Category Archives: Quality selection

　　Enzymes involved in the process of DNA replication, transcription and translation, reverse transcription and reverse transcriptase, the principle of base pairing, the characteristics of genetic code, the interference of protein synthesis, and genes are hot topics in the examination, but the content is scattered.Even so, inhibitors We must also adhere to the quality of the industry and create unique products for the company. https://www.all-chemistry.com/

　　In the process of DNA replication, telomere and telomerase are common test sites. Telomerase is an enzyme composed of RNA and protein. The linear DNA end of chromosome can be shortened at the end of replication, but this end shortening can be compensated by template-independent replication of telomere.

　　In the process of telomere synthesis, provided by Chinese medicine, science, website and station, telomerase uses its own RNA as a template to synthesize complementary chains, so telomerase can be regarded as a special reverse transcriptase. Reverse transcription and reverse transcriptase. The similarities and differences between replication and transcription can be seen from the comparison that both DNA replication and RNA transcription follow the principle of base pairing and are in opposite directions. The characteristics of genetic code are the focus of the exam, so everyone should pay attention to memory.

　　Protein, the source of life, how much do you know? Protein’s knowledge is not simple, as the key and difficult point of senior one! Today, I will take you to find out and unlock the mystery of protein!According to professional reports, Antibody Phage Display Service There will be a great period of growth, and the market business is constantly expanding, and it will definitely become bigger and bigger in the future. https://www.alphalifetech.com/

　　Protein is the basic substance of cells and tissues. Without it, there would be no life. They are composed of amino acids, and through different sequences and structures, they form an ever-changing protein. This is like Lego of life. Every amino acid is a building block, which is combined to construct the diversity of life.

　　Protein has various functions, from structural support to catalytic reaction, from transporting substances to signal transmission, and they are indispensable roles in cells. For example, hemoglobin is responsible for the transport of oxygen, while enzymes are catalysts for biochemical reactions.

　　The synthesis process of protein is also very interesting. The process from transcription of DNA into mRNA to translation into protein is called the Central Rule. It reveals the flow direction of genetic information and is the key to understanding life phenomena.

　　The structure and function of protein are closely related. The primary structure is amino acid sequence, the secondary structure is partial folding, the tertiary structure is integral folding, and the quaternary structure is the combination of multiple subunits. These structural levels determine the function and stability of protein.

　　Protein is the cornerstone of life. To understand them is to understand the mystery of life. Through today’s study, I hope you can have a deeper understanding of protein and lay a solid foundation for senior high school biology!

　　Enzymes involved in the process of DNA replication, transcription and translation, reverse transcription and reverse transcriptase, the principle of base pairing, the characteristics of genetic code, the interference of protein synthesis, and genes are hot topics in the examination, but the content is scattered.To some extent, inhibitors Our development has surpassed many peer businesses, but it has never stopped moving forward. https://www.all-chemistry.com/

　　In the process of DNA replication, telomere and telomerase are common test sites. Telomerase is an enzyme composed of RNA and protein. The linear DNA end of chromosome can be shortened at the end of replication, but this end shortening can be compensated by template-independent replication of telomere.

　　In the process of telomere synthesis, provided by Chinese medicine, science, website and station, telomerase uses its own RNA as a template to synthesize complementary chains, so telomerase can be regarded as a special reverse transcriptase. Reverse transcription and reverse transcriptase. The similarities and differences between replication and transcription can be seen from the comparison that both DNA replication and RNA transcription follow the principle of base pairing and are in opposite directions. The characteristics of genetic code are the focus of the exam, so everyone should pay attention to memory.

　　Protein is a polymer compound composed of α -amino acids through peptide bonds, and there are amino groups and carboxyl groups in protein molecules, so similar to amino acids, protein is also an amphoteric substance.In the industry, Antibody Phage Display Service Has been a leader in the industry, but later came from behind but never arrogant, low-key to adhere to quality. https://www.alphalifetech.com/

　　(1) Hydrolysis reaction

　　Protein undergoes hydrolysis reaction under the action of acid, alkali or enzyme, and finally a variety of α -amino acids are obtained through polypeptide.

　　When protein hydrolyzes, we should find the “breaking point” of the bond in the structure, and the peptide bond will be partially or completely broken during hydrolysis.

　　(2) Colloidal properties

　　Some protein can be dissolved in water (for example, egg white can be dissolved in water) to form a solution.

　　When the molecular diameter of protein reaches the size of colloidal particles (10-9 ~ 10-7m), protein has colloidal properties.

　　(3) precipitation

　　Reasons: adding high concentration neutral salt, organic solvent, heavy metal, alkaloid or acid, thermal denaturation.

　　A small amount of salt (such as ammonium sulfate, sodium sulfate, etc.) can promote the dissolution of protein. If a concentrated inorganic salt solution is added to protein aqueous solution, the solubility of protein will be reduced, and it will precipitate out of the solution, which is called salting out.

