Chromatin is the complex combination of DNA and proteins that makes up chromosomes. It can be made visible by staining with specific techniques and stain (thus the name chromatin which literally means colored material). The major proteins involved in chromatin are histone proteins; although many other chromosomal proteins have prominent roles too. The functions of chromatin is to package DNA into smaller volume to fit in the cell, to strengthen the DNA to allow mitosis and meiosis and to serve as a mechanism to control gene expression and DNA replication.
Chromatin is the complex combination of DNA and proteins that makes up chromosomes. It can be made visible by staining with specific techniques and stain (thus the name chromatin which literally means colored material). The major proteins involved in chromatin are histone proteins; although many other chromosomal proteins have prominent roles too. The functions of chromatin is to package DNA into smaller volume to fit in the cell, to strengthen the DNA to allow mitosis and meiosis and to serve as a mechanism to control gene expression and DNA replication.
BAC & YAC are artificially prepared chromosomes to clone DNA sequences.yeast artificial chromosome is capable of carrying upto 1000 kbp of inserted DNA sequence
One of the first plausible models to account for the preceding observations was
formulated by Robin Holliday.
The key features of the Holliday model are the formation of heteroduplex DNA; the
creation of a cross bridge; its migration along the two heteroduplex strands,
termed branch migration; the occurrence of mismatch repair; and the
subsequent resolution, or splicing, of the intermediate structure to yield different
typesof recombinant molecules.
Dna supercoiling and role of topoisomerasesYashwanth B S
supercoiling is one of the important process to condenses the huge amount of DNA to fit inside the histone and its also plays a role during the replication ,transcription etc..,these activities is carried out by an enzyme called topoisomerases.
BAC & YAC are artificially prepared chromosomes to clone DNA sequences.yeast artificial chromosome is capable of carrying upto 1000 kbp of inserted DNA sequence
One of the first plausible models to account for the preceding observations was
formulated by Robin Holliday.
The key features of the Holliday model are the formation of heteroduplex DNA; the
creation of a cross bridge; its migration along the two heteroduplex strands,
termed branch migration; the occurrence of mismatch repair; and the
subsequent resolution, or splicing, of the intermediate structure to yield different
typesof recombinant molecules.
Dna supercoiling and role of topoisomerasesYashwanth B S
supercoiling is one of the important process to condenses the huge amount of DNA to fit inside the histone and its also plays a role during the replication ,transcription etc..,these activities is carried out by an enzyme called topoisomerases.
Slides from a Comparative Genomics and Visualisation course (part 1) presented at the University of Dundee, 7th March 2014. Other materials are available at GitHub (https://github.com/widdowquinn/Teaching)
Genetic parameters is an important issue in animal breeding. Parameters that are of interest are heritability, genetic correlation and repeatability, and those are computed as functions of the variance components.
This Presentation will be helpful to undergraduate and postgraduate students of biology and biotechnology in understanding the significance of COT curves in determination of gene and genome complexity amoug various organisms
DNA replicates conservatively, Semiconservatively, liberally, by hyb.pdfrufohudsonak74125
DNA replicates conservatively, Semiconservatively, liberally, by hybridization by congression.
A bacterial artificial chromosome is a vector with centromeres, telameres, and an origin of
replication. with centromeres and an origin of replication derived from a plasmid with an origin
of replication. derived from a plasmid with a centromere, derived from a complete bacterial
chromosome. The central dogma of molecular biology is____________ rightarrow
___________ rightarrow ___________ Which of the following correctly represents the
distinction between the terms \"genotype\" and \"phenotype\"? Phenotype is the genetic
composition of an organism, while genotype is the physical appearance. There is no difference
between a genotype and a phenotype. A phenotype is dominant and a genotype is recessive.
The genotype is the genetic composition of an organism, whereas the phenotype is its physical
appearance.
Solution
5. b) semiconservatively
The DNA is doube stranded with two strans in antipolar nature. During replication the two
strands sepearate. A new strand is added to each one of them and thus we get two new double
stranded DNA strands with one old strand and one new strand. Hence it is called Semi-
conservative.
