Joke Collection Website - Talk about mood - Junior high school biological knowledge virus
Junior high school biological knowledge virus
Virus is a small and simple structure, containing only one kind of nucleic acid (DNA or RNA), which must be parasitic in living cells and reproduce through replication.
Virus is a cell-free life form, which consists of a long nucleic acid chain and a protein shell. Viruses do not have their own metabolic mechanism and enzyme system. So when the virus leaves the host cell, it becomes a chemical substance that has no life activity and cannot reproduce on its own. Once it enters the host cell, it can use the material and energy in the cell and the ability of replication, transcription and translation to produce a new generation of viruses like it according to the genetic information contained in its own nucleic acid.
Viruses are not only divided into plant viruses, animal viruses and bacterial viruses. Structurally, it is also divided into single-stranded RNA virus, double-stranded RNA virus, single-stranded DNA virus and double-stranded DNA virus.
The life process of virus can be roughly divided into five steps: adsorption, injection (genetic material), synthesis (reverse transcription/integration into host cell DNA), assembly (using host cell to transcribe RNA and translate protein for reassembly) and release. Because the virus will narrow the distance between cells, it is easy for cells to fuse to form multinucleated cells and then crack.
Extended data:
1, smallpox
Smallpox is a virus. It was one of the main killers threatening human beings until it was controlled by vaccines in the twentieth century. Smallpox has been eradicated all over the world, but it is worrying that * * * may spread new varieties.
Unlike anthrax, the main hazard of smallpox is its strong infectivity. Its spread and mortality are extremely fast. Up to 40% of people infected with this virus will die in about two weeks, and there is no good treatment for this disease. Vaccine is the main protective measure, but it is only effective to vaccinate before infection.
2. Botulinum toxin
Botox can produce botulinum toxin; This toxin can kill people in very small doses (as little as one billionth of a gram). This toxin can inhibit the release of chemicals in nerve cells that promote muscle contraction, resulting in muscle paralysis.
3. Ebola virus
With the publication of two novels by tom clancy, Ebola virus has become one of the most familiar biological warfare agents. The virus can kill infected people in a week or so and can spread through direct contact.
References:
Sogou encyclopedia biological virus
References:
Sogou encyclopedia biochemical weapons
2. Little knowledge of biology in Grade One.
Little knowledge, physical interest-the "weight of things" that will change. After learning the relevant physical knowledge, students may know that the weight of the object itself is not static, that is, it is sometimes "weightless"; Sometimes it is "overweight".
What causes the change in the weight of an object? Don't worry, let's look at the following story first: Once upon a time, there was a story: a businessman bought 5000 tons of herring from Dutch fishermen, loaded it on a boat and transported it from a Dutch city to the seaport of Maga, an African city near the equator. When I got there, I weighed it and found that the herring was nearly 19 tons short.
Strange! Where did it go? It can't be stolen because the ship didn't call all the way. At that time, no one could reveal the secret, but now we finally know the reason: it turned out that this was a joke played by gravity.
Because the earth is slightly oval, its radius of north and south poles is 20 kilometers smaller than that of equator. The smaller the radius, the greater the attraction; or vice versa, Dallas to the auditorium
Therefore, when the Dutch 5000 tons of herring are transported near the equator, the weight of herring naturally becomes "light". In addition, the weight of the object changes a lot! If you are on a high mountain, it is lighter than on the flat ground; The equator is lighter than the poles; It is much lighter in water than on land, and so on.
As you can imagine, if you fly to a high altitude area where the gravity of the earth can't reach, there is no weight at all, because the gravity of the earth is very small. However, no matter how it changes, the quality of the object will not change! Well, now everyone knows the truth! In fact, there are many similar problems around us. As long as we can find it in time and combine it with theory, we can find the correct answer.
I believe that if you encounter similar problems in the future, don't be "helpless"! A cat has 230 bones. Cats are more sensitive to hearing than people and dogs.
