideas, methods, and connections with other disciplines of life sciences.

This book can be used as a textbook or reference book for molecular biology courses for undergraduates and graduate students majoring in biology, biotechnology, medicine, and other majors related to agriculture and forestry.

Molecular biology medical relationship

The rise of molecular biology is a major event in the entire natural science, and it has brought the entire life science research to a whole new stage. In practical applications, it is an important theoretical basis for bioengineering technology, which is playing an increasingly important role in industrial and agricultural production and environmental protection. As an important part of life sciences, medicine is particularly affected by the penetration and influence of molecular biology.

One. Molecular biology brings medical science research to the molecular level

Classical biology can only describe and summarize certain laws of life activities from changes in biological phenotypes. So-called genes are also abstract concepts, and the molecular basis of phenotypes has not been identified. The same is true of previous medical research. Only the study of molecular biology has brought all medical disciplines to the level of genes and molecules, which led to the emergence of so-called molecular microbiology, molecular immunology, molecular physiology, molecular pathology, molecular pharmacology, molecular cardiology, and molecular neurology. , Molecular endocrinology and so on. Not only is theoretical research like this, in clinical practice, gene diagnosis and gene therapy are also mentioned on the agenda, some diagnostic methods are being implemented, and some are being actively explored.

Major breakthroughs in cancer research

The discovery of oncogenes is a major achievement in molecular biology research. In the past, the mixed opinions on cancer etiology are improving. The activation or abnormal expression of oncogenes caused by various internal and external factors is likely to be the root cause of cancer. Oncogene is one of the normal genes. What is its physiological function? How is it regulated? What is the mechanism of abnormal expression and activation? What is the relationship between oncogene products and growth factors? Are there negative regulators of anti-oncogenes and growth? and many more. These issues are the current hotspots of research, and progress is being made with each passing day. Related to this is that the study of AIDS (AIDS) has received close attention worldwide. This issue, academically speaking, belongs to molecular immunology and molecular virology The category and molecular mechanism of its pathogenesis are being gradually and deeply elucidated. If the results of molecular biology research and social preventive measures can be well combined, the epidemic of this disease will be stopped soon.

three. Genetic disease

With the deepening of medical molecular biology research, some concepts about genetic diseases are changing. First, these diseases are no longer as rare as previously thought. So far, more than 3,000 genetic diseases have been found to be inherited according to the Mendelian method. If the relationship between disease susceptibility and genetic variation is estimated, the scope of genetic diseases will be further expanded. For example, genes susceptible to heart disease, emphysema, hypercholesterolemia, diabetes, allergies, and gastric ulcer are being separated. Even cancer, some scholars believe that it can also belong to the category of genetic diseases, and the root cause is DNA damage. Second, gene probe technology is gradually expanding the scope of prenatal diagnosis and genetic disease diagnosis. Obviously, detecting genes that are susceptible to a disease is very valuable information for personal health care, and it is also the scientific basis for taking preventive measures against disease risk factors. In terms of treatment, all the previous therapies for genetic diseases can only be symptomatic. In theory, only gene therapy is the only cure for genetic diseases. Of course, there are still many theoretical and technical difficulties to be overcome to put this method into practice.

IV. Drugs and vaccines

The first industry sector to benefit from the boom in genetic engineering is the pharmaceutical industry. Some peptide or protein drugs, such as human insulin, growth hormone, and interferon, can be produced in large quantities through "engineering bacteria", and more drugs are being developed. The development of vaccines is greatly promoting the development of preventive medicine. For example, hepatitis B vaccine, non-A non-B hepatitis vaccine, rotavirus vaccine, malaria vaccine, etc., some have been put into use, and some are still under development. Through protein engineering techniques and the use of site-directed mutagenesis, new types of proteins can also be expected. For example, interleukin 2 and interferon beta are two kinds of proteins with anti-cancer effects. Each of them has three cysteine residues in its polypeptide chain, but only forms a pair of disulfide bonds. One cysteine residue, so two molecules can easily associate with each other to form a dimer and be inactivated. Using site-directed mutation to change the codon of cysteine to a serine codon can prevent the formation of dimers. The half-life of these two proteins is greatly prolonged without compromising activity, improving the efficacy.