Cell life cycle, cell division, mitotis, meiosis, amitosis and endomitosis

Август 11, 2022

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Биология
Cell life cycle, cell division, mitotis, meiosis, amitosis and endomitosis

Содержание

2. CELL LIFE CYCLE : The cell cycle is an ordered series of events involving cell growth
4. STAGES OF CELL LIFE CYCLE : The cell cycle consists of four discrete phases: G1, S,
5. IMPORTANCE OF CELL CYCLE : The cell cycle is the replication and reproduction of cells, whether
6. CELL DIVISION : The cell cycle is the replication and reproduction of cells, whether in eukaryotes
7. CELL DIVISION :
8. Mitosis is how somatic—or non-reproductive cells—divide. Somatic cells make up most of your body's tissues and
9. MITOTIS - CELL DIVISION Mitosis cell division creates two genetically identical daughter diploid cells. The major
10. Before a cell starts dividing, it is in the "Interphase." It seems that cells must be
12. MITOTIS – CELL DIVISION The mitosis cell cycle includes several phases that result in two new
13. MEIOSIS CELL DIVISION : Meiosis is the other main way cells divide. Meiosis is cell division
15. The meiosis cell cycle has two main stages of division -- Meiosis I and Meiosis II.
16. MEIOSIS CELL CYCLE : Meiosis has two cycles of cell division, conveniently called Meiosis I and
17. AMITOSIS: A direct type of cell division wherein the nucleus and the cytoplasm go through a
19. ENDOMITOTIS : Endomitosis : The replication of chromosomes in the absence of cell or nuclear division,
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CELL LIFE CYCLE :
The cell cycle is an ordered series of events involving cell growth

and cell division that produces two new daughter cells. Cells on the path to cell division proceed through a series of precisely timed and carefully regulated stages of growth, DNA replication, and division that produces two identical (clone) cells.
Three scientists who discovered key elements in cell cycle regulation won Nobel Prize in Medicine. Dr. Paul Nurse and Dr. Tim Hunt, both from Imperial Cancer Research Fund (ICRF), London and Dr.May.

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STAGES OF CELL LIFE CYCLE :
The cell cycle consists of four

discrete phases: G1, S, G2, and M. The S or synthesis phase is when DNA replication occurs, and the M or mitosis phase is when the cell actually divides. The other two phases — G1 and G2, the so-called gap phases — are less dramatic but equally important.

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IMPORTANCE OF CELL CYCLE :
The cell cycle is the replication

and reproduction of cells, whether in eukaryotes or prokaryotes. It is important to organisms in different ways, but overall it allows them to survive. For prokaryotes, the cell cycle, called Binary Fission, allows for them to live on by dividing into two new daughter cells.

The

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CELL DIVISION :
The cell cycle is the replication and reproduction of cells, whether in

eukaryotes or prokaryotes. It is important to organisms in different ways, but overall it allows them to survive. For prokaryotes, the cell cycle, called Binary Fission, allows for them to live on by dividing into two new daughter cells.All multicellular organisms use cell division for growth and the maintenance and repair of cells and tissues. Single-celled organisms use cell division as their method of reproduction. Somatic cells divide regularly; all human cells (except for the cells that produce eggs and sperm) are somatic cells.

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CELL DIVISION :

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Mitosis is how somatic—or non-reproductive cells—divide. Somatic cells make up most

of your body's tissues and organs, including skin, muscles, lungs, gut, and hair cells. Reproductive cells (like eggs) are not somatic cells. In mitosis, the important thing to remember is that the daughter cells each have the same chromosomes and DNA as the parent cell. The daughter cells from mitosis are called diploid cells. Diploid cells have two complete sets of chromosomes. Since the daughter cells have exact copies of their parent cell's DNA, no genetic diversity is created through mitosis in normal healthy cells.

MITOSIS CELL DIVISION :

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MITOTIS - CELL DIVISION
Mitosis cell division creates two genetically

identical daughter diploid cells. The major steps of mitosis are shown here.

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Before a cell starts dividing, it is in the "Interphase." It

seems that cells must be constantly dividing (remember there are 2 trillion cell divisions in your body every day), but each cell actually spends most of its time in the interphase. Interphase is the period when a cell is getting ready to divide and start the cell cycle. During this time, cells are gathering nutrients and energy. The parent cell is also making a copy of its DNA to share equally between the two daughter cells. The mitosis division process has several steps or phases of the cell cycle—interphase, prophase, prometaphase, metaphase, anaphase, telophase, and cytokinesis—to successfully make the new diploid cell

MITOTIS CELL CYCLE :

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MITOTIS – CELL DIVISION
The mitosis cell cycle includes several phases that

result in two new diploid daughter cells. Each phase is highlighted here and shown by light microscopy with fluorescence.
When a cell divides during mitosis, some organelles are divided between the two daughter cells. For example, mitochondria are capable of growing and dividing during the interphase, so the daughter cells each have enough mitochondria. The Golgi apparatus, however, breaks down before mitosis and reassembles in each of the new daughter cells. Many of the specifics about what happens to organelles before, during and after cell division are currently being researched.

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MEIOSIS CELL DIVISION :
Meiosis is the other main way cells divide.

Meiosis is cell division that creates sex cells, like female egg cells or male sperm cells. What is important to remember about meiosis? In meiosis, each new cell contains a unique set of genetic information. After meiosis, the sperm and egg cells can join to create a new organism.
Meiosis is why we have genetic diversity in all sexually reproducing organisms. During meiosis, a small portion of each chromosome breaks off and reattaches to another chromosome. This process is called "crossing over" or "genetic recombination." Genetic recombination is the reason full siblings made from egg and sperm cells from the same two parents can look very different from one another.

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The meiosis cell cycle has two main stages of division --

Meiosis I and Meiosis II. The end result of meiosis is four haploid daughter cells that each contain different genetic information from each other and the parent cell.

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MEIOSIS CELL CYCLE :
Meiosis has two cycles of cell division, conveniently

called Meiosis I and Meiosis II. Meiosis I halves the number of chromosomes and is also when crossing over happens. Meiosis II halves the amount of genetic information in each chromosome of each cell. The end result is four daughter cells called haploid cells. Haploid cells only have one set of chromosomes - half the number of chromosomes as the parent cell.
Before meiosis I starts, the cell goes through interphase. Just like in mitosis, the parent cell uses this time to prepare for cell division by gathering nutrients and energy and making a copy of its DNA. During the next stages of meiosis, this DNA will be switched around during genetic recombination and then divided between four haploid cells.

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AMITOSIS:
A direct type of cell division wherein the nucleus and the

cytoplasm go through a simple mass divisionCell division is the process in which a parent cell divides, giving rise to two or more daughter cells. It is an essential biological process in many organisms. It is the means used by multicellular organisms in order to grow, replenish (repair), and reproduce. In unicellular organisms, a cell division is equivalent to reproduction. There are two forms of cell division: (1) direct cell division and (2) indirect cell division.
The direct cell division is one in which the cell directly divides and does not undergo complicated changes before it divides, just as in indirect cell division (such as mitosis). The nucleus and the cytoplasm of the cell divide by constriction without the prior formation of chromosomes. This type of direct cell division is also called amitosis.

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ENDOMITOTIS :
Endomitosis : The replication of chromosomes in the absence

of cell or nuclear division, resulting in numerous copies within each cell. It occurs notably in the salivary glands of Drosophila and other flies. Cells in these tissues contain giant chromosomes (see polyteny), each consisting of over a thousand intimately associated, or synapsed, chromatids.

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