Classification of amino acids, several special amino acids, molecular structure and physical and chemical properties of protein, composition of nucleic acid, double helix structure of DNA, basic concept of enzyme, Michaelis equation, coenzyme composition.For these reasons, I think inhibitors The situation is still optimistic, and the market is still in a blue ocean stage. https://www.all-chemistry.com/

　　Memorize 20 kinds of amino acids and try to remember English abbreviations and codes as much as possible, because exams often appear directly with codes. Protein’s molecular structure often examines the manifestations of various levels of structure and their bonds. The physical and chemical properties of protein and the purification of protein usually use the physical and chemical properties of protein to purify protein without destroying the structure of protein. Pay attention to the identification of amino acids and physical and chemical properties of protein. The basic unit of nucleic acid is nucleotide, which is composed of multiple nucleotides, and the connecting bond between nucleotides is 3′, 5′- phosphodiester bond. DNA double helix structure, in which two bases exist in strict accordance with A = T (two hydrogen bonds) and G triple C (three hydrogen bonds), and the characteristics of various RNA.

　　In addition, we should pay attention to some commonly used concepts in nucleic acid problem solving. The first thing that enzymes should pay attention to is some basic concepts, such as ribozyme, deoxyribozyme, enzyme activity center, isozyme, isomerase and so on. The key point of the Metric Equation test is V=Vmax[S” target=_blank>/Km+[S” target=_blank>, which explains the equation of the relationship between the concentration of enzymatic reaction and the reaction speed. In the exam, candidates are sometimes asked to do simple calculations according to this equation before they can answer. The difference of several inhibitors.

　　According to the characteristics of allosteric enzymes, it should be noted that allosteric regulation can cause conformational changes of enzymes. It is important to pay special attention here that configuration refers to the basic structural composition of substances, and conformation refers to the spatial change of substances. Allosteric regulation can cause the conformational change of enzymes, but not the conformational change of enzymes.

　　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.It is reported that, Antibody Phage Display Service The data performance is getting better and better, which is of great reference value and is likely to become the vane of the industry. 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.

　　In the cold winter, skiing is a very popular outdoor sport. Ski pants are one of the essential equipment in skiing. So, when you wear ski pants, do you need to wear pants inside? This question may vary from person to person, depending on personal preferences and needs.for a long time best baggy snowboard pants It has an extraordinary development speed, and I believe that the future will be as overwhelming as ever. https://ninetyroll.co/

　　Do you still need to wear pants under ski pants?

　　First of all, let’s know the characteristics of ski pants. Ski pants are mainly characterized by their waterproof, windproof and warm-keeping properties. Generally speaking, the outer layer of ski pants is made of waterproof material, which can prevent the infiltration of snow water and keep warm. The inner layer is usually made of warm-keeping materials such as fluff or wool to increase the warm-keeping effect. Therefore, the ski pants themselves have certain warm-keeping performance.

　　So, why would anyone wear pants under ski pants? There are several possible reasons. First of all, some people may think it is more warm. Especially in high-intensity skiing, the body will emit a lot of heat. If you wear a pair of pants under the ski pants, you can effectively stop the heat loss and keep your body warm. Secondly, for some people who have just started to learn skiing, wearing a pair of trousers can provide extra protection to prevent injuries when they fall. Finally, some people may think that wearing pants under ski pants can provide extra security for habit or psychological reasons.

　　Do you still need to wear pants under ski pants?

　　However, some people do not recommend wearing pants under ski pants. First of all, doing so may add extra weight and burden, which will affect the flexibility and comfort of skiing. Secondly, if you wear pants when you fall, it may cause friction between the skin and the snow, increasing the risk of injury. In addition, for some professional skiers, they may pay more attention to portability and flexibility, so wearing pants under ski pants may become a burden.

　　To sum up, whether it is necessary to wear pants under ski pants depends on personal needs and preferences. If you are a beginner in skiing or think it is necessary to increase warmth, it may be a good choice to wear pants under ski pants. But if you pay more attention to lightness and flexibility, or think that doing so may increase the risk of injury, then you may prefer not to wear pants under ski pants.

