Mitosis and meiosis both involve cell division, but have key differences:
Mitosis produces two identical diploid daughter cells through one nuclear division, while meiosis produces four non-identical haploid gametes through two nuclear divisions. Meiosis involves homologous chromosome pairing and crossing over during prophase I, which introduces genetic variation. The first meiotic division reduces the chromosome number by half to produce haploid cells, and the second division separates sister chromatids. Meiosis is essential for sexual reproduction to generate egg and sperm cells.
4. Cell division - Anatomy - BSc Nursing 1st Semester - by M. Thirumurugan.pptxthiru murugan
It is the process by which a parent cell divides into two or more daughter cells. Cell division usually occurs as part of a larger cell cycle.
It is an essential biological process in many organisms. It is the means used by multicellular organisms in order to grow, repair, and reproduce.
Types of Cell division:
Mitosis
Meiosis
Mitosis: Mitosis is a division of the nucleus to produce two new daughter cells containing chromosomes identical to the parent cell.
Phases of Mitosis:
Mitosis is a continuous process and divided into different phases based on the appearance and behavior of the chromosomes.
Prophase
Prometaphase
Metaphase
Anaphase
Telophase
Cytokinesis
1.Prophase:
Early prophase:
During prophase chromatin (the complex of DNA and proteins contained in the nucleus), condense and become visible in a light microscope
Nucleolus disappears & Paired centrioles move to opposite ends of the cell.
The replicated chromosomes have an X shape and are called sister chromatids. The sister chromatids are joined at a point called the centromere.
Late prophase:
Nuclear membrane disappears
a structure called the mitotic spindle begins to form at opposite ends of the cell (responsible for separating the sister chromatids into two cells)
2. Prometaphase: Prometaphase is the second stage of mitosis. In prometaphase,
Chromosomes continue to condense
Kinetochores appear at the centromeres
Mitotic spindle attach to kinetochores
Centrosomes move toward opposite poles
3. Metaphase:
Metaphase is the third step in mitosis.
Mitotic spindle is fully developed
Sister chromatids line up at the spindle equator
At the end of metaphase, the centromeres start to divide
4.Anaphase:
Anaphase begin with the separation of the centromeres
Sister chromatids together break down
Sister chromatids (now called chromosomes) are pulled toward opposite poles
The sister chromatids are drawn to opposite poles of the cell by contraction of spindle fibers
5.Telophase:
Telophase begin when the two sets of daughter chromosomes have reached the two poles of the cell.
The spindle fibers breaks down,
The nuclear membrane forms around each set of daughter chromosomes and the nucleoli reappear
The chromosomes uncoil and become less visible under the light microscope
6. Cytokinesis:
Cytokinesis is the sixth and final step of mitosis & A cleavage furrow separates the daughter cells
Cytokinesis is the process of cytoplasmic division to form two daughter cells.
Cytokinesis takes place when the Cytoplasm divides and two cells with identical genetic material are formed Daughter Cells
Meiosis:
Meiosis Takes place in the Gametes of an organism
People have a Chromosome count of 46
When an egg joins a sperm the count must stay at 46 to remain human
So, the egg can only have 23 chromosomes, and the sperm can only have 23 chromosomes
But, the integrity of the organism must be maintained.
During Meiosis diploid cells are reduced to haploid cells
Diploid (2n) to Haploid (n):
During Meiosis gamete (sex
This includes detailed description of the Cell Cycle and Cell Cycle regulation. Courtesy: Campbell Biology Book, And Dr, Rosemary Redfield Lectures, University of British Columbia.
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)
A Strategic Approach: GenAI in EducationPeter Windle
Artificial Intelligence (AI) technologies such as Generative AI, Image Generators and Large Language Models have had a dramatic impact on teaching, learning and assessment over the past 18 months. The most immediate threat AI posed was to Academic Integrity with Higher Education Institutes (HEIs) focusing their efforts on combating the use of GenAI in assessment. Guidelines were developed for staff and students, policies put in place too. Innovative educators have forged paths in the use of Generative AI for teaching, learning and assessments leading to pockets of transformation springing up across HEIs, often with little or no top-down guidance, support or direction.
This Gasta posits a strategic approach to integrating AI into HEIs to prepare staff, students and the curriculum for an evolving world and workplace. We will highlight the advantages of working with these technologies beyond the realm of teaching, learning and assessment by considering prompt engineering skills, industry impact, curriculum changes, and the need for staff upskilling. In contrast, not engaging strategically with Generative AI poses risks, including falling behind peers, missed opportunities and failing to ensure our graduates remain employable. The rapid evolution of AI technologies necessitates a proactive and strategic approach if we are to remain relevant.
