After eating, Li Duo came to the dissection room to urge Chen Yanxi to ask for the results of the autopsy, Chen Yanxi looked up at him and said, "Well, I know, you go back first, but I sent it to him after a while, and I found sperm in her body. liquid, but fine. The DNA test results of the liquid haven't been sent back to me, so let him wait a little longer? After the autopsy was completed, Chen Yanxi covered Yang Xinxin with a white cloth, washed her hands by the pool, took off her white coat and walked out of the forensic room with Li Duo.

Li Duo returned to the office of the Serious Crime Team, while Chen Yanxi went to the Technical Appraisal Center to get the appraisal results. pressed his fingerprint on the glass door of the identification center and walked in.

The little technician who was inspecting it inside was bombarded: "Du'er, you don't take this palace too seriously, the things I handed over to you have been almost eight hours now, and you haven't made it for me, looking for death!" ”

Du Jiang didn't need to look back to know who it was, pushed the black-framed glasses on the bridge of his nose, and said lightly: "Grandma, you spare me, give me so many things, I can't check them the same." ”

"I'll only give you a sample, so for half a day?" Chen Yanxi only thought that he was trying to be lazy and make excuses.

"Although there is only one copy of the sample, I am fine in this one. DNA from at least six individuals was found in the samples. Du Jiang glanced at her and continued his work.

"What did you say?" Chen Yanxi said in surprise.

"I said that the essence in the victim's body. liquid, at least six sperm. The mixture of liquids can be reported to the special case, and this is the result of the analysis. Du Jiang handed her a stack of report sheets on the table.

Chen Yanxi looked at the DNA test results and was surprised, this was the first time she had encountered such a complex strong in her years of forensic work. Rape and homicide.

"No wonder the victim is down. The congestion of the body will be so severe, I originally thought that the perpetrator was violent, but it seems that my thinking is wrong. Chen Yanxi left the technical appraisal center, muttering to herself all the way.

When she returned to the office, everyone was dozing off, probably waiting for her autopsy report to open the case analysis before they came home.

"Comrades, the results are out," Chen Yanxi said, standing at the door.

"Huh?" Mu Haoran snuggled up in the chair and took a nap, and almost fell off the chair when she heard her voice.

Mu Haoran took a sip of water, shook his head, and drove away the sleepiness: "Let's be refreshed, have a short meeting, and when you're done, go back to sleep and persevere." ”

Everyone sat down at the small conference table and began to discuss the case, and Chen Yanxi gave everyone a brief description of the autopsy report: "First of all, the victims all died of mechanical suffocation, and the deceased Yang Xinxin was suffocated to death after being choked by the neck, and then the body was thrown from a high-rise building, creating the illusion of falling from the building. ”

"The second point is that through the analysis of the dissolved matter in the stomach of the deceased, they had eaten food four hours before the crime, and they ate food such as fast food."

"The third point is that the deceased Yang Xinxin had pregnancy experience, and through the test of her pelvis, she was pregnant at least three times, and I found levonorgestrel in the dissolution in her stomach, which is commonly known as the contraceptive pill."

"The fourth and most important point is the essence that I extracted from the body of the deceased. liquid, through the semen. Liquid acid phosphatase and DNA tests showed that the deceased had sex with at least six men at the time of the incident. Close. system, of course, does not exclude coercion/sexuality/behavior. ”

"I'm dripping, I've been pregnant three times since seventeen or eighteen, what kind of child is this, pull it out, and the rod will be punished a hundred" Hearing that Yang Xinxin had already had many pregnancy experiences, Li Duo felt a little incredible.

"Today's children are so different from when we were at that time, when I was seventeen or eighteen, I didn't even hold a girl's hand." An elderly in-house also lamented the openness of today's society, and what today's children have experienced, some of them have never experienced at this age.

"Wait......" Mu Haoran suddenly shouted.

Everyone looked at him in surprise, what kind of madness was this, Li Duo asked, "Team deputy, what are you doing?" ”

"Yeon-hee, are you saying that Yang Xinxin had taken birth control pills before she was killed?" Mu Haoran corrected the doubts that existed here.

"That's right, according to the blood concentration test of the drug in her body, when the deceased was killed, the blood concentration of levonorgestrel in her body reached its peak, and she was taking the drug in the three or four hours before she was killed."

Mu Haoran patted the table after hearing this: "There is." ”

"Comrades, Yang Xinxin had already taken contraceptive pills before the crime, what does this mean, it shows that she is aware of what is about to happen at night, then the possibility of a stranger committing the crime is ruled out, and the suspect must be someone she knows."

"But when I visited, her classmates said that she never had a boyfriend at school, and their teachers said that she had been doing very well!" Li Duo replied puzzled.

"I've seen her chat history, her social relationship seems to be very complicated, and the chat content in the group marked as classmates is relatively normal, but there is a group of contacts, the chat content is more ambiguous. It's like a conversation between a boyfriend and a girlfriend. Xu Ruoyuan told what she had discovered.

