Biological Sciences
Cell Division
Cell division is the process by which a parent cell divides into two or more daughter cells. It is essential for growth, repair, and reproduction in living organisms. The two main types of cell division are mitosis, which produces two identical daughter cells, and meiosis, which produces four genetically diverse daughter cells.
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eBook - PDF- Emea, A(Authors)
- 2018(Publication Date)
- Agri Horti Press(Publisher)
Cell Divisions 1 C HAPTER 1 Cell Divisions Cell Division is the process that cells go through in order to divide. Cells may divide for several reasons, and there are two types of Cell Division depending on the purpose. The Cell Division associated with sexual reproduction is one type, called meiosis. The other type, the Cell Division associated with growth and cell replacement or repair, is called mitosis. In both types of Cell Division, the nucleus splits and DNA is replicated. The Cell Division called mitosis produces daughter cells that have all the genetic material of the parent cell — a complete set of chromosomes. However, chromosomes are not the only material that needs to be divided and transferred to the daughter cells: there are cytoplasm and the cell membrane to divide as well. Cytokinesis is the process of dividing the cytoplasm and the cell membrane, and this process may follow immediately after mitosis or occur separately, depending on the organism involved. Together, these two processes make up the mitotic phases of the cell cycle. The phases of Cell Division are prophase, metaphase, anaphase, and telophase, and these occur in both mitosis and meiosis. A fifth phases called prometaphase occurring between prophase and metaphase is designated by some, but not all sources. Interphase, which is not part of mitosis, is a preparatory stage during which the parent cell makes a copy of its genetic material so that each daughter cell can have a complete set. Therefore, mitosis is an ongoing and repetitive process, alternating with interphase. Cell Division is the complex phenomenon by which cellular material is divided equally between daughter cells. This process is the final, and microscopically visible, phase of an underlying change that has occurred at molecular and biochemical levels. Before the cell divides by mitosis, its fundamental components have duplicated-particularly those involved in hereditary transmission.
eBook - PDF- Rathoure, Ashok Kumar(Authors)
- 2021(Publication Date)
- Daya Publishing House(Publisher)
Other fields focus primarily on the mechanical processes of cell cleavage into two daughter cells at the end of mitosis and on the condensation and decondensation of chromatin. Originally, cell cycle studies were the preserve of microscopy, but today many specific techniques in addition to those widely employed in cell and molecular biology are applied. Fluorescence activated cell sorting has allowed biologists to both identify cells at particular points of the cell cycle and isolate them. It is possible to monitor how cells that have been exposed to different agents can progress through the cycle. Cell Division is a very important process in all living organisms. During the division of a cell, DNA replication and cell growth also take place. All these processes i.e . Cell Division, DNA replication, and cell growth, hence, have to take place in a coordinated way to ensure correct division and formation of progeny cells containing intact genomes. The sequence of events by which a cell duplicates its genome, synthesises the other constituents of the cell and eventually divides into two daughter cells is termed cell cycle. Although, cell growth (in terms of cytoplasmic increase) is a continuous process, DNA synthesis occurs only during one specific stage in the cell cycle. Then replicated chromosomes (DNA) are distributed to daughter nuclei by a complex series of events during Cell Division. These events are themselves under genetic control. This ebook is exclusively for this university only. Cannot be resold/distributed. Cell Cycle The cell cycle or Cell Division cycle is the series of events that take place in a eukaryotic cell leading to its replication. These events can be divided in two broad periods; interphase during which the cell grows, accumulating nutrients needed for mitosis and duplicating its DNA and the mitotic (M) phase, during which the cell splits itself into two distinct cells called daughter cells.
