Meiosis is a type of cell division that produces haploid gametes from a diploid cell for sexual reproduction. It involves two rounds of division called Meiosis I and Meiosis II. In Meiosis I, the chromosome number is halved and homologous chromosomes are separated into different daughter cells. Meiosis II then separates sister chromatids so that each daughter cell receives a single set of chromosomes. This process ensures genetic diversity in offspring by independent assortment of chromosomes.
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)
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)
– Male and female gametes fuse together during fertilization to form a zygote. The chromosome number is halved during the formation of gametes by the process of meiosis. This maintains the chromosome number generations after generations. Meiosis leads to genetic diversity which is very essential for evolution.
Cell cycle & Mitosis presentation to help understand the basic concepts related to the topic. This topic is included in the Maharashtra Board curriculum for XIth Std Biology paper. All videos inserted in this powerpoint have their respective copyrights. Unauthorized distribution and copying of the same is prohibited
– Male and female gametes fuse together during fertilization to form a zygote. The chromosome number is halved during the formation of gametes by the process of meiosis. This maintains the chromosome number generations after generations. Meiosis leads to genetic diversity which is very essential for evolution.
Cell cycle & Mitosis presentation to help understand the basic concepts related to the topic. This topic is included in the Maharashtra Board curriculum for XIth Std Biology paper. All videos inserted in this powerpoint have their respective copyrights. Unauthorized distribution and copying of the same is prohibited
The diagnostic imaging market continues to grow, MRI presents the highest increase in scans. However, the market is also experiencing a growing shortage of professionals. Learn how to keep up with demand while maintaining a profitable growth.
Meiosis is the special type of cell division in which the number of chromosomes in daughter cells reduces to half, as compared to the parent cell. It takes place in diploid cells only, in animals at the time of gamete formation, while in plants when spores are produced.
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
ntry points of glucogenicamino acids after transamination
are indicated by arrows extended from circles
the key gluconeogenicenzymes are enclosed in double
bordered boxes. oated fashion. They are interdependent; each forms a strand in the web of life. Parasitology is
the science that deals with organisms living in the human body (the host) and the medical significance of
this host-parasite relationship.
ASSOCIATION BETWEEN PARASITE AND HOST
A parasite is a living organism, which takes its nourishment and other needs from ahost; the host is an
organism which supports the parasite. The hosts vary depending on whether they harbor the various
stages in parasitic development
DIFFERENT KINDS OF PARASITES
Ectoparasite – a parasitic organism that lives on the outer surface of its host, e.g. lice, ticks, mites etc.
Endoparasites parasites that live inside the body of their host, e.g. Entamoeba histolytica.
Obligate Parasite- This parasite is completely dependent on the host during a segment or all of its life
cycle, e.g. Plasmodium spp.
Facultative parasite – an organism that exhibits both parasitic and non-parasitic modes of living and
hence does not absolutely depend on the parasitic way of life but is capable of adapting to it if paced on
a host. E.g. Naegleria fowleri
Accidental parasite – when a parasite attacks an unnatural host and survives. E.g. Hymenolepis diminuta
(rat tapeworm).
Erratic parasite - is one that wanders in to an organ in which it is not usually found. E.g. Entamoeba
histolytica in the liver or lung of humans.
Most of the parasites which live in/on the body of the host do not cause disease (non-pathogenic
parasites). In Medical parasitology we focus on most of the disease causing (pathogenic) parasites.
However, understanding parasites which do not ordinariy produce disease in heathy
(immunocompetent) individuals but do cause illness in individuals with impaired defense mechanism
(opportunistic parasites) is becoming of paramount importance because of the increasing prevaence of
HIV/AIDS in our country.
DIFFERENT KINDS OF HOSTS
Definitive host – a host that harbors a parasite in the adult stage or where the parasite undergoes a
sexual method of reproduction.
Intermediate host - harbors the arval stages of the parasite or an asexual cycle of development takes
pace. In some cases, larval development is completed in two different intermediate hosts, referred to
as first and second intermediate hosts.
Paratenic host – a host that serves as a temporary refuge and vehicle for reaching an obligatory host,
usually the definitive host, i.e. it is not necessary for the completion of the parasites life cycle.
Reservoir host – a host that makes the parasite available for the transmission to another host and is
usually not affected by the infection.
Natural host a host that is naturally infected with certain species of parasite.
Accidental host – a host that is under normal circumstances not infected with th
Meiosis is reductional division in which the chromosome number is reduced to half. During meiosis, four haploid daughter cells are formed from one parental cell.
