Cells can only arise through the division of pre-existing cells. The first cells on Earth likely developed from non-living organic molecules through a process of self-assembly and the development of membranes. Louis Pasteur's experiments disproved the theory of spontaneous generation and provided evidence that cells only come from other cells. The endosymbiotic theory explains the origin of eukaryotic cells through the engulfment of prokaryotic cells that developed into organelles like mitochondria and chloroplasts.
in this ppt, i had discuss about cell,its structure,function.types of cells, plant and animal cell.and difrrence between plant and animal cell / prokaryotic and eukaryotic cell.
A prelude to genetics of Mitochondria and Chloroplasts
the theory provides an explanation for the presence and source of organellar genome in eukaryotic cell
in this ppt, i had discuss about cell,its structure,function.types of cells, plant and animal cell.and difrrence between plant and animal cell / prokaryotic and eukaryotic cell.
A prelude to genetics of Mitochondria and Chloroplasts
the theory provides an explanation for the presence and source of organellar genome in eukaryotic cell
The presentation gives an overview of Cell & Molecular Biology for Under-graduate students of Indian Universities. For Practical aspects, students may refer 'Research Techniques in Genetics, Molecular Biology & Biotechnology - HK Garg & Jaya Garg LAMBERT Academic Publishing, Germany'.
Life, living matter are those that shows certain attributes that include responsiveness, growth, metabolism, energy transformation and reproduction.
In biology origin of life or abiogenesis is the natural process by which life has arisen from non-living matter, such as simple organic compounds.
It means the emergence of heritable and evolvable self-reproduction.
It is a complex subject and oftentimes controversial.
Several attempts have been made from time to time to explain the origin of life on earth.
There are several theories which offer their own explanation on the possible mechanism of origin of life.
The presentation gives an overview of Cell & Molecular Biology for Under-graduate students of Indian Universities. For Practical aspects, students may refer 'Research Techniques in Genetics, Molecular Biology & Biotechnology - HK Garg & Jaya Garg LAMBERT Academic Publishing, Germany'.
Life, living matter are those that shows certain attributes that include responsiveness, growth, metabolism, energy transformation and reproduction.
In biology origin of life or abiogenesis is the natural process by which life has arisen from non-living matter, such as simple organic compounds.
It means the emergence of heritable and evolvable self-reproduction.
It is a complex subject and oftentimes controversial.
Several attempts have been made from time to time to explain the origin of life on earth.
There are several theories which offer their own explanation on the possible mechanism of origin of life.
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/
Multi-source connectivity as the driver of solar wind variability in the heli...Sérgio Sacani
The ambient solar wind that flls the heliosphere originates from multiple
sources in the solar corona and is highly structured. It is often described
as high-speed, relatively homogeneous, plasma streams from coronal
holes and slow-speed, highly variable, streams whose source regions are
under debate. A key goal of ESA/NASA’s Solar Orbiter mission is to identify
solar wind sources and understand what drives the complexity seen in the
heliosphere. By combining magnetic feld modelling and spectroscopic
techniques with high-resolution observations and measurements, we show
that the solar wind variability detected in situ by Solar Orbiter in March
2022 is driven by spatio-temporal changes in the magnetic connectivity to
multiple sources in the solar atmosphere. The magnetic feld footpoints
connected to the spacecraft moved from the boundaries of a coronal hole
to one active region (12961) and then across to another region (12957). This
is refected in the in situ measurements, which show the transition from fast
to highly Alfvénic then to slow solar wind that is disrupted by the arrival of
a coronal mass ejection. Our results describe solar wind variability at 0.5 au
but are applicable to near-Earth observatories.
Professional air quality monitoring systems provide immediate, on-site data for analysis, compliance, and decision-making.
Monitor common gases, weather parameters, particulates.
Richard's entangled aventures in wonderlandRichard 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.
Introduction:
RNA interference (RNAi) or Post-Transcriptional Gene Silencing (PTGS) is an important biological process for modulating eukaryotic gene expression.
It is highly conserved process of posttranscriptional gene silencing by which double stranded RNA (dsRNA) causes sequence-specific degradation of mRNA sequences.
dsRNA-induced gene silencing (RNAi) is reported in a wide range of eukaryotes ranging from worms, insects, mammals and plants.