"The school and the family didn't know about their relationship, which shows that she deliberately concealed the fact that she had a boyfriend, and no one around her noticed anything unusual, so is it possible that her friend was someone from outside the school," Chen Yanxi guessed.

"Of course, this possibility is not ruled out, I heard that some of today's children can sell their most precious things just for a few dollars of snacks and a pleasant dress, and what else can't they do?" Xu Ruoyuan said with a somewhat solemn face.

"Next, we will focus on tracking down the six men, and in a while I will urge the technical investigators to send me the results tomorrow morning, and they will all go back to rest and disperse." Mu Haoran intimately handed his cotton coat to Chen Yanxi, the cold wind at night was bleak, and he was reluctant to let her suffer a little cold.

In the ridiculed eyes of everyone, Chen Yanxi blushed and walked out of the office with Mu Haoran, this man really spared no effort when he was sullen.

? DNA is deoxyribonucleic acid.

Deoxyribonucleic acid, also known as deoxyribonucleic acid, is a molecule, double-stranded structure composed of deoxyribonucleotides. It can form genetic instructions to guide biological development and life functions.

The main function is long-term information storage, which can be likened to a "blueprint" or "recipe". It contains instructions that are needed to build other compounds in the cell, such as proteins and RNA.

The DNA fragments that carry genetic information are called genes, and other DNA sequences, some of which function directly on their own, and some of which are involved in regulating the performance of genetic information.

A simple life requires at least 265 to 350 genes.

?

Deoxyribonucleic acid (DNA, abbreviation of English Deoxyribonucleic?acid), also known as deoxyribonucleic acid, is the main chemical component of the DNA chromosome, and it is also the material that makes up genes. It is also sometimes referred to as a "genetic particle" because during reproduction, the parents will copy a portion of their own DNA into the offspring, thus completing the transmission of the trait. [1]

Structure of DNA: The structure of DNA can generally be divided into primary structure, secondary structure, and tertiary. There are four levels of graded structure and quadruple structure.

DNA[1] is a long-chain polymer composed of four deoxynucleotides, namely adenine deoxynucleotide (dAMP deoxyadenosine), thymine deoxynucleotide (dTMP deoxythymidine), cytosine deoxynucleotide (dCMP deoxycytidine), guanine deoxynucleotide (dGMP deoxyguanosine). Deoxyribose sugar (five-carbon sugar) and phosphate molecules are connected by ester bonds to form their long chain backbone, which is arranged on the outer side, and the four bases are arranged on the inner side. Each sugar molecule is linked to one of four bases that follow the long DNA strands that form the genetic code that guides protein synthesis. The process of reading a code, called transcription, is the process of transcribing a piece of nucleic acid molecule called mRNA (messenger RNA) from a single strand of DNA as a template.

Most RNAs carry the information for the synthesis of proteins, while others have their own special functions, such as rRNA, snRNA, and siRNA. Within cells, DNA can combine with proteins to form chromosomes, and the entire set of chromosomes is collectively called the chromosomes. In humans, there are 46 chromosomes in a normal body thin. Chromosomes will complete replication in the interphase before cell division, and the interphase of cell division can be divided into: G1 phase - DNA synthesis phase, S phase - DNA synthesis phase, G2-DNA synthesis phase. For eukaryotes, such as animals, plants, and fungi, chromosomes are mainly found in the nucleus; Whereas, for prokaryotes, such as bacteria, they are mainly found in the cytoplasm within the nucleoid. Chromatin proteins on chromosomes, such as cathesin, organize and compress DNA to help it interact with other proteins, which in turn regulates gene transcription.

DNA Extraction Method:

One. Phenol extraction method: first use egg enzyme K, SDS to break the cells, digest the protein, and then use phenol and phenol-chloride DNA size of 100-150kb

Two. Formamide depolymerization method: Break the cells as above, and then use high concentration of formamide to depolymerize the protein and combine with DNA, and then dialyze to obtain DNA to obtain about 200kb of DNA.

Three. Glass rod winding method: the cells are lysed with guanidine hydrochloride, the lysate is spread on ethanol, and then the hook or U-shaped glass rod is gently stirred at the interface, and the DAN precipitate is wound around the glass rod. Approximately 80 kb of DNA is generated.

Four. Isopropanol precipitation method: basically the same as the 1 method, only two times the volume of isopropanol is used to replace ethanol, which can remove small RNA molecules

Five. Rapid preparation of surfactant: Cells are disrupted with TritonX-100A or N, P40 surfactant, followed by protein removal with proteinase K or phenol, ethanol precipitation or dialysis.

Six. Rapid preparation by heating method: heat 96°C-100°C for five minutes, then centrifuge to take the supernatant, which can be used for PCR reaction.

Seven. Rapid preparation of alkali denaturation: first act with NaOH for 20 minutes, then add HCI to neutralize, centrifugation and take the supernatant, containing a small amount of DNA.

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