Compared with its size, cats have bigger eyes than any mammal. The normal pulse of a cat is between 1 10 and 170 beats per minute.
The normal temperature of a cat is about 39 degrees. The vertical jumping height of a cat can reach five times its own height.
A cat's nose print is unique. No two cats have the same nose print. Cats react more strongly to women than men because women's voices are more frequent than men's.
The running speed of domestic cats is about 55 to 60 kilometers per hour. Cats are the most sleepy mammals, sleeping about 16 hours a day.
Birds are interesting and have little knowledge. What bird is not easily noticed? When you pass a tree with a woodcock in the forest, you may not notice that there is a woodcock in the tree. The woodcock is not a very small bird, but a big bird, but its beautiful feathers look like fallen leaves in autumn, so it is not easy to be noticed because it pretends to be motionless. The woodcock stands in the tree, always paying attention to the surrounding situation, even if there is a little movement behind him, it can immediately detect it.
This is because its eyes are located at the back of its head, so no enemy can escape its sight. Of course, few insects can escape it.
Where does grouse live? Grogrouse lives in the cold zone of the northern and southern hemispheres and is one of the few birds in the cold zone. In winter, birds perch on pine or fir trees.
In order to resist the cold climate, it must eat a lot of needles to generate energy. Near the polar regions, the days are short and the nights are long in winter, so grouse eat almost all day.
Spring has come, and grouse have started courtship. They usually choose the male bird by the female bird, and they must win the competition to win the favor of the female bird.
Do parrots chat with each other? "Baby, get up!" Some parrots can talk, but they don't really talk. Parrots' owners patiently teach them to say some simple words. Although they can read them, they don't understand the meaning at all.
Animals can communicate with each other in their own way, not in the language we understand. Their crying may mean: "I'm afraid"; "Please touch me"; "I found food" or "danger! Run! " Colors, movements and smells can also be used as communication tools between animals.
Hunters can set traps by imitating their sounds and smells, and let them trap themselves. Penguins can't build nests? In fact, penguins can't build nests.
When the mother penguin went to the sea to look for food, the father penguin stood on the land, put the egg between his feet, covered the egg with a fat belly, and hatched the egg. Penguins hatch their eggs in the same place every year. They use their beaks and wings to deal with possible enemies and protect their offspring.
Newborn penguins will look for food in their parents' mouths. Penguins feed on fish, shrimp and shells.
In the summer when food is abundant, they spend all their time supplementing nutrition, and can usually dive into the sea hundreds of meters deep to find food. Can Penguin Fly Penguin is a very strange animal, dull but cute.
Their feet are like wearing the same trouser legs, and it is very difficult to walk. Penguins always contract their wings to keep their balance.
Although they can't fly, they still belong to birds. Their heavy clothes are covered with very tight little feathers, which are all covered with oil.
Penguins flap their wings in the water as if equipped with an engine. Penguins are very lively and like diving and playing in the water very much.
When they avoid natural enemies, they often surface and can glide in the air 1 m or more. What kind of nest is the most beautiful? There are many kinds of birds flying in the sky, and each bird has a different nest.
Hummingbirds' nests are smaller than spoons, and some eagles' nests are bigger than cars. Birds use fluff, branches, saliva or cobwebs as nesting materials.
The shape of the bird's nest, some like bowls, some like balls; Some hang like cradles, others float on the water like rafts. There are hundreds of species of weaver birds in Africa, and their nests are very complicated. Some birds also paint their nests to attract the attention of females.
There are many kinds of bird's nest in the world, which one is the most beautiful! How do birds fly long distances? Birds fly in groups for days on a long journey. For example, terns fly from the North Pole to the South Pole in this way, which is about 20 thousand kilometers away.
The long-distance flight of birds is actually 636f F f.
3. Virus information (freshmen)
References:
A virus is a tiny microorganism, which can only be seen with an electron microscope. The virus has a simple structure, belongs to a cell-free microorganism, and consists of a genetic material nucleic acid and an outer protein shell. Viruses cannot live independently, but must live in the living cells of other organisms to grow and reproduce.
