Gene expression in eukaryotes is controlled at multiple levels, including chromatin structure, transcription, RNA processing, and translation. Chromatin structure determines if genes are transcriptionally active or inactive. Transcription is regulated by the interaction of promoters, transcription factors, and enhancers. RNA processing controls splicing and transport of mRNA. Finally, translation and post-translational modifications further regulate gene expression. Overall, eukaryotic gene expression is tightly controlled through complex mechanisms at the chromatin, transcription, RNA, translation, and protein levels.
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.
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.
Gene regulation in eukaryotes in a nutshell covering all the important stages of gene regulation in eukaryotes at transcriptional level, translation level and post-translational level.
Regulation of gene expression in eukaryotesAnna Purna
Â
Presence of nucleus and complexity of eukaryotic organism demands a well controlled gene regulation in eukaryotic cell. Tissue specific gene expression is essential as they are multicellular organisms in which different cells perform different functions. This PPT deals with various control points for the gene regulation and expression within a cell.
RNA transport
Multiple classes of RNA are exported from the nucleus
Transportation through nuclear pore complex.
Ribosomal subunits are assembled in the nucleolus and exported by exportin 1
tRNAs are exported by a dedicated exportin
Messenger RNAs are exported from the nucleus as RNA-protein complexes
Messenger RNAs are exported from the nucleus as RNA-protein complexes
hnRNPs move from sites of processing to NPCs
Precursors to microRNAs are exported from the nucleus and processed in the cytoplasm
This presentation provides an overview of What is a transposon,different types of transposons, their mechanism of action, examples for each type of transposons, changes caused due to insertion of transposon into the target gene and applications of Transposons. They are controlling factors in gene expression. Jumping genes is a special area of interest in Genetic research.
REGULATION OF
GENE EXPRESSION
IN PROKARYOTES & EUKARYOTES .
This presentation is enriched with lots of information of gene expression with many pictures so that anyone can understand gene expression easily.
Gene expression is the process by which the information encoded in a gene is used to direct the assembly of a protein molecule.
Gene expression is explored through a study of protein structure and function, transcription and translation, differentiation and stem cells.
It is the process by which information from a gene is used in the synthesis of a functional gene product.
These products are often proteins, but in non-protein coding genes such as ribosomal RNA (rRNA), transfer RNA (tRNA) or small nuclear RNA (snRNA) genes, the product is a functional RNA.
The process of gene expression is used by all known life - eukaryotes (including multicellular organisms), prokaryotes (bacteria and archaea)
Regulation of gene expression:
Regulation of gene expression includes a wide range of mechanisms that are used by cells to increase or decrease the production of specific gene products (protein or RNA).
Gene regulation is essential for viruses, prokaryotes and eukaryotes as it increases the versatility and adaptability of an organism by allowing the cell to express protein when needed.
CLASSIFICATION OF GENE WITH RESPECT TO THEIR EXPRESSION:
Constitutive ( house keeping) genes:
Are expressed at a fixed rate, irrespective to the cell condition.
Their structure is simpler.
Controllable genes:
Are expressed only as needed. Their amount may increase or decrease with respect to their basal level in different condition.
Their structure is relatively complicated with some response elements.
TYPES OF REGULATION OF GENE:
positive & negative regulation.
Steps involving gene regulation of prokaryotes & eukaryotes.
Operon-structure,classification of mechanisms- lac operon,tryptophan operon ,
and many things related to gene expression.
This is a video slide so anyone can understand this topic easily by seeing pictures included in this slide.
CBCS 4TH SEM ,
CHARGING, STRUCTURE AND FUNCTION OF tRNA,
AMINOACYL RNA SYNTHETASE(ASR) PROOFREADING AND EDITING
https://www.youtube.com/watch?v=YzOVMWYLiCE
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
Almost 98 of the human genome does not encode proteins
o The non coding transcripts less than 200 bases are called small non
coding RNA and comprise of tRNA, rRNA, miRNA, snoRNA, piwi
interacting RNA (pi RNA)
o RNA molecules that are of more than 200 bases in length are known
as long non coding RNA (
o lncRNAs are more than 200 nucleotides in length and also can be
more than 2 Kb
o Such long noncoding RNAs usually have limited coding potential due
to the absence of open reading frames, 3 UTR and termination
region while their coding potential is less than 100 amino acids
Gene regulation in eukaryotes in a nutshell covering all the important stages of gene regulation in eukaryotes at transcriptional level, translation level and post-translational level.
