Biological question, the essence of the transformation of pneumococcus is genetic recombination?

The DNA of type S bacteria converts type R bacteria into live, virulent type S bacteria.

Mix the live R-type bacteria with the S-type DNA molecule fragments. When the growth of the R-type flora reaches its peak, the bacteria lose their local cell wall, and the bacteria at this time are called competent bacteria. The cell membrane surface of this competent bacterium has about 30-80 binding points that can bind to S-type DNA molecular fragments, so that DNA molecular fragments with transformation function are transformation factors.

Bind to the cell surface of R-type bacteria. Then, one strand of the DNA molecule fragment is broken down by nucleases on the cell membrane of the R-type cell, and the other strand enters the R-type cell cell. And through the integration of DNA recombination with type R cells.

In this way, the R-type cells, which receive the molecular fragments of S-type DNA, are transformed into Pneumococcus s. This means that only competent bacteria are able to accept and eventually transform.

Because in the "transformation experiment of pneumococcus", there is an unavoidable suspicion: what if the DNA molecule of the extracted S-type bacteria contains a small amount of protein?

Because the DNA extraction technology was not very mature at that time, it was difficult to prove that the extracted DNA molecule was absolutely pure, and it was impossible to prove whether it contained a small amount of protein, and it was impossible to prove that the protein did not work. , 1, it is the phage that infects Escherichia coli, and the experiment shows that DNA is a chromosome, 0, the transformation experiment of Pneumoniae bijingcoccus proves that DNA is genetic material, and protein is not genetic material. Experiments with bacteriophage infecting bacteria are further proof that it is more direct and convincing.

0, why not the transformation experiment of Pneumococcus pneumococcus proves that DNA is a good and auspicious substance.

The experiment that proves that DNA is genetic material is the experiment of phage infection of bacteria, so why not the "transformation experiment of pneumococcus".

The transformation of R-type bacteria into S-type bacteria exhibits the characteristics of S-type bacteria, and this variation belongs to genetic recombination.

The transformation experiment of Pneumococcus pneumococcus is an experiment in which Griffith uses R and S strains as experimental materials to conduct experiments on genetic material, and he injects live, non-toxic R-type (capsule-free, coarse colony) Pneumococcus pneumococcus or heat-killed toxic Pneumococcus s. into mice, and the mice are unharmed; Live, toxic type S (capsulated, colony smooth) pneumococcus or a large number of toxic type S pneumococcus killed by heating and a small amount of non-toxic, live type R type pneumococcus were mixed into the body of the mouse respectively, as a result, the mouse died of disease, and the live type S bacteria were isolated from the mouse, which reflected the genetic recombination.

I'm speechless, it's like this:

The test point of this question is the difference between R type bacteria and S type bacteria, and the difference between in vivo and in vitro.

Type R bacteria do not have a capsule and are easily killed in the human body, so there is a significant decline curve in the human body.

However, outside the human body, it is only affected by space, food, etc., and has an S-shaped growth curve.

Type S bacteria are not easy to kill, multiply quickly in the human body, and can be converted into Type S after the death of type R, so they grow quickly. In vitro, there is competition from R-type bacteria, which is restricted, so it does not grow as fast as in vivo.

Hope it works, ps stay.

Carbohydrates of type D bacteria + type S bacteria R type bacteria R type bacteria + Proteins of type S bacteria R type bacteria.

DNA of type R bacteria + type S bacteria S type bacteria.

DNA of type R bacteria + type S bacteria + deoxyribonuclease + DNA type R bacteria.

Choose B, is there a lack of conditions for your question, is there no S bacteria at the beginning, only the DNA of S bacteria, because the S type can transform the R type into the S type, so there are no S bacteria at the beginning, but there will be S bacteria over time, and there will be more and more S bacteria.

Griffith Stone reverted to the pneumoniae double spheroid bacteria in vivo transformation to verify that the DU in the "S" bacteria contains a certain "ZHI transformation factor", which can transform the non-virulent DAO type R bacteria into virulent S bacteria The ingenuity of Avery and his colleagues' experiment was to purify the DNA, proteins, and polysaccharides of the S bacteria and add them to the medium used to culture the R bacteria, and observe their effects separately, proving that DNA is genetic material

The process by which the phage infects the bacteria: adsorption Injection (injection of DNA into the phage) Synthesis (controller: DNA of the phage; Ingredients:

Chemical composition of bacteria) Assemble Release Protocol for phage infection of bacteria: Labeling phages with 35S or 32p, respectively Mixed culture of phages with E. coli Infection of unlabeled bacteria Stirring in a stirrer followed by centrifugation to detect radioactive material in the supernatant and precipitate The results proved that DNA is genetic material

Therefore, d

a. Ribosomes.

It is the site of protein synthesis, Pneumococcus is a prokaryotic organism with its own ribosomes, and can synthesize its own proteins on its own ribosomes, a error;

b. Hemoglobin.

It is a protein in red blood cells, which belongs to intracellular proteins, which is synthesized in free ribosomes in Chai Zhou, and does not require the modification and processing of endoplasmic reticulum, b error;

c. Lysosomes.

It contains a variety of hydrolytic enzymes, which can engulf and kill viruses and germs that invade the cell, and the chemical essence of a variety of hydrolyzed linglao enzymes in lysosomes is protein, c is correct;

d. The diversity of protein structure and function is the direct cause of biodiversity, and the size leakage diversity of DNA is the root cause of biodiversity

Therefore, c

The essence of this experiment is the recombination between the DNA or gene of the S type and the DNA of the living bacteria of the R type, so that the latter can obtain new genetic information.

Once the exogenous DNA molecule (i.e., the S-type DNA) finds its endogenous homolog (i.e., the DNA of the R-type bacteria).

These two molecules can then be genetically exchanged.

The result of the exchange is the integration of exogenous DNA and the separation of homologous endogenous DNA molecules from the DNA of R-type bacteria.

This results in the genetic transformation from R-type bacteria to S-type bacteria.

A. Avery's in vitro transformation experiment proved that the white matter of the white matter of the empty egg segment is not genetic material, and A is wrong;

b. Avery's in vitro transformation experiments proved that DNA is genetic material and protein is not genetic material, and B is wrong;

C. Avery's in vitro transformation experiments proved that DNA is genetic material, and C was wrong;

d. Avery's in vitro transformation experiments proved that DNA is genetic material, and d is correct Therefore, D