Lecture 17 - Cell Cycle- Mitosis and Meiosis | Cell Biology- Botany PDF Download

 Page 1


Cell Cycle - Mitosis and Meiosis 
Institute of Lifelong Learning, University of Delhi 
 
 
 
 
 
 
 
 
 
Lesson: Cell Cycle - Mitosis and Meiosis 
Lesson Developer: Rama Sisodia 
College/ Department: Department of Botany, Maitreyi College, University 
of Delhi 
 
  
 
 
 
 
 
 
 
 
Page 2


Cell Cycle - Mitosis and Meiosis 
Institute of Lifelong Learning, University of Delhi 
 
 
 
 
 
 
 
 
 
Lesson: Cell Cycle - Mitosis and Meiosis 
Lesson Developer: Rama Sisodia 
College/ Department: Department of Botany, Maitreyi College, University 
of Delhi 
 
  
 
 
 
 
 
 
 
 
Cell Cycle - Mitosis and Meiosis 
Institute of Lifelong Learning, University of Delhi 1 
 
Table of Contents       
Chapter: Cell Cycle 
? Introduction 
? Phases of cell cycle 
? Interphase 
? Mitosis 
? Prophase 
? Metaphase 
? Anaphase 
? Telophase 
? Cytokinesis 
? Meiosis 
? Stages of meiosis 
? Meiosis I 
? Meiosis II 
? Cytokinesis 
? Significance of meiosis 
? Meiosis in animals: Oogenesis and 
Spermatogenesis 
? Summary  
? Exercise/ Practice 
? Glossary 
? References/ Bibliography/ Further Reading 
Page 3


Cell Cycle - Mitosis and Meiosis 
Institute of Lifelong Learning, University of Delhi 
 
 
 
 
 
 
 
 
 
Lesson: Cell Cycle - Mitosis and Meiosis 
Lesson Developer: Rama Sisodia 
College/ Department: Department of Botany, Maitreyi College, University 
of Delhi 
 
  
 
 
 
 
 
 
 
 
Cell Cycle - Mitosis and Meiosis 
Institute of Lifelong Learning, University of Delhi 1 
 
Table of Contents       
Chapter: Cell Cycle 
? Introduction 
? Phases of cell cycle 
? Interphase 
? Mitosis 
? Prophase 
? Metaphase 
? Anaphase 
? Telophase 
? Cytokinesis 
? Meiosis 
? Stages of meiosis 
? Meiosis I 
? Meiosis II 
? Cytokinesis 
? Significance of meiosis 
? Meiosis in animals: Oogenesis and 
Spermatogenesis 
? Summary  
? Exercise/ Practice 
? Glossary 
? References/ Bibliography/ Further Reading 
Cell Cycle - Mitosis and Meiosis 
Institute of Lifelong Learning, University of Delhi 2 
Introduction 
One of the characteristic features of living organisms is their capacity to grow and 
reproduce. As the cells grow in size, the limited capacity to expand as the cells increase in 
size to accommodate the increasing contents necessitates the cell to divide. Cells arise by 
division of existing cells (“Omnis cellula e cellula”, Rudlof Virchow, 1955). Cell division plays 
an important role in - 
? single celled prokaryotes, for e.g. amoeba that divided asexually by a simple 
process of binary fission. 
 
 
 
 
 
 
 
 
 
 
Figure: Amoeba proteus dividing by binary fission. The division of the nuclei is 
followed by the separation of the cytoplasm to form two daughter cells. 
Source: http://biodiversitywiki-
shayna.wikispaces.com/file/view/amoeba8.jpg/175484073/amoeba8.jpg (cc) 
? growth and development of multicelled eukaryotic organisms. The multicelled 
organisms begin their life from a single celled zygote that divides and 
differentiates to assume the form and function of an adult. 
Page 4


Cell Cycle - Mitosis and Meiosis 
Institute of Lifelong Learning, University of Delhi 
 
 
 
 
 
 
 
 
 
Lesson: Cell Cycle - Mitosis and Meiosis 
Lesson Developer: Rama Sisodia 
College/ Department: Department of Botany, Maitreyi College, University 
of Delhi 
 
  
 
 
 
 
 
 
 
 
Cell Cycle - Mitosis and Meiosis 
Institute of Lifelong Learning, University of Delhi 1 
 
Table of Contents       
Chapter: Cell Cycle 
? Introduction 
? Phases of cell cycle 
? Interphase 
? Mitosis 
? Prophase 
? Metaphase 
? Anaphase 
? Telophase 
? Cytokinesis 
? Meiosis 
? Stages of meiosis 
? Meiosis I 
? Meiosis II 
? Cytokinesis 
? Significance of meiosis 
? Meiosis in animals: Oogenesis and 
Spermatogenesis 
? Summary  
? Exercise/ Practice 
? Glossary 
? References/ Bibliography/ Further Reading 
Cell Cycle - Mitosis and Meiosis 
Institute of Lifelong Learning, University of Delhi 2 
Introduction 
One of the characteristic features of living organisms is their capacity to grow and 
reproduce. As the cells grow in size, the limited capacity to expand as the cells increase in 
size to accommodate the increasing contents necessitates the cell to divide. Cells arise by 
division of existing cells (“Omnis cellula e cellula”, Rudlof Virchow, 1955). Cell division plays 
an important role in - 
? single celled prokaryotes, for e.g. amoeba that divided asexually by a simple 
process of binary fission. 
 
