2023 في الانقسام المنصف تكون الخلايا الناتجة أحادية المجموعة الكروموسومية .

أنت تبحث عن في الانقسام المنصف تكون الخلايا الناتجة أحادية المجموعة الكروموسومية . ، سنشارك معك اليوم مقالة حول انقسام منصف – ويكيبيديا تم تجميعها وتحريرها بواسطة فريقنا من عدة مصادر على الإنترنت. آمل أن تكون هذه المقالة التي تتناول موضوع في الانقسام المنصف تكون الخلايا الناتجة أحادية المجموعة الكروموسومية . مفيدة لك.

انقسام منصف – ويكيبيديا

meiosis or Meiosis or remedy or meiosis[1] (in English: meiosisIt occurs in living reproductive cells called mother sex cells, and this type of division differs in that the number of chromosomes is reduced by half.[2][3][4] The importance of meiosis lies in the fact that it is necessary to preserve organisms that reproduce sexually, and by means of meiosis the stability of the number of chromosomes is maintained, and it helps in the diversity of the characteristics of organisms of the same strain.

In animals, the meiosis occurs in the testes of males to form sperms, and in females in the ovaries to form eggs. In plants, it occurs in the anther to form pollen grains, and in the ovary to form ovules.

The products of this division are four cells that are genetically asymmetric and therefore possess new characteristics other than those of the mother cell. Also, this division is characterized by the fact that the resulting cell does not complete the cycle as it happens in mitosis, and that the number of chromosomes in the resulting cell is the half number (1n), which will return to the double number (2n) when the male and female gametes unite.

Stages of meiosis[عدل]

Meiosis has two main stages, in addition to a stage before them, which is the interphase, and its explanation is as follows:

interphase[عدل]

This phase occupies most of the life of the cell – usually – and precedes the stage of division itself. In this phase, the chromosomes have doubled in the stage of synthesis (DNA synthesis stage) – which is one of the stages of the interphase – so that each chromosome consists of two chromatids that are completely identical in the genetic material, and they are called the two sister chromatids, and they unite at a point called the centromere. central (centromere). In this phase, the centrosome also doubles.

The first stage of meiosis[عدل]

The first introductory phase[عدل]

This phase occupies the largest part of the process of meiosis (about 90%), in which the chromosomes begin to condense and appear clear under the microscope, and each chromosome consists of two sister chromatids united at the centromere. The chromosomes are lined up so that each two identical chromosomes are adjacent to each other and therefore, and since the chromosomes are very close to each other, overlap may occur between two non-sister chromatids from each two identical chromosomes (note the figure) and this process is called: crossing over, in which part of the genetic material is exchanged between two identical chromosomes Where part of the genetic material leaves the first chromosome, and a similar part of the genetic material leaves the second chromosome, and the first part is attached to the place of the second part on the second chromosome, and the second is linked to the place of the first, and this process is responsible for the presence of new characteristics in the next generation, different from the next generation the first.

In the process of crossing over, crossover occurs between the two homologous chromosomes by means of a protein called the synaptonemal complex. In each quadruple, one or more cross-links, and the synaptic filamentous complex keeps the two chromosomes connected until the dissociative phase.

Also at this stage the following occurs: the nucleus disappears, the centrioles move towards the poles of the cell, and spindle fibers begin to form, similar to what happens in the process of mitosis. The centromere region contains a protein called the kinetochore, to which the spindle fibers attach, and then the homologous chromosomes move towards the equator of the cell, as follows.

The first equatorial phase[عدل]

In this phase, the tetrapods move towards the equator of the cell, so that each chromosome from each of the two homologous chromosomes faces one of the poles of the cell, and in this phase the kinetochore is connected to one of the spindle threads formed from one of the two centrosomes (the centrosomes).

The first dissociative phase[عدل]

The chromosomes begin to separate, and each of them heads towards one of the poles of the cell (every two identical chromosomes each head towards one of the poles of the cell), and the sister chromatids remain connected here, but what separates is the chromosomes, note the difference here between the first meiotic phase in meiosis and the meiosis in equilibrium; What separates here is the chromosomes, not the chromatids. In the phase of separation in mitosis, the chromatids divide. Know here that the orientation of the chromosomes towards one of the poles of the cell is led by the spindle threads, but the spindle threads do not pull the chromosome by force, but there is a motor protein located on the kinetochore located in the centromere region, this protein breaks the spindle threads into tubulin units so that it follows the path of spindle threads in breaking it; This means that the spindle fibers are shortened from their ends (the place of their attachment to the chromosome) and not from their beginnings (the place of their formation from the centrosome side).

first final instar and telogen[عدل]

At this stage, each cell contains half the number of chromosomes (1n), and in this stage the cytoplasm divides. The final phase usually begins with the process of shortening, and here the division of the chromosomes does not occur because they were previously divided. In animal cells, the process of contraction occurs and the formation of an incision or furrow in the middle of the cell that divides it into two halves; In plant cells, the so-called “middle lamina” is formed, and cellulose and other components of the cell wall are deposited on both sides of it. In some species, the chromosomes condense and the nuclear membrane and nucleolus form again.