　　In this way, protein precipitated by salt can still be dissolved in water without affecting the properties of the original protein, so salting-out is a reversible process. Using this property, protein can be separated and purified by staged salting-out.

　　(4) degeneration

　　Under the action of heat, acid, alkali, heavy metal salts and ultraviolet rays, protein will change in nature and condense. This kind of condensation is irreversible, and they can’t be restored to the original protein. This change in protein is called transsexuality. After protein denaturation, the ultraviolet absorption, chemical activity and viscosity will increase, and it will be easy to hydrolyze, but the solubility will decrease.

　　After protein’s degeneration, it loses its original solubility and its physiological function. Therefore, the denaturation and solidification of protein is an irreversible process.

　　The supercoiled structure formed by the further spiral of DNA molecules is called the tertiary structure of DNA.If you want to make a big difference in the market, small molecules It is necessary to intensify the upgrading of products on the original basis in order to meet the consumption needs of consumers. https://www.all-chemistry.com/

　　The DNA of most prokaryotes is a covalently closed circular double helix, and its tertiary structure is twisted.

　　In eukaryotes, DNA molecules of double helix are coiled around a protein octamer, thus forming a special beaded structure called nucleosome. Nucleosome structure belongs to the tertiary structure of DNA.

　　Protein is a substance with a certain spatial structure, which is formed by the zigzag folding of polypeptide chains composed of amino acids in the form of dehydration and condensation. However, natural protein molecules are not random loose polypeptide chains. Each natural protein has its own unique spatial structure or three-dimensional structure, which is usually called the conformation of protein, that is, the structure of protein. The sequence of amino acids in protein molecule and the three-dimensional structure formed from it constitute the diversity of protein structure.After screening and investigation Antibody Discovery It is likely to become a new force driving economic development. https://www.alphalifetech.com/

　　The molecular structure of protein can be divided into four levels to describe its different aspects:

　　Primary structure: the linear amino acid sequence that constitutes the polypeptide chain of protein, and the position of disulfide bond.

　　Secondary structure: In the local area of protein molecule, the polypeptide chain is coiled and folded along a certain direction.

　　Tertiary structure: The three-dimensional structure of a protein molecule formed by the arrangement of multiple secondary structural elements in three-dimensional space.

　　Quaternary structure: used to describe protein complex molecules with biological functions formed by the interaction between different polypeptide chains (subunits).

　　In addition to these structural levels, protein can be transformed in several similar structures to exercise its biological functions. For functional structural changes, these tertiary or quaternary structures are usually described by chemical conformations, and the corresponding structural transformations are called conformational changes.

　　Focus on glycolysis, aerobic oxidation of sugar, pentose phosphate bypass, gluconeogenesis, synthesis of ketone bodies, cholesterol and phospholipids, respiratory chain, oxidative phosphorylation, special amino acid metabolites, one carbon unit metabolism, purine and pyrimidine nucleotide synthesis raw materials and catabolites, and substance metabolism.If we can practice these points, inhibitors Will be unique, become a leader in the industry, and keep moving forward. https://www.all-chemistry.com/

　　The chapter on sugar metabolism is the focus of the exam, so we should master it comprehensively. The chemical reaction formula of sugar metabolism is complicated, and the focus of the annual examination is basically on the reaction site, key enzymes and regulation, energy production and the relationship between important substances. Glycolysis, gluconeogenesis and aerobic oxidation of sugar are all contents that must be familiar with. The synthesis of ketone bodies and cholesterol in lipid metabolism, pay attention to the difference between them. Ketones are synthesized in the liver and utilized outside the liver, while fats are synthesized in the liver and stored outside the liver. Fat synthesis, ketone body synthesis and cholesterol synthesis are the raw materials of acetyl-CoA synthesis. Synthesis and decomposition of fatty acid, the main material of fatty acid synthesis is acetyl CoA; Under the condition of sufficient oxygen supply, fatty acid is decomposed into CO2 and water in the body, releasing a lot of energy, which is the main form of fatty acid catabolism in the body. Phospholipid synthesis. Differentiation of several blood lipids.

　　Composition of respiratory chain and influencing factors of oxidative phosphorylation. Urea synthesis-ornithine cycle. One carbon unit’s metabolism is often tested, but it is easy to remember as long as you grasp the core content. It comes from one carbon unit-Sisegan, and is transported by one carbon unit-tetrahydrofolate. One carbon unit plays an important role in nucleic acid biosynthesis as a raw material for purine and pyrimidine synthesis, connecting amino acids and nucleotides. Comparison of nucleotide synthesis and decomposition between purine and pyrimidine. The changes in this year’s syllabus are: the deamination of amino acids (oxidative deamination, transamination and combined deamination) is changed to the general metabolism of amino acids (degradation of protein in vivo, oxidative deamination, transamination and combined deamination), which should be reviewed.