The French Revolution, which began in 1789, was a period of radical social and political upheaval in France. It marked the decline of absolute monarchies, the rise of secular and democratic republics, and the eventual rise of Napoleon Bonaparte. This revolutionary period is crucial in understanding the transition from feudalism to modernity in Europe.
For more information, visit-www.vavaclasses.com
Biological screening of herbal drugs: Introduction and Need for
Phyto-Pharmacological Screening, New Strategies for evaluating
Natural Products, In vitro evaluation techniques for Antioxidants, Antimicrobial and Anticancer drugs. In vivo evaluation techniques
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Antifertility, Toxicity studies as per OECD guidelines
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It is possible to hide or invisible some fields in odoo. Commonly using “invisible” attribute in the field definition to invisible the fields. This slide will show how to make a field invisible in odoo 17.
The Roman Empire A Historical Colossus.pdfkaushalkr1407
The Roman Empire, a vast and enduring power, stands as one of history's most remarkable civilizations, leaving an indelible imprint on the world. It emerged from the Roman Republic, transitioning into an imperial powerhouse under the leadership of Augustus Caesar in 27 BCE. This transformation marked the beginning of an era defined by unprecedented territorial expansion, architectural marvels, and profound cultural influence.
The empire's roots lie in the city of Rome, founded, according to legend, by Romulus in 753 BCE. Over centuries, Rome evolved from a small settlement to a formidable republic, characterized by a complex political system with elected officials and checks on power. However, internal strife, class conflicts, and military ambitions paved the way for the end of the Republic. Julius Caesar’s dictatorship and subsequent assassination in 44 BCE created a power vacuum, leading to a civil war. Octavian, later Augustus, emerged victorious, heralding the Roman Empire’s birth.
Under Augustus, the empire experienced the Pax Romana, a 200-year period of relative peace and stability. Augustus reformed the military, established efficient administrative systems, and initiated grand construction projects. The empire's borders expanded, encompassing territories from Britain to Egypt and from Spain to the Euphrates. Roman legions, renowned for their discipline and engineering prowess, secured and maintained these vast territories, building roads, fortifications, and cities that facilitated control and integration.
The Roman Empire’s society was hierarchical, with a rigid class system. At the top were the patricians, wealthy elites who held significant political power. Below them were the plebeians, free citizens with limited political influence, and the vast numbers of slaves who formed the backbone of the economy. The family unit was central, governed by the paterfamilias, the male head who held absolute authority.
Culturally, the Romans were eclectic, absorbing and adapting elements from the civilizations they encountered, particularly the Greeks. Roman art, literature, and philosophy reflected this synthesis, creating a rich cultural tapestry. Latin, the Roman language, became the lingua franca of the Western world, influencing numerous modern languages.
Roman architecture and engineering achievements were monumental. They perfected the arch, vault, and dome, constructing enduring structures like the Colosseum, Pantheon, and aqueducts. These engineering marvels not only showcased Roman ingenuity but also served practical purposes, from public entertainment to water supply.
Read| The latest issue of The Challenger is here! We are thrilled to announce that our school paper has qualified for the NATIONAL SCHOOLS PRESS CONFERENCE (NSPC) 2024. Thank you for your unwavering support and trust. Dive into the stories that made us stand out!
Unit 8 - Information and Communication Technology (Paper I).pdfThiyagu K
This slides describes the basic concepts of ICT, basics of Email, Emerging Technology and Digital Initiatives in Education. This presentations aligns with the UGC Paper I syllabus.
Macroeconomics- Movie Location
This will be used as part of your Personal Professional Portfolio once graded.
Objective:
Prepare a presentation or a paper using research, basic comparative analysis, data organization and application of economic information. You will make an informed assessment of an economic climate outside of the United States to accomplish an entertainment industry objective.
Instructions for Submissions thorugh G- Classroom.pptxJheel Barad
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June 3, 2024 Anti-Semitism Letter Sent to MIT President Kornbluth and MIT Cor...Levi Shapiro
Letter from the Congress of the United States regarding Anti-Semitism sent June 3rd to MIT President Sally Kornbluth, MIT Corp Chair, Mark Gorenberg
Dear Dr. Kornbluth and Mr. Gorenberg,
The US House of Representatives is deeply concerned by ongoing and pervasive acts of antisemitic
harassment and intimidation at the Massachusetts Institute of Technology (MIT). Failing to act decisively to ensure a safe learning environment for all students would be a grave dereliction of your responsibilities as President of MIT and Chair of the MIT Corporation.