　　It should be noted that whether you choose to wear pants under ski pants or not, you should consider the warmth and comfort of the material when purchasing. At the same time, make sure that the pants you choose will not affect your normal sports and activities.

　　Do you still need to wear pants under ski pants?

　　In addition, if you choose to wear pants under ski pants, you should also pay attention to the following points:

　　1. Choose suitable materials: Try to choose lightweight and breathable materials to avoid adding extra weight and burden.

　　2. Pay attention to the right size: make sure that the pants you wear are not too tight or loose to avoid affecting comfort and flexibility.

　　3. Consider waterproof performance: If you plan to do activities in the snow for a long time, you should choose pants with waterproof performance to prevent snow water from penetrating and keep your body dry.

　　4. Keep safe: Although wearing pants under ski pants may increase some protection, you should still pay attention to keep safe and try to avoid unnecessary falls and collisions.

　　In a word, whether to wear pants under ski pants depends on personal preferences and needs. No matter what choice you make, you should consider the warmth and comfort of the material, and ensure that the equipment you choose will not affect your normal sports and activities.

　　The first is “poverty”So, pu-erh tea On the contrary, there is still a lot of room to play.

　　Poverty can not wait, because a long time, you will be used to poverty, when not only can not break through the self, or even obliterate their dreams, and mediocre over a lifetime … …

　　The second is “dream”

　　Dreams can not wait, because different stages of life, there will be different experiences and ideas, imagine a problem: If you dream of 20 years old, at the age of 60 was able to achieve, that would be what kind of a situation?

　　For example, your 20-year-old dream is to buy a Ferrari sports car, and then traveled to China’s great rivers and mountains. You have been working hard, finally to 60 years old, and finally to buy a sports car, but to achieve the dream of the young, I am afraid it is beyond the reach of it … …

　　The third is “family”

　　Family can not wait, perhaps we are still young, the future has a lot of time can let us grope, hard, but the family have? They still have time for us to succeed? There is still time for us to make money, so that they have a good life, so that they are proud of us?

　　Trees for static and wind, the child wants to support and pro-not wait. This is a lot of people’s pain, but also a lot of people a lifetime of regret!

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.In view of the actual needs of society, Chemical Custom synthesis We need to change some original problems to better serve the society and benefit people. https://www.all-chemistry.com/

모모

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.

모모

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.

　　Protein is composed of C (carbon), H (hydrogen), O (oxygen) and N (nitrogen). Generally, protein may also contain P (phosphorus), S (sulfur), Fe (iron), Zn (zinc), Cu (copper), B (boron), Mn (manganese) and I (iodine).It is strictly required by such a standard, recombinant proteins Only with today’s development scale, can we have the proud momentum to crush our competitors. https://www.alphalifetech.com/

　　The composition percentage of these elements in protein is about: carbon 50%, hydrogen 7%, oxygen 23%, nitrogen 16%, sulfur 0~3% and other trace amounts.

　　(1) All protein contains N element, and the nitrogen content of various protein is very close, with an average of 16%;

　　(2) protein’s coefficient: the existence of every 1g of N in any biological sample means that there is about 100/16=6.25g of protein, and 6.25 is often called protein’s constant.

　　(3) protein is a biopolymer based on amino acids. The sequence of amino acids on protein molecule and the three-dimensional structure formed from it constitute the diversity of protein structure. Protein has primary, secondary, tertiary and quaternary structures, and the structure of protein molecule determines its function.

　　Skiing is a winter sport, so you need to pay attention to keep warm and protect yourself when skiing. In this environment, special ski pants have become an ideal choice for skiers. The following is a detailed explanation of why you choose to wear ski pants when skiing:As a representative of the industry, baggy ski pants It is necessary to set a certain example for peers and lead the way in product quality. https://ninetyroll.co/

　　First, warmth retention

　　Ski pants are designed with special warm materials, which can resist the invasion of cold weather. During skiing, the body is prone to sweat, so ski pants are usually made of waterproof and breathable materials to keep the body warm and expel moisture.