Viruses are widely distributed in nature, and people, animals, insects, plants, fungi and bacteria can all be infected by viruses. Virus is one of the important pathogens that cause human infectious diseases.
In human infectious diseases, viruses are far more than bacteria and other microorganisms, accounting for about 3/4, such as influenza, hepatitis, epidemic hemorrhagic fever, chickenpox, herpes zoster, AIDS and so on. The virus is also associated with some tumors, congenital malformations and Alzheimer's disease.
There are many kinds of viruses, which can be divided into animal viruses, plant viruses and bacterial viruses according to different hosts. According to the clinical and infection routes, it can be divided into respiratory tract infection virus, digestive tract infection virus, hepatitis virus, Japanese encephalitis virus, nerve virus, sexually transmitted virus and so on. Different viruses have different modes of transmission and pathogenic characteristics after invading human body, some only cause local infection, and some can spread with blood or nerves.
The virus has an incubation period from infection to onset, and the shortest is only 1~3 days, such as influenza virus; Older people can last for months or even years, such as rabies virus. Most people can develop immunity after being infected with the virus, but the duration is different.
Viruses can directly invade the skin and cause skin damage, and a few of them can cause skin allergic reactions and rashes due to the antigenicity of viruses. Because the pathogenic viruses are different, their clinical manifestations are also different. Viral dermatoses are generally divided into three types in clinic: (1) Blister lesions are mainly blisters.
Common are herpes simplex, herpes zoster, chickenpox, herpetic eczema and so on. (2) Neobiotype skin lesions are verrucous.
There are various common warts (common wart, plantar wart, flat wart, condyloma acuminatum, molluscum contagiosum, etc. (3) The eruptive lesions are erythema or papules.
Common are measles, rubella and acute rash in children. Parvovirus is a kind of microorganism without cell structure, but with life characteristics such as heredity and self-replication. They are the smallest creatures.
Pure virus is a beautiful crystal, you can't see its vitality at all, but once it is combined with cells, you will immediately know how vicious it is. Viruses are much smaller than bacteria.
Before the virus was discovered, the first person to find life smaller than bacteria was American young scholar Ricky. 1909, when studying typhus, a pathogenic microorganism was found. In memory of others, this creature is called Rickettsia.
A year later, this outstanding young man who was only 39 years old died of typhus. Compared with the real virus, rickettsia is very large, although it is much smaller than bacteria.
From the later review, we now know that the first person to see this virus was the Scottish doctor Buster. He saw the vaccinia virus, which is the biggest virus. This happened on 1887.
The person who can clearly see the basic shape and structure of the virus is American astronomer Williams, who invented the projection method to let people really see the true face of the virus, while Finn Vilska used the low-speed electron microscope to let people see the fine structure of the virus. There is a joke about the appearance of a virus. A teacher asked a student what cowhide was for, and a student replied that it was used to wrap cows.
In fact, this is very correct. Any living thing seems to have a shell or something, and most viruses are no exception. Their shell is protein, and they are a kind of nucleic acid.
Someone once peeled off the shell of one virus and replaced it with another protein, but the virus after reproduction was the same as the original one. This shows that protein shell is not the decisive factor of virus, but it can prevent the nucleic acid inside from being destroyed by external chemical or physical effects.
Of course there are exceptions. For example, potato virus has no shell. More extreme is the scrapie virus of sheep, which has no nucleic acid at all, but only an "inhibitor" that can turn substances in other cells, including genes, into its own appearance. It may be the smallest virus in the world.
Recently, a scientist cultivated a human ear in a mouse, which should be said to be inspired by some kind. This is very important. If the cost of cultivation can be reduced to a very low level, the life span of human beings may be more than doubled.