This Congress will not stand idly by and allow an environment hostile to Jewish students to persist. The House believes that your institution is in violation of Title VI of the Civil Rights Act, and the inability or
unwillingness to rectify this violation through action requires accountability.
Postsecondary education is a unique opportunity for students to learn and have their ideas and beliefs challenged. However, universities receiving hundreds of millions of federal funds annually have denied
students that opportunity and have been hijacked to become venues for the promotion of terrorism, antisemitic harassment and intimidation, unlawful encampments, and in some cases, assaults and riots.
The House of Representatives will not countenance the use of federal funds to indoctrinate students into hateful, antisemitic, anti-American supporters of terrorism. Investigations into campus antisemitism by the Committee on Education and the Workforce and the Committee on Ways and Means have been expanded into a Congress-wide probe across all relevant jurisdictions to address this national crisis. The undersigned Committees will conduct oversight into the use of federal funds at MIT and its learning environment under authorities granted to each Committee.
• The Committee on Education and the Workforce has been investigating your institution since December 7, 2023. The Committee has broad jurisdiction over postsecondary education, including its compliance with Title VI of the Civil Rights Act, campus safety concerns over disruptions to the learning environment, and the awarding of federal student aid under the Higher Education Act.
• The Committee on Oversight and Accountability is investigating the sources of funding and other support flowing to groups espousing pro-Hamas propaganda and engaged in antisemitic harassment and intimidation of students. The Committee on Oversight and Accountability is the principal oversight committee of the US House of Representatives and has broad authority to investigate “any matter” at “any time” under House Rule X.
• The Committee on Ways and Means has been investigating several universities since November 15, 2023, when the Committee held a hearing entitled From Ivory Towers to Dark Corners: Investigating the Nexus Between Antisemitism, Tax-Exempt Universities, and Terror Financing. The Committee followed the hearing with letters to those institutions on January 10, 202
2. Objectives
• Identify the phases in a cell cycle
• Understanding the processes of mitosis and meiosis
• State the importance of mitosis and meiosis
• Explain the importance of controlled mitosis
• Understanding the process of cloning and its characteristics
3. Chromosomes
• DNA are stored as chromosomes in the nucleus.
• Chromosomal number is the characteristics number
of chromosomes of a species.
• In some cases, chromosomes can be found in pair,
which share the same structure, referred as
homologous chromosomes.
• Somatic cells of a diploid organisms contain two
pair of chromosome (2n).
• Gametes or haploid organisms contain only one set
of chromosome (n).
染色体
染色体数
同源染色体
二倍体体细胞
配子 单倍体
4. Karyotype
• A karyotype is the number and appearance of chromosomes in the
nucleus of a eukaryotic cell.
A female genome visualized with fluorescent in situ
hybridization (FISH).
Karyotype variability in different cultivars of maize demonstrated
using FISH.
核型
5. The cell cycle
• The cell cycle is a cyclic
sequences of events that a cell
undergoes, from the time it is
formed until it divides
completely into two.
• Two main phrases in the cell
cycle is:
• Interphase 间期 – cell grows and
prepares for cell division
• Cell division (M phase) – cell
divides its nucleus and
cytoplasm
细胞周期
循环
7. G1 phase
• The first gap phase where the chromosomes are
not very visible and appeared as chromatin.
• The cell grows larger.
• If the environmental condition is flavourable, the
cell will decide to proceed to cell division.
• The centrosome duplication process starts.
Left: Fluorescence microscopic images of nuclei and
chromosomes of BY-2 cells
染色质
中心体
8. S phase
• Synthesis of DNA occurs in this phase.
• DNA is replicated and each chromosome contain two identical sister
chromatids that are joined together by a centromere.
9. G2 phase
• The cell continue to grow in the second
gap phase.
• Organelles are synthesis and metabolism
is active.
• The DNA are present as chromatin.
• The pair of centrosomes has matured.
Fluorescence microscopic images of nuclei and chromosomes
of BY-2 cells
10. Cell division 细胞分裂
• Cell division is the process of forming of new cell(s) from pre-existing
cell.
• Cell division can be achieved by the process of mitosis or meiosis,
followed by cytokinesis.
• Mitosis is the division of the cell nucleus which results in the
production of two identical daughter nuclei.
• Meiosis is a the division of the cell nucleus which results in the
production of four unidentical daughter nuclei with half of the
chromosome number of the parent cell.