　　Second, the protection

　　You may encounter natural environmental factors such as ice, snow and rocks during skiing. Ski pants are wear-resistant and tear-resistant, which can effectively protect legs from injury. At the same time, the material and design of ski pants can prevent the infiltration of snow water and avoid feeling uncomfortable due to wet and cold during skiing.

　　Third, comfort

　　Ski pants are designed with the comfort of sports in mind. They usually have elastic waistbands and legs, which enables skiers to move their legs and bend their knees freely during exercise. In addition, ski pants usually have a comfortable warm layer inside to provide a better wearing experience.

　　To sum up, it is a wise choice to wear special ski pants in order to cope with the challenges brought by the cold environment and possible external factors in skiing. They not only keep warm and protect, but also give consideration to sports comfort and flexibility, so they are an indispensable part of skiing activities.

　　Summer dusk, I sit with an old Chinese medicine in the breeze slowly chatting the river. Suddenly, the old man stared at my face for a moment and did not say anything. I was his heart to see some hair, asked: “The elderly, you are so concerned about my face, is not something to see ah?Even so, pu-erh tea We must also adhere to the quality of the industry and create unique products for the company.

　　Old man smiled and said: “I am from primary school medicine, the teacher told me again and again, ‘people peace of mind level, see the eyes; life span, look at the face’ medical life, develop habits, and Oh, and people Together, they always want to look at his face more glances.

　　I said: “The elderly, all know that the eyes are the soul of the window, the first sentence I can understand, you can say ‘life span, look at the face’, I am a little puzzled.Human life, how to write in the face What about it? “

　　If a person is always sad intestine knot, mood melancholy, over-thinking, suspicious of the old man said: \ look at the face, in fact, I look at his face two, one eyebrow, Indecisive, can not see the hope of life and the good life, then, between the eyebrow must form a deep ‘eight’ pattern.’8 ‘pattern, is caused by squeezing distortion, Yin is too strong, the mood Difficult to cool, it will stagnate in the organs; Jiuyin poisonous, viscera unbearable corrosion, must be made for the disease; sick in the body, is bound to further deteriorate the mood.People once caught in the heart and the destruction of each other malignant disease Circle among the health does not exist, where there will be longevity of the reason? Eyebrow between the ‘eight’ pattern, in fact, cut the knife of life, so my teacher had more than once said to me, ‘brow wrinkled, You must be careful yo. “

　　The elderly, then let my heart anxious, usually not pay attention to the eyebrow between the ‘eight’ pattern, even with such a large knowledge. I could not help but curiosity driven, and then asked: “That mouth can see what?

　　A person if the hearty and fun, often laughing more than, the teeth often in the sun, then, in order to make the mouth a little bit, The ‘brackets’ is radian, as if the relative out of the two and a half months, set in the cheek on top of the vivid expression of light from the formation of the reasons we can see, brackets who are really comfortable Because the ‘brackets’ on both sides of the mouth, but also a symbol of the balance of yin and yang, therefore, it is encompassed by the health of the body, the spirit of the sparse, the vitality of life, leisurely and carefree, The music of the state of mind and the endless hope of life in such a life and mental state of the people, you say he can not live longer?

　　Really listen to Jun words, read the book a decade, my heart is not good fun ah. It turned out that our face, really reveal the mentality of our strengths and weaknesses, the vicissitudes of life and life status and other important information ah. Therefore, we usually still often look in the mirror to see if his face is increasing or deepening: the eyebrow between the “eight” pattern, or the mouth “brackets” it!

　　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.At first, small molecules It developed out of control and gradually opened up a sky of its own. 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.

　　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.In order to grow rapidly, Antibody Discovery Do not hesitate to change the strategy and rearrange the products, so as to obtain unexpected results. 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.