This process mediates resistance to both endogenous parasitic and exogenous pathogenic nucleic acids, and regulates the expression of protein-coding genes.
What are small ncRNAs?
micro RNA (miRNA)
short interfering RNA (siRNA)
Properties of small non-coding RNA:
Involved in silencing mRNA transcripts.
Called “small” because they are usually only about 21-24 nucleotides long.
Synthesized by first cutting up longer precursor sequences (like the 61nt one that Lee discovered).
Silence an mRNA by base pairing with some sequence on the mRNA.
Discovery of siRNA?
The first small RNA:
In 1993 Rosalind Lee (Victor Ambros lab) was studying a non- coding gene in C. elegans, lin-4, that was involved in silencing of another gene, lin-14, at the appropriate time in the
development of the worm C. elegans.
Two small transcripts of lin-4 (22nt and 61nt) were found to be complementary to a sequence in the 3' UTR of lin-14.
Because lin-4 encoded no protein, she deduced that it must be these transcripts that are causing the silencing by RNA-RNA interactions.
Types of RNAi ( non coding RNA)
MiRNA
Length (23-25 nt)
Trans acting
Binds with target MRNA in mismatch
Translation inhibition
Si RNA
Length 21 nt.
Cis acting
Bind with target Mrna in perfect complementary sequence
Piwi-RNA
Length ; 25 to 36 nt.
Expressed in Germ Cells
Regulates trnasposomes activity
MECHANISM OF RNAI:
First the double-stranded RNA teams up with a protein complex named Dicer, which cuts the long RNA into short pieces.
Then another protein complex called RISC (RNA-induced silencing complex) discards one of the two RNA strands.
The RISC-docked, single-stranded RNA then pairs with the homologous mRNA and destroys it.
THE RISC COMPLEX:
RISC is large(>500kD) RNA multi- protein Binding complex which triggers MRNA degradation in response to MRNA
Unwinding of double stranded Si RNA by ATP independent Helicase
Active component of RISC is Ago proteins( ENDONUCLEASE) which cleave target MRNA.
DICER: endonuclease (RNase Family III)
Argonaute: Central Component of the RNA-Induced Silencing Complex (RISC)
One strand of the dsRNA produced by Dicer is retained in the RISC complex in association with Argonaute
ARGONAUTE PROTEIN :
1.PAZ(PIWI/Argonaute/ Zwille)- Recognition of target MRNA
2.PIWI (p-element induced wimpy Testis)- breaks Phosphodiester bond of mRNA.)RNAse H activity.
MiRNA:
The Double-stranded RNAs are naturally produced in eukaryotic cells during development, and they have a key role in regulating gene expression .
Deep Behavioral Phenotyping in Systems Neuroscience for Functional Atlasing a...Ana Luísa Pinho
Functional Magnetic Resonance Imaging (fMRI) provides means to characterize brain activations in response to behavior. However, cognitive neuroscience has been limited to group-level effects referring to the performance of specific tasks. To obtain the functional profile of elementary cognitive mechanisms, the combination of brain responses to many tasks is required. Yet, to date, both structural atlases and parcellation-based activations do not fully account for cognitive function and still present several limitations. Further, they do not adapt overall to individual characteristics. In this talk, I will give an account of deep-behavioral phenotyping strategies, namely data-driven methods in large task-fMRI datasets, to optimize functional brain-data collection and improve inference of effects-of-interest related to mental processes. Key to this approach is the employment of fast multi-functional paradigms rich on features that can be well parametrized and, consequently, facilitate the creation of psycho-physiological constructs to be modelled with imaging data. Particular emphasis will be given to music stimuli when studying high-order cognitive mechanisms, due to their ecological nature and quality to enable complex behavior compounded by discrete entities. I will also discuss how deep-behavioral phenotyping and individualized models applied to neuroimaging data can better account for the subject-specific organization of domain-general cognitive systems in the human brain. Finally, the accumulation of functional brain signatures brings the possibility to clarify relationships among tasks and create a univocal link between brain systems and mental functions through: (1) the development of ontologies proposing an organization of cognitive processes; and (2) brain-network taxonomies describing functional specialization. To this end, tools to improve commensurability in cognitive science are necessary, such as public repositories, ontology-based platforms and automated meta-analysis tools. I will thus discuss some brain-atlasing resources currently under development, and their applicability in cognitive as well as clinical neuroscience.