But then again, if our world is basically the world of the elderly, it will be really boring. Don't be angry with your old friends:-) Now briefly talk about the structure of the virus: it is like a light bulb, the glass part is protein shell, and the filament part is evil nucleic acid.
4. Junior high school biology knowledge points are all summarized, (all)
Unit 1: Biology and Biosphere 1. The same characteristics of living things: plant nutrition: organic matter is mostly produced through photosynthesis; Animal nutrition: Get ready-made nutrition from outside.
2) living things can breathe. 3) Organisms can excrete wastes from their bodies.
The way animals excrete waste: sweating, exhaling and urinating. The way plants excrete waste: fallen leaves.
4) living things can react to the outside world. Exodus: The zebra flees quickly after discovering the enemy's harm.
The response of mimosa to * * * *. 5) Organisms can grow and reproduce.
6) All living things are made up of cells except viruses. 2. Scope of the biosphere: the bottom of the atmosphere, most of the hydrosphere and the surface of the lithosphere.
3. The biosphere provides basic conditions for living things: nutrients, sunlight, air and water, suitable temperature and a certain living space. 4. Environmental factors affecting biological survival: abiotic factors: light, temperature, moisture, etc. Biological factors: other organisms that affect the life of a certain organism.
Exodus: Ladybug septempunctata preys on aphids, which is a predatory relationship. Weeds and rice in rice fields compete for sunlight, which is a competitive relationship.
Division and cooperation of family members of ants and bees. 5. Explore: the influence of light on the life of mouse and girl 1) Ask a question: Will light affect the life of mouse and girl? 2) Make a hypothesis: light will affect the life of a female rat.
3) Make a plan: to test whether the hypothesis is correct, we need to explore it through experiments. The experimental scheme requires that a control experiment needs to be designed, and illumination is the only variable in this inquiry experiment.
Other conditions are the same. 4) Implementation plan 5) Conclusion 6) Expression and communication 6. Biological adaptation and influence on the environment: 1) Example of biological adaptation to the environment: Camels in the desert have little urine.
The underground roots of Alhagi are much longer than the aboveground parts. Seals in cold seas, thick subcutaneous fat on the chest, flag trees, etc.
2) Biological impact on the environment: Earthworms move in the soil, which can loosen the soil, and their feces increase the fertility of the soil; Sand plants such as windbreak and sand fixation belong to the biological influence environment. 7. Concept and composition of ecosystem: The unified whole formed by organisms and environment in a certain area is called ecosystem.
Composition: including biological part and abiotic part. The biological part includes producers, consumers and decomposers.
Abiotic parts include sunlight, water, air, temperature, etc. 8. Food chain and food web: The relationship between producers and consumers is mainly the relationship between eating and being eaten, thus forming a food chain. There are often many food chains in an ecosystem, which often cross each other to form a food web.
Unit 29. Names and functions of various parts of optical microscope: mirror base-stable mirror body. Column—Supports the component above the column.
Mirror arm-the part that supports the mirror. Stage-the place where the slide specimen is placed.
There is a light hole in the middle and two flat clips on both sides. Lens barrel-the eyepiece is installed at the upper end and the converter is installed at the lower end.
Converter-a turntable with an objective lens. Coarse focus screw-when rotating, the lens barrel can be greatly raised and lowered.
Fine-tuning the focus screw-when rotating, the lifting range of the lens barrel is small, which can make the image clearer. Eyepiece and objective lens-the eyepiece is the lens for eyes to observe; An objective lens is a lens close to an object.
Shader-there are round holes of different sizes on it, called aperture. The light intensity can be adjusted for light holes with different apertures.
Reflector-one side is a flat mirror (used in strong light) and the other side is a concave mirror (used in low light). Rotating the reflector can make the light reflect upward through the light hole.
The magnification of the object image is the magnification of the eyepiece multiplied by the magnification of the objective lens. 10, observe and load with microscope ① The object seen from the eyepiece is an inverted image.