The second stage of meiosis[عدل]

The second introductory phase[عدل]

The formation of spindle threads here and then the chromosomes begin to move towards the equator of the cell.

The second equatorial phase[عدل]

The chromosomes are lined up at the equator of the cell, as happens in the process of mitosis, and the kinetochore on each pole is connected to tubules from one of the two centrioles. Note here that the chromosomes are not genetically identical, because of the crossing-over that occurred in prophase I.

The second dissociative phase[عدل]

The two centromeres (centromerans) of each chromosome separate from each other. Note here that the chromatids will separate from each other, not the homologous chromosomes.

The second final phase and telogen[عدل]

The nuclei appear again, the chromosomes begin to condense, and the process of shortening begins.

Here, the output in the process of meiosis is 4 cells, each of which contains half the number of chromosomes (1n), and also note that each of the resulting cells does not resemble any of the other cells in its characteristics, due to the process of crossing over that occurred in the first prophase in addition to the separation Randomization of homologous chromosomes during the first meiotic prophase.

Importance and benefits[عدل]

maintenance of multicellular organisms; By preserving the original number of chromosomes for each of these organisms, the first part of the meiosis bisects the number of chromosomes in half, and when the two gametes (the two pairs) unite, the double number of chromosomes returns.

See also[عدل]

  • List of human genes
  • equal split
  • fusiform apparatus
  • motor space

Reference[عدل]

  1. ^ The Egyptian curriculum – the third preparatory year – science
  2. ^ “Information about split fairness on britannica.com”. britannica.com. Archived from the original on April 26, 2019.
  3. ^ “Information about equitable dichotomy on the website universalis.fr”. universalis.fr. Archived from the original on August 16, 2017.
  4. ^ “Information about fair split on snl.no”. snl.no. Archived from the original on October 19, 2016.
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Retrieved from «https://en.wikipedia.org/w/index.php?title=teksim_mnisef&oldid=59905224»

فيديو حول في الانقسام المنصف تكون الخلايا الناتجة أحادية المجموعة الكروموسومية .

طريقة جميلة وجديدة لتمييز خلية n عن 2n في الانقسام الخلوي

طريقة جديدة وسهلة لتمييز الخلية أحادية المجموعة الكروموسومية n عن الخلية ثنائية المجموعة الكروموسومية 2n في دورة حياة الخلية وذلك بالتركيز فقط على عدد السنتروميرات.
مشاهدة ممتعة

د. ظافر القرني

سؤال حول في الانقسام المنصف تكون الخلايا الناتجة أحادية المجموعة الكروموسومية .

إذا كانت لديك أي أسئلة حول في الانقسام المنصف تكون الخلايا الناتجة أحادية المجموعة الكروموسومية . ، فيرجى إخبارنا ، وستساعدنا جميع أسئلتك أو اقتراحاتك في تحسين المقالات التالية!

تم تجميع المقالة في الانقسام المنصف تكون الخلايا الناتجة أحادية المجموعة الكروموسومية . من قبل أنا وفريقي من عدة مصادر. إذا وجدت المقالة في الانقسام المنصف تكون الخلايا الناتجة أحادية المجموعة الكروموسومية . مفيدة لك ، فالرجاء دعم الفريق أعجبني أو شارك!

قيم المقالات انقسام منصف – ويكيبيديا

التقييم: 4-5 نجوم
التقييمات: 8 7 0 6
المشاهدات: 5 8 4 5 5 8 1 0

بحث عن الكلمات الرئيسية في الانقسام المنصف تكون الخلايا الناتجة أحادية المجموعة الكروموسومية .

[الكلمة الرئيسية]
طريقة في الانقسام المنصف تكون الخلايا الناتجة أحادية المجموعة الكروموسومية .
برنامج تعليمي في الانقسام المنصف تكون الخلايا الناتجة أحادية المجموعة الكروموسومية .
في الانقسام المنصف تكون الخلايا الناتجة أحادية المجموعة الكروموسومية . مجاني

المصدر: ar.wikipedia.org

Read  2023 يعتمد مقدار التيار الكهربائي المار على الجهد الكهربائي والمقاومة الكهربائية

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