460 BC - Greek philosopher proposes the existence of the atom
He pounded materials until he made them into smaller and smaller parts
He called them atoma which is Greek for “indivisible”.
460 BC - Greek philosopher proposes the existence of the atom
He pounded materials until he made them into smaller and smaller parts
He called them atoma which is Greek for “indivisible”.
An entry in the 'schools for you' project. By Aneesh Bapat, class 8 from Abhinav Vidyalaya English Medium High School, Pune, India.About the various theories by different scientists about the structure of the atom.
(May 29th, 2024) Advancements in Intravital Microscopy- Insights for Preclini...Scintica Instrumentation
Intravital microscopy (IVM) is a powerful tool utilized to study cellular behavior over time and space in vivo. Much of our understanding of cell biology has been accomplished using various in vitro and ex vivo methods; however, these studies do not necessarily reflect the natural dynamics of biological processes. Unlike traditional cell culture or fixed tissue imaging, IVM allows for the ultra-fast high-resolution imaging of cellular processes over time and space and were studied in its natural environment. Real-time visualization of biological processes in the context of an intact organism helps maintain physiological relevance and provide insights into the progression of disease, response to treatments or developmental processes.
In this webinar we give an overview of advanced applications of the IVM system in preclinical research. IVIM technology is a provider of all-in-one intravital microscopy systems and solutions optimized for in vivo imaging of live animal models at sub-micron resolution. The system’s unique features and user-friendly software enables researchers to probe fast dynamic biological processes such as immune cell tracking, cell-cell interaction as well as vascularization and tumor metastasis with exceptional detail. This webinar will also give an overview of IVM being utilized in drug development, offering a view into the intricate interaction between drugs/nanoparticles and tissues in vivo and allows for the evaluation of therapeutic intervention in a variety of tissues and organs. This interdisciplinary collaboration continues to drive the advancements of novel therapeutic strategies.
A brief information about the SCOP protein database used in bioinformatics.
The Structural Classification of Proteins (SCOP) database is a comprehensive and authoritative resource for the structural and evolutionary relationships of proteins. It provides a detailed and curated classification of protein structures, grouping them into families, superfamilies, and folds based on their structural and sequence similarities.
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.
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 .
2. Atomic Theory - Democritus
Democritus
Atomic theory
Leucippus
All matter is composed of tiny particles called atoms.
(atoms comes from the Greek work atoma which
means uncuttable)
Began with _________ ≈ 400 B.C. Greek
philosopher proposed the ___________ along with
his teacher ________.
Their Atomic Theory Stated:
4. John Dalton
Self educated - his family was too poor to
send him to school
Elaborated on the atomic theory
One of the first to start collecting ____ for
atomic theory.
data
5. John Dalton
Dalton’s Atomic Theory
1) Elements are made of tiny particles called _____
2) Atoms of the same element are ________
3) Atoms of different elements have different
properties.
4) Atoms of different elements can combine to form
___________
5) Atoms are unchanged by _________________
atoms
identical
compounds
chemical reactions
7. J.J. Thomson
First to suggest ________ particles
through the use of a cathode ray tube.
Showed that there was a ________
charged component of atoms
He also knew that atoms were neutral, so
if there was a negative component, there
should also be a ______ component.
subatomic
negatively
positive
10. J.J. Thomson
Charged plates deflected a stream of
particles, so Thomson reasoned their was
a charged component to atoms.
Credited with the discovery of the electron
11. J.J. Thomson
___________ model. Atoms are solid
positively charged spheres with negatively
charged particles imbedded in it.
Plum Pudding
12. Ernest Rutherford
First to suggest the idea that atoms are
mostly __________
First to suggest the idea of the _______
Conducted the _________________
Shot positively charged Alpha Particles at
Gold Foil (like aluminum foil, but gold).
If Thomson’s model was correct (atoms are
solid), the particles would all ___________
empty space
nucleus
Gold Foil Experiment
bounce back
13. Ernest Rutherford
However, Rutherford thought atoms were
mostly empty space and most of the particles
would __________________
Rutherford was partly right – most of the
particles shot through, but some bounced off
at angles, and some even came straight back
Rutherford claimed this was as surprising as
firing a canon at tissue paper, and the canon
ball bouncing back
shoot straight through
16. Ernest Rutherford
What did he reason?
Atoms must be mostly empty space with a
small dense positively charged center (like
charges repel each other – responsible for the
deflection)
He called this center the ____________
Still confusion as to the location of the
negative charge.
atomic nucleus
17. Niels Bohr
Niels Bohr suggested negative charges are
________ around the nucleus
They are in very specific ______ levels (radii
around nucleus)
Reasoned this because elements have specific
spectra (only emit specific colors of light)
He also reasoned electrons must be ______.
Why? Or else they would collect on the ______
charges of the nucleus.
electrons
positive
energy
moving
19. Erwin Schrödinger
Schrödinger worked with Louis de Brogle
Claimed electrons could be particles or
_____.
Developed quantum mechanical model of
the atom- uses math to explain atoms.
Specifically the location of electrons
waves
20. Schrödinger
Schrödinger’s Cat thought experiment
Explained that just because something can’t
be observed directly doesn’t mean it doesn’t
exist
Claimed that the measurements we make to
observe electrons cause them to act like
particles
However, if we are not observing them they
act like waves – double slit experiment
21. James Chadwick
He discovered last missing particle, the
______.
He knew there was a missing particle
because atoms were much more massive
than expected.
He was able to isolate a beam of particles
not affected by positive or negative
charges.
neutron
23. Modern Advances
Are all protons, neutrons, and electrons
made of something too?
All matter is made up of elements
Next logical thought?
All elements are made up of atoms
All atoms are made up of protons,
neutrons, and electrons
24. Murray Gell-Mann (still alive)
Broke protons and neutrons into smaller
particles which he called ______.
Up quarks have a + 2/3 charge
Down quarks have a - 1/3 charge
One proton = two up quarks and one
down quark
One neutron = one up quark and two
down quarks
quarks