Cell reproduction occurs through mitosis and meiosis. Mitosis produces two identical daughter cells and is used for growth and repair. Meiosis produces four non-identical gametes through two cell divisions and genetic mixing during prophase I. This ensures genetic variation in offspring that is important for evolution of species.
It is the presentation on the MEIOSIS phase of the Cell division.
It includes all the details and definitions that are related to the topic of meiosis with the labelled diagrams.
If you have any query or a question, you may ask in the comment box.
thanks.
It is the presentation on the MEIOSIS phase of the Cell division.
It includes all the details and definitions that are related to the topic of meiosis with the labelled diagrams.
If you have any query or a question, you may ask in the comment box.
thanks.
This presentation explains the topic of CELL CYCLE and CELL DIVISION.
It includes cell mitosis of both Plant cell and Animal cell with labelled diagrams.
The slides contain all about meiosis. in this slides i collected all information about meiosis. which is useful for everyone.
so watch these slides and comment for any problems.
thanks
Mitosis and meosis are two common phenomenons, one can get plenty information about these two but its significance is very rarely provided on social networks. Here is its significance, have a look.
This presentation explains the topic of CELL CYCLE and CELL DIVISION.
It includes cell mitosis of both Plant cell and Animal cell with labelled diagrams.
The slides contain all about meiosis. in this slides i collected all information about meiosis. which is useful for everyone.
so watch these slides and comment for any problems.
thanks
Mitosis and meosis are two common phenomenons, one can get plenty information about these two but its significance is very rarely provided on social networks. Here is its significance, have a look.
DNA replication is a semiconservative process. It means that each strand acts as a template for the synthesis of a new complementary strand. Therefore, this process takes us from one parent molecule to two daughter molecules, with each newly formed double helix containing one new and one old strand.
-Cell Division Process In Prokaryotes & Eukaryotes
-Compacting DNA into Chromosomes
-Types of Cell Reproduction
-Phases of the Cell Cycle
-Mitosis
-Meiosis
-Oogenesis & Spermatogenesis
-Comparison of Divisions
1. Describe how variation in meiosis happens and why it is beneficia.pdffashioncollection2
1. Describe how variation in meiosis happens and why it is beneficial? Steps and functions of
mitosis and meiosis? ( I am having a hard time with defining each step in mitosis and meiosis.
There is meiosis I and II and I get confused on the steps with functions. Any ideas how I can
remember?)
TIA :)
Solution
Explanation:-
Variation in meiosis:-
During meiosis in humans, 1 diploid cell (with 46 chromosomes or 23 pairs) undergoes 2 cycles
of cell division but only 1 round of DNA replication. The result is 4 haploidHaving one copy of
each chromosome, or having a single set of chromosomes. Gametes (egg and sperm cells) are
haploid. daughter cells known as gametes or egg and sperm cells (each with 23 chromosomes – 1
from each pair in the diploid cell).
At conception, an egg cell and a sperm cell combine to form a zygote (46 chromosomes or 23
pairs). This is the 1st cell of a new individual. The halving of the number of chromosomes in
gametes ensures that zygotes have the same number of chromosomes from one generation to the
next. This is critical for stable sexual reproduction through successive generations.
Benefits of Meiosis:-
1. New Cell Generation-
The chromosomes created during meiosis are composed of 50% copies of the parent cell and
50% new cells. ‘Â These new cells are produced during the cross-over stages of the cell division
process. ‘Â During this stage half of the genetic material from the parent cell is copied into the
new cells, with the other half having distinct properties and characteristics.
2. DNA Replication
The process of meiosis involves copying or replication of genetic material from the parent cell
into the new cells. ‘Â As much as half of the genetic properties of the parent cell are copied into
the newly-created cells. ‘Â When applied to humans for example, DNA from both parents will
partly be copied onto the cells of their offspring. ‘Â When DNA is copied or replicated, the
offspring will also have similar qualities with either or both of his/her parents.
3. Genetic Variation
With meiosis, only half of the genetic material is replicated into the new cells. ‘Â This simply
means that the remaining half will be composed of unique genetic properties making each cell
different from the other. ‘Â Through this process, humans for example will all have different
genetic material and structure.
With the process involved in meiosis, humans are able to reproduce similar yet distinct offspring.
‘Â The whole process basically explains the fact that babies may share some genetic traits from
their parents but they will also have unique sets of personalities because of their unique genetic
composition.
Meiosis Stages:-
Prophase I
Chromosomes condense, Crossing over occurs
Metaphase I
Homologous chromosomes pair up and align in middle of cell
Anaphase I
Homologous chromosomes pulled apart
Telophase I
Nuclear Envelope reforms
Cytokinesis I
Cell splits into two
Prophase II
Centrioles divide and move to opposite poles
Metaphase II
Chromoso.
Forensic Science - 03 Fibres and fabricsIan Anderson
A closer look at how forensic scientists investigate fibres and fabrics as part of a criminal investigation for Year 9 students at Saint Ignatius College Geelong.