• Cytokinesis is the division of the cytoplasm into two.
有丝分裂 减数分裂
胞质分裂 细胞质
12. Significance of mitosis 有丝分裂
• Increase number of cells for growth
• Replacing dead or worn out cells, such as blood cells, epithelial cells
• Repair injured organs and regenerate lost parts, such as tail of a lizard
• Asexual reproduction
• Binary fission in Amoeba
• Budding in yeast
• Vegetative reproduction in plants using rhizomes, tubers and bulbs
无性繁殖
13. The M phase (mitosis and cytokinesis)
• Mitosis can be subdivided
into four continuous phases:
prophase, metaphase,
anaphase and telophase.
• Following telophase,
cytokinesis occurs.
14. Prophase
• In the nucleus, chromosomes condense,
appear shorter and thicker and are
visible under the light microscope.
• In the cytoplasm, spindle fibres begin to
form from the centrioles. Each pair of
centrioles migrates to the opposite site
poles of the cell.
• The chromatids are attached to the
spindle fibres by their centromeres.
• The nucleolus disappears and the
nuclear membrane disintegrates at the
end of prophase.
纺锤体
着丝粒
核仁
核膜
前期
15. Metaphase
• Centromeres of all the chromosome are
lined up on the metaphase plate.
• The mitotic spindle is now fully formed.
• Each sister chromatid is attached to a
spindle fibre originated from opposite
pole.
赤道板
中期
16. Anaphase
• The two sister chromatids of each
chromosome separate at the centrode.
• The sister chromatids are pulled apart to
the opposite poles by the shortening of the
spindle fibres.
• Once separated, the chromatids are
referred as daughter chromosomes.
• By the end of anaphase, two poles of the
cell have complete and equivalent set of
chromosomes.
后期
姐妹染色单体
17. Telophase
• The chromosomes uncoil and revert back
to extended chromatin.
• The chromosomes become less visible
under the microscope.
• The spindle fibres disappear.
• New nuclear membrane forms.
• Nucleolus re-forms in each nucleus.
末期
18. Cytokinesis in animal
• In animal cell, actin filaments in the
cytoplasm contracts to pull a ring of the
plasma membrane inwards, forming a
groove called a cleavage furrow.
• Eventually the cell breaks at the
constricted region and two daughter
cells are form.
胞质分裂
槽 卵裂沟
19. Cytokinesis in plant
• In the plant cells, vesicles gather at a
plant cells equator to form a cell plate.
• The cell plate grow until it fuses to
from new cell walls and plasma
membrane.
胞质分裂
细胞板
21. Comparison of mitosis in plant and animal
• Similarities
• Involves interphase, prophase, metaphase, anaphase, telophase, cytokinesis
• Nucleus divides once and cytoplasm divide once
• Daughter cells are genetically identical to the parent cells.
• Differences
Animal cell Plant cell
Spindle threads emerge from
centrioles.
Spindle threads do not emerge from
centrioles.
Cytokinesis occurs by constriction of
the cytoplasm – cleavage furrow is
formed.
Cytokinesis occurs by the formation of
cell plate.
22.
23.
24. Importance of controlled mitosis
• Correct number of chromosomes is
obtained by the daughter cell
• Correct growth, development and
maintenance of tissues
• To avoid presence of cancerous cells that
divide uncontrollably and form tumour
Left: Atomic-force microscopy
(AFM) maps of adhesion of
the AFM probe to the cell
surface of (a) normal, (b)
immortal (premalignant), and
(c) cancer cells. SEM images of
(d) normal, (e) immortal, and
(f) cancer cells. AFM provided
a higher 3D resolution
compared to SEM. [Sokolov et
al, New Journal of Physics]
Top, Spectral karyogram of normal human male chromosomes.
Image by Nallasivam Palanisamy, Ph.D., Michigan Center for
Translational Pathology. Bottom, Spectral karyogram of a
breast cancer cell line. Image by Mira Grigorova and Paul
Edwards
25. Application of mitosis: cloning
• Cloning is the process of producing
genetically identical organisms through
asexual reproducing, such as budding,
binary fission, grafting, stem cuttings and
tissue culture.
• Tissue culture is the growth of tissues and
cells in sterile culture medium.
• Plant cells will form undifferentiated
callus, but later can developed into
embryo, plantlets and adult plant.
• Genetic engendering can altered the genes
of the plant to enhance crop performance.
组织培养
愈合组织
胎
苗
26. Application of mitosis: animal cloning
• Animal cloning
involves the transfer of
the nucleus from a
somatic cell to an
ovum or embryonic
cell with the nucleus
removed.
