Cell division occurs through mitosis and meiosis. Mitosis produces two identical daughter cells and is used for cell growth and repair. Meiosis produces four haploid cells through two cell divisions and is involved in sexual reproduction to create sex cells. The key differences are that mitosis maintains chromosome number while meiosis reduces it, and meiosis involves homologous chromosome pairing and genetic recombination during prophase I.
The document summarizes the processes of mitosis and meiosis in eukaryotic cells. It describes the stages of the cell cycle including interphase and mitosis. Mitosis is divided into prophase, metaphase, anaphase and telophase where chromosomes are aligned and separated. Meiosis produces gametes through two cell divisions and a single DNA replication. This reduces the chromosome number by half to maintain genetic diversity between generations. Crossing over and random chromosome segregation in meiosis lead to genetic variation important for evolution.
Mitosis is the process where a cell nucleus divides to form two daughter cells. It occurs in multiple stages: interphase, prophase, metaphase, anaphase, and telophase. During interphase, DNA replicates and organelles duplicate. In prophase, chromosomes condense and the nuclear envelope breaks down. Metaphase arranges the chromosomes in the center. Anaphase separates the sister chromatids and moves them to opposite poles. Finally, in telophase, the nuclear envelope reforms and cytokinesis divides the cell into two identical daughter cells with identical genetic material.
LINKAGE AND CROSSING-OVER SMG
A brief description of Linkage - Bateson and Punnett's Experiment on Sweet pea, Lathyrus odoratus, Coupling and Repulsion Theory, Complete and Incomplete Linkage, Significance of Linkage, Crossing-over: Cytological basis, Types, Factors influencing the frequency , Significance, Mitotic crossing-over
Cell division occurs through a process called mitosis, which produces two genetically identical daughter cells. Mitosis is divided into five stages - prophase, metaphase, anaphase, telophase, and cytokinesis. During interphase, the cell grows and duplicates its DNA in preparation for division. In prophase, the nuclear envelope breaks down and spindle fibers form. In metaphase, chromosomes line up in the cell's equator. In anaphase, sister chromatids are separated and moved to opposite poles. Telophase involves the formation of two daughter cell nuclei. Cytokinesis then divides the cytoplasm, completing cell division. Mitosis is essential for growth, healing, and replacing dead or damaged cells.
Microsporogenesis involves the formation of pollen grains in the anthers. It begins with the formation of archesporial cells that develop into primary sporogenous cells. These cells undergo mitosis and differentiate into microspore mother cells. The microspore mother cells undergo meiosis to form microspores still connected in tetrads. The tetrads separate into individual microspores which are released from the anther as mature pollen grains. Key tissues involved include the sporogenous tissue, tapetum, and anther wall layers.
Mitosis is the process of nuclear division in eukaryotic cells. It is divided into four main stages: prophase, metaphase, anaphase and telophase. During prophase, the nuclear envelope and nucleolus disappear. In metaphase, chromosomes align along the metaphase plate. In anaphase, chromatids separate and move towards opposite poles. Finally, in telophase, nuclear envelopes form around the separated chromosomes and cytokinesis occurs to divide the cytoplasm. Mitosis plays an important role in growth, development, and repair of multicellular organisms.
The document summarizes the cell cycle and its regulation. It describes the main stages of the cell cycle - interphase consisting of G1, S, and G2 phases and the M phase. Key regulators of the cell cycle include cyclins, cyclin-dependent kinases, and checkpoints like G1, G2, and M that ensure fidelity of DNA replication and chromosome segregation. Dysregulation of these processes can lead to genomic instability and cancer.
The document discusses different types of secretory tissues in plants, specifically laticifers. Laticifers are specialized parenchyma cells that transport latex, a suspension containing various substances like resins, proteins, oils, alkaloids and sugars. Laticifers can be non-articulate or articulate. Non-articulate laticifers are long multinucleated cells that branch extensively through tissues. Articulate laticifers form longitudinal chains of cells joined end to end, resembling xylem vessels. Articulate laticifers can be non-anastomosing or anastomosing, where the latter form net-like reticula through lateral connections. Specific plant families and examples of
The document summarizes the processes of mitosis and meiosis in eukaryotic cells. It describes the stages of the cell cycle including interphase and mitosis. Mitosis is divided into prophase, metaphase, anaphase and telophase where chromosomes are aligned and separated. Meiosis produces gametes through two cell divisions and a single DNA replication. This reduces the chromosome number by half to maintain genetic diversity between generations. Crossing over and random chromosome segregation in meiosis lead to genetic variation important for evolution.
Mitosis is the process where a cell nucleus divides to form two daughter cells. It occurs in multiple stages: interphase, prophase, metaphase, anaphase, and telophase. During interphase, DNA replicates and organelles duplicate. In prophase, chromosomes condense and the nuclear envelope breaks down. Metaphase arranges the chromosomes in the center. Anaphase separates the sister chromatids and moves them to opposite poles. Finally, in telophase, the nuclear envelope reforms and cytokinesis divides the cell into two identical daughter cells with identical genetic material.
LINKAGE AND CROSSING-OVER SMG
A brief description of Linkage - Bateson and Punnett's Experiment on Sweet pea, Lathyrus odoratus, Coupling and Repulsion Theory, Complete and Incomplete Linkage, Significance of Linkage, Crossing-over: Cytological basis, Types, Factors influencing the frequency , Significance, Mitotic crossing-over
Cell division occurs through a process called mitosis, which produces two genetically identical daughter cells. Mitosis is divided into five stages - prophase, metaphase, anaphase, telophase, and cytokinesis. During interphase, the cell grows and duplicates its DNA in preparation for division. In prophase, the nuclear envelope breaks down and spindle fibers form. In metaphase, chromosomes line up in the cell's equator. In anaphase, sister chromatids are separated and moved to opposite poles. Telophase involves the formation of two daughter cell nuclei. Cytokinesis then divides the cytoplasm, completing cell division. Mitosis is essential for growth, healing, and replacing dead or damaged cells.
Microsporogenesis involves the formation of pollen grains in the anthers. It begins with the formation of archesporial cells that develop into primary sporogenous cells. These cells undergo mitosis and differentiate into microspore mother cells. The microspore mother cells undergo meiosis to form microspores still connected in tetrads. The tetrads separate into individual microspores which are released from the anther as mature pollen grains. Key tissues involved include the sporogenous tissue, tapetum, and anther wall layers.
Mitosis is the process of nuclear division in eukaryotic cells. It is divided into four main stages: prophase, metaphase, anaphase and telophase. During prophase, the nuclear envelope and nucleolus disappear. In metaphase, chromosomes align along the metaphase plate. In anaphase, chromatids separate and move towards opposite poles. Finally, in telophase, nuclear envelopes form around the separated chromosomes and cytokinesis occurs to divide the cytoplasm. Mitosis plays an important role in growth, development, and repair of multicellular organisms.
The document summarizes the cell cycle and its regulation. It describes the main stages of the cell cycle - interphase consisting of G1, S, and G2 phases and the M phase. Key regulators of the cell cycle include cyclins, cyclin-dependent kinases, and checkpoints like G1, G2, and M that ensure fidelity of DNA replication and chromosome segregation. Dysregulation of these processes can lead to genomic instability and cancer.