It is a process in which the chromosomes duplicate only once but the cell divides twice.
It results in formation of four haploid cells. Hence, it is also called reduction division.
Richard's aventures in two entangled wonderlandsRichard Gill
Since the loophole-free Bell experiments of 2020 and the Nobel prizes in physics of 2022, critics of Bell's work have retreated to the fortress of super-determinism. Now, super-determinism is a derogatory word - it just means "determinism". Palmer, Hance and Hossenfelder argue that quantum mechanics and determinism are not incompatible, using a sophisticated mathematical construction based on a subtle thinning of allowed states and measurements in quantum mechanics, such that what is left appears to make Bell's argument fail, without altering the empirical predictions of quantum mechanics. I think however that it is a smoke screen, and the slogan "lost in math" comes to my mind. I will discuss some other recent disproofs of Bell's theorem using the language of causality based on causal graphs. Causal thinking is also central to law and justice. I will mention surprising connections to my work on serial killer nurse cases, in particular the Dutch case of Lucia de Berk and the current UK case of Lucy Letby.
Seminar of U.V. Spectroscopy by SAMIR PANDASAMIR PANDA
Spectroscopy is a branch of science dealing the study of interaction of electromagnetic radiation with matter.
Ultraviolet-visible spectroscopy refers to absorption spectroscopy or reflect spectroscopy in the UV-VIS spectral region.
Ultraviolet-visible spectroscopy is an analytical method that can measure the amount of light received by the analyte.
Earliest Galaxies in the JADES Origins Field: Luminosity Function and Cosmic ...Sérgio Sacani
We characterize the earliest galaxy population in the JADES Origins Field (JOF), the deepest
imaging field observed with JWST. We make use of the ancillary Hubble optical images (5 filters
spanning 0.4−0.9µm) and novel JWST images with 14 filters spanning 0.8−5µm, including 7 mediumband filters, and reaching total exposure times of up to 46 hours per filter. We combine all our data
at > 2.3µm to construct an ultradeep image, reaching as deep as ≈ 31.4 AB mag in the stack and
30.3-31.0 AB mag (5σ, r = 0.1” circular aperture) in individual filters. We measure photometric
redshifts and use robust selection criteria to identify a sample of eight galaxy candidates at redshifts
z = 11.5 − 15. These objects show compact half-light radii of R1/2 ∼ 50 − 200pc, stellar masses of
M⋆ ∼ 107−108M⊙, and star-formation rates of SFR ∼ 0.1−1 M⊙ yr−1
. Our search finds no candidates
at 15 < z < 20, placing upper limits at these redshifts. We develop a forward modeling approach to
infer the properties of the evolving luminosity function without binning in redshift or luminosity that
marginalizes over the photometric redshift uncertainty of our candidate galaxies and incorporates the
impact of non-detections. We find a z = 12 luminosity function in good agreement with prior results,
and that the luminosity function normalization and UV luminosity density decline by a factor of ∼ 2.5
from z = 12 to z = 14. We discuss the possible implications of our results in the context of theoretical
models for evolution of the dark matter halo mass function.
Professional air quality monitoring systems provide immediate, on-site data for analysis, compliance, and decision-making.
Monitor common gases, weather parameters, particulates.
Slide 1: Title Slide
Extrachromosomal Inheritance
Slide 2: Introduction to Extrachromosomal Inheritance
Definition: Extrachromosomal inheritance refers to the transmission of genetic material that is not found within the nucleus.
Key Components: Involves genes located in mitochondria, chloroplasts, and plasmids.
Slide 3: Mitochondrial Inheritance
Mitochondria: Organelles responsible for energy production.
Mitochondrial DNA (mtDNA): Circular DNA molecule found in mitochondria.
Inheritance Pattern: Maternally inherited, meaning it is passed from mothers to all their offspring.
Diseases: Examples include Leber’s hereditary optic neuropathy (LHON) and mitochondrial myopathy.
Slide 4: Chloroplast Inheritance
Chloroplasts: Organelles responsible for photosynthesis in plants.
Chloroplast DNA (cpDNA): Circular DNA molecule found in chloroplasts.
Inheritance Pattern: Often maternally inherited in most plants, but can vary in some species.
Examples: Variegation in plants, where leaf color patterns are determined by chloroplast DNA.
Slide 5: Plasmid Inheritance
Plasmids: Small, circular DNA molecules found in bacteria and some eukaryotes.
Features: Can carry antibiotic resistance genes and can be transferred between cells through processes like conjugation.
Significance: Important in biotechnology for gene cloning and genetic engineering.
