You are a doctor in a hospital, and a patient is experiencing trouble with her skin repairing itself from a cut. The patient is also expecting a child, but the cells in the reproduction development are experiencing malfunction in cell division.

Describe the stages of each type of cell reproduction process from a normal patient whose body cells can repair themselves and normal cell division during the reproductive development of the unborn baby.

 

There are two types of cell division one is mitosis that works for the growth and repair of body tissues and the other is meiosis which is required during sexual reproduction to reduce the chromosome number to half.

 

Stages in Mitosis:

Mitosis is a type of cell division where in the parent cells divide and form two identical daughter cells. It occurs in all somatic cells, and involved in the mechanisms like healing, regeneration etc. The number of chromosomes in the parent and the daughter cells are same. Hence this division is called Equational division.

It is divided into 4 stages of nuclear division and later followed by cytokinesis.

Prophase: It is the first stage of mitosis.It is marked by the initiation of condensation of chromosomal material. The chromosomal material condenses and organises to form compact mitotic chromosome. Initiation of the assembly of mitotic spindles also occur.

Metaphase: Chromosomes are moved to spindle equator and get aligned along the metaphase plate through spindle fibres to both plates.  

Anaphase: Centromeres split and chromatids seperate. The chromatids move to the opposite poles.

Telophase: Chromosomes cluster at opposite spindle pools and their identity is lost as discrete elements. The nuclear envelope assembles around the chromosome clusters. Nucleolus, golgi complex and ER form.

Cytokinesis: This is the division of the cytoplasm, which begins at the end of the telophase of the nuclear division.

 

Stages of Meiosis:

It is the reductional division that occurs during the process of gametes formation. The daughter cells are haploid in nature.

It is divided into two phases:

Meiosis-I : It is divided further four stages:

Prophase-1: Prophase of the first meiotic division is typically longer and more complex when compared to the prophase of mitosis.It is further divided into-

LEPTOTENE: The compaction of chromosomes occur throughout this phase.

ZYGOTENE: During this stage, the chromosomes start pairing and this process is called Synapsis. This leads to the formation of Homologous chromosomes.

PACHYTENE: This stage is characterized by the appearance of recombination nodules, at the sites where the crossing over occur. Crossing over is the exchange of genetic material between the two homologous chromosomes.

DIPLOTENE: Seperation of the bivalent homologous chromosomes occur except at the site of the Crossing over. It leads to the formation of Chiasmata.

DIAKINESIS: During this phase, the chromosomal material are fully condensed and the meiotic spindle is assembled to prepare the homologous chromosomes for seperation. Diakinesis represents transition to metaphase.

Metaphase-I: The bivalent chromosomes align on the equatorial plate.

Anaphase-I: The homologous chromosomes seperate, while sister chromatids remain associated at the centromeres.

Telophase-I: The nuclear membrane and the nucleolus reappear.

 

Meiosis-II : It is similar to the stages and events in Mitosis.

These include:

Prophase-II

Metaphase-II

Anaphase-II

Telophase-II

 

Mitosis-

Advantages-

Identical cells are produced which means that if cell repair is required in certain specialized tissue mitosis will offer a better opportunity as it will produce the same kind of tissue which is injured. For example, kidney tissue will form kidney tissues and liver tissues will form liver tissues. The process is quicker.

 

Disadvantages-

No diversity is produced by mitosis and it eventually can lead to the production of the same clone of cells again and again and we know that diversity is the spice of life. It is needed to continue life. Mitosis can amplify negative traits.

 

Meiosis-

Advantages-

Provide ample diversity as it allows a type of cell division where genetic recombination of homologous chromosomes from both the parents provide new combination in the offspring causing diversity in genes. This division is responsible for the development of more advanced characters and thus evolution on the whole.

 

Disadvantages-

it is a bit complex and lengthy process with high energy usage.