Embracing GenAI - A Strategic ImperativePeter 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.
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.
How to Make a Field invisible in Odoo 17Celine George
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.
Francesca Gottschalk - How can education support child empowerment.pptxEduSkills OECD
Francesca Gottschalk from the OECD’s Centre for Educational Research and Innovation presents at the Ask an Expert Webinar: How can education support child empowerment?
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
Model Attribute Check Company Auto PropertyCeline George
In Odoo, the multi-company feature allows you to manage multiple companies within a single Odoo database instance. Each company can have its own configurations while still sharing common resources such as products, customers, and suppliers.
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!
2. Cell reproduction.
All cells are derived from pre-existing cells.
Enables the genes and cell components of parent cell
to passed onto the daughter cells.
Cells must reproduce for
growth of the organism.
repair of damaged cells.
replacement of dying cells.
reproduction of the species.
3. Cell cycle.
The series of event that take place in a cell leading to
its division (i.e. interphase + mitosis).
Source: http://www.scq.ubc.ca/the-cell-cycle-a-universal-cellular-division-program/
4. Cell cycle.
Interphase.
Cells spend most of their lives in interphase.
Three stages:
G1 (Gap 1)
Cell growing.
S (Synthesis)
DNA replication occurs chromosomes duplicating.
G2 (Gap 2)
Cell grows & preparation for the next cellular division.
Mitosis.
5. DNA replication.
Why is DNA replication necessary?
When cells divide new daughter cells are produced.
These daughter cells need to have functioning DNA in
order to survive.
DNA of the parent cell is therefore copied and each
daughter cell gets a copy.
Source: http://updateyourself-2012.blogspot.com.au/
6. DNA replication.
Steps of DNA replication.
1. DNA helicase unwinds DNA by breaking the weak
hydrogen bonds holding the base pairs together.
2. DNA polymerase attaches to each of the two strands
and pairs each exposed nucleotide with a new
complimentary nucleotide.
Replication can only proceed in the 3’ to 5’ direction of the
original molecule (i.e adds nucleotides in the 5’ to 3’
direction of the new strand).
Leading strand = bases added continuously.
Lagging strand = bases added in short fragments
(Okazaki ) & joined by DNA ligase.
7. 3. When replication is nearing completion, the two new
molecules of DNA separate and become individual
chromosomes.
The two new molecules of DNA (chromosomes) are
identical to each other.
DNA replication is semi-conservative.
DNA replication.
Source:
http://www.biologycorner.com/bio1/DNA
9. Mitosis.
Occurs in eukaryotic organisms.
Single celled eukaryotes e.g. paramecium.
Regions of growth & repair in animals.
Roots & shoot tips of plants (+ other meristemic tissue).
Mitotic cell division is used
To provide new cells for growth.
Repair and maintenance of tissues.
Asexual reproduction.
10. Mitosis.
Occurs in somatic cells.
Involves one nuclear division.
Results in two genetically identical daughter cells.
Both daughter cells are diploid (2n).
Four stages (although process is continuous).
Prophase, Metaphase, Anaphase & Telophase.
12. Mitosis.
Interphase:
Not really part of mitosis [but often included].
Cell looks like it normally does when not dividing.
Nuclear membrane present.
Chromosomes are not clearly visible – chromatin.
DNA replication occurs (during S stage).
13. Mitosis.
Prophase:
Chromosomes condense & become visible (consisting of
two sister chromatids joined at centromere).
Nuclear membrane breaks down.
Centrioles move to opposite poles of the cell & extend
spindle fibres across cell.
Centrioles not present in plants.
14. Mitosis.
Metaphase:
Centromeres (point of attachment for the two sister
chromatids) attach to spindle fibres.
Chromosomes line up along the equator.
Anaphase:
Chromatids separate and move to opposite poles (called
chromosomes again from now on).
15. Mitosis.
Telophase:
Nuclear membrane reforms around chromosomes.
Spindle fibres disperse.
Cell cleavage
Animal cells – cytoplasm constricts to form two separate cells.
Plant cells – the rigid cell wall requires that a cell plate be
synthesised between the two daughter cells.
Interphase:
Cells return to interphase.
16. Meiosis.
Occurs in eukaryotic organisms.
Single celled eukaryotes.
Gonads of animals.
Flowers (stamens & pistil) of plants.
Meiotic cell division is essential for sexual
reproduction
Preserves genome size post fertilisation of gametes.
Increases variability within a species.
17. Meiosis.
Involves two divisions.
Results in 4 daughter cells – gametes/spores.
Daughter cells are all haploid (n) – half the number of
parent cell.
Each division has four stages.
Prophase I, Metaphase I, Anaphase I & Telophase I.
Prophase II, Metaphase II, Anaphase II & Telophase II.
19. Meiosis.
Interphase:
Not really part of meiosis [but often included].
Cell looks like it normally does when not dividing.
