How did life originate? How does life last?
In the 20th century, biology gave birth to molecular biology, which made people understand biology at the molecular level.
For hundreds of years, it has been easier for people to know the outside world than to know themselves. We can draw all kinds of star maps to analyze all kinds of objects, but we don't know anything about such problems as "where people come from and how to get there"
Simplicity is just a theory of "God made", however, this is not an explanation. Physicists study the basic properties of matter, but biologists have not found anything similar to establish a discipline.
No clue can be found in studying any phenomenon. No one can sum up the similarities and commonness in biology. Studying frog's diet has nothing to do with corn diseases; There is no angle to study the habits of owls, and how pine trees develop.
What about physics? There are a series of concepts, such as strength, movement, quality and so on; What about chemistry? The combination of reaction, energy, atoms and molecules; Only biology knows nothing, including evolution, anatomy, nerves, fossils and so on.
This situation gradually changed from Mendel's rediscovery. In fact, the communication between general knowledge and specific knowledge is the foundation of molecular biology. That is, all life on earth is actually a complex molecule that stores and transmits genetic information.
In the science of genetics, people study the genetic basis of biological reproduction and development, and nucleic acid plays a vital role here.
Mendel was the first person to base heredity on scientific research. He found that heredity can be based on the genetic characteristics of animals and plants; It includes a simple mathematical proportional relationship between dominant traits and recessive traits.
Mendel was buried for 36 years, and his paper was not rediscovered until 1900. But he just initiated the direction of genetic research, and the later work needs future generations to complete.
Father Mendel did not explain how genetic traits were inherited, and the mystery left people with endless exploration space.
The central idea of Mendel's theory is "genetic factors". Although this idea is rough, it still has his correct thinking.
Finding or denying genetic factors has become an important goal of people's research.
From 65438 to 0879, German anatomist Fleming observed cells. He used the method of dyeing. It was found that there were still some unstained areas in the cell, and the stained substances were concentrated in the nucleus, which absorbed a lot of basic aniline dyes.
1882, Fleming found that these dyes (which were not named at that time) split. After division, the two daughter cells each obtained the same amount of chromatin as the mother cell. This is actually what we call a chromosome.
Fleming didn't know Mendel's achievements at that time, so he couldn't realize the significance of chromosomes.
1904, American biologist Sutton proved the existence of chromosomes in pairs and suspected that there were genetic factors on chromosomes.
In 1906, batson found that some characteristics of peas are always inherited together with other characteristics.
1909, Danish botanists put forward the word "gene".
In the 1920s, a group of Columbia University researchers led by Moore, a Kentucky native, put forward an explanation.