eBook - ePub- Britannica Educational Publishing, Kara Rogers(Authors)
- 2010(Publication Date)
- Britannica Educational Publishing(Publisher)
CHAPTER 5Cell Division, Growth, and DifferentiationI n unicellular organisms, Cell Division is the means of reproduction. In multicellular organisms, it is the means of tissue growth and maintenance. Survival of multicellular eukaryotes depends upon interactions between many cell types, and it is essential that a balanced distribution of types be maintained. This is achieved by the highly regulated process of cell proliferation. The growth and division of different cell populations are regulated in different ways, but the basic mechanisms are similar throughout multicellular organisms.Most tissues of the body grow by increasing their cell number, but this growth is highly regulated to maintain a balance between different tissues. In adults most Cell Division is involved in tissue renewal rather than growth, with many types of cells undergoing continuous replacement. Skin cells, for example, are constantly being sloughed off and replaced. In this case, the mature differentiated cells do not divide, but their population is renewed by division of immature stem cells. In certain other cells, such as those of the liver, mature cells remain capable of division to allow growth or regeneration after injury.In contrast to these patterns, other types of cells either cannot divide or are prevented from dividing by certain molecules produced by nearby cells. As a result, in the adult organism, some tissues have a greatly reduced capacity to renew damaged or diseased cells. Examples of such tissues include heart muscle, nerve cells of the central nervous system, and lens cells in mammals. Maintenance and repair of these cells is limited to replacing intracellular components rather than replacing entire cells.DUPLICATION OF THE GENETIC MATERIAL
Before a cell can divide, it must accurately and completely duplicate the genetic information encoded in its DNA in order for its progeny cells to function and survive. This is a complex problem because of the great length of DNA molecules. Each human chromosome consists of a long double spiral, or helix, each strand of which consists of more than 100 million nucleotides.
eBook - PDF- John H. Lawrence, Cornelius A. Tobias, John H. Lawrence, Cornelius A. Tobias(Authors)
- 2013(Publication Date)
- Academic Press(Publisher)
There have appeared in recent years a number of important reviews covering various aspects of Cell Division, notably those of Schräder (95), Hughes (45), and Ris (89). See also note added in proof, p. 118. It is a consequence of the cell theory that the growth of a biological system is a discontinuous process. The extent to which a cell can add to its content of matter is strictly limited; when the limits are reached it must divide into two cells, each of which can resume the process of adding to its mass at the expense of the physical world. Perhaps more funda-mental is the fact that the overall process is governed by the cycle of reproduction of nuclei. The increase in the number of cells in a growing system is incidental to the increase in the number of nuclei. This is illus-trated by syncytia such as skeletal muscle fibers and heart muscle, in which nuclear multiplication is paralleled by increase in tissue mass with-out the formation of boundaries between the newly formed nuclei. Cellu-larity, in the sense of the establishment of walls between the masses of cytoplasm serviced by individual nuclei, is perhaps only derivatively related to the main process of growth, providing for (1) the most favorable solution to the diffusion problems that living masses have to face, (2) fractionation of processes such as conduction and contraction that might BIOCHEMISTRY AND BIOPHYSICS OF Cell Division 71 otherwise be restricted by all-or-nothing behavior, and (3) a somewhat greater flexibility of functional differentiation than is possible within the confines of a single cell or syncytium. The significance of Cell Division for growth is perhaps more apparent than the part it plays as a replacement mechanism in mature organisms. This had been rather difficult to assay quantitatively before certain recent advances.
eBook - PDFMolecular Cytology V1
The Cell Cycle
- Jean Brachet(Author)
- 2012(Publication Date)
- Academic Press(Publisher)
CHAPTER 5 Cell Division I. GENERAL BACKGROUND There are two characteristics of Cell Division that sharply distinguish living organisms from nonliving machines: reproduction and heredity. When cells di-vide, the two daughter cells have the same heredity because they have received identical DNA molecules (both in amount and in sequence organization). In culture, they will give rise to identical strains until mutations and DNA rear-rangements induce the inevitable diversification that characterizes all living organisms. Finally, Cell Division remains the only method of reproduction for all asexual organisms. Sexual reproduction will be touched upon when we discuss oocytes and eggs in Volume 2, Chapter 2. In Biochemical Cytology, Chapter 5 was entitled Mitosis, not Cell Division. This change is due to the fact that, in 1957, little was known of the existence of a cell cycle. Although this idea had been proposed as early as 1953 by Howard and Pelc, it had little immediate impact on cytological research and thinking. The progress in this field in the years that followed was the subject of a book by Prescott (1976); a review by Hochhauser et al. (1981) includes about 1200 references on the subject. Today we know that the cell prepares for mitotic division by a series of complex events that ultimately lead to a revolution: mitosis, which produces two (in theory, at least) genetically identical daughter cells. We may call this a revolution because it is accompanied by a complete rearrangement of almost all of the cell constituents that have been considered so far. The preparatory events that culminate in mitosis are dominated by DNA replication. This phase of DNA synthesis (Fig. 1) is called the S phase of the cell cycle. Prior to DNA synthesis is the G! phase, which lasts for a variable length of time (it is even absent during the cleavage of fertilized eggs in most animal species).