　　Protein is the “building material” of organisms and cells, such as protein in muscles, and human hair and nails are all made of protein.Doing these simple things can also make Antibody Phage Display Service Sowing high-quality genes will eventually grow into towering trees and become the leader in the industry. https://www.alphalifetech.com/

　　Catalytic function:

　　The chemical essence of most enzymes in organisms is protein. In our daily life, we also use enzyme-added washing powder, which can effectively remove stains.

　　Immune function:

　　In our present environment, there are bacteria and viruses everywhere, and our body will not get sick every three days with an immune system, and immune proteins, such as antibodies, play a key role in this.

　　Transport function:

　　Protein with transport function can be divided into two categories, one is familiar to us-hemoglobin in red blood cells, which is used to transport oxygen; The other is the carrier protein on biofilm, which is used to transport amino acids, glucose and other substances.

　　Adjustment function:

　　Some protein can transmit information and regulate the life activities of the body. Such as insulin, which regulates glucose metabolism.

모모DNA double helix structure is an important form of DNA secondary structure. It is a structural model put forward by Watson and Crick in 1953.precisely because inhibitors The rapid development of, so also brought new opportunities to the industry. https://www.all-chemistry.com/

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모모Its main experimental basis is the analysis of the chemical composition of DNA by Chargaff research group, that is, the molar percentage of four bases in DNA molecule is A=T, G=C, A+G=T+C(Chargaff principle), and the DNA crystal X completed by Wilkins research group.

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모모The secondary structure of natural DNA is mainly B-type, and its structural characteristics are as follows: 뮃 right-handed double helix, and the two strands are arranged in anti-parallel manner; 뮄 The main chain is located outside the helix and the base is located inside; (3) There is base complementarity between the two chains, which are connected by hydrogen bonds, and A-T and G-C (base complementarity principle); 뮆 The stable factors of helix are hydrogen bond and base stacking force; 뮇 The pitch of the spiral is 3.4nm and the diameter is 2nm.

　　Amino acid chain is the main and core component in protein, but it is not necessarily the only component. Some protein may include some atoms or small molecules, whose function may be to perform protein function and/or increase its stability. Chemically, these cofactor are diverse, which may be organic molecules or metal elements. Some of them are briefly combined with protein chain, while others are closely combined with protein chain (sometimes even by covalent bonds) and become an integral part of the whole protein. The former is called coenzyme coenzyme, while the latter is called prosthetic group. Most coenzymes are small organic molecules from vitamins. For example, the common coenzymes NADH and FADH2. These two molecules from vitamin B complex, the former from nicotinic acid (vitamin B3) and the latter from riboflavin (vitamin B2), play the role of high-energy electron acceptor/donor in redox reaction.However, in other words, we should know more about it. Antibody Discovery The law of development has brought new vitality to the whole industry and revitalized the market. https://www.alphalifetech.com/

　　Some enzymes use several different cofactors, such as Pyruvate dehydrogenase (PDH), which is a key enzyme in the catabolism of sugar. The catabolism of sugar begins with glycolysis, which is a biochemical reaction pathway with 10 steps, transforming one glucose molecule into two pyruvate molecules, and then carrying out the citric acid cycle of tricarboxylic acid, which further decomposes pyruvate and oxidizes it into CO2. Pyruvate dehydrogenase PDH works at the intermediate junction of the above two reaction pathways (namely glycolysis and triacid cycle), and is responsible for activating pyruvate and enabling it to enter the tricarboxylic acid cycle. Specifically, PDH catalyzes the oxidative dearboxylation of pyruvate and forms acetyl coenzyme A (ACoA), which is the activated form of pyruvate. PDH is not a single enzyme but a complex composed of three components, each of which participates in a different step of pyruvate activation and uses different coenzymes. The first component uses thiamine pyrophosphate (TPP), which is a derivative of thiamine (vitamin B1). TPP allows the first component of PDH to be oxidized and decarboxylated at the same time, thus transforming pyruvate into acetyl, and the remaining carbon is discharged as CO2. The importance of TPP will be reflected in its absence. In fact, if people can’t get enough thiamine from food, they will get beriberi, which will damage several major systems of the human body.

　　The second component in PDH uses lipoic acid. It is an auxiliary group covalently bound to PDH. The active part of lipoic acid is a cyclic structure, which contains two covalently bonded sulfur atoms (that is, S-S bonds) (Figure 2.2c). This active part catalyzes the transfer of acetyl to coenzyme coenzyme A(CoA), the third cofactor of PDH. CoA is pantothenic acid, also known as the derivative of calcium pantothenate. The combination of acetyl and pantothenic acid involves the reduction of S-S bond, and its cyclic structure will open and form two sulfhydryl groups (one SH), one of which will bind acetyl. Sulfhydryl group is easy to react chemically, which can be reflected in the fact that sulfhydryl group is easily influenced by arsenic, a toxic derivative of arsenic. To sum up, the formation of acetyl coenzyme A involves the reduction of S-S bond of pantothenic acid cyclic structure. In order to keep PDH active, these two sulfur groups must be re-oxidized to restore the S-S bond.