6. c) Derived from plasmid with an origin of replication.
The Bacterial artificial chromosome is derived from fully functional F plasmid. It is used to
clone large DNA inserts and express inside E. coli. It has its own origin of replication and genes
for homologous recombination. This Ori, helps it to replicate on its own inside the bacterial cell
and maintain itself. However unlike actual chromosome it does not contain centromers or
telomeres. Hence answer is option C.
7. DNA --> RNA --> Protein
It is the central dogma of Biology, in which the DNA acts as genetic material passes on its
information to RNA (mRNA-messenger RNA) by a process called as Transcription. The mRNA
is later Translated with the help of ribosomes into proteins. Athough there is another transition
exists in which RNA is converted back to DNA, which is called reverse transcription ( Not
mentioned in the question ).
8. d) The genotype is the genetic compostion of an organism, whereas the phenotype is its
physical appearance.
The genotype is the genetic content, what genes the organism possesses. These genes gets
transcribed and translated into proteins, which make up the appearance of the organism, in other
words Phenotype. Phenotype depends largely on the genotype and genotype is hereditory..
Full presentation, including notes pages from the FDA presentation can be downloaded here: http://www.vaxchoicevt.com/wp-content/uploads/2013/08/FDA-2005-DNA-in-Vaccines.ppt. In it, for example, you will read:
"As we know, all vaccines and biological products contain contaminating DNA derived from the cell substrate used for manufacture."
"The amount of residual cell-substrate DNA in a vaccine will depend on the degree to which the vaccine can be purified."
"For example, a protein vaccine or a subunit vaccine, such as the influenza vaccine, would usually have less contaminating DNA than an inactivated, whole virus vaccine, such as the inactivated poliovirus vaccine, and both of these would have less DNA than a live attenuated vaccine, such as the OPV (oral polio vaccine), MMR (measles - mumps - rubella), or varicella vaccines."
http://hrst.mit.edu/hrs/evolution/public/profiles/king.html
http://hrst.mit.edu/hrs/evolution/public/profiles/jukes.html
http://hrst.mit.edu/hrs/evolution/public/papers/simpson1964/simpson1964.pdf
http://hrst.mit.edu/hrs/evolution/public/kimura1968/kimura1968.pdf
http://hrst.mit.edu/hrs/evolution/public/papers/kimura1968/kimura1968.pdf
http://hrst.mit.edu/hrs/evolution/public/papers/simpson1964/simpson1964.pdf
DISREGARD:
Evolutionary Rate at the Molecular Level
b y
M O T 0 0 KIMURA
National Institute of Genetics,
Japan
Calculating the rate of evolution in terms of nucleotide substitutions
seems t o give a value so high that many of the mutations involved
must be neutral ones.
COMPARATIVE studies of haemoglobin molecules among change in for a chain consisting of some amino-
different groups of animals suggest that, during the acids. For example, by comparing the and chains of
evolutionary history of mammals, amino-acid substitution man with those of horse, pig, cattle and rabbit, the
has taken place roughly at the rate of one amino-acid figure of one amino-acid change in x was obtained'.
http://hrst.mit.edu/hrs/evolution/public/profiles/kimura.html
http://hrst.mit.edu/hrs/evolution/public/papers/zuckerkandlpauling1965/zuckerkandlpauling1965.pdf
This is roughly equivalent to the rate of one amino-acid
substitution in for a chain consisting of
amino-acids.
A comparable value has been derived from the study
of the haemoglobin of primates. The rate of amino-acid
substitution calculated by comparing mammalian and
avian cytochrome c (consisting of about 100 amino-acids)
turned out to be one replacement in 48 x 106 yr (ref. 3).
Also by comparing the amino-acid composition of human
triosephosphate dehydrogenase with that of rabbit and
figure of a t least one amino-acid substitution
for every X yr can be obtained for the chain con-
sisting of about amino-acids. This figure is roughly
equivalent to the rate of one amino-acid substitution in
x yr for a chain consisting of amino-acids.