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.
Observation of Io’s Resurfacing via Plume Deposition Using Ground-based Adapt...Sérgio Sacani
Since volcanic activity was first discovered on Io from Voyager images in 1979, changes
on Io’s surface have been monitored from both spacecraft and ground-based telescopes.
Here, we present the highest spatial resolution images of Io ever obtained from a groundbased telescope. These images, acquired by the SHARK-VIS instrument on the Large
Binocular Telescope, show evidence of a major resurfacing event on Io’s trailing hemisphere. When compared to the most recent spacecraft images, the SHARK-VIS images
show that a plume deposit from a powerful eruption at Pillan Patera has covered part
of the long-lived Pele plume deposit. Although this type of resurfacing event may be common on Io, few have been detected due to the rarity of spacecraft visits and the previously low spatial resolution available from Earth-based telescopes. The SHARK-VIS instrument ushers in a new era of high resolution imaging of Io’s surface using adaptive
optics at visible wavelengths.
2. Understandings, Applications and Skills
• Statement
• Guidance
Statement Guidance
1.5 U1 Cells can only be formed by division of pre-
existing cells.
Students should be aware
that the 64codons in the genetic
code have the same meanings in
nearly all organisms, but that
there are some minor
variations that are likely to
have accrued since the common
origin of life on Earth.
1.5 U2 The first cells must have arisen from non-living
material.
1.5 U3 The origin of eukaryotic cells can be explained by
the endosymbiotic theory.
Evidence for the endosymbiotic
theory is expected. The origin of
eukaryote cilia and flagella does
not need to be included.
1.5 A1 Evidence from Pasteur’s experiments that
spontaneous generation of cells and organisms
does not now occur on Earth
3. Spontaneous generation
• It was believed that; Spontaneous generation
is the formation of living organisms from non-
living matter.
• Louis Pasteur responded by carrying out
experiments with swan-necked flasks, which
established beyond reasonable doubt that
spontaneous generation of life does not now
occur.
4. Biologists accepts
• Pasteur found that cells only come from pre-
existing cells:
– A cell is a highly complex structure and no natural
mechanism has been suggested for producing cells
from simpler subunits.
– No example is known of increases in the number of
cells in a population, organism or tissue without cell
division occurring.
– Viruses are produced from simpler subunits but they
do not consist of cells, and they can only be produced
inside the host cells that they have infected.
5. Louis Pasteur
• Evidence from Pasteur’s experiments that
spontaneous generation of cells and
organisms does not now occur on Earth.
6. Louis Pasteur
• Louis Pasteur designed an experiment to test whether
sterile nutrient broth could spontaneously generate
microbial life.
• Method:
– Two experiments were setup
– In both, Pasteur added nutrient broth to flasks and bent
the necks of the flasks into S shapes
– Each flask was then heated to boil the broth in order than
all existing microbes were killed.
– After the broth had been sterilized, Pasteur broke off the
swan necks from the flasks in Experiment 1, exposing the
nutrient broth within them to air from above.
– The flasks in Experiment 2 were left alone.
7. Louis Pasteur
• Results
– The broth in Experiment 1 turned cloudy whilst
the both in Experiment 2 remained clear.
– This indicates that microbe growth only occurred
in Experiment 1.
8. Louis Pasteur
• Conclusion:
– Pasteur rejected the hypothesis of spontaneous
generation as for growth of microbes to occur a
source of contamination was needed.
9. Cell theory
• All living things are composed of cells (or cell
products)
• The cell is the smallest unit of life
• Cells only arise from pre-existing cells
10. Pre-existing cells
• Cells can only be formed by division of pre-
existing cells.
– Cells multiply through division
– Mitosis results in genetically identical diploid
daughter cells
– Meiosis generates haploid gametes (sex cells)
11. Evidence
• Cells are highly complex structures and no
mechanism has been found for producing cells
from simpler subunits.
