Cells are complex, small structures in any living organism, and they are responsible for reproducing and maintaining life.
Cells divide and split daily. As per estimates, around two trillion cell divisions can occur in the human body every day.
Every cell undergoes cell division. The cells engage with each other and undergo biochemical reactions that guide them, so they know when and how to divide.
According to the latest research, a cell divides into two after a single cell grows big enough and produces four key proteins sufficiently. Once it reaches the required criteria, the single cell divides into two cells. The healing of a wound is also repaired through cell division.
As per the Hayflick Limit, a normal human cell can replicate and divide only 4-60 times After that, cells lose their ability to divide and become damaged cells. So, the different cells self-destruct, which is called apoptosis. It's the process by which our body gets rid of unwanted or old cells or genetically damaged cells.
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Cell Meaning And Cell Division Meaning
Cells are the basic structure of all organisms. The basic functions of a cell are to ensure the flow of substances across the cell membrane, cell division to make a new cell, and protein synthesis for DNA replication.
There are two varieties of cells, namely prokaryotic cells and eukaryotic cells. Prokaryotes or prokaryotic organisms are simple-celled organisms, such as archaea and bacteria, that don't have a nuclear membrane or cell nucleus.
Eukaryotes, or eukaryotic organisms, are larger and more complex and made up of one cell or multiple cells, such as amoeba, plants, animals, and humans. Eukaryotic organisms eat, breathe, move, grow, reproduce, and excrete. In eukaryotic organisms, every cell contains three parts: the cell membrane, nucleus, and cytoplasm.
The outer layer of cells is a cell membrane, which protects the contents of the cell. The cell nucleus is the control center and decides the structure of the cell and its function.
It is lined by a nuclear membrane and holds a fluid called nucleoplasm. The nucleus also holds the chromatin, which has the genetic material of the cell or deoxyribonucleic acid (DNA).
There is also a nucleolus that has ribonucleic acid (RNA). The cytoplasm is a fluid that is inside every cell. It fills the space between the cell membrane and the nucleus and contains the cytoplasmic organelles such as mitochondrion, ribosomes, the Golgi apparatus, lysosomes, and endoplasmic reticulum. It acts as a channel for chemical reactions to take place.
Each human cell also contains 46 chromosomes or 23 pairs of chromosomes.
Cell division is a special process that takes place in living organisms. Also termed cell reproduction, it occurs when a parent cell splits and forms two daughter cells.
New cells are created by the division of existing cells in the body. During the division, the nucleus, mitochondria, and the number of chromosomes also divide.
The process of cell division has four purposes, which are: repairing or replacing tissues; growth of the organism; asexual reproduction in the case of plants; and the development of embryos in animals and humans. Our body ensures that when a cell divides, the DNA is copied properly and the two new daughter cells are genetically identical.
Types Of Cell Division With Example
There are three types of cell division that take place. These are known as binary fission, mitosis, and meiosis. Binary fission indicates the asexual reproduction that takes place in prokaryotic organisms. In binary fission, the organism duplicates its genetic material and divides into two identical cells or two single-celled organisms. Binary fission occurs in archaea and bacteria.
In multicellular organisms, cell reproduction takes place through mitosis and meiosis. Mitosis takes care of this fundamental life process of creating new cells for any organism. It is regulated by the genes in the body. The resultant new cells will be exact copies of each other.
When mitosis takes place, somatic cells called parent cells duplicate themselves, including all of their contents and their set of chromosomes. It forms two identical daughter cells, or diploid cells, with two sets of chromosomes, or 46 chromosomes each, that share 100% of the DNA.
Examples of mitosis can be seen in our body cells, such as skin cells, cells in muscles, blood cells, and more.
On the other hand, meiosis is the unique process of creating gametes, or specialized sex cells or reproductive cells, called sperm and egg cells. The purpose of meiosis is to make sure that humans have the same number of chromosomes generation after generation.
It involves gene shuffling and allows genetic variations when the cells divide. In meiosis, the parent cell replicates only 50% of its DNA, and the cell divides into four daughter cells, or haploid cells, each with one set of chromosomes or 23 chromosomes that aren't identical.
This type of cell division occurs as a two-step process. First, when the 46 chromosomes become half the number (23), they form eggs and sperm cells.
Later, during conception, when the sperm and eggs (consisting of 23 chromosomes each) of two people fuse to produce an embryo that will have 46 chromosomes again. Meiosis occurs in animals as well as in humans.
Importance Of Cell Division
Cell division has three functions: reproducing entire single-celled organisms, growing and repairing tissues in multicellular organisms, and forming eggs and sperm for sexual reproduction in multicellular organisms.
Cell division occurs in an organized manner, step-wise, and in different phases that eventually constitute the cell cycle. The phases of the cell division in both mitosis and meiosis are named interphase, prophase, metaphase, anaphase, and telophase. This is followed finally by cytokinesis or division of the cytoplasm.
The mitosis cell cycle starts with the interphase. It is the longest part of the cell cycle and is the resting period between two consecutive cell divisions where the cell is in its natural, functional state.
In prophase, the chromosomes condense into coils and each chromosome has two identical chromatids, called sister chromatids, united by a centromere. Furthermore, a spindle-like structure starts to form after the nuclear membrane collapses.
In metaphase, the chromosomes align alongside an equatorial plate or the central axis of the cell. The spindles develop fully and fibers from them attach to the chromosomes.
Anaphase the shortest of the five phases, sees the spindle fibers separate the two sister chromatids to opposite poles of the cell. Once apart the chromatids are referred to as daughter chromosomes.
In telophase, the cell starts to split, with nuclear membranes reforming around the two daughter chromosomes. They begin to uncoil, the spindle fibers disappear, and two identical daughter nuclei appear. Finally, during cytokinesis, the cytoplasm divides and two identical cells or two daughter cells are formed with identical genetic information similar to their parent cell.
Meiosis has two cell cycles called meiosis I and meiosis II.
Meiosis I sees the division of homologous chromosome pairs, while meiosis II sees the division of the sister chromatids. Meiosis II is short and simple, and cells from meiosis I start meiosis II, but without copying the DNA. The haploid cells, with one chromosome and two sister chromatids, separate.
Meiosis II is similar to mitosis but done for haploid cells. After telophase II, cytokinesis splits the chromosome sets into new cells. The result is four haploid cells, or eggs and sperm.
Genetic mutations, if any, occur when the DNA strands are duplicated before meiosis.
Which part of cell division is different in plant and animal cells?
Cell division in plant cells and animal cells is similar, but the difference will be visible in how the cytokinesis takes place.
Cytokinesis in plant cells occurs through the formation of a cell wall at the cell center that grows out, meets the lateral wall, and divides the cell. The cell plate later becomes the middle lamella between two cells.
In animal cells, cytokinesis occurs by forming a furrow in the plasma membrane that joins the center, splits the cell, resulting in separate cells.
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Martha MartinsBachelor of Arts specializing in Linguistics
Martha is a full-time creative writer, content strategist, and aspiring screenwriter who communicates complex thoughts and ideas effectively. She has completed her Bachelor's in Linguistics from Nasarawa State University. As an enthusiast of public relations and communication, Martha is well-prepared to substantially impact your organization as your next content writer and strategist. Her dedication to her craft and commitment to delivering high-quality work enables her to create compelling content that resonates with audiences.
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