eBook - PDF- Gerald Karp, Janet Iwasa, Wallace Marshall(Authors)
- 2021(Publication Date)
- Wiley(Publisher)
638 CHAPTER 14 Cell Division 14.1 The Cell Cycle The process by which new cells arise from other living cells is called Cell Division. For a multicellular organism, such as a human or an oak tree, countless divisions of a single-celled zygote produce an organism of astonishing cellular complexity and organization. Cell Division does not stop with the forma- tion of the mature organism but continues in certain tissues throughout life. Millions of cells residing within the marrow of your bones or the lining of your intestinal tract are undergoing division at this very moment. This enormous output of cells is needed to replace cells that have aged or died. Although Cell Division occurs in all organisms, it takes place very differently in prokaryotes and eukaryotes. We restrict dis- cussion to the eukaryotic version. Two distinct types of eukary- otic Cell Division are discussed in this chapter. Mitosis leads to production of cells that are genetically identical to the parent, whereas meiosis leads to production of cells with half the genetic content of the parent. Mitosis serves as the basis for producing new cells, and meiosis is the basis for producing new sexually reproducing organisms. Together, these two types of Cell Division form the links in the chain between parents and their offspring and, in a broader sense, between living species and the earliest eukaryotic life forms present on Earth. Phases of the Cell Cycle In a population of dividing cells, whether inside the body or in a culture dish, each cell passes through a series of defined stages, which constitutes the cell cycle (Figure 14.1). The cell cycle can be divided into two major phases based on cellular activities readily visible with a light microscope: M phase and interphase. M phase includes (1) the process of mitosis, during which duplicated chromosomes are separated into two nuclei, and (2) cytokinesis, during which the entire cell divides into two daughter cells.
eBook - PDF- Cecie Starr, Beverly McMillan(Authors)
- 2015(Publication Date)
- Cengage Learning EMEA(Publisher)
When you were born , your body consisted of about a trillion cells. The growth that transforms a zygote—the first cell of a new individual—into an infant, and eventually into an adult, depends on one of the two types of Cell Division that occur in the body. The other type of Cell Division takes place only in cells of the testes or ovaries that produce gametes—a male’s sperm or a female’s eggs. In this chapter, we look at both these mechanisms by which cells reproduce. As you’ll see, understanding Cell Division provides answers to some basic biological questions. For example, how do cells receive the genetic information that determines their structure and function? And how are traits passed from one generation to the next? This chapter builds on the discussion in Chapter 3 of the cell nucleus and chromosomes and explains how microtu-bules assist in Cell Division (3.6, 3.9). You will also learn more about how eggs and sperm form during the processes of oogenesis and spermatogenesis (16.2 and 16.4). You will gain a fuller understanding of how the union of sperm and egg at fertilization (16.6) provides a zygote with the full set of parental chromosomes required for normal development. KEY CONCEPTS LINKS TO EARLIER CONCEPTS Basic Principles of Cell Division Cells reproduce by duplicating their chromosomes and then dividing the chromosomes and cell cytoplasm among the daughter cells. Sections 18.1–18.2 Mitosis: Body Growth and Repair The body grows and tissues are repaired when cells divide by the type of Cell Division called mitosis. This mechanism divides the nucleus so that each newly formed cell has the same number of chromosomes as the parent cell. Sections 18.3, 18.4, 18.9 Meiosis: Cells for Sexual Reproduction Sperm and oocytes form by the type of Cell Division called meiosis. Meiosis reduces the number of chromosomes so that each gamete has half the number of chromo-somes of the parent cell. Sections 18.6–18.9 © iStockphoto.com/ArtisticCaptures 353 Top: L.