Averaging those figures for haemoglobin, cytochrome c
and triosephosphate’ dehydrogenase gives an evolutionary
rate of approximately one substitution in 28 x 108 yr for
a polypeptide chain consisting of 100 amino-acids.
I intend to show that this evolutionary rate, although
appearing to be very low for each polypeptide chain of a
size of cytochrome c, actually amounts t o a very high
rate for the entire genome.
First, the DNA content in each nucleus is roughly the
same among different species of mammals such as man,
cattle and rat (see, for example, ref. 5 ) . Furthermore, we
note that the G-C content of DNA is fairly uniform among
mammals, lying roughly within the range of 40-44 per
These two facts suggest that nucleotide substitution
played a principal part in mammalian evolution.
I n t h e following calculation, I shall assume that the
haploid c ...
Protoplasts are the cells of which cell walls are removed and cytoplasmic membrane is the
outermost layer in such cells.Protoplast can be obtained by specific lytic enzymes to remove
cell wall.Protoplast fusion is a physical phenomenon,during fusion two or more protoplasts
come in contact and adhere with one another either spontaneously or in presence of fusion
inducing agents.
This pdf is about the Schizophrenia.
For more details visit on YouTube; @SELF-EXPLANATORY;
https://www.youtube.com/channel/UCAiarMZDNhe1A3Rnpr_WkzA/videos
Thanks...!
Professional air quality monitoring systems provide immediate, on-site data for analysis, compliance, and decision-making.
Monitor common gases, weather parameters, particulates.
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.
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 .
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.
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.
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.
(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.
2. Definition: The C-Value Paradox
Total amount of DNA is present in genome, it is
expressed in base pair. OR
Quantity of DNA in an organism per cell, in all cells, is
always constant, for a given species.
The list of organisms on this planet, with teaming
millions, each have its own genome whose size varies
from one species to the other and no two species have
the same amount of genome nor the same genomic
value or character?
Variation in genomic content (both qualitatively and
quantitatively) within a phylum or an order or genus is
surprisingly large from 10×5 bp to 10×12 bps.
Animals show variations range more than 3,300-fold,
and in land plants among them differ by a factor of
about 1,000. Protists genomes have been surprisingly
vary more than 300,000-fold in size.
3. Origin of the term the term C
“What is C Value- is it the Content, Complement,
Concentration or what?, if it is content then what
content, 2n or n. Many authors have assumed that
the "C" in "C-value" refers to "characteristic",
"content", or "complement".
Swift's study of this topic related specifically to
variation (or lack thereof) among chromosome sets
in different cell types within individuals, but his
notation evolved into "C-value" in reference to the
haploid DNA content of individual species and
retains this usage today”.
4. C Value: The amount DNA found in haploid
genome, measured in million base pairs or in
pg; the C may mean constancy of the genome in
the species.
G Value: The number of genes found in the
haploid genome; the number includes predicted
and known ORFs.
I value: The amount of information embedded
in the genome; their estimates effective number
of genes which encompasses alternative
splicing, post translational modifications, multi-
domain proteins and gene redundancy plus gene
expression and gene interaction.
5. Example in C value
Mycoplasma 10^5 bp
(-) Bacteria 4.2 to 5x10^6 bp
(+) Bacteria 2 to 8x10^6 bp
Algae 5 to 8x10^7 bp
Worms 7x10^7 to 2x10^8 bp
Insects 1.5x10^8 to 6x10^9 bp
Mammals 3x10^9 to 5x10^9 bp
It is clear from above values “ as complexity
increases the C-value increases from simplex
to complex forms”
6. “There linear relationship between genome
size and organism complexity”
7. The complexity related to C-value,
i.e. there is not linear relationship between
genome size and organism complexity
Eg. Housefly-8.6×10×8
Both are in same group
Drosophila 1.4×10×8
Eg. Plethodon richmondi has genome size
more than Plethodon larsilli.
8. Application
Due to presence of highly repetitive DNA
i.e. the sequence which repeat in the
genome many times