Nuclear membrane present.
Chromosomes are not clearly visible – chromatin.
DNA replication occurs (during S stage).
20. Meiosis.
Prophase I:
Chromosomes condense & become visible.
Chromosomes line up together (called synapsis) and
form homologous pairs.
Crossing over can occur.
Nuclear membrane breaks down.
Centrioles move to opposite poles of the cell & extend
spindle fibres across cell.
21. Meiosis.
Metaphase I:
Centromeres (point of attachment for the two sister
chromatids) attach to spindle fibres.
Homologous chromosomes line up along the equator.
Mendel’s second Law of Independent Assortment.
Anaphase I:
Homologous pairs separate and move to opposite poles.
22. Meiosis.
Telophase I:
Nuclear membrane reforms around chromosomes.
Spindle fibres disperse.
Cytokinesis occurs (or partly occurs).
Results in two daughter cells, each containing only one
of the homologous pairs of chromosomes (n).
Interphase:
Cells return to a brief interphase.
DNA does not duplicate again.
23. Meiosis.
Prophase II:
Chromosomes condense & become visible as two
chromatids joined at centromere.
Nuclear membrane breaks down.
Centrioles move to opposite poles of the cell & extend
spindle fibres across cell.
24. Meiosis.
Metaphase II:
Centromeres (point of attachment for the two sister
chromatids) attach to spindle fibres.
Chromosomes line up along the equator.
Anaphase II:
Sister chromatids separate and move to opposite poles.
25. Meiosis.
Telophase II:
Nuclear membrane reforms around ‘new’ chromosomes.
Spindle fibres disperse.
Cytokinesis occurs.
Final result is four haploid (n) daughter cells.
In humans – sperm (4 gametes) v ovum (1 egg & 3 polar
bodies).
26. Meiosis.
Crossing over.
The exchange of equivalent portions of DNA between
homologous chromosomes.
Occurs during Prophase I.
Chromatids of the homologs are in close contact (synapsed)
with each other.
Homologous, non-sister chromatids become entangled and
then exchange segments.
Crossing over location = chiasma.
Crossing over can occur at a number of locations (chiasmata)
on a chromosome.
On average 2-3 crossovers occur per human chromosome.
28. Meiosis.
Crossing over.
Allows new combinations of genetic information (called
genetic recombination) and results in increased genetic
variability.
Without crossing only two kinds of genetically different
gametes are formed, however with crossing over, four
genetically different gametes are formed.
Source: Enger et al. (2012)
Synapsis and crossing over at two locations.
29. Meiosis.
Independent assortment of chromosomes.
The random orientation of pairs of homologous
chromosomes during Meiosis I.
Each pair of homologous chromosomes is positioned
independently of the other pairs.
The number of possible combinations when
chromosomes sort independently = 2n (where n =
haploid number of cell).
e.g. In humans (n=23) 8.4 million (223) possible
chromosome combinations for each gamete.
31. Meiosis.
Significance of meiosis.
Results in the production of gametes, each with the
haploid number (n) of chromosomes.
Diploid number (2n) is restored when two gametes fuse
during sexual reproduction.
Provides opportunities for new combinations of gene
alleles to occur in the gamete cells increased variation
within the species.
Crossing over (Prophase I).
Independent assortment of chromosomes (Metaphase I).
Random combination of gametes during fertilisation.
32. Mitosis v Meiosis.
Mitosis Meiosis
Produces cells for growth
and repair; and in some
species asexual reproduction
Produces gametes, reduces
number of chromosomes by
half and introduces genetic
variability among gametes
One cell division Two cell divisions
Chromosomes line up
individually
Chromosomes line up in
homologous pairs
Produces two diploid (2n)
daughter cells, each
genetically identical from
the parent cell
Produces four haploid (n)
daughter cells, each
genetically different from the
parent cell
Daughter cells are genetically
identical
Daughter cells are not
genetically identical
33. Binary fission.
Occurs in all prokaryotic & some eukaryotic
organisms.
Not mitosis!
Asexual reproduction.
Prokaryotes have single circular chromosome.
Chromosome is duplicated and attaches to cell
membrane.
Cell membrane divides with one strand going into
each daughter cell.
35. Apoptosis.
Cells have a limited life span
They age and eventually become unable to effectively
carry out their role.
They become infected or ‘sick’.
Due to development of the organism, they no longer
have a functional role.
e.g. full webbing between the fingers & toes of an embryo is
not needed if they are to become independent digits.
36. Apoptosis.
Cells are therefore pre-programmed to age and die
Apoptosis = programmed cell death.
37. Apoptosis.
Controlled by genes that are activated
During specific stages of development (e.g. a tadpole
losing its tail).
In response to cell damage or viral invasion.
During apoptosis the cell is broken down into
fragments and wrapped in a membranes. These
fragments are then engulfed by phagocytes.
Cancerous cells avoid apoptosis and therefore are able
to grow and reproduce unchecked.