Example: If you see a "D" in the field of vision of a microscope, then "P" is written on transparent paper. ② Eyepiece magnification ╳ objective magnification = microscope magnification 1 1, basic structure and function of cells ① Cell membrane-it has the function of protecting the inside of cells and controlling the entry and exit of substances inside and outside cells.
② Cytoplasm-Cytoplasm contains many fine structures related to various life activities. The cytoplasm of living cells has fluidity, which is beneficial to the material exchange between cells and the external environment.
③ Nucleus-plays an important role in biological inheritance. The nucleus contains a kind of material closely related to biological heredity-genetic material.
12, the difference between plant cells and animal cells. In addition to cell membrane, cytoplasm and nucleus, plant cells generally have cell walls, chloroplasts and vacuoles. 13. Production and observation of onion epidermal cells. Manufacturing steps: (1) First, drop a drop of water in the center of a clean glass slide.
(2) Break the onion scales outward, and tear off a small piece of transparent film from the inner surface of the scales with tweezers. (3) Put the torn film into the water drop in the center of the glass slide and flatten it gently with a dissecting needle.
(4) Clamp the edge of one side of a cover glass with tweezers, first touch the other side with water drops, then gently flatten it and cover it on the film. Be careful not to leave bubbles under the cover glass.
(5) After dyeing with iodine solution. (6) Observe the prepared onion epidermal cells under a low-power microscope 14, and make and observe the oral epithelial cells (1). Drop a drop of physiological saline in the center of a clean glass slide with a dropper.
(2) Rinse your mouth with cold boiled water and scrape it gently from the buccal wall of your mouth with a toothpick. (3) Put some crumbs attached to the toothpick in the normal saline on the glass slide for a few drops. (4) Cover the cover glass and be careful not to leave bubbles.
(5) After dyeing with iodine solution. (6) The prepared oral epithelial cells were sliced and observed under a low-power microscope.
5. All junior high school biology knowledge
Biology Review Materials Unit 1 Biology and Biosphere Chapter 1 Understanding Biology The living environment of the organisms on the earth's surface and organisms constitutes the life of biosphere organisms, which need nutrition: organisms need to constantly obtain nutrition from the outside to survive.
Living things can breathe: most living things need to inhale oxygen and exhale carbon dioxide. Biology can eliminate the waste produced in the body. Living things can respond to all kinds of * * * from the environment. Living things can grow and reproduce. Except for viruses, all living things are made up of cells.
Chapter II The biosphere is the home of all living things. Living things can't exist in the crust. In fact, there is only a thin biosphere on its surface, including the bottom of the atmosphere, most of the hydrosphere and the surface of the lithosphere. There are many gases in the atmosphere, including all the oceans, rivers and lakes on the earth. The lithosphere is a solid part of the earth's surface. Living things need nutrition, sunlight, air and water to survive. There is also a suitable temperature and a certain living space. Environmental factors affecting biological life can be divided into two categories: abiotic factors and biological factors. When one or several factors in the environment change dramatically, it will affect the life of organisms and even lead to their death. Biological factors refer to other organisms that affect the life of a certain organism. In the natural environment, various factors affect organisms, and organisms constantly adapt to the environment in their survival and development, and at the same time influence and change the environment.
All living things have morphological structures and lifestyles that adapt to the surrounding environment. In a certain area, the unified whole formed by biology and environment is called ecosystem. In an ecosystem, there are often many food chains, which are intertwined to form a food web. Matter and energy in the ecosystem flow along the food chain and food web, and toxic substances can accumulate in the food chain. The ecosystem has certain adjustment ability. The ecosystem in p27 biosphere includes forest ecosystem, grassland ecosystem, marine ecosystem, fresh water ecosystem, wetland ecosystem, farmland ecosystem and urban ecosystem.