28. Meiosis 减数分裂
• Meiosis is a type of cell division that reduces the number of
chromosomes in the parent cell by half and produces four gamete
cells.
• This process is required to produce egg and sperm cells for sexual
reproduction.
• Sexual reproduction involves the fusion of two haploid gametes (n)
during fertilization to produce a diploid zygote (2n).
• Meiosis is divided into meiosis I and meiosis II.
二倍体
单倍体
有性生殖
29. Meiosis I
• Meiosis I takes place after the interphase.
• Here, gene recombination occurs here to generate diversity in the
offspring.
• The chromosomal number is reduced in the daughter cells produced
in meiosis I.
30. Prophase I
• The chromosomes condensed.
• The homologous chromosomes come
together to form bivalents (tetrads) through a
process called synapsis.
• Non-sister chromatids exchange segments of
DNA in a process called crossing over.
• The point at which the chromatids cross over
is called chiasmata.
• At the end of prophase I, the nucleolus and
nuclear membrane disappear, centrioles
migrate to the opposite poles of the cell and
spindle fibre form.
交點
「二價體」或「四分體」聯會
染色體的交換
前期 I
32. Metaphase I
• The chromosome are lined up side by side
as tetrads on the metaphase plate.
• Each tetrad is attached with two spindle
fibre from the opposite pole.
• The centromere does not divide.
中期 I
33. Anaphase I
• The spindle fibres pull the homologous
chromosome away.
• Each chromosome still consists of two
sister chromatids.
后期 I
34. Telophase I
• Each pole has a haploid daughter nucleus
because it contains only one set of
chromosome.
• The spindle fibres dissapear.
• The nuclear membrane and nucleolus
reappear.
• Cytokinesis usually occurs simultaneously
with telophase I.
末期 I
35. Meiosis II
• Meiosis II generally occurs immediately after cytokinesis, usually with
no interphase between them.
• The chromatids still have two sister chromatids.
• In meiosis II, the sister chromatids will be separated.
36. Prophase II
• Chromosome condensed.
• The nuclear membranes disintegrate.
• Spindle fibres reformed.
前期 II
37. Metaphase II
• The chromosome are rearranged in the
metaphase plate with the sister
chromatids of each chromosome pointing
towards the opposite poles.
• Each sister chromatid is attached to the
spindle fibres at the centromere.
中期 II
38. Anaphase II
• The centromeres of the sister chromatids
separate.
• The sister chromatids become individual
chromosome.
• The chromosomes movet owards the
opposite poles of the cell.
后期 II
39. Telophase II
• Nucleolus and nuclear membrane reform.
• Spindle fibre break down.
• Cytokinesis occurs after telophase II.
• The daughter cells are haploid.
末期 II
43. Comparison between mitosis and meiosis
Mitosis Meiosis
One nuclear division Two nuclear division
Two diploid daughter cell Four haploid daughter cell
Daughter cells identical to parent cell Daughter cells unlike parent cell
No genetic variation in daughter cells Genetic variation in daughter cells
45. Mutation
• Mutation is the permanent alteration of the nucleotide sequence of
the genome of an organism, virus, or extrachromosomal DNA or other
genetic elements.
• Radiation, carcinogenic chemicals such as nicotine, and food
preservations (sodium nitrite 亚硝酸钠, benzene 苯, formaldehyde
甲醛) are known to cause changes to the DNA molecule or disturb
mitosis and meiosis.
• Mitosis and meiosis gone awry can lead to mutation.
突变
致癌
46. Down’s Syndrome
• Down syndrome is usually caused by an error in
cell division called "nondisjunction."
• Nondisjunction is the failure of one or more pairs
of homologous chromosomes or sister chromatids
to separate normally during anaphase I or II.
• Nondisjunction results in an embryo with three
copies of chromosome 21 instead of the usual
two.
• Characteristic of affected individuals have slanted
eyes, short stature and mental retardation.
染色体不分离
唐氏综合症
47. Summary
• Two main phrases in the cell cycle is:
• Interphase – cell grows and prepares for cell division
• Cell division (M phase) – cell divides its nucleus and cytoplasm
• Mitosis is the division of the cell nucleus which results in the
production of two identical daughter nuclei.
• Meiosis is a the division of the cell nucleus which results in the
production of four unidentical daughter nuclei with half of the
chromosome number of the parent cell.
• Down’s syndrome is usually caused by an error in meiosis.
Characteristic of affected individuals have slanted eyes, short stature
and mental retardation.