eBook - PDF- Ram J. Singh(Author)
- 2016(Publication Date)
- CRC Press(Publisher)
85 4 Cell Division 4.1 INTRODUCTION Cell Division is a continuous process that occurs in all living organisms. It has been divided into two categories: mitosis and meiosis. Both forms of nuclear division occur in eukaryotes and these pro-cesses comprise the cell cycle: G 1 (growth) → S (synthesis of DNA) → G 2 (growth) → M (mitosis or meiosis) → C (cytokinesis) (Smith and Kindfield, 1999). Mitosis occurs in somatic tissues where each chromosome is divided identically into halves, both qualitatively and quantitatively, producing genetically identical to the parent nucleus. In contrast, meiosis takes place in germ cells with the consequence that nuclei with haploid chromosome numbers are produced. Both types of cell divi-sion play an important role in the development and hereditary continuity of a eukaryotic organism. 4.2 MITOSIS 4.2.1 P ROCESS OF M ITOSIS The term mitosis is derived from the Greek word mitos for thread; coined by Flemming in 1879 (see Chapter 1 ). The synonym of mitosis is karyokinesis, that is, the actual division of a nucleus into two identical parental daughter nuclei. It is also known as equational division because the exact longitudinal division of each chromosome into identical chromatids and their precise distribution into daughter nuclei leads to the formation of two cells; identical to the original cell from which they were derived. The process of mitotic Cell Division has been divided into six stages: (1) interphase, (2) prophase, (3) metaphase, (4) anaphase, (5) telophase, and (6) cytokinesis. 4.2.1.1 Interphase Two more terms, resting stage and metabolic stage, have been used to identify interphase cells. However, interphase cells should not be described as being in a “resting stage” because their nuclei are very active as they prepare for Cell Division. The DNA replication and transcription occur during interphase (Manuelidis, 1990).
eBook - ePub- Ram J. Singh(Author)
- 2016(Publication Date)
- CRC Press(Publisher)
4 Cell Division 4.1 INTRODUCTIONCell Division is a continuous process that occurs in all living organisms. It has been divided into two categories: mitosis and meiosis. Both forms of nuclear division occur in eukaryotes and these processes comprise the cell cycle: G1 (growth) → S (synthesis of DNA) → G2 (growth) → M (mitosis or meiosis) → C (cytokinesis) (Smith and Kindfield, 1999). Mitosis occurs in somatic tissues where each chromosome is divided identically into halves, both qualitatively and quantitatively, producing genetically identical to the parent nucleus. In contrast, meiosis takes place in germ cells with the consequence that nuclei with haploid chromosome numbers are produced. Both types of Cell Division play an important role in the development and hereditary continuity of a eukaryotic organism.4.2 MITOSIS4.2.1 PROCESS OF MITOSISThe term mitosis is derived from the Greek word mitos for thread; coined by Flemming in 1879 (see Chapter 1 ). The synonym of mitosis is karyokinesis, that is, the actual division of a nucleus into two identical parental daughter nuclei. It is also known as equational division because the exact longitudinal division of each chromosome into identical chromatids and their precise distribution into daughter nuclei leads to the formation of two cells; identical to the original cell from which they were derived.The process of mitotic Cell Division has been divided into six stages: (1) interphase, (2) prophase, (3) metaphase, (4) anaphase, (5) telophase, and (6) cytokinesis. 4.2.1.1 InterphaseTwo more terms, resting stage and metabolic stage, have been used to identify interphase cells. However, interphase cells should not be described as being in a “resting stage” because their nuclei are very active as they prepare for Cell Division. The DNA replication and transcription occur during interphase (Manuelidis, 1990). Interphase consists of three phases: G1 (gap 1; pre-DNA synthesis) phase, S phase (DNA synthesis), and G2 (gap 2; post-DNA synthesis). The duration of mitotic division is short compared to time required for the cells going through interphase (Figure 4.1 ). Thus, “metabolic stage” is a more appropriate term for the interphase cells. The interphase nucleus contains one or more prominent nucleoli and numerous chromocenters depending on the heterochromatic nature of the chromosomes. Chromosomes cannot be traced individually and they are very lightly stained (Figure 4.2a
- Cecie Starr, Christine Evers, Lisa Starr, , Cecie Starr, Cecie Starr, Christine Evers, Lisa Starr(Authors)
- 2020(Publication Date)
- Cengage Learning EMEA(Publisher)
This micrograph shows dividing cells making up an actively growing root tip of an onion plant. Chromosomes are stained blue. Cell Divisions by mitosis are the basis of growth in multicelled eukaryotes. Steve Gschmeissner/Science Photo Library/Getty Images 9 How Cells Reproduce 9.1 Henrietta’s Immortal Cells 159 9.2 Multiplication by Division 160 9.3 Mitosis and Cytoplasmic Division 163 9.4 Cell Cycle Control 165 9.5 Sex and Alleles 169 9.6 Meiosis in Sexual Reproduction 171 CONCEPT CONNECTIONS Mitosis is the basis of growth and tissue repair in multicelled eukaryotes (20.1, 20.6, 27.3, 28.6). Many single-celled eukaryotes can reproduce asexually by mitosis (14.6, 27.1), but sexual reproduction (27.2, 29.3) requires meiosis. Natural selection operates on variation in shared traits among members of a popula- tion (10.2, 13.2). This variation is an outcome of variations in DNA sequence (7.3) that arise by mutation (7.6). Mutations that disrupt regulatory molecules (8.7) governing Cell Division can lead to cancer (10.6, 11.1, 20.3, 24.3, 26.2, 27.8). This chapter also revisits the structure of cells (3.3–3.5) and chromosomes (7.4). Copyright 2021 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. HOW CELLS REPRODUCE CHAPTER 9 159 APPLICATION 9.1 Henrietta’s Immortal Cells Each human starts out as a fertilized egg. By the time of birth, that single cell has given rise to about a trillion other cells, all organized as a human body. Even in an adult, billions of cells divide every day as new cells replace worn-out ones.