Regulation of gene expression in eukaryotesAnna Purna
Â
Presence of nucleus and complexity of eukaryotic organism demands a well controlled gene regulation in eukaryotic cell. Tissue specific gene expression is essential as they are multicellular organisms in which different cells perform different functions. This PPT deals with various control points for the gene regulation and expression within a cell.
RNA transport
Multiple classes of RNA are exported from the nucleus
Transportation through nuclear pore complex.
Ribosomal subunits are assembled in the nucleolus and exported by exportin 1
tRNAs are exported by a dedicated exportin
Messenger RNAs are exported from the nucleus as RNA-protein complexes
Messenger RNAs are exported from the nucleus as RNA-protein complexes
hnRNPs move from sites of processing to NPCs
Precursors to microRNAs are exported from the nucleus and processed in the cytoplasm
This presentation provides an overview of What is a transposon,different types of transposons, their mechanism of action, examples for each type of transposons, changes caused due to insertion of transposon into the target gene and applications of Transposons. They are controlling factors in gene expression. Jumping genes is a special area of interest in Genetic research.
REGULATION OF
GENE EXPRESSION
IN PROKARYOTES & EUKARYOTES .
This presentation is enriched with lots of information of gene expression with many pictures so that anyone can understand gene expression easily.
Gene expression is the process by which the information encoded in a gene is used to direct the assembly of a protein molecule.
Gene expression is explored through a study of protein structure and function, transcription and translation, differentiation and stem cells.
It is the process by which information from a gene is used in the synthesis of a functional gene product.
These products are often proteins, but in non-protein coding genes such as ribosomal RNA (rRNA), transfer RNA (tRNA) or small nuclear RNA (snRNA) genes, the product is a functional RNA.
The process of gene expression is used by all known life - eukaryotes (including multicellular organisms), prokaryotes (bacteria and archaea)
Regulation of gene expression:
Regulation of gene expression includes a wide range of mechanisms that are used by cells to increase or decrease the production of specific gene products (protein or RNA).
Gene regulation is essential for viruses, prokaryotes and eukaryotes as it increases the versatility and adaptability of an organism by allowing the cell to express protein when needed.
CLASSIFICATION OF GENE WITH RESPECT TO THEIR EXPRESSION:
Constitutive ( house keeping) genes:
Are expressed at a fixed rate, irrespective to the cell condition.
Their structure is simpler.
Controllable genes:
Are expressed only as needed. Their amount may increase or decrease with respect to their basal level in different condition.
Their structure is relatively complicated with some response elements.
TYPES OF REGULATION OF GENE:
positive & negative regulation.
Steps involving gene regulation of prokaryotes & eukaryotes.
Operon-structure,classification of mechanisms- lac operon,tryptophan operon ,
and many things related to gene expression.
This is a video slide so anyone can understand this topic easily by seeing pictures included in this slide.
CBCS 4TH SEM ,
CHARGING, STRUCTURE AND FUNCTION OF tRNA,
AMINOACYL RNA SYNTHETASE(ASR) PROOFREADING AND EDITING
https://www.youtube.com/watch?v=YzOVMWYLiCE
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
Almost 98 of the human genome does not encode proteins
o The non coding transcripts less than 200 bases are called small non
coding RNA and comprise of tRNA, rRNA, miRNA, snoRNA, piwi
interacting RNA (pi RNA)
o RNA molecules that are of more than 200 bases in length are known
as long non coding RNA (
o lncRNAs are more than 200 nucleotides in length and also can be
more than 2 Kb
o Such long noncoding RNAs usually have limited coding potential due
to the absence of open reading frames, 3 UTR and termination
region while their coding potential is less than 100 amino acids
Presentation made during the EISBM workshop, 13-15 June 2012 by Luigi Ceccaroni (BDigital), Isaac Cano (IDIBAPS), David Gomez-Cabrero (Karolinska Institute).