The document discusses different types of secretory tissues in plants, specifically laticifers. Laticifers are specialized parenchyma cells that transport latex, a suspension containing various substances like resins, proteins, oils, alkaloids and sugars. Laticifers can be non-articulate or articulate. Non-articulate laticifers are long multinucleated cells that branch extensively through tissues. Articulate laticifers form longitudinal chains of cells joined end to end, resembling xylem vessels. Articulate laticifers can be non-anastomosing or anastomosing, where the latter form net-like reticula through lateral connections. Specific plant families and examples of
Chromosomes are known as hereditary vehicles
They are formed of strands of DNA molecules which contain information for the development of different characteristics and performance of various metabolic activities of the cells
The coordination of various function is brought about through the formation of enzymes which are complex protein molecules
Mitochondria are organelles found in cells that act as the powerhouse, producing energy through cellular respiration. They contain their own DNA and divide independently of the cell. Mitochondria likely originated from ancient bacteria that established an endosymbiotic relationship with early eukaryotic cells. They have a double membrane structure and folded inner membranes containing enzymes that facilitate ATP production. Mitochondrial diseases can affect multiple body systems and are often inherited from the mother due to maternal inheritance of mitochondrial DNA. Symptoms, diagnosis, and treatment depend on the specific disease but may involve supplements, exercise, and various therapies.
Cell determination and differentiation are important processes in development. Cell determination involves genes being selectively activated or inactivated, committing an embryonic cell to a specific type. Differentiation then further specializes the cell, changing its size, shape and function. Gene expression plays a key role, with different genes being switched on or off in different cell types. The environment also influences cell fate and specialization.
The nucleus and nucleolus are running for president and vice president of the cell. The nucleus is described as the brain and leader of the cell, containing the DNA and directing major cellular activities. The DNA in the nucleus allows for protein synthesis. The nucleolus is the largest organelle in the nucleus and acts as the ribosome factory, regulating protein and cellular functions. It has a dense fibrilla component, fibrilla centers, and granular components that make up its structure.
A chromosomal disorder, anomaly, aberration, or mutation is a missing, extra, or irregular portion of chromosomal DNA. It can be from a typical number of chromosomes or a structural abnormality in one or more chromosomes. Chromosome mutation was formerly used in a strict sense to mean a change in a chromosomal segment, involving more than one gene. The term "karyotype" refers to the full set of chromosomes from an individual.
Cytogenetics examines chromosomes microscopically to detect abnormalities in chromosome number or structure. Chromosomes are stained and have characteristic banding patterns used to identify them. Variations in chromosome structure include deficiencies/deletions, duplications, inversions, and translocations. Deficiencies occur when a chromosome fragment is lost. Duplications involve repetition of a chromosomal segment. Inversions flip a segment to the opposite orientation. Translocations exchange genetic material between non-homologous chromosomes. These structural variations can impact phenotypes but many are phenotypically normal.
This document discusses structural chromosomal aberrations involving changes in the number or location of genes. It focuses on deletions, which involve the loss of a chromosomal segment, and duplications, which involve the occurrence of a segment twice in the same chromosome. Deletions can be terminal or intercalary. Duplications can be intrachromosomal in a tandem or reverse tandem orientation, or interchromosomal as a displaced or translocated duplication. The effects of deletions and duplications are also summarized.
CONTROL OF XYLEM AND PHOLEM DIFFERENTIATION .pptxHarshalaNaik3
Plant vascular systems are usually composed of phloem and xylem. Phloem often develops without xylem, whereas xylem does not form without phloem. Low levels of auxin induce phloem differentiation but not xylem, while high auxin induces both. Other factors like gibberellic acid, sugars, leaves, roots, cytokinins, pressure and ethylene also influence phloem and xylem differentiation. The dynamic interplay between these various signals precisely controls vascular development.
This document provides an overview of two types of cell division: amitosis and meiosis. It summarizes amitosis as a direct form of cell division where the nucleus elongates and divides into two daughter nuclei without chromosome condensation or spindle formation. Meiosis is described as occurring in germ cells and involving two nuclear divisions to produce four haploid cells from one diploid parent cell. The two stages of meiosis - Meiosis I and Meiosis II - are explained, with Meiosis I separating homologous chromosomes and reducing the number from 2N to N, while Meiosis II separates sister chromatids to form individual haploid cells. Key stages of meiosis I prophase including leptotene, zy
This document discusses double fertilization and endosperm development in plants. It explains that double fertilization involves one male gamete fusing with the egg to form a diploid zygote, and the other fusing with the central cell's polar nuclei to form a triploid endosperm nucleus. This triggers endosperm development, which provides nourishment for the developing embryo. The document outlines three types of endosperm - nuclear, cellular, and helobial - based on whether cell walls form during division of the primary endosperm nucleus.
It is a network of protein filaments in the cytoplasm of a cell
It provides structural framework to the cell.it also helps in the cell movement and movement of cytoplasmic components during several processes such as phagocytosis,endocytosis and exocytosis.
It consists of main three components microfilaments,microtubules and intermediate filament
Double fertilization is the process found in angiosperms in which out of the two male gametes released inside the embryo sac, one fuses with the egg cell (syngamy) and another fuse with secondary nucleus (triple fusion).
This document discusses several principles of inheritance:
1) Mendel's laws of segregation, independent assortment, and dominance.
2) Codominance and incomplete dominance where both alleles are expressed in heterozygotes.
3) Multiple alleles where a single gene can have more than two forms.
4) Gene interactions and how Morgan's work with fruit flies demonstrated chromosomes contain genes and determine sex inheritance.
5) Extrachromosomal inheritance where traits are inherited through organelle DNA rather than chromosomes.
CHROMOSOMES - Dr. P. Saranraj, Assistant Professor, Department of Microbiology, Sacred Heart College (Autonomous), Tirupattur, Vellore District, Tamil Nadu, India.
Meiosis is the process by which diploid cells in organisms undergo two cell divisions to produce four haploid gametes. In meiosis I, homologous chromosomes pair up and undergo crossing over, then separate so each daughter cell has one of each type of chromosome. Meiosis II then separates the sister chromatids, resulting in four haploid cells each containing one set of chromosomes. This allows for genetic variation between gametes and offspring through independent assortment of chromosomes and new combinations from crossing over during meiosis I.
Specialized tissue or secretary tissue produce and secrete a variety of substances. There are two main types of secretory tissues: laticiferous tissues and glandular tissues. Laticiferous tissues consist of elongated ducts that contain latex, a milky substance rich in proteins, carbohydrates, and other compounds. Glandular tissues contain glands that secrete oils, resins, enzymes and other substances. Secretions may remain within the cells or be released and have various functions in the plant or commercial value.
This presentation summarizes the process of meiosis. Meiosis is the type of cell division that produces gametes, such as sperm and egg cells, which have half the number of chromosomes as regular body cells. It involves two cell divisions: Meiosis I and Meiosis II. In Meiosis I, homologous chromosomes pair up and may exchange genetic material through crossing over. This results in daughter cells with half the original number of chromosomes. Meiosis II then separates the sister chromatids, resulting in four haploid gametes total. Through meiosis, genetic variation is generated while maintaining the chromosome number from one generation to the next.
1. Selaginella is a heterosporous plant that produces megaspores and microspores. The spores develop into male and female gametophytes within their spore walls.
2. Microspores develop into male gametophytes containing antherozoids for fertilization. Megaspores develop into female gametophytes containing archegonia.
3. Fertilization occurs when antherozoids enter the archegonia through openings in the neck canal cells. This leads to the development of a diploid sporophyte within the megaspore.
This document provides information about cell division through mitosis and meiosis. It discusses the three main types of cell division - binary fission in prokaryotes, mitosis in eukaryotes for growth and repair, and meiosis in eukaryotes for sexual reproduction. The stages of mitosis (prophase, metaphase, anaphase, telophase) and meiosis I and II are described in detail. The cell cycle is also summarized, including the interphase and mitotic phases.
Cell division is the process by which a parent cell divides into two or more daughter cells. There are two main types of cell division: mitosis and meiosis. Mitosis produces two identical daughter cells during growth and repair of the body. It ensures the genetic makeup remains the same. Meiosis produces gametes with half the number of chromosomes and involves two cell divisions. It results in genetic diversity that is important for sexual reproduction.
Chromosomes are known as hereditary vehicles
They are formed of strands of DNA molecules which contain information for the development of different characteristics and performance of various metabolic activities of the cells
The coordination of various function is brought about through the formation of enzymes which are complex protein molecules
Mitochondria are organelles found in cells that act as the powerhouse, producing energy through cellular respiration. They contain their own DNA and divide independently of the cell. Mitochondria likely originated from ancient bacteria that established an endosymbiotic relationship with early eukaryotic cells. They have a double membrane structure and folded inner membranes containing enzymes that facilitate ATP production. Mitochondrial diseases can affect multiple body systems and are often inherited from the mother due to maternal inheritance of mitochondrial DNA. Symptoms, diagnosis, and treatment depend on the specific disease but may involve supplements, exercise, and various therapies.
Cell determination and differentiation are important processes in development. Cell determination involves genes being selectively activated or inactivated, committing an embryonic cell to a specific type. Differentiation then further specializes the cell, changing its size, shape and function. Gene expression plays a key role, with different genes being switched on or off in different cell types. The environment also influences cell fate and specialization.
The nucleus and nucleolus are running for president and vice president of the cell. The nucleus is described as the brain and leader of the cell, containing the DNA and directing major cellular activities. The DNA in the nucleus allows for protein synthesis. The nucleolus is the largest organelle in the nucleus and acts as the ribosome factory, regulating protein and cellular functions. It has a dense fibrilla component, fibrilla centers, and granular components that make up its structure.
A chromosomal disorder, anomaly, aberration, or mutation is a missing, extra, or irregular portion of chromosomal DNA. It can be from a typical number of chromosomes or a structural abnormality in one or more chromosomes. Chromosome mutation was formerly used in a strict sense to mean a change in a chromosomal segment, involving more than one gene. The term "karyotype" refers to the full set of chromosomes from an individual.
Cytogenetics examines chromosomes microscopically to detect abnormalities in chromosome number or structure. Chromosomes are stained and have characteristic banding patterns used to identify them. Variations in chromosome structure include deficiencies/deletions, duplications, inversions, and translocations. Deficiencies occur when a chromosome fragment is lost. Duplications involve repetition of a chromosomal segment. Inversions flip a segment to the opposite orientation. Translocations exchange genetic material between non-homologous chromosomes. These structural variations can impact phenotypes but many are phenotypically normal.
This document discusses structural chromosomal aberrations involving changes in the number or location of genes. It focuses on deletions, which involve the loss of a chromosomal segment, and duplications, which involve the occurrence of a segment twice in the same chromosome. Deletions can be terminal or intercalary. Duplications can be intrachromosomal in a tandem or reverse tandem orientation, or interchromosomal as a displaced or translocated duplication. The effects of deletions and duplications are also summarized.
CONTROL OF XYLEM AND PHOLEM DIFFERENTIATION .pptxHarshalaNaik3
Plant vascular systems are usually composed of phloem and xylem. Phloem often develops without xylem, whereas xylem does not form without phloem. Low levels of auxin induce phloem differentiation but not xylem, while high auxin induces both. Other factors like gibberellic acid, sugars, leaves, roots, cytokinins, pressure and ethylene also influence phloem and xylem differentiation. The dynamic interplay between these various signals precisely controls vascular development.
This document provides an overview of two types of cell division: amitosis and meiosis. It summarizes amitosis as a direct form of cell division where the nucleus elongates and divides into two daughter nuclei without chromosome condensation or spindle formation. Meiosis is described as occurring in germ cells and involving two nuclear divisions to produce four haploid cells from one diploid parent cell. The two stages of meiosis - Meiosis I and Meiosis II - are explained, with Meiosis I separating homologous chromosomes and reducing the number from 2N to N, while Meiosis II separates sister chromatids to form individual haploid cells. Key stages of meiosis I prophase including leptotene, zy
This document discusses double fertilization and endosperm development in plants. It explains that double fertilization involves one male gamete fusing with the egg to form a diploid zygote, and the other fusing with the central cell's polar nuclei to form a triploid endosperm nucleus. This triggers endosperm development, which provides nourishment for the developing embryo. The document outlines three types of endosperm - nuclear, cellular, and helobial - based on whether cell walls form during division of the primary endosperm nucleus.
It is a network of protein filaments in the cytoplasm of a cell
It provides structural framework to the cell.it also helps in the cell movement and movement of cytoplasmic components during several processes such as phagocytosis,endocytosis and exocytosis.
It consists of main three components microfilaments,microtubules and intermediate filament
Double fertilization is the process found in angiosperms in which out of the two male gametes released inside the embryo sac, one fuses with the egg cell (syngamy) and another fuse with secondary nucleus (triple fusion).
This document discusses several principles of inheritance:
1) Mendel's laws of segregation, independent assortment, and dominance.
2) Codominance and incomplete dominance where both alleles are expressed in heterozygotes.
3) Multiple alleles where a single gene can have more than two forms.
4) Gene interactions and how Morgan's work with fruit flies demonstrated chromosomes contain genes and determine sex inheritance.
5) Extrachromosomal inheritance where traits are inherited through organelle DNA rather than chromosomes.
CHROMOSOMES - Dr. P. Saranraj, Assistant Professor, Department of Microbiology, Sacred Heart College (Autonomous), Tirupattur, Vellore District, Tamil Nadu, India.
Meiosis is the process by which diploid cells in organisms undergo two cell divisions to produce four haploid gametes. In meiosis I, homologous chromosomes pair up and undergo crossing over, then separate so each daughter cell has one of each type of chromosome. Meiosis II then separates the sister chromatids, resulting in four haploid cells each containing one set of chromosomes. This allows for genetic variation between gametes and offspring through independent assortment of chromosomes and new combinations from crossing over during meiosis I.
Specialized tissue or secretary tissue produce and secrete a variety of substances. There are two main types of secretory tissues: laticiferous tissues and glandular tissues. Laticiferous tissues consist of elongated ducts that contain latex, a milky substance rich in proteins, carbohydrates, and other compounds. Glandular tissues contain glands that secrete oils, resins, enzymes and other substances. Secretions may remain within the cells or be released and have various functions in the plant or commercial value.
This presentation summarizes the process of meiosis. Meiosis is the type of cell division that produces gametes, such as sperm and egg cells, which have half the number of chromosomes as regular body cells. It involves two cell divisions: Meiosis I and Meiosis II. In Meiosis I, homologous chromosomes pair up and may exchange genetic material through crossing over. This results in daughter cells with half the original number of chromosomes. Meiosis II then separates the sister chromatids, resulting in four haploid gametes total. Through meiosis, genetic variation is generated while maintaining the chromosome number from one generation to the next.
1. Selaginella is a heterosporous plant that produces megaspores and microspores. The spores develop into male and female gametophytes within their spore walls.
2. Microspores develop into male gametophytes containing antherozoids for fertilization. Megaspores develop into female gametophytes containing archegonia.
3. Fertilization occurs when antherozoids enter the archegonia through openings in the neck canal cells. This leads to the development of a diploid sporophyte within the megaspore.
This document provides information about cell division through mitosis and meiosis. It discusses the three main types of cell division - binary fission in prokaryotes, mitosis in eukaryotes for growth and repair, and meiosis in eukaryotes for sexual reproduction. The stages of mitosis (prophase, metaphase, anaphase, telophase) and meiosis I and II are described in detail. The cell cycle is also summarized, including the interphase and mitotic phases.
Cell division is the process by which a parent cell divides into two or more daughter cells. There are two main types of cell division: mitosis and meiosis. Mitosis produces two identical daughter cells during growth and repair of the body. It ensures the genetic makeup remains the same. Meiosis produces gametes with half the number of chromosomes and involves two cell divisions. It results in genetic diversity that is important for sexual reproduction.
The sequence of events by which a cell duplicates its genome, synthesizes the other constituents of the cell and eventually divides into two daughter cells is termed cell cycle
Cell division occurs through mitosis and meiosis. Mitosis produces two identical daughter cells and is important for growth and repair. It has four phases: prophase, metaphase, anaphase and telophase. Meiosis reduces the chromosome number by half and produces genetic variation important for sexual reproduction. Meiosis has two divisions and involves homologous chromosome pairing, crossing over and separation into four haploid cells. The key difference is that mitosis maintains ploidy levels while meiosis reduces them, resulting in genetic variation.
The document summarizes the cell cycle and different types of cell division. It discusses the stages of interphase (G1, S, G2 phases), mitosis and its four phases (prophase, metaphase, anaphase, telophase), and cytokinesis. It also describes the two types of cell division - mitosis which produces identical daughter cells and meiosis which reduces the chromosome number by half to produce gametes. Meiosis involves two cell divisions, Meiosis I and Meiosis II, with chromosome segregation occurring once in each division.
The cell cycle consists of 4 main phases - G1, S, G2, and M phase. During interphase (G1, S, G2 phases), the cell grows and duplicates its DNA. Mitosis (M phase) then follows, which divides the cell into two identical daughter cells through four stages: prophase, metaphase, anaphase and telophase. Cytokinesis subsequently divides the cytoplasm.
Mitosis is a type of cell division that results in two daughter cells with identical genetic material to the parent cell. It occurs through the stages of prophase, metaphase, anaphase and telophase. During interphase, the cell grows and duplicates its DNA in preparation for division. Mitosis ensures growth, repair of tissues, and asexual reproduction. Meiosis produces gametes through two divisions and results in four haploid cells each with half the number of chromosomes as the original cell. This allows for genetic variation in offspring.
Cells divide through the cell cycle in order to grow, replace old cells, and make organisms grow. The cell cycle involves cell growth, DNA replication, and cell division through mitosis or meiosis. Mitosis produces two identical daughter cells through the phases of interphase, prophase, metaphase, anaphase, telophase, and cytokinesis. Meiosis reduces the chromosome number by half and produces genetically distinct gametes for sexual reproduction.
Cell division occurs through either mitosis or meiosis. Mitosis produces two identical daughter cells during somatic cell division. It has four phases: prophase, metaphase, anaphase and telophase. Meiosis produces gametes through two cell divisions that result in four haploid cells each with one copy of each chromosome. Meiosis has two rounds: meiosis I which separates homologous chromosomes, and meiosis II which separates sister chromatids. Both ensure genetic variation between offspring.
The document discusses the cell cycle and cell reproduction. It describes the main stages as interphase, where the cell grows and prepares for division, and the M phase where the nucleus and cell divide. Interphase includes the G1, S, and G2 phases where the cell makes proteins, organelles and replicates DNA. The M phase consists of mitosis, where the nucleus divides, and cytokinesis, where the cell splits into two. Mitosis is further broken down into the prophase, metaphase, anaphase and telophase stages where the chromosomes align and separate. Cytokinesis differs in animal and plant cells in how the cell membrane pinches or a cell plate forms to divide the cell. The result of
The document discusses the processes of mitosis and meiosis. It explains that mitosis is how eukaryotic cells divide to produce identical daughter cells through nuclear division. Meiosis involves two cell divisions that result in four haploid cells each with half the number of chromosomes as the original cell. The stages of mitosis include prophase, metaphase, anaphase and telophase. Similarly, meiosis has two divisions - meiosis I and meiosis II - which each consist of prophase, metaphase, anaphase and telophase stages. The document provides detailed explanations of each stage of mitosis and meiosis.
The study of the cell cycle focuses on mechanisms that regulate the timing and frequency of DNA duplication and cell division. As a biological concept, the cell cycle is defined as the period between successive divisions of a cell. During this period, the contents of the cell must be accurately replicated.
The cell cycle is regulated by cyclins and cyclin-dependent kinases.
How long is one cell cycle?
Depends. Eg. Skin cells every 24 hours. Some bacteria every 2 hours. Some cells every 3 months. Cancer cells very short. Nerve cells never.
Programmed cell death:
Each cell type will only do so many cell cycles then die. (Apoptosis)
Cell division occurs through mitosis and meiosis. Mitosis produces two identical daughter cells for growth and tissue repair. It has four stages: prophase, metaphase, anaphase and telophase, followed by cytokinesis. Meiosis produces four non-identical sex cells and reduces the chromosome number by half. It has two rounds of division followed by cytokinesis. The cell cycle regulates cell division, consisting of interphase and the mitotic phase.
Mitotic cell division is the process by which somatic cells reproduce through nuclear division (mitosis) and cytoplasmic division (cytokinesis). During mitosis, the genetic material duplicates and the duplicated chromosomes are separated into two identical nuclei. Cytokinesis then divides the cytoplasm and organelles, producing two daughter cells with identical genetic and cytoplasmic content to the original cell. The cell cycle coordinates cell growth and division, consisting of interphase where the cell grows and replicates its DNA, and the mitotic phase where it undergoes mitosis and cytokinesis to divide.
CELL CYCLE , MITOSIS ,MEIOSIS AND CELL REGULATIONLIFE SCIENCES
The document discusses the cell cycle and its regulation. It describes the main phases of the cell cycle including interphase with G1, S, and G2 phases, and mitosis. It also covers meiosis and the key differences between mitosis and meiosis. Cell cycle checkpoints are mentioned which allow the cell cycle to be halted at certain points if conditions are not favorable for progression.
Meiosis is a two-step process of cell division that results in four daughter cells each with half the number of chromosomes as the original parent cell. It occurs only in sex cells. In meiosis I, homologous chromosomes separate and are distributed into two daughter cells. Meiosis II then separates the sister chromatids, resulting in a total of four haploid daughter cells. The purpose of meiosis is to produce gametes for sexual reproduction.
This document provides an overview of cell division, specifically mitosis and meiosis. It begins with definitions of the key types of cell division - amitosis, mitosis, and meiosis. It then covers the stages and processes of mitosis, including interphase and the four stages of mitosis (prophase, metaphase, anaphase, telophase). The document also discusses the cell cycle and DNA content during cell division. Meiosis is then introduced, focusing on its production of gametes and halving of chromosome number compared to mitosis.