• All known examples of growth be it of a tissue,
an organism or a population, are all a result of
cell division.
12. Evidence
• Viruses are produced from simpler subunits, but
they do not consist of cells and they can only be
produced inside the host cells that they have
infected.
• Genetic code is universal each of the 64 codons (a
codon is a combination of 3 DNA bases) produces
the same amino acid in translation, regardless of
the organism.
(means; all cells have arisen as the result of cell
division from a single common ancestor).
13. First cells came from non-living
material
• If there were times in the history of the Earth
when cells did not exist, then ‘The first cells
must have arisen from non-living material’.
• Other possible explanation is that life, in the
form of cells, was transported here from
elsewhere in the universe.
• How did the first cells arise?
14. Evidence
a. Production of carbon compounds such as
sugars and amino acids
b. Assembly of these organic molecules into
polymers
c. Formation of polymers that can self replicate
(enabling inheritance)
d. Formation of membranes to package the
organic molecules
15. Carbon compounds
• Stanley Miller and Harold Urey passed steam
through a mixture of methane, hydrogen and
ammonia.
• The mixture was thought to be representative
of the atmosphere of the early Earth.
• Electrical discharges were used to simulate
lightning.
• They found that amino acids and other carbon
compounds needed for life were produced.
16.
17. Forming polymers
• A possible site for the origin of the first carbon
compounds is around deep-sea vents.
• These are cracks in the Earth’s surface,
characterized by gushing hot water carrying
reduced inorganic chemicals such as iron
sulphide.
• These chemicals represent readily accessible
supplies of energy, a source of energy for the
assembly of these carbon compounds into
polymers.
18.
19. Formation of membranes
• If phospholipids or other amphipathic carbon
compounds were among the first carbon
compounds, they would have naturally
assembled into bilayers.
• Experiments have shown that these bilayers
readily form vesicles resembling the plasma
membrane of a small cell.
• This would have allowed different internal
chemistry from that of the surroundings to
develop.
20.
21. Inheritance mechanism
• Living organisms currently have genes made of DNA
and use enzymes as catalysts.
• To replicate DNA and be able to pass genes on to
offspring, enzymes are needed.
• However, for enzymes to be made, genes are needed.
• The solution to this conundrum may have been an
earlier phase in evolution when RNA was the genetic
material.
• It can store information in the same way as DNA but it
is both self-replicating and can itself, act as a catalyst.
22. Endosymbiosis
• Endosymbiotic theory explains the existence
of several organelles of eukaryotes.
• The theory states that the organelles (e.g.
mitochondria and chloroplasts) originated as
symbioses between separate single-celled
organisms.
23. Endosymbiosis
• Development of the Nucleus
– A prokaryote grows in size and develops folds in
it’s membrane to maintain an efficient SA:Vol
– The infoldings are pinched off forming an internal
membrane
– The nucleoid region is enclosed in the internal
membrane and hence becomes the nucleus
25. Endosymbiosis
• Development of Mitochondria
– An aerobic proteobacterium enters a larger
anaerobic prokaryote (possibly as prey or a
parasite)
– It survives digestion to become a valuable
endosymbiont
– The aerobic proteobacterium provides a rich
source of ATP to it’s host enabling it to
outcompete other anaerobic prokaryotes
26. Endosymbiosis
– As the host cell grows and divides so does the
aerobic proteobacterium therefore subsequent
generations automatically contain aerobic
proteobacterium.
• The aerobic proteobacterium evolves and is assimilated
and to become a mitochondrion.
• The development of chloroplasts would be a
very similar process except the benefit to the
cell would be glucose/starch instead of ATP
27.
28. Endosymbiotic theory
• The evidence supporting the endosymbiotic
theory for mitochondria and chloroplasts:
– They have their own DNA (which is naked and
circular)
– They have ribosomes that are similar to
prokaryotes (70S)
– They have a double membrane and the inner
membrane has proteins similar to prokaryotes
29. Endosymbiotic theory
• They are roughly the same size as bacteria and
are susceptible to the antibiotic
chloramphenicol
• They transcribe their DNA and use the mRNA
to synthesize some of their own proteins.
• They can only be produced by division of
preexisting mitochondria and chloroplasts.