 

Now in the above case if a mother is facing some problem related to cell division then obviously the child will be affected too. The child developing could be abnormal due to the absence of proper cell division mechanisms. There could be non-disjunction of chromosomes that could lead to polyploidy or many other syndromes eventually leading to improper physical or mental development in the child.

Step-by-step explanation

There are two types of cell division one is mitosis that works for the growth and repair of body tissues and the other is meiosis which is required during sexual reproduction to reduce the chromosome number to half.

 

Stages in Mitosis:

Mitosis is a type of cell division where in the parent cells divide and form two identical daughter cells. It occurs in all somatic cells, and involved in the mechanisms like healing, regeneration etc. The number of chromosomes in the parent and the daughter cells are same. Hence this division is called Equational division.

It is divided into 4 stages of nuclear division and later followed by cytokinesis.

Prophase: It is the first stage of mitosis.It is marked by the initiation of condensation of chromosomal material. The chromosomal material condenses and organises to form compact mitotic chromosome. Initiation of the assembly of mitotic spindles also occur.

Metaphase: Chromosomes are moved to spindle equator and get aligned along the metaphase plate through spindle fibres to both plates.  

Anaphase: Centromeres split and chromatids seperate. The chromatids move to the opposite poles.

Telophase: Chromosomes cluster at opposite spindle pools and their identity is lost as discrete elements. The nuclear envelope assembles around the chromosome clusters. Nucleolus, golgi complex and ER form.

Cytokinesis: This is the division of the cytoplasm, which begins at the end of the telophase of the nuclear division.

 

Stages of Meiosis:

It is the reductional division that occurs during the process of gametes formation. The daughter cells are haploid in nature.

It is divided into two phases:

Meiosis-I : It is divided further four stages:

Prophase-1: Prophase of the first meiotic division is typically longer and more complex when compared to the prophase of mitosis.It is further divided into-

LEPTOTENE: The compaction of chromosomes occur throughout this phase.

ZYGOTENE: During this stage, the chromosomes start pairing and this process is called Synapsis. This leads to the formation of Homologous chromosomes.

PACHYTENE: This stage is characterized by the appearance of recombination nodules, at the sites where the crossing over occur. Crossing over is the exchange of genetic material between the two homologous chromosomes.

DIPLOTENE: Seperation of the bivalent homologous chromosomes occur except at the site of the Crossing over. It leads to the formation of Chiasmata.

DIAKINESIS: During this phase, the chromosomal material are fully condensed and the meiotic spindle is assembled to prepare the homologous chromosomes for seperation. Diakinesis represents transition to metaphase.

Metaphase-I: The bivalent chromosomes align on the equatorial plate.

Anaphase-I: The homologous chromosomes seperate, while sister chromatids remain associated at the centromeres.

Telophase-I: The nuclear membrane and the nucleolus reappear.

 

Meiosis-II : It is similar to the stages and events in Mitosis.

These include:

Prophase-II

Metaphase-II

Anaphase-II

Telophase-II

 

Mitosis-

Advantages-

Identical cells are produced which means that if cell repair is required in certain specialized tissue mitosis will offer a better opportunity as it will produce the same kind of tissue which is injured. For example, kidney tissue will form kidney tissues and liver tissues will form liver tissues. The process is quicker.

 

Disadvantages-

No diversity is produced by mitosis and it eventually can lead to the production of the same clone of cells again and again and we know that diversity is the spice of life. It is needed to continue life. Mitosis can amplify negative traits.

 

Meiosis-

Advantages-

Provide ample diversity as it allows a type of cell division where genetic recombination of homologous chromosomes from both the parents provide new combination in the offspring causing diversity in genes. This division is responsible for the development of more advanced characters and thus evolution on the whole.

 

Disadvantages-

it is a bit complex and lengthy process with high energy usage.

 

Now in the above case if a mother is facing some problem related to cell division then obviously the child will be affected too. The child developing could be abnormal due to the absence of proper cell division mechanisms. There could be non-disjunction of chromosomes that could lead to polyploidy or many other syndromes eventually leading to improper physical or mental development in the child.