The document summarizes the cell cycle, cell division, mitosis, and meiosis. The cell cycle consists of interphase and cell division. Interphase includes G1, S, and G2 phases where DNA is synthesized. Cell division includes karyokinesis and cytokinesis. Mitosis produces identical daughter cells through prophase, metaphase, anaphase, and telophase. Meiosis reduces chromosome number by half and produces genetic variation through homologous chromosome pairing, crossing over, and two cell divisions. Meiosis is important for sexual reproduction and genetic recombination.
Meiosis is a type of cell division that produces gametes with half the number of chromosomes from a diploid cell. It involves two rounds of division called Meiosis I and Meiosis II. In Meiosis I, homologous chromosomes pair and may exchange genetic material through crossing over. The homologous chromosomes then separate, resulting in two haploid cells. Meiosis II then separates the sister chromatids, resulting in four haploid cells each containing a random assortment of one chromosome from each homologous pair.
This document provides an overview of environmental biotechnology and bioremediation. It defines environmental biotechnology as using biotechnology to study and solve environmental problems, particularly through applying microorganisms and their products to treat waste and clean up pollution. The document outlines various bioremediation techniques like biotreatment, phytoremediation, and discusses factors that influence bioremediation like nutrients, oxygen, pH, temperature. It also provides examples of bioremediation of specific pollutants like heavy metals and hydrocarbon contaminants.
This document provides an overview of parasitic diseases, discussing protozoan and helminth infections that impact human and animal health globally. It outlines the life cycles and transmission routes of diseases like malaria, amoebiasis, ascariasis, hookworm infections, schistosomiasis, and others. While chemotherapy is currently the primary treatment approach, vaccines and immunotherapy are being developed to help control and eliminate parasitic infections.
Protein prenylation involves the addition of farnesyl or geranylgeranyl groups to cysteine residues on target proteins by farnesyltransferase (FTase) or geranylgeranyltransferase (GGTase). FTase and GGTase are heterodimers that recognize CaaX box motifs and catalyze signal transduction pathways related to cell growth. Protein prenylation, especially of Ras proteins by FTase, is important in cancer development, and FTase inhibitors are used as anticancer drugs. While FTase and GGTase-I typically recognize the same CaaX box motifs, some exceptions exist, such as K-Ras being geranylger
Protein prenylation involves the addition of farnesyl or geranylgeranyl groups to cysteine residues on target proteins by farnesyltransferase (FTase) or geranylgeranyltransferase (GGTase). FTase and GGTase are heterodimers that recognize CaaX box motifs and catalyze signal transduction pathways related to cell growth. Protein prenylation, especially of Ras proteins by FTase, is important in cancer development, and FTase inhibitors are used as anticancer drugs. While FTase and GGTase-I typically recognize the same CaaX box motifs, some exceptions exist, such as K-Ras being geranylger
Microarray data analysis involves several key steps:
1) Feature extraction converts the scanned microarray image into quantifiable gene expression values.
2) Quality control assesses the microarray for errors through diagnostic plots of intensities and distributions.
3) Normalization controls for technical variations between assays while preserving biological variations.
4) Differential expression analysis identifies genes with different expression levels between conditions, while correcting for multiple testing.
5) Biological interpretation and public database submission provide meaning and accessibility of the results.
Data Retreival, Protein sequence database, Gene Pridiction 3.pptxsanarao25
This document discusses protein characterization and localization. It mentions predicting protein localization based on compartmental and transmembrane signatures. The document also notes looking for specific signatures when characterizing proteins.
COPI, COPII, and TRAPIII are protein complexes involved in vesicle transport between organelles. Vesicles bud from one organelle, are targeted to another using Rab GTPases and SNARE proteins, and fuse via SNARE pairing. The secretory pathway modifies and sorts proteins in the ER and Golgi before delivery to their final destinations, such as the plasma membrane, lysosomes, or secretory vesicles.
This document discusses somatic hybridization techniques for crop improvement using potato and its wild relatives as an example. Somatic hybridization involves fusing plant protoplasts from two different species to create a hybrid plant. The author has used this technique to introduce disease resistances from wild potato species into cultivated potato. Specifically, late blight resistance was captured from Solanum bulbocastanum and introgressed into potato breeding lines. Somatic hybridization also allows for the combination of traits from different species and the creation of novel germplasm. The author discusses applications to citrus improvement as well, including creating seedless varieties and improving rootstocks.
Marker is a piece of DNA associated with a trait. There are four main types of markers: morphological, biochemical, chromosomal, and genetic. Molecular markers reveal DNA level variations and have advantages like being co-dominant, allowing nondestructive assays, and being randomly distributed throughout the genome. Common molecular marker techniques include RAPD, RFLP, AFLP, microsatellites, and SNPs. Molecular markers can be used for applications like gene mapping, disease diagnosis, evolution studies, parentage determination, and marker assisted selection in animal breeding.
An efficient cucumber (Cucumis sativus L.pdfsanarao25
This document describes establishing an efficient cucumber protoplast isolation and transient expression system. It outlines optimizing conditions for protoplast isolation from cucumber cotyledons and leaves, including enzymolysis time and mannitol concentration. High transformation efficiency was obtained using PEG4000-mediated transfection of isolated protoplasts with a GFP expression plasmid. The transient expression system provides a tool for further molecular biology and genetic studies in cucumber.
This document discusses plant protoplasts, which are plant cells that have had their cell walls removed. It covers the structure and function of plant cell walls. The two main methods for isolating protoplasts are mechanical and enzymatic isolation. Enzymatic isolation using cellulase, pectinase, and hemicellulase enzymes is now the standard method. Leaves are a common source material for protoplast isolation. Isolation involves incubating tissue in enzyme solutions to break down the cell wall. Protoplasts must then be maintained in an hypertonic solution to prevent bursting due to loss of cell wall pressure. Culture media for protoplasts is based on Murashige and Sk
1) John Helgeson at the University of Wisconsin-Madison uses somatic hybridization to introduce disease resistance genes from wild potato species into cultivated potatoes.
2) Somatic hybridization involves fusing protoplasts (plant cells without walls) from different potato species using an enzyme solution, which can then regenerate into whole new potato plants.
3) Some somatic hybrids produced by Helgeson have shown resistance to late blight, early blight, nematodes, soft rot bacteria, bacterial wilt, and potato viruses, transferring useful traits from wild to cultivated species.
This document discusses polygenic inheritance and continuous variation. Polygenic traits are influenced by two or more genes and exhibit a wide range of overlapping phenotypes in a population, such as height, skin color, and intelligence. The additive model is presented, where dominant alleles each contribute equally to a quantitative trait like height, while recessive alleles make no contribution. The number of possible phenotypic classes increases with the number of gene pairs involved. Multifactorial and complex traits result from an interaction between genes and environmental factors, though determining these interactions can be difficult. Heritability estimates the genetic contribution to phenotypic variation by comparing relatives.
Gametogenesis is the process by which haploid gametes are formed from diploid germ cells through cell division and maturation. It occurs in four phases: primordial germ cell formation, mitotic proliferation, meiosis, and gamete maturation. In males (spermatogenesis), it occurs in the testes and produces sperm through spermatogonial mitosis and spermatocyte meiosis. In females (oogenesis), it occurs in the ovaries and arrests at two points during meiotic prophase I to produce ova.
This document discusses gene-gene interactions (epistasis) and their relationship to additive genetic models. Some key points made:
- Epistasis can be strong between genes yet generate little epistatic variance and additive models can still fit data well.
- A substantial portion of variation caused by epistatic interactions is captured in the additive genetic variance.
- The infinitesimal model, where many loci each have small effects, can accommodate epistasis and remains a useful model even though individual loci may not be identifiable.
- While individual pairwise epistatic effects may be small and undetectable, the aggregate effect of many such interactions could contribute to genotype-phenotype associations.
1) The eukaryotic cell cycle involves cell growth, DNA replication, and cell division through mitosis to produce two identical daughter cells.
2) The cell cycle consists of interphase and mitosis. Interphase includes gap 1, DNA synthesis, and gap 2 phases. Mitosis is nuclear division followed by cytokinesis.
3) Meiosis produces gametes through two cell divisions resulting in four haploid cells each with half the number of chromosomes as the original cell.
1. The document describes the processes of mitosis and meiosis. Mitosis produces identical daughter cells through nuclear division and cytokinesis, while meiosis produces haploid gametes through two nuclear divisions.
2. It explains the stages of the cell cycle including interphase and mitosis. Interphase involves cell growth and DNA replication while mitosis involves nuclear division and cytokinesis.
3. Meiosis involves two nuclear divisions and produces four haploid daughter cells through independent assortment and crossing over, introducing genetic variation.
BREEDING METHODS FOR DISEASE RESISTANCE.pptxRASHMI M G
Plant breeding for disease resistance is a strategy to reduce crop losses caused by disease. Plants have an innate immune system that allows them to recognize pathogens and provide resistance. However, breeding for long-lasting resistance often involves combining multiple resistance genes
This presentation explores a brief idea about the structural and functional attributes of nucleotides, the structure and function of genetic materials along with the impact of UV rays and pH upon them.
Comparing Evolved Extractive Text Summary Scores of Bidirectional Encoder Rep...University of Maribor
Slides from:
11th International Conference on Electrical, Electronics and Computer Engineering (IcETRAN), Niš, 3-6 June 2024
Track: Artificial Intelligence
https://www.etran.rs/2024/en/home-english/
The ability to recreate computational results with minimal effort and actionable metrics provides a solid foundation for scientific research and software development. When people can replicate an analysis at the touch of a button using open-source software, open data, and methods to assess and compare proposals, it significantly eases verification of results, engagement with a diverse range of contributors, and progress. However, we have yet to fully achieve this; there are still many sociotechnical frictions.
Inspired by David Donoho's vision, this talk aims to revisit the three crucial pillars of frictionless reproducibility (data sharing, code sharing, and competitive challenges) with the perspective of deep software variability.
Our observation is that multiple layers — hardware, operating systems, third-party libraries, software versions, input data, compile-time options, and parameters — are subject to variability that exacerbates frictions but is also essential for achieving robust, generalizable results and fostering innovation. I will first review the literature, providing evidence of how the complex variability interactions across these layers affect qualitative and quantitative software properties, thereby complicating the reproduction and replication of scientific studies in various fields.
I will then present some software engineering and AI techniques that can support the strategic exploration of variability spaces. These include the use of abstractions and models (e.g., feature models), sampling strategies (e.g., uniform, random), cost-effective measurements (e.g., incremental build of software configurations), and dimensionality reduction methods (e.g., transfer learning, feature selection, software debloating).
I will finally argue that deep variability is both the problem and solution of frictionless reproducibility, calling the software science community to develop new methods and tools to manage variability and foster reproducibility in software systems.
Exposé invité Journées Nationales du GDR GPL 2024
ESR spectroscopy in liquid food and beverages.pptxPRIYANKA PATEL
With increasing population, people need to rely on packaged food stuffs. Packaging of food materials requires the preservation of food. There are various methods for the treatment of food to preserve them and irradiation treatment of food is one of them. It is the most common and the most harmless method for the food preservation as it does not alter the necessary micronutrients of food materials. Although irradiated food doesn’t cause any harm to the human health but still the quality assessment of food is required to provide consumers with necessary information about the food. ESR spectroscopy is the most sophisticated way to investigate the quality of the food and the free radicals induced during the processing of the food. ESR spin trapping technique is useful for the detection of highly unstable radicals in the food. The antioxidant capability of liquid food and beverages in mainly performed by spin trapping technique.
What is greenhouse gasses and how many gasses are there to affect the Earth.moosaasad1975
What are greenhouse gasses how they affect the earth and its environment what is the future of the environment and earth how the weather and the climate effects.
The binding of cosmological structures by massless topological defectsSérgio Sacani
Assuming spherical symmetry and weak field, it is shown that if one solves the Poisson equation or the Einstein field
equations sourced by a topological defect, i.e. a singularity of a very specific form, the result is a localized gravitational
field capable of driving flat rotation (i.e. Keplerian circular orbits at a constant speed for all radii) of test masses on a thin
spherical shell without any underlying mass. Moreover, a large-scale structure which exploits this solution by assembling
concentrically a number of such topological defects can establish a flat stellar or galactic rotation curve, and can also deflect
light in the same manner as an equipotential (isothermal) sphere. Thus, the need for dark matter or modified gravity theory is
mitigated, at least in part.
hematic appreciation test is a psychological assessment tool used to measure an individual's appreciation and understanding of specific themes or topics. This test helps to evaluate an individual's ability to connect different ideas and concepts within a given theme, as well as their overall comprehension and interpretation skills. The results of the test can provide valuable insights into an individual's cognitive abilities, creativity, and critical thinking skills
Phenomics assisted breeding in crop improvementIshaGoswami9
As the population is increasing and will reach about 9 billion upto 2050. Also due to climate change, it is difficult to meet the food requirement of such a large population. Facing the challenges presented by resource shortages, climate
change, and increasing global population, crop yield and quality need to be improved in a sustainable way over the coming decades. Genetic improvement by breeding is the best way to increase crop productivity. With the rapid progression of functional
genomics, an increasing number of crop genomes have been sequenced and dozens of genes influencing key agronomic traits have been identified. However, current genome sequence information has not been adequately exploited for understanding
the complex characteristics of multiple gene, owing to a lack of crop phenotypic data. Efficient, automatic, and accurate technologies and platforms that can capture phenotypic data that can
be linked to genomics information for crop improvement at all growth stages have become as important as genotyping. Thus,
high-throughput phenotyping has become the major bottleneck restricting crop breeding. Plant phenomics has been defined as the high-throughput, accurate acquisition and analysis of multi-dimensional phenotypes
during crop growing stages at the organism level, including the cell, tissue, organ, individual plant, plot, and field levels. With the rapid development of novel sensors, imaging technology,
and analysis methods, numerous infrastructure platforms have been developed for phenotyping.
Remote Sensing and Computational, Evolutionary, Supercomputing, and Intellige...University of Maribor
Slides from talk:
Aleš Zamuda: Remote Sensing and Computational, Evolutionary, Supercomputing, and Intelligent Systems.
11th International Conference on Electrical, Electronics and Computer Engineering (IcETRAN), Niš, 3-6 June 2024
Inter-Society Networking Panel GRSS/MTT-S/CIS Panel Session: Promoting Connection and Cooperation
https://www.etran.rs/2024/en/home-english/
Nucleophilic Addition of carbonyl compounds.pptxSSR02
Nucleophilic addition is the most important reaction of carbonyls. Not just aldehydes and ketones, but also carboxylic acid derivatives in general.
Carbonyls undergo addition reactions with a large range of nucleophiles.
Comparing the relative basicity of the nucleophile and the product is extremely helpful in determining how reversible the addition reaction is. Reactions with Grignards and hydrides are irreversible. Reactions with weak bases like halides and carboxylates generally don’t happen.
Electronic effects (inductive effects, electron donation) have a large impact on reactivity.
Large groups adjacent to the carbonyl will slow the rate of reaction.
Neutral nucleophiles can also add to carbonyls, although their additions are generally slower and more reversible. Acid catalysis is sometimes employed to increase the rate of addition.
Travis Hills' Endeavors in Minnesota: Fostering Environmental and Economic Pr...Travis Hills MN
Travis Hills of Minnesota developed a method to convert waste into high-value dry fertilizer, significantly enriching soil quality. By providing farmers with a valuable resource derived from waste, Travis Hills helps enhance farm profitability while promoting environmental stewardship. Travis Hills' sustainable practices lead to cost savings and increased revenue for farmers by improving resource efficiency and reducing waste.
The debris of the ‘last major merger’ is dynamically youngSérgio Sacani
The Milky Way’s (MW) inner stellar halo contains an [Fe/H]-rich component with highly eccentric orbits, often referred to as the
‘last major merger.’ Hypotheses for the origin of this component include Gaia-Sausage/Enceladus (GSE), where the progenitor
collided with the MW proto-disc 8–11 Gyr ago, and the Virgo Radial Merger (VRM), where the progenitor collided with the
MW disc within the last 3 Gyr. These two scenarios make different predictions about observable structure in local phase space,
because the morphology of debris depends on how long it has had to phase mix. The recently identified phase-space folds in Gaia
DR3 have positive caustic velocities, making them fundamentally different than the phase-mixed chevrons found in simulations
at late times. Roughly 20 per cent of the stars in the prograde local stellar halo are associated with the observed caustics. Based
on a simple phase-mixing model, the observed number of caustics are consistent with a merger that occurred 1–2 Gyr ago.
We also compare the observed phase-space distribution to FIRE-2 Latte simulations of GSE-like mergers, using a quantitative
measurement of phase mixing (2D causticality). The observed local phase-space distribution best matches the simulated data
1–2 Gyr after collision, and certainly not later than 3 Gyr. This is further evidence that the progenitor of the ‘last major merger’
did not collide with the MW proto-disc at early times, as is thought for the GSE, but instead collided with the MW disc within
the last few Gyr, consistent with the body of work surrounding the VRM.
2. CELL DIVISION
• It’s the process by which a cell divides to
form two new cells
• • Three types of cell division or cell
reproduction in an organism
• • Prokaryotes (bacteria)
- Binary fission
- • Divides forming two new identical cells
3. • Eukaryotes
-Mitosis
• Cell or organism growth • Replacement or
repair of damaged cells
-Meiosis • formation of sex cells, or gametes
4. WHY DO CELLS DIVIDE?
• Cells divide for growth, development,
repair of worn-out tissues and
reproduction
• To facilitate the exchange of materials
• To control DNA overloading
5. PROKARYOTIC CELL
DIVISION
• 1. Binary Fission
• Three (3) major steps;
• DNA Replication DNA is copied resulting into two
identical chromosomes
• Chromosome Segregation Chromosomes
separate and move towards ends (poles) of cell
• Cytokinesis (Separation) Cytoplasm divides
forming two (2) cells
• Each new daughter cell is Genetically Identical to
parent cell
6.
7. EUKARYOTIC CELL DIVISION
• Cell division that results in two daughter cells each
having the same number and kind of chromosomes
as the parent cell
• 1. MITOSIS
• Two (2) main steps:
1. Mitosis
• Fours steps;
[Prophase>Metaphase>Anaphase>Telophase]
2. Cytokinesis
• Cytoplasm divides forming two new daughter cells
• Each daughter cell is Genetically Identical to parent
cell
8.
9. The function of mitosis is first to construct an exact
copy of each chromosome and then to distribute,
through division of the original (mother) cell, an
identical set of chromosomes to each of the two
progeny cells, or daughter cells.
10. • Cell division that results in four daughter cells
2. MEIOSIS
• Two (2) major steps:
1. Mitosis Fours steps;
[Prophase>Metaphase>Anaphase>Telophase]
2. Cytokinesis
• Cytoplasm divides forming two new daughter
cells
• Each daughter cell is NOT Genetically Identical to
parent cell
11. THE CELL CYCLE
• The sequence of events from the time a cell first
arises as a result of cell division until the time when
that cell itself divides.
• Arise – Divide
• This consist of periods of;
• Growth and Development
• DNA Replication
• Preparation For Division
• Cell Division
• Cell after division begins a new cycle
12. The Cell Cycle
• Consist of two(2) main periods;
I. Interphase
II. Mitotic Phase
13. Interphase
• Interphase: period of growth and DNA replication
between cell divisions
• Three (3) phases:
• G1 Phase ‒ Cell increases in size
• S Phase ‒ Replication of DNA ‒ Two sister strands
of DNA called chromatids are produced
• G2 Phase ‒ Organelles double ‒ New cytoplasm
forms ‒ All other structures needed for mitosis form
15. Mitotic Phase
• Mitotic phase is the stage when a cell divides
• Mitosis – the division of a single nucleus into two
genetically identical daughter nuclei • This division
involves two(2) processes;
‒ Division of the nucleus
‒ Separation of the cytoplasm and the new nuclei
into daughter cells
16. Mitotic Phase
• Divided into two (2) mitotic phases
• 1st Mitotic Phase contain four stages (P-
MAT)
‒ Prophase, metaphase, anaphase and
telophase
• 2nd Mitotic Phase is cytokinesis
18. Interphase
• The period when the cell is in a non-dividing state
• A cell spends most of its time in this phase
• During this time, it grows, replicates its
chromosomes and prepares for cell division.
• The cell then leaves interphase, undergoes
mitosis, and completes its division.
19. Early Prophase
• Chromatids condense becoming chromosomes
• Nucleolus disappears
• Centrioles separate and start moving to opposite
ends of the cell
• Spindle begins to form
20. Late Prophase
• The nuclear membrane fragments and the
microtubules invade the nuclear area
• Centrioles have moved to the opposite poles
• The spindle is completely formed
21. Metaphase
• The chromosomes are aligned at the metaphase
plate
• Centrioles move at polar ends and projects
spindle fibers to connect each chromosome
22. Anaphase
• The paired chromosomes (sister chromatids)
separate
• Separated chromatids move to opposite pole
• Partial division of cytoplasm begins
23. Telophase
• Chromosomes are at the poles
• Chromosomes uncoil-turn chromatin
• Nuclear envelops reforms
• Spindle fiber disappear
24. Cytokinesis
• Occurs at the end of mitosis
• Animal cells: a cleavage furrow separates the
daughter cells
• Plant cell: a cell plate separates the daughter cells
• Daughter cells are genetically identical
25. CONTROL OF THE CELL
CYCLE
• Regulatory proteins called cyclins control the cell
cycle at checkpoints:
• G1 Checkpoint—decides whether or not cell will
divide
• S Checkpoint—determines if DNA has been
properly replicated
• Mitotic Spindle Checkpoint—ensures
chromosomes are aligned at mitotic plate
26. MEIOSIS
• Meiotic cell division occurs in germ cells of all
living organisms.
• During meiosis, the genetic material of a diploid
germ cell undergoes two nuclear divisions and
resulting in four haploid daughter cells.
• Each daughter cells has one half of the number
of chromosomes as the parent cell.