eBook - ePubTwo from One
A Short Introduction to Cell Division Mechanisms
- Michael Polymenis(Author)
- 2022(Publication Date)
- Wiley(Publisher)
2 Cell Growth and Division- How do we measure cell growth?
- What is the relationship between cell growth and division?
- When and how do cells grow in the cell cycle?
2.1 Balanced Growth and Cell Proliferation
As the unit of life, the cell must carry out all the processes associated with life. Cells are open thermodynamic systems, exchanging both matter and energy with their environment. The entire enterprise of synthesizing a cell encompasses many more processes than those needed to duplicate and segregate the genome. Furthermore, the rate at which cells can divide usually depends not on how fast they can replicate their genome but on how fast they can synthesize everything else that goes into a newborn cell. If “The dream of every cell is to become two cells (Francois Jacob),” it is cell growth that makes those dreams come true.Imagine an environment where cells have constant nutrients and growth factors, and toxic products do not accumulate. When the number of cells is measured over successive cell cycles in such an environment, cell growth and division appear balanced. General cellular properties (e.g., cell size and composition) and cell proliferation rate remain constant. In these situations, cell proliferation behaves like a first‐order autocatalytic reaction. The change in the number of cells (N) over time (t) can be described with a simple equation: dN/dt = kN. The proportionality constant, k, is the specific proliferation rate constant. It solely reflects cells’ intrinsic properties and their ability to grow and divide in that particular environment. The apparent balance of growth and division means that the time it takes to double the number of cells is the same as the amount of time it takes to duplicate every cell component, from chromosomes to individual protein and RNA molecules. A plot of the logarithm of the number of cells over time will be a straight line, with a slope equal to k (Figure 2.1
eBook - PDFCells and Tissues in Culture
Methods, Biology and Physiology
- E. N. Willmer(Author)
- 2015(Publication Date)
- Academic Press(Publisher)
CHAPTER 6 Cell Division H. F I R K E T Laboratoire d'Anatomie pathologique 3 Universite de Liege, Belgium I. Introduction 203 II. Mitosis 4 A. General survey 204 B. Special aspects 206 III. The Cell Cycle 218 A. Duration of the cycle 218 B. Morphological changes 220 C. Metabolic changes (DNA cycle) 220 D. General considerations 225 E. Effect of ionizing radiations on the cell cycle 226 IV. Mitogenesis 227 V. Synchronism of Divisions in Cultures 229 VI. Conclusions 230 References 231 I. I N T R O D U C T I O N Ever since tissues were first cultivated in vitro, cultures have constituted one of the best biological objects for the study of Cell Division. They combine various favourable conditions to an unusual extent: flattening out of the cells enlarges the images of division as compared to more compact tissues in the animal; observation on the living cells, which is necessary to understand the variations—experimental or otherwise —of an essentially dynamic phenomenon, is particularly easy; cell multiplication can occur at a high rate and in reproducible conditions; cells used are similar to or even identical with those found in the mammalian body. To these advantages is added the immense array of experimental interventions made possible by in vitro cultivation. To understand Cell Division is a challenge of such magnitude that all possible materials have been analysed with this aim in view. Almost every year, symposia or general reviews are devoted to some special aspect of Cell Division (e.g., in recent years, Anderson, 1956; Stern, 1956; Mazia, 1956; Swann, 1957, 1958; Gross, 1960; Levine, 1961). These 204 H. FIRKET reviews are often longer than the present chapter could reasonably be, so the latter is bound to be very incomplete. Most of the older literature was reviewed in Hughes' book The Mitotic Cycle (1952) and the very large and recent treatise by Mazia (1961) covers an immense and varied ground.
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