Each cell in the human contains all the genetic material for the growth and development of a human
Some of these genes will be need to be expressed all the time
These are the genes that are involved in of vital biochemical processes such as respiration
Other genes are not expressed all the time
They are switched on an off at need
Each cell in the human contains all the genetic material for the growth and development of a human
Some of these genes will be need to be expressed all the time
These are the genes that are involved in of vital biochemical processes such as respiration
Other genes are not expressed all the time
They are switched on an off at need
Most bacteria are free-living organisms that grow by increasing
in mass and then divide by binary fission.
Growth and division are controlled by genes, the expression
of which must be regulated appropriately. Genes
whose activity is controlled in response to the needs of a
cell or organism are called regulated genes. All organisms
also have a large number of genes whose products
are essential to the normal functioning of a growing and
dividing cell, no matter what the conditions are. These
genes are always active in growing cells and are known as
constitutive genes or housekeeping genes; examples include
genes that code for the enzymes needed for protein
synthesis and glucose metabolism. Note that all genes are
regulated on some level. If normal cell function is impaired
for some reason, the expression of all genes, including
constitutive genes, is reduced by regulatory
mechanisms. Thus, the distinction between regulated
and constitutive genes is somewhat arbitrary.
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.
The control of gene expression or protein synthesis is called gene regulation or it is the process of turning genes on and off
Gene regulation in prokaryotes is most extensively observed at the initiation of transcription.
Most genes are controlled by extracellular signals- present in medium.
Repressor, a negative regulatory molecule, binds to the operator gene and interferes with the expression of genes. Activator, a positive regulatory molecule, enhances the expression of the genes.
Operon : a group or cluster of structural genes under a single promoter; bacterial operons are polycistronic transcripts that are able to produce multiple proteins from one mRNA
Francois Jacob and Jacques Monod in 1961
“Lac operon is an operon or a group of genes with a single promoter that encode genes for the transport and metabolism of lactose in E.coli and other bacteria.”
Lac operon concept is an example of prokaryotic gene regulation.
Most bacteria are free-living organisms that grow by increasing
in mass and then divide by binary fission.
Growth and division are controlled by genes, the expression
of which must be regulated appropriately. Genes
whose activity is controlled in response to the needs of a
cell or organism are called regulated genes. All organisms
also have a large number of genes whose products
are essential to the normal functioning of a growing and
dividing cell, no matter what the conditions are. These
genes are always active in growing cells and are known as
constitutive genes or housekeeping genes; examples include
genes that code for the enzymes needed for protein
synthesis and glucose metabolism. Note that all genes are
regulated on some level. If normal cell function is impaired
for some reason, the expression of all genes, including
constitutive genes, is reduced by regulatory
mechanisms. Thus, the distinction between regulated
and constitutive genes is somewhat arbitrary.
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.
The control of gene expression or protein synthesis is called gene regulation or it is the process of turning genes on and off
Gene regulation in prokaryotes is most extensively observed at the initiation of transcription.
Most genes are controlled by extracellular signals- present in medium.
Repressor, a negative regulatory molecule, binds to the operator gene and interferes with the expression of genes. Activator, a positive regulatory molecule, enhances the expression of the genes.
Operon : a group or cluster of structural genes under a single promoter; bacterial operons are polycistronic transcripts that are able to produce multiple proteins from one mRNA
Francois Jacob and Jacques Monod in 1961
“Lac operon is an operon or a group of genes with a single promoter that encode genes for the transport and metabolism of lactose in E.coli and other bacteria.”
Lac operon concept is an example of prokaryotic gene regulation.
lac operon is a negatively controlled inducible operon.E.coli can use lactose as a source of carbon.
The enzymes required for the use of lactose as a source of carbon are synthesised only when the lactose is available as carbon source.
The lac operon is an example of nagatively controlled inducible operon.
Structure
The lac operon consists of 5 structural units.
Promoter
Operator
Structural genes
CAP binding sites
Regulatory gene
Gene regulation can be defined as any kind of alteration in the gene to give rise to a different expression which might result in a change in the synthesized amino acid sequence.”
Gene expression is basically the synthesis of the polypeptide chain encoded by a particular gene.
Therefore the expression of the gene can be quantified in terms of the amount of protein synthesised by the genes.
This is my first presentation share in this platform. Hope this is helpful for you! Here, I have tried to explain MECHANISM OF LAC OPERON in E.Coli in informative and crisp manner with simple language and few images.
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 .
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.
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 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.
This pdf is about the Schizophrenia.
For more details visit on YouTube; @SELF-EXPLANATORY;
https://www.youtube.com/channel/UCAiarMZDNhe1A3Rnpr_WkzA/videos
Thanks...!
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.
Professional air quality monitoring systems provide immediate, on-site data for analysis, compliance, and decision-making.
Monitor common gases, weather parameters, particulates.
1. THE lac OPERON
Rudrakshi B.Raut
The Institute Of Science,Mumbai
M.sc-2 (sem:3)
Paper-2
Roll no.17
2. CONTENT
Introduction
Concept of lac operon
Operon model
Functioning of lac operon
Different Scenarios
Lac mutations :
Structural Mutation
Operator Mutation
Promoter Mutation
Positive and Negative control
References
3. INTRODUCTION
• Operon is operating units which can be
defined as the cluster of genes located
together on the chromosomes &
transcribed together.
• It is group of closely linked structure
genes & associated control gene which
regulate the metabolic activity.
• All the genes of an operon are
coordinately controlled by a mechanism
1st described in 1961 by Francois Jacob
& Jaques Monod of the Pasture institute
of Paris.
Jacob, Monod & Lwoff
4. The lac operon
• The lactose operon designated as lac operon.
• The lac operon codes for enzymes involved in
the catabolism (degradation) of lactose.
• lactose is the disaccharide which is made up
of glucose & galactose.
• It is the inducible operon since the presence
of lactose induce the operon to switched on.
6. Designation
of gene
Codes for
enzyme
Function of the enzyme
lac Z β-galactosidase Breaks down lactose into
glucose & galactose.
lac y galactose
permease
This protein, found in the
E.coli cytoplasmic membrane,
actively transports lactose
into the cells
lac a Thio-galactoside
trans acetylase
The function of this
enzyme is not known. It is
coded for by the gene
lacA.
7. Element Purpose
Operator (lacO) Binding site for repressor
Promoter (lacP) Binding site for RNA Polymerase
Repressor Gene encoding the lac repressor
protein. Binds to DNA at the
operator & blocks binding of RNA
Polymerase at the promoter.
lacI Controls production of the
repressor protein
8. FUNCTIONING OF LAC OPERON
• In the absence of lactose(inducer), the
regulator gene produce a repressor protein
which bind to the operator site & prevent the
transcription as a result, the structural gene
do not produce mRNA & the proteins are not
formed.
9.
10. • When lactose(inducer), introduce in the
medium, binds to the repressor the repressor
now fails to binds to the operator.
• Therefore the operoter is made free &
induces the RNA polymerase to bind to the
initiation site on promoter which results in
the synthesis of lac mRNA.
• This mRNA codes for three enzyme necessary
for lactose catabolism.
11.
12. A simplified E. coli
bacterial cell.
The lac operon gene
sequence.
13. The repressor
molecule, bound to
the controlling
region.
Lactose molecules added to
the environment outside of
the cell.
14. Lactose molecules bound
to the repressor.
This releases the
repressor from the DNA.
RNA polymerase
transcribing the genes in
the lac operon into mRNA.
15. Ribosomes translating
the mRNA into proteins.
One of the proteins
(yellow) encoded by the
lac operon allows
lactose to enter the cell
at a high rate.
16. A second protein
(orange) digests the
lactose as it enters the
cell.
The lactose molecules
bound to the repressor
are released.
19. 1. When lactose is absent
• A repressor protein is continuously synthesised. It
sits on a sequence of DNA just in front of the lac
operon, the Operator site
• The repressor protein blocks the Promoter site
where the RNA polymerase settles before it starts
transcribing
Regulator
gene
lac operonOperator
site
z y a
DNA
I
O
Repressor
protein
RNA
polymeraseBlocked
20. 2. When lactose is present
• A small amount of a sugar allolactose is
formed within the bacterial cell. This fits onto
the repressor protein at another active site
(allosteric site)
• This causes the repressor protein to change its
shape (a conformational change). It can no
longer sit on the operator site. RNA
polymerase can now reach its promoter site
z y a
DNA
I O
21. 2. When lactose is present
• A small amount of a sugar allolactose is
formed within the bacterial cell. This fits onto
the repressor protein at another active site
(allosteric site)
• This causes the repressor protein to change its
shape (a conformational change). It can no
longer sit on the operator site. RNA
polymerase can now reach its
promoter site
Promotor site
z y a
DNA
I O
22. 3. When both glucose and lactose are present
• When glucose and lactose are present RNA
polymerase can sit on the promoter site but it
is unstable and it keeps falling off.
Promotor site
z y a
DNA
I O
Repressor
protein removed
RNA polymerase
23. 4. When glucose is absent and lactose is present
• Another protein is needed, an activator protein.
This stabilises RNA polymerase.
• The activator protein only works when glucose is
absent
• In this way E. coli only makes enzymes to
metabolise other sugars in the absence of glucose
Promotor site
z y a
DNA
I O
Transcription
Activator
protein steadies
the RNA
polymerase
24. Summary
Carbohydrates Activator
protein
Repressor
protein
RNA
polymerase
lac Operon
+ GLUCOSE
+ LACTOSE
Not bound
to DNA
Lifted off
operator site
Keeps falling
off promoter
site
No transcription
+ GLUCOSE
- LACTOSE
Not bound
to DNA
Bound to
operator site
Blocked by the
repressor
No transcription
- GLUCOSE
- LACTOSE
Bound to
DNA
Bound to
operator site
Blocked by the
repressor
No transcription
- GLUCOSE
+ LACTOSE
Bound to
DNA
Lifted off
operator site
Sits on the
promoter site
Transcription
25. LAC MUTATIONS
• Jacob & Monod workout the structure &
function of lac operon by analyzing mutations
that affects lactose metabolism.
• To help define the role of the different
components of the operon, they use partial
diploid stain of E.coli.
• They determine that some part of the lac
operon are cis acting where other are trans
acting.
26. STRUCTURAL-GENE MUTATION
• Jacob and Monod first discovered some
mutant strains that had lost the ability to
synthesize either β-galactosidase or
permease.
• The mutation which occurred on lacZ and LacY
structural genes altered the amino acid
sequences of the proteins encoded by the
genes.
27. a) In the absence of inducer, the lacO+ operon is
turned off, whereas the lacOc operon produces
functional β-galactosidase from the lacZ+ gene and
nonfunctional permease molecules from the lacY-
gene with missense mutation.
28. b) In the presence of inducer the functional β-
galactosidase and defective permease are produce
from the lacOc operon, whereas the lacO+ operon
produces nonfunctional β-galactosidase from the
lacZ- gene & functional permease from lacY+ gene.
29. OPERATOR MUTATIONS
• Jacob & Monod find another constitutive mutants to a
site adjacent to lacZ.
• This mutations occurred at the operator site & were
referred to as lacOc.
• The lacOc mutations altered the sequence of DNA at
the operator so that the repressor protein was no
longer able to bind.
• A partial diploid with genotype lacI+ lacOc lacz+ /lacI+
lacO + lacz+ exhibited constitutive synthesis of β-
galactosidase, indicating that lacOc is dominant over
lacO +.
30.
31. PROMOTER MUTATION:
• Mutations affecting lactose metabolism have also been
isolated at the promoter site; these mutations are
designated lacP- ,and they interfere with the binding of
RNA polymerase to the promoter.
• This binding is essential for the transcription of the
structural gene.
• E.coli strain with lacP- mutation does not produce lac
proteins either in a presence or absence of lactose.
• lacP- mutations are cis acting.
32. • The lac operon is under two forms of
control; positive and negative control.
• Negative control occurs when the binding
of a protein prevents an event.
• Positive control is when the binding
causes the event.
33. POSITIVE CONTROL
• When glucose is available, gene that participate in the
metabolism other sugars are repressed, in a
phenomenon known as catabolite repression.
• Catabolite repression Is a type of +ve control in the lac
operon.
• The catabolite activator protein(CAP), complex cAMP,
binds to a site near the promoter & stimulates the
binding of RNA polymerase.
• A cellular level of cAMP are controlled by glucose;
allolactose level increases the abundance of cAMP &
enhance the transcription of the lac structural genes.
34.
35. NEGATIVE CONTROL
• The lac repressor bind to the operator.
• The DNA sequence cover by the repressor
overlaps the DNA sequence recognized by the
RNA polymerase.
• Therefore, when the repressor is bound to the
operator, RNA polymerase cannot bind to the
promoter & transcription can not occur, the lac
operon is said to be under –ve control.
36.
37. POSITIVE VS NEGATIVE CONTROL
Regulatory
protein is
present
Mutate
regulatory
gene to lose
function
Positive control
Negative control
Example of
regulatory
protein
Operon ON
Operon OFF
Operon OFF
Operon ON
Activator
Repressor
38. REFERENCE
Books :
• Genetics by Benjamin Pierce
• iGenetics by Peter J.Russell
Internet :
• Www.google.com
• https://www.google.co.in/search?q=The+lac+operon
+in+e.coli.ppt&client=opera&hs=OtG&biw=1366&bih
=586&source=lnms&tbm=isch&sa=X&ei=OzQ0VJu1N4
2xuATqjIH4BQ&ved=0CAYQ_AUoAQ