• There are two successive nuclear divisions in
meiosis as compared to the one division found
in mitosis.
27. • The two stages of meiosis are
1. Meiosis I
2. 2.Meiosis II
• Meiosis I also called as Reductional Division
• Meiosis II also called as Equational Division
• Before a dividing cell enters meiosis, it
undergoes a period of growth called Interphase.
28.
29. INTERPHASE
• The interphase just prior to the entry of cell in to
meiosis is known as pre meiotic interphase.
• During the S phase of pre meiotic interphase,
chromosome replication takes place.
30. MEIOSIS I
• Meiosis I separate homologous chromosomes
and produce two cells with haploid chromosome
number (N) for that reason it is known as
Reductional Division.
• Meiosis I consist of four stages,
• Prophase I
• Metaphase I
• Anaphase I and
• Telophase I.
31. PROPHASE I
• Prophase I is the longest in duration compared to
Prophase in mitosis.
• It takes about 85 - 95 percent of the total time for
meiosis and also much more complex.
• The Prophase I divided into 5 stages (Le Za Pa Di
Dia).
• Leptotene
• Zygotene
• Pachytene
• Diplotene and
• Diakinesis
32. i. LEPTOTENE
• The first stage of Prophase I is called Leptotene or
leptonema.
• All the chromosomes begin
to condense, so, they become
visible as fine thread.
• There is a marked increase
in the nuclear volume.
• A process of 'homology search' which is essential
to the initial pairing of
• homologs, begins
• during this phase.
33. ZYGOTENE
• The zygotene stage is also known as zygonema.
• This stage begins with the initiation of pairing between
homologous chromosomes, and it ends with complete
pairing.
• The process of pairing (at end to end) between homologous
chromosomes is known as Synapsis (pairing of two
chromosomes).
34. • The synaptonemal complex (a protein structure
that forms between homologous chromosomes
during meiosis and is thought to mediate
chromosome pairing, synapsis, and
recombination) is formed during this zygotene
stage.
• At the completion of zygotene, the paired
homologs take the form of bivalents.
• The number of bivalents in each species is equal
to the haploid number.
35. PACHYTENE
• The pachytene stage is also known as pachynema.
• The process of synapsis is complete.
• The two homologous of each bivalent appear to be
attached to each other at one or more points, these
attachments are known as chiasmata.
36. • Crossing over is a precise breakage,
swapping, and reunion between two non-
sister chromatids.
• Crossovers make new gene combinations,
and which are an important source of
genetic variations in populations.
37. DIPLOTENE
• The diplotene stage is also known as diplonema.
• DNA recombination is complete.
• The chromatids continue to shorten and thicken
and the four sister chromatids in a group are called
tetrad.
• The synaptonemal complex begins to break down.
38. • The paired chromatids begin to pull apart,
causing the strands to separate
longitudinally.
• The chiasmata tend to become terminals
as the meiotic prophase continues.
39. DIAKINESIS
• The chromosomes become shorter and thicker
due to condensation.
• Nucleolus and nuclear envelope disappear
towards the end of diakinesis.
• The spindle apparatus becomes organized.
• The centrioles migrate away from one another.
40. METAPHASE I
• All the bivalents migrate within a cell migrate to
metaphase plate.
• One homolog is pulled above the metaphase
plate, the other below.
• The centromeres of homologous chromosomes of
each bivalent stretch out on either side.
41. • The centrioles are at opposite poles of the
cell.
• Spindle fibers from one pole of the cell
attach to one chromosome and spindle
fibers from the opposite pole attach to the
homologous chromosome.
42. ANAPHASE I
• Chromosomes move to the opposite poles.
• The microtubules and the kinetochore fibers
interact, which causes the movement.
• A difference between mitosis and meiosis is that
sister chromatids remain joined after metaphase
in meiosis I, whereas in mitosis they separate.
43. • During Anaphase I original chromosomes
separate, so reduction in the number of
chromosomes from 2N to N number, yet
the sister chromatids remain together
44. TELOPHASE I
• The homologous chromosome completes its
migration to the two poles because of the
shortening of spindles.
• The nuclear envelope is organized around two
groups of chromosomes.
• The nucleolus also
• reappears.
45. Cytokinesis
• Cytokinesis involves the formation of a cleavage furrow,
resulting in the pocketing of the cell into two cells.
• At the end of Telophase, I and Cytokinesis, two daughter
cells are produced, each with one-half of the number of
chromosomes (haploid set of replicated chromosomes)
of the original parent cell.
46. INTERKINESIS
• Interkinesis (Interphase II) is similar to
interphase
• The cell now rests for a bit before beginning the
second meiotic division. During this period,
called interkinesis, the nuclear membrane in
each of the two cells reforms around the
chromosomes. In some cells, the spindle also
disintegrates, and the chromosomes relax.
47. MEIOSIS II
• Meiosis II is the second part MEIOSIS II of the
meiotic process.
• Meiosis II consists
• Prophase II Each dyad is composed of a pair of
sister chromatids attached by a common
centromere.
• Metaphase II Centromeres are positioned at the
equatorial plane.
• Anaphase II Centromeres divide, and the sister
chromatids of each dyad are pulled to opposite
poles
48. Telophase II
• One member of each pair of homologous
chromosomes is present in each pole.
• Each chromosome is referred to as a monad (a
combination of maternal and paternal genetic
information).
• Nuclei reform around chromosomes at the poles.
• Following cytokinesis and finally four haploid
gametes result from a single meiotic event.
49. Functions of Meiosis
1. Production of haploid (n) gametes: so, that
fertilization restores the normal somatic (2n)
chromosome number.
2. Production of tremendous amounts of genetic
variation.
3. Segregation of the two alleles of each gene.
This takes place due to the pairing between the
two homologs of each chromosome and their
separation at the first anaphase.
50. 4. Recombination between linked genes due to
crossing over during pachytene stage.
5. Meiosis facilitates segregation and independent
assortment of chromosomes and genes.
6. In sexually reproducing species, meiosis is
essential for the continuity of generation. Because
meiosis results in the formation of male and female
gametes and union of such gametes lead to the
development of zygotes and thereby new
individual.
51. Mitosis Meosis
1 Occurs in somatic cells Occurs in reproductive cells
2 One cell produces two daughter cells One cell produces four
daughter cells
3 It is an equational division separating sister
chromatids.
It is a reduction division.
The first stage is a reduction
division which separates
homologous chromosomes
at first anaphase. Sister
chromatids separate in an
equational division at II
anaphase.
4 Only one division per cycle i.e. one cytoplasmic
division (cytokinesis) per equational division
Two divisions per cycle i.e.
two cytoplasmic divisions,
one reduction division and
equation division.
5 Chromosomes fail to synapse. No chiasmata
formation.
Chromosomes synapse and
form chiasmata.
6 Genetic exchange between homologous
chromosomes does not occur
Genetic exchange through
chiasmata occurs between
homologous chromosomes.
52. Mitosis Meosis
7 Genetic contents of daughter cells are
identical
Genetic contents of
daughter cells are
different.
8 Chromosome number of daughter cells is
the same as that of mother cell.
Chromosome number of
daughter cells is half of
that of mother cells.
9 Daughter cells are capable of undergoing
additional mitotic divisions.
Daughter cells are not
capable of undergoing
another meiotic division
although they may
undergo mitotic division.
10 Start at the zygote stage and continues
through the life of the organism.
Occurs only after
puberty, in higher
organisms, but occurs in
the zygote of algae and
fungi.