Forest ecosystems are distributed in humid areas, grassland ecosystems with many animals are distributed in arid areas, and marine ecosystems with relatively few species of animals and plants are composed of marine and marine life. Freshwater systems with a variety of animals and plants are freshwater waters such as rivers, lakes or ponds, and wetland ecosystems with freshwater organisms are formed under conditions of excessive moisture and humidity. Farmland ecosystem with a variety of animals and plants is an artificial ecosystem. The importance of animals and plants to human beings in urban ecosystem is relatively low, and there are relatively few plant species. The biosphere is a unified whole, the largest ecosystem on the earth and the home of all living things. Unit 2 Biology and Cells Chapter 1 Observing the Structure of Cells The image seen from the eyepiece is inverted. The product of the magnification of the eyepiece and the objective lens is the magnification of the microscope. Slices cut from organisms are made into smears, and liquid biomaterials are smeared. A small amount of material torn or removed from living things is made into the outermost layer, which is a transparent thin wall called cell wall.
A very thin membrane, called cell membrane, protects and supports cells, protects objects inside and controls the entry and exit of objects into plant cells. There is an approximately spherical nucleus inside the cell membrane, and the structure outside the nucleus is called cytoplasm. Cytoplasmic vacuole
In the green part of the plant, there are chloroplasts in the cells. The various structures of plant cells have their own functions, and they coordinate with each other. * * The basic shapes and structures of human cells and animal cells are the same as those of human cells. Although human cells and animal cells have different shapes and the same basic structure, they all have cell membranes, cytoplasm and nuclei. Chapter 2: Living water and sugar are important substances in cells, and substances in cells can be divided into two categories: one is molecular comparison. One is larger molecules, which generally contain carbon, such as sugars, lipids, protein and nucleic acids, which are all organic substances. Cell membranes control the entry and exit of substances. Chlorophyll and mitochondria are energy converters in cells.
Genetic information The carrier of genetic information in the nucleus is an organic substance called DNA. Spiral DNA molecules are very long and can be divided into many segments, each of which has specific genetic information. These fragments are called gene chromosomes. The number of chromosomes composed of DNA and DNA protein is constant, which is very important for the normal life of organisms and the spread of seeds. There are chromosomes in the nucleus, and there are genetic information in the chromosomes. When a cell divides, the cytoplasm is divided into two parts, and each part contains a nucleus. The chromosome morphology and number of the two cells are the same, and the genetic material of the new cell and the original cell is the same. Chapter 3 How cells form organisms. The growth and development of animals and humans all start from one cell, which makes fertilized eggs have different functions in the development process. They have gradually changed in shape and structure. This process is called cell differentiation, which produces different cell groups. Each cell group consists of cells with similar shapes, structures and functions. Such cell groups are called tissues. The four basic tissues of human body are epithelial tissue, muscle tissue, nerve tissue and connective tissue.
Epithelial tissue is composed of epithelial cells, muscle tissue with protection and secretion function is mainly composed of muscle cells, and nerve tissue with contraction and relaxation function is mainly composed of nerve cells. There are many kinds of connective tissues that can generate and conduct excitement. Bone tissue and blood belong to connective tissues. Connective tissue has the functions of support, connection, protection and nutrition.
Different tissues are combined in a certain order to form an organ, which can be combined with multiple organs that perform several or one physiological function in a certain order to form a system. There are eight systems in human body, namely, exercise system, digestive system, respiratory system, circulatory system, two-bird system, nervous system, endocrine system and reproductive system.
- Previous article:Talking about the mother taking her children to climb the mountain.
- Next article:Write beautiful paragraphs of Sophora japonica sentences
- Related articles
- On better and better sentences in 2023
- Is toothache a disease after all?
- What poems describe friendship?
- Top sentimental copy 222 (extract 6 sentences)
- I was adopted and I feel very tired. What is this? Have you ever had the same experience as me?
- Is it legal to leave all your inheritance to your son?
- Hello, tell me about it
- Men's eyes and faces
- 2022 Sentences about how your husband loves to be jealous
- The alliance is immortal, and the blood is hard to cool down——To S9