 
 
 
 
 
 
 
 
 
Figure: Amoeba proteus dividing by binary fission. The division of the nuclei is 
followed by the separation of the cytoplasm to form two daughter cells. 
Source: http://biodiversitywiki-
shayna.wikispaces.com/file/view/amoeba8.jpg/175484073/amoeba8.jpg (cc) 
? growth and development of multicelled eukaryotic organisms. The multicelled 
organisms begin their life from a single celled zygote that divides and 
differentiates to assume the form and function of an adult. 
Cell Cycle - Mitosis and Meiosis 
Institute of Lifelong Learning, University of Delhi 3 
 
Figure: The single celled zygote divides by repeated divisions and eventually develops into 
an individual. 
Source: http://upload.wikimedia.org/wikipedia/commons/c/c4/Gray9.png 
? the continuous growth and renewal of cells in multicelled eukaryotes. 
 
There are two types of cell division: 
1. Mitosis – is a type of cell division involved in the development of a single celled 
zygote into an adult organism, growth and repair of tissues and in asexual 
reproduction. In mitosis the parent cell divides into two daughter cells that are 
genetically identical to parent cell,i.e. the chromosome number is same to parent 
cell. The fidelity of the process ensures the heritable transmission of traits essential 
for maintaining the continuity of life.  
2. Meiosis - by which the germ cells divide to form gametes. Each parent cell produces 
four daughter cells in which the chromosome number is reduced to half. Meiosis 
involves genetic recombination by the process of crossing over. 
Phases of cell cycle 
 
 
 
Page 5


Cell Cycle - Mitosis and Meiosis 
Institute of Lifelong Learning, University of Delhi 
 
 
 
 
 
 
 
 
 
Lesson: Cell Cycle - Mitosis and Meiosis 
Lesson Developer: Rama Sisodia 
College/ Department: Department of Botany, Maitreyi College, University 
of Delhi 
 
  
 
 
 
 
 
 
 
 
Cell Cycle - Mitosis and Meiosis 
Institute of Lifelong Learning, University of Delhi 1 
 
Table of Contents       
Chapter: Cell Cycle 
? Introduction 
? Phases of cell cycle 
? Interphase 
? Mitosis 
? Prophase 
? Metaphase 
? Anaphase 
? Telophase 
? Cytokinesis 
? Meiosis 
? Stages of meiosis 
? Meiosis I 
? Meiosis II 
? Cytokinesis 
? Significance of meiosis 
? Meiosis in animals: Oogenesis and 
Spermatogenesis 
? Summary  
? Exercise/ Practice 
? Glossary 
? References/ Bibliography/ Further Reading 
Cell Cycle - Mitosis and Meiosis 
Institute of Lifelong Learning, University of Delhi 2 
Introduction 
One of the characteristic features of living organisms is their capacity to grow and 
reproduce. As the cells grow in size, the limited capacity to expand as the cells increase in 
size to accommodate the increasing contents necessitates the cell to divide. Cells arise by 
division of existing cells (“Omnis cellula e cellula”, Rudlof Virchow, 1955). Cell division plays 
an important role in - 
? single celled prokaryotes, for e.g. amoeba that divided asexually by a simple 
process of binary fission. 
 
 
 
 
 
 
 
 
 
 
Figure: Amoeba proteus dividing by binary fission. The division of the nuclei is 
followed by the separation of the cytoplasm to form two daughter cells. 
Source: http://biodiversitywiki-
shayna.wikispaces.com/file/view/amoeba8.jpg/175484073/amoeba8.jpg (cc) 
? growth and development of multicelled eukaryotic organisms. The multicelled 
organisms begin their life from a single celled zygote that divides and 
differentiates to assume the form and function of an adult. 
Cell Cycle - Mitosis and Meiosis 
Institute of Lifelong Learning, University of Delhi 3 
 
Figure: The single celled zygote divides by repeated divisions and eventually develops into 
an individual. 
Source: http://upload.wikimedia.org/wikipedia/commons/c/c4/Gray9.png 
? the continuous growth and renewal of cells in multicelled eukaryotes. 
 
There are two types of cell division: 
1. Mitosis – is a type of cell division involved in the development of a single celled 
zygote into an adult organism, growth and repair of tissues and in asexual 
reproduction. In mitosis the parent cell divides into two daughter cells that are 
genetically identical to parent cell,i.e. the chromosome number is same to parent 
cell. The fidelity of the process ensures the heritable transmission of traits essential 
for maintaining the continuity of life.  
2. Meiosis - by which the germ cells divide to form gametes. Each parent cell produces 
four daughter cells in which the chromosome number is reduced to half. Meiosis 
involves genetic recombination by the process of crossing over. 
Phases of cell cycle 
 
 
 
Cell Cycle - Mitosis and Meiosis 
Institute of Lifelong Learning, University of Delhi 4 
Embed Animation: https://highered.mcgraw-
hill.com/sites/0072495855/student_view0/chapter2/animation__how_the_cell_cycle_works.
html 
The life of a cell from the time it is formed to its division is called as cell cycle. The cell cycle 
consists of several well-coordinated phases – growth of the cell, replication of DNA, 
distribution of replicated chromosomes between the two daughter cells and cell division. The 
entire cell cycle in a eukaryotic cell as shown by a cultured human cell takes 24 hrs to 
complete. This is divided in a long interphase (23 hrs) which is further divisible into three 
phases- G1, S and G2, and  short divisional stage- mitosis (1 hr).  
 
Figure: The cell cycle 
Source: http://www.hartnell.edu/tutorials/biology/images/cellcyclediagram.jpg (CC-BY-SA) 
The duration of the four phases of cell cycle differs in various cell types. In a human cell 
which is rapidly proliferating the total 24 hr cycle has a 11 hr G
1
 phase, 8 hrs S phase, G
2
 of 
about 4 hrs and M phase of 1 hr. The cell cycle is considerably shorter in rapidly dividing 
cells like Saccharomyces cerevisiae (90 min) and early embryo cells (30 min). The latter has 
no gap phase and has a very short S phase.