Basics of Undergraduate/university fellows
Transcription is more complicated in eukaryotes than in prokaryotes because
eukaryotes possess three different classes of RNA polymerases and because of the
way in which transcripts are processed to their functional forms.
ďˇ More proteins and transcription factors are involved in eukaryotic transcription.
Khaled El Masry, is an assistant Lecturer of Human Anatomy & Embryology, Mansoura University, Egypt. Great thanks to Prof. Dr Salwa Gawish, professor of Cytology & Histology, Mansoura University, for her great effort in explaining Genetics course.
Activation of gene expression by transcription factorsSaad Salih
Â
in eukaryotic cells, environmental stimuli commonly lead to activation of transcription factors and alteration of gene expression levels1. ... For example, the interaction between a transcription factor and DNA can be perturbed by either a change in DNA sequence or a change in the accessibility of the DNA by nucleosomes
Generating a custom Ruby SDK for your web service or Rails API using Smithyg2nightmarescribd
Â
Have you ever wanted a Ruby client API to communicate with your web service? Smithy is a protocol-agnostic language for defining services and SDKs. Smithy Ruby is an implementation of Smithy that generates a Ruby SDK using a Smithy model. In this talk, we will explore Smithy and Smithy Ruby to learn how to generate custom feature-rich SDKs that can communicate with any web service, such as a Rails JSON API.
Dev Dives: Train smarter, not harder â active learning and UiPath LLMs for do...UiPathCommunity
Â
đĽ Speed, accuracy, and scaling â discover the superpowers of GenAI in action with UiPath Document Understanding and Communications Miningâ˘:
See how to accelerate model training and optimize model performance with active learning
Learn about the latest enhancements to out-of-the-box document processing â with little to no training required
Get an exclusive demo of the new family of UiPath LLMs â GenAI models specialized for processing different types of documents and messages
This is a hands-on session specifically designed for automation developers and AI enthusiasts seeking to enhance their knowledge in leveraging the latest intelligent document processing capabilities offered by UiPath.
Speakers:
đ¨âđŤ Andras Palfi, Senior Product Manager, UiPath
đŠâđŤ Lenka Dulovicova, Product Program Manager, UiPath
Encryption in Microsoft 365 - ExpertsLive Netherlands 2024Albert Hoitingh
Â
In this session I delve into the encryption technology used in Microsoft 365 and Microsoft Purview. Including the concepts of Customer Key and Double Key Encryption.
The Art of the Pitch: WordPress Relationships and SalesLaura Byrne
Â
Clients donât know what they donât know. What web solutions are right for them? How does WordPress come into the picture? How do you make sure you understand scope and timeline? What do you do if sometime changes?
All these questions and more will be explored as we talk about matching clientsâ needs with what your agency offers without pulling teeth or pulling your hair out. Practical tips, and strategies for successful relationship building that leads to closing the deal.
Smart TV Buyer Insights Survey 2024 by 91mobiles.pdf91mobiles
Â
91mobiles recently conducted a Smart TV Buyer Insights Survey in which we asked over 3,000 respondents about the TV they own, aspects they look at on a new TV, and their TV buying preferences.
Slack (or Teams) Automation for Bonterra Impact Management (fka Social Soluti...Jeffrey Haguewood
Â
Sidekick Solutions uses Bonterra Impact Management (fka Social Solutions Apricot) and automation solutions to integrate data for business workflows.
We believe integration and automation are essential to user experience and the promise of efficient work through technology. Automation is the critical ingredient to realizing that full vision. We develop integration products and services for Bonterra Case Management software to support the deployment of automations for a variety of use cases.
This video focuses on the notifications, alerts, and approval requests using Slack for Bonterra Impact Management. The solutions covered in this webinar can also be deployed for Microsoft Teams.
Interested in deploying notification automations for Bonterra Impact Management? Contact us at sales@sidekicksolutionsllc.com to discuss next steps.
Builder.ai Founder Sachin Dev Duggal's Strategic Approach to Create an Innova...Ramesh Iyer
Â
In today's fast-changing business world, Companies that adapt and embrace new ideas often need help to keep up with the competition. However, fostering a culture of innovation takes much work. It takes vision, leadership and willingness to take risks in the right proportion. Sachin Dev Duggal, co-founder of Builder.ai, has perfected the art of this balance, creating a company culture where creativity and growth are nurtured at each stage.
