Neurons transmit electrical signals along their axons via action potentials. At synapses, neurons interact and transmit signals to other neurons or effector cells. When an action potential reaches the axon terminal, neurotransmitters are released, which can modulate the signal transmission. Propagation occurs as local currents depolarize successive parts of the axon, causing each section to reach the threshold potential and fire an action potential.
My first attempt at this presentation for the IB Diploma Programme Biology course: topic 6.5 neurons and synapses. I'm hoping another great educator out there can take this, make it look a lot better, and then share it :)
Thanks to Steven Taylor and Chris Paine for all of their work and inspiration.
Please download and modify as you wish.
final note: I actually made this in google slides - I just checked the presentation and none of the links to the videos I used are there. Here is a link to the google slide presentation so you can find the videos: https://docs.google.com/a/igbis.edu.my/presentation/d/1eabpxEtwlDGt7EPRqQ_GPwxUBerszZQquWAhjRnU_WE/edit?usp=sharing
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.
My first attempt at this presentation for the IB Diploma Programme Biology course: topic 6.5 neurons and synapses. I'm hoping another great educator out there can take this, make it look a lot better, and then share it :)
Thanks to Steven Taylor and Chris Paine for all of their work and inspiration.
Please download and modify as you wish.
final note: I actually made this in google slides - I just checked the presentation and none of the links to the videos I used are there. Here is a link to the google slide presentation so you can find the videos: https://docs.google.com/a/igbis.edu.my/presentation/d/1eabpxEtwlDGt7EPRqQ_GPwxUBerszZQquWAhjRnU_WE/edit?usp=sharing
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.
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.
Nutraceutical market, scope and growth: Herbal drug technologyLokesh Patil
As consumer awareness of health and wellness rises, the nutraceutical market—which includes goods like functional meals, drinks, and dietary supplements that provide health advantages beyond basic nutrition—is growing significantly. As healthcare expenses rise, the population ages, and people want natural and preventative health solutions more and more, this industry is increasing quickly. Further driving market expansion are product formulation innovations and the use of cutting-edge technology for customized nutrition. With its worldwide reach, the nutraceutical industry is expected to keep growing and provide significant chances for research and investment in a number of categories, including vitamins, minerals, probiotics, and herbal supplements.
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 increased availability of biomedical data, particularly in the public domain, offers the opportunity to better understand human health and to develop effective therapeutics for a wide range of unmet medical needs. However, data scientists remain stymied by the fact that data remain hard to find and to productively reuse because data and their metadata i) are wholly inaccessible, ii) are in non-standard or incompatible representations, iii) do not conform to community standards, and iv) have unclear or highly restricted terms and conditions that preclude legitimate reuse. These limitations require a rethink on data can be made machine and AI-ready - the key motivation behind the FAIR Guiding Principles. Concurrently, while recent efforts have explored the use of deep learning to fuse disparate data into predictive models for a wide range of biomedical applications, these models often fail even when the correct answer is already known, and fail to explain individual predictions in terms that data scientists can appreciate. These limitations suggest that new methods to produce practical artificial intelligence are still needed.
In this talk, I will discuss our work in (1) building an integrative knowledge infrastructure to prepare FAIR and "AI-ready" data and services along with (2) neurosymbolic AI methods to improve the quality of predictions and to generate plausible explanations. Attention is given to standards, platforms, and methods to wrangle knowledge into simple, but effective semantic and latent representations, and to make these available into standards-compliant and discoverable interfaces that can be used in model building, validation, and explanation. Our work, and those of others in the field, creates a baseline for building trustworthy and easy to deploy AI models in biomedicine.
Bio
Dr. Michel Dumontier is the Distinguished Professor of Data Science at Maastricht University, founder and executive director of the Institute of Data Science, and co-founder of the FAIR (Findable, Accessible, Interoperable and Reusable) data principles. His research explores socio-technological approaches for responsible discovery science, which includes collaborative multi-modal knowledge graphs, privacy-preserving distributed data mining, and AI methods for drug discovery and personalized medicine. His work is supported through the Dutch National Research Agenda, the Netherlands Organisation for Scientific Research, Horizon Europe, the European Open Science Cloud, the US National Institutes of Health, and a Marie-Curie Innovative Training Network. He is the editor-in-chief for the journal Data Science and is internationally recognized for his contributions in bioinformatics, biomedical informatics, and semantic technologies including ontologies and linked data.
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 .
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.
Multi-source connectivity as the driver of solar wind variability in the heli...
neurons and synapses
1. 6.5 Neurons and
synapses
Essential idea: Neurons transmit the message, synapses
modulate the message.
Nature of science:
Cooperation and collaboration between groups of scientists—
biologists are contributing to research into memory and
learning. (4.3)
2. Understandings:
Neurons transmit electrical impulses.
The myelination of nerve fibres allows for saltatory conduction.
Neurons pump sodium and potassium ions across their membranes to
generate a resting potential.
An action potential consists of depolarization and repolarization of
the neuron.
Nerve impulses are action potentials propagated along the axons of
neurons.