Slide 6: Mechanisms of Extrachromosomal Inheritance
Non-Mendelian Patterns: Do not follow Mendel’s laws of inheritance.
Cytoplasmic Segregation: During cell division, organelles like mitochondria and chloroplasts are randomly distributed to daughter cells.
Heteroplasmy: Presence of more than one type of organellar genome within a cell, leading to variation in expression.
Slide 7: Examples of Extrachromosomal Inheritance
Four O’clock Plant (Mirabilis jalapa): Shows variegated leaves due to different cpDNA in leaf cells.
Petite Mutants in Yeast: Result from mutations in mitochondrial DNA affecting respiration.
Slide 8: Importance of Extrachromosomal Inheritance
Evolution: Provides insight into the evolution of eukaryotic cells.
Medicine: Understanding mitochondrial inheritance helps in diagnosing and treating mitochondrial diseases.
Agriculture: Chloroplast inheritance can be used in plant breeding and genetic modification.
Slide 9: Recent Research and Advances
Gene Editing: Techniques like CRISPR-Cas9 are being used to edit mitochondrial and chloroplast DNA.
Therapies: Development of mitochondrial replacement therapy (MRT) for preventing mitochondrial diseases.
Slide 10: Conclusion
Summary: Extrachromosomal inheritance involves the transmission of genetic material outside the nucleus and plays a crucial role in genetics, medicine, and biotechnology.
Future Directions: Continued research and technological advancements hold promise for new treatments and applications.
Slide 11: Questions and Discussion
Invite Audience: Open the floor for any questions or further discussion on the topic.
THE IMPORTANCE OF MARTIAN ATMOSPHERE SAMPLE RETURN.Sérgio Sacani
The return of a sample of near-surface atmosphere from Mars would facilitate answers to several first-order science questions surrounding the formation and evolution of the planet. One of the important aspects of terrestrial planet formation in general is the role that primary atmospheres played in influencing the chemistry and structure of the planets and their antecedents. Studies of the martian atmosphere can be used to investigate the role of a primary atmosphere in its history. Atmosphere samples would also inform our understanding of the near-surface chemistry of the planet, and ultimately the prospects for life. High-precision isotopic analyses of constituent gases are needed to address these questions, requiring that the analyses are made on returned samples rather than in situ.
3. MEIOSIS
• Meiosis is a special type of cell division
necessary for sexual reproduction in
eukaryotes.
• Meiosis reduces the chromosome number
by half results in the production of haploid
daughter cells.
• It involves two sequential cycles of nuclear
and cell division called meiosis I and
meiosis II
4.
5. MEIOSIS I
It is also called the reduction
division, here reduction of
chromosome number takes place.
Meiosis I contained 4 stages,
1. prophase
2. metaphase
3. anaphase
4. telophase
6.
7. Prophase I
• Longest phase in meiosis.
• Sub divided into 5 phases based on
chromosomal behaviour,
1.Leptotene
2.Zygotene
3.Pachytene
4.Diplotene
5.Diakinesis
9. Metaphase I
Spindle formatuon is completede.
Chromosomes are arranged at the
equater of spindle.
10. Anaphase I
Chromosomes are move alone with
spindle towards the poles.
At the end of anaphase the diploid
number of chromosomes is redused into
haploid condition.
11. Telophase I
The nuclear membrane and nucleolus
reappear.
Cytokinesis follows and this is called as
diade of cell.
12. Meiosis II
• Also called equational division.
• Meiosis II contains 4 phases they are,
1. Prophase II
2. Metaphase II
3. Anaphase II
4. Telophase II
13.
14. Prophase II
• Sister chromatids of each chromosome
being to condence.
• The nucleolus and nuclear envelope
disappear in both nuclei.
• Spindle fibres are formed.
15. Metaphase II
• The spindle formation is completed.
• Chromosomes align at the equator.
16. ANAPHASE II
• The division of centromere takes place
longitudinally.
• The chromatides separate and go to the
opposite pole.
17. Telophase II
• The four group of chromosomes on reaching the
poles organise into four daughter nuclei.
• Nuclei and nuclear envelop are appear.
• Each nucleus has haploid number of
chromosomes.
• Chromosomes recognize into chromatin fibres.
18. Cytokinesis
• The cell itself is divided into two daughter
cells by a separate process called
cytokinesis.
• In animal cell cytokinesis is done the
appearance of a furrow in he plasma
membrane. The furrow gradually
disappear and ultimately joins in the
center dividing the cell cytoplasm into
two.