UiPath Test Automation using UiPath Test Suite series, part 4DianaGray10
Â
Welcome to UiPath Test Automation using UiPath Test Suite series part 4. In this session, we will cover Test Manager overview along with SAP heatmap.
The UiPath Test Manager overview with SAP heatmap webinar offers a concise yet comprehensive exploration of the role of a Test Manager within SAP environments, coupled with the utilization of heatmaps for effective testing strategies.
Participants will gain insights into the responsibilities, challenges, and best practices associated with test management in SAP projects. Additionally, the webinar delves into the significance of heatmaps as a visual aid for identifying testing priorities, areas of risk, and resource allocation within SAP landscapes. Through this session, attendees can expect to enhance their understanding of test management principles while learning practical approaches to optimize testing processes in SAP environments using heatmap visualization techniques
What will you get from this session?
1. Insights into SAP testing best practices
2. Heatmap utilization for testing
3. Optimization of testing processes
4. Demo
Topics covered:
Execution from the test manager
Orchestrator execution result
Defect reporting
SAP heatmap example with demo
Speaker:
Deepak Rai, Automation Practice Lead, Boundaryless Group and UiPath MVP
Kubernetes & AI - Beauty and the Beast !?! @KCD Istanbul 2024Tobias Schneck
Â
As AI technology is pushing into IT I was wondering myself, as an âinfrastructure container kubernetes guyâ, how get this fancy AI technology get managed from an infrastructure operational view? Is it possible to apply our lovely cloud native principals as well? What benefitâs both technologies could bring to each other?
Let me take this questions and provide you a short journey through existing deployment models and use cases for AI software. On practical examples, we discuss what cloud/on-premise strategy we may need for applying it to our own infrastructure to get it to work from an enterprise perspective. I want to give an overview about infrastructure requirements and technologies, what could be beneficial or limiting your AI use cases in an enterprise environment. An interactive Demo will give you some insides, what approaches I got already working for real.
Key Trends Shaping the Future of Infrastructure.pdfCheryl Hung
Â
Keynote at DIGIT West Expo, Glasgow on 29 May 2024.
Cheryl Hung, ochery.com
Sr Director, Infrastructure Ecosystem, Arm.
The key trends across hardware, cloud and open-source; exploring how these areas are likely to mature and develop over the short and long-term, and then considering how organisations can position themselves to adapt and thrive.
Software Delivery At the Speed of AI: Inflectra Invests In AI-Powered QualityInflectra
Â
In this insightful webinar, Inflectra explores how artificial intelligence (AI) is transforming software development and testing. Discover how AI-powered tools are revolutionizing every stage of the software development lifecycle (SDLC), from design and prototyping to testing, deployment, and monitoring.
Learn about:
⢠The Future of Testing: How AI is shifting testing towards verification, analysis, and higher-level skills, while reducing repetitive tasks.
⢠Test Automation: How AI-powered test case generation, optimization, and self-healing tests are making testing more efficient and effective.
⢠Visual Testing: Explore the emerging capabilities of AI in visual testing and how it's set to revolutionize UI verification.
⢠Inflectra's AI Solutions: See demonstrations of Inflectra's cutting-edge AI tools like the ChatGPT plugin and Azure Open AI platform, designed to streamline your testing process.
Whether you're a developer, tester, or QA professional, this webinar will give you valuable insights into how AI is shaping the future of software delivery.
Connector Corner: Automate dynamic content and events by pushing a buttonDianaGray10
Â
Here is something new! In our next Connector Corner webinar, we will demonstrate how you can use a single workflow to:
Create a campaign using Mailchimp with merge tags/fields
Send an interactive Slack channel message (using buttons)
Have the message received by managers and peers along with a test email for review
But thereâs more:
In a second workflow supporting the same use case, youâll see:
Your campaign sent to target colleagues for approval
If the âApproveâ button is clicked, a Jira/Zendesk ticket is created for the marketing design team
Butâif the âRejectâ button is pushed, colleagues will be alerted via Slack message
Join us to learn more about this new, human-in-the-loop capability, brought to you by Integration Service connectors.