Propagation of nerve impulses is the result of local currents that cause
each successive part of the axon to reach the threshold potential.
Synapses are junctions between neurons and between neurons and
receptor or effector cells.
When presynaptic neurons are depolarized they release a
neurotransmitter into the synapse.
A nerve impulse is only initiated if the threshold potential is reached.
3. Applications and skills:
Application: Secretion and reabsorption of acetylcholine
by neurons at synapses.
Application: Blocking of synaptic transmission at
cholinergic synapses in insects by binding of
neonicotinoid pesticides to acetylcholine receptors.
Skill: Analysis of oscilloscope traces showing resting
potentials and action potentials.
4. Nervous System
The master controlling
and communicating
system of the body
Functions
Sensory input –
monitoring stimuli
Integration –
interpretation of
sensory input
Motor output –
response to stimuli
5. Organization of the Nervous
System
Central nervous system (CNS)
Brain and spinal cord
Integration and command center
Peripheral nervous system (PNS)
Paired spinal and cranial nerves
Carries messages to and from the spinal cord and brain
6. Histology of Nerve Tissue
The two principal cell types of the nervous system are:
Neurons – excitable cells that transmit electrical signals
Supporting cells – cells that surround and wrap neurons
7. Neurons (Nerve Cells)
Structural units of the nervous system
Composed of a body, axon, and dendrites
Long-lived, amitotic, and have a high metabolic rate
Their plasma membrane function in:
Electrical signaling
Cell-to-cell signaling during development
8. Cell body (soma)
Figure 11.4b
Contains the nucleus and a
nucleolus
Contains an axon hillock –
cone-shaped area from
which axons arise
10. Axons
Slender processes of uniform diameter
arising from the hillock
Usually there is only one unbranched
axon per neuron
Axonal terminal – branched terminus of
an axon
11. Neuron Classification
Functional:
Sensory (afferent) — transmit impulses toward the CNS
Motor (efferent) — carry impulses away from the CNS
Interneurons (relay neurons) — shuttle signals through CNS
pathways
12. Neurophysiology
Neurons are highly irritable
Action potentials, or nerve impulses, are:
Electrical impulses carried along the length of axons
Always the same regardless of stimulus
The underlying functional feature of the nervous system
13. Gated Channels
When gated channels are open:
Ions move quickly across the membrane
Movement is along their electrochemical gradients
An electrical current is created
Voltage changes across the membrane
14. Electrochemical Gradient
chemical gradient - when ions move from high
concentration to low concentration
electrical gradient - when ions move toward an area of
opposite charge
electrochemical gradient – the electrical and chemical
gradients taken together
15. Resting Membrane Potential (Vr)
potential difference (–70 mV) across the membrane of a resting neuron
Differential permeability to Na+ and K+
sodium-potassium pump
16. Changes in Membrane
Potential
Changes are caused by three events
Depolarization – the inside of the membrane becomes less
negative
Repolarization – the membrane returns to its resting
membrane potential
Hyperpolarization – the inside of the membrane becomes
more negative than the resting potential
17. Action Potentials (APs)
brief reversal of membrane potential
only generated by muscle cells and neurons
do not decrease in strength over distance
18. Resting Potential
Na+ and K+ channels are closed
Leakage accounts for small movements
of Na+ and K+
20. Action Potential: Repolarization Phase
Sodium channel close, K+ channel open
K+ exits the cell and internal negativity of the resting
neuron is restored
21. Action Potential:
Hyperpolarization
Potassium gates remain open, causing an excessive efflux
of K+
This efflux causes hyperpolarization of the membrane
(undershoot)
The neuron is
insensitive to
stimulus and
depolarization
during this time
Figure 11.12.4
22. Action Potential:
Role of the Sodium-Potassium Pump
Repolarization
Restores the resting electrical conditions of the neuron
Does not restore the resting ionic conditions
Ionic redistribution back to resting conditions is restored by the sodium-
potassium pump
24. Propagation of an Action Potential
(Time = 0ms)
Na+ influx causes a patch of
the axonal membrane to
depolarize
Positive ions in the axoplasm
move toward the polarized
(negative) portion of the
membrane
25. Propagation of an Action Potential
(Time = 2ms)
Ions of the extracellular fluid move
toward the area of greatest
negative charge
A current is created that
depolarizes the adjacent
membrane in a forward direction
The impulse propagates away from
its point of origin
26. Propagation of an Action Potential
(Time = 4ms)
The action potential moves
away from the stimulus
Where sodium gates are
closing, potassium gates are
open and create a current
flow
Editor's Notes
positive sodium flows in, depolarization begins. Then the influx creates a self-propagating depolarization. Explosive positive feedback. Lasts 1 millisec.
Inactivation gates “swing shut” sodium influx stops. SLOW voltage gated potassium channels open and K+ flows OUT of cell. Repolarization “overshoots”
THIS RESTORES POTENTIAL BUT NOT THE CHEMICAL GRADIENTS!!!
graph shows the action potential and the permiability of the plasma membrane to Na and K