And...
Speakers:
Akshay Agnihotri, Product Manager
Charlie Greenberg, Host
GraphRAG is All You need? LLM & Knowledge GraphGuy Korland
Â
Guy Korland, CEO and Co-founder of FalkorDB, will review two articles on the integration of language models with knowledge graphs.
1. Unifying Large Language Models and Knowledge Graphs: A Roadmap.
https://arxiv.org/abs/2306.08302
2. Microsoft Research's GraphRAG paper and a review paper on various uses of knowledge graphs:
https://www.microsoft.com/en-us/research/blog/graphrag-unlocking-llm-discovery-on-narrative-private-data/
2. Gene Regulation in Prokaryotes
and Eukaryotes
ď Gene is the sequence of nucleotides in DNA that
code one mRNA molecule or one polypeptide chain
ď In prokaryotes the primary control point is the
process of transcription initiation
ď In eukaryotes expression of gene into proteins can
be controlled at various locations.
2
3. Check Points for Gene Expression in
Eukaryotes
1. Synthesis of proteins is controlled right from the
chromatin stage.
2. Expression of gene is controlled at many steps
during the process of transcription and translation.
3
4. 1.Chromatin Structure
Two forms of chromatin
ďEuchromatin â A lesser coiled transcriptionally
active region which can be easily accessed by the
RNA polymerases.
ďHeterochromatin â A highly condensed
transcriptionally inactive region. The genes in this
region cannot be accessed by the RNA
polymerases for active transcription.
4
5. 1.Chromatin Structure
Mechanisms which affect the chromatin structure
and hence the expression of gene are:
1.Histone modifications â These modifications
make a region of gene either transcriptionally
active or inactive.
a)Acetylation(addition of an acetyl (CH3CO) group to one of the histone)
⢠âAcetylation ----â Condensation of DNA ----- â
Transcription of genes in that region
5
6. 1.Chromatin Structure
b. Methylation
⢠Methylation of histone H4 on R4 (arginine residue at
the 4th position) ââ opens the chromatin structure
ââ leading to transcriptional activation
⢠Methylation of histone H3 on K4 and K79 (lysines
residues at the 4th and 79th position) ââ opens the
chromatin structure ââ leading to transcriptional
activation
⢠Methylation of histone H3 on K9 and K27 (lysines
residues at the 9th and 27th position) ââ condenses
the chromatin structure ââ leading to transcriptional
inactivation
6
7. 1.Chromatin Structure
a) Ubiquitination
ďźUbiquitination of H2A â Transcriptional inactivation
ďźUbiquitination of H2B - Transcriptional activation
2) Methylation of DNA
ď Target sites of methylation are - The cytidine residues
which exist as a dinucleotide, CG (written as CpG i.e
Cytosine bound to guanine by phosphodiester bond).
ď âmethylated cytidine -- âTranscriptional activity
7
8. 2.Regulation of Transcription
⢠The differences in the mechanisms by which the
transcription of gene is controlled in prokaryotes
and eukaryotes are listed below:
Prokaryotes Eukaryotes
The linked genes are organized
into clusters known as operons
which are under the control of a
single promoter.
Eukaryotic genes are not
organized into operons and
each of these genes requires its
own promoter.
These genes are primarily
regulated by repressors.
Regulation by repressors is very
occasional and the primary role
of regulation is played by the
transcriptional activators known
as transcription factors.
8
9. 2.Regulation of Transcription
Prokaryotes Eukaryotes
A promoter sequence which
controls an operon lies upstream
of the operon.
Accessory or the regulatory
proteins control the recognition of
the transcriptional initiation sites
by RNA polymerases
Those genes which code
for a protein have a basic
structure consisting of:
ďŽExons â Gene sequences which
encode for a polypeptide
ďŽIntrons â These sequences will
get removed from the mRNA
before it gets translated.
ďŽA transcription initiation site
ďŽPromoter sequences.
A single operon gets transcribed
into a polycistronic mRNA which
can be translated into multiple
proteins
Monocistronic mRNAs which can
produce a single polypeptide are
produced
9
10. 10
2.Regulation of
Transcription
Promoters
The region necessary to initiate transcription.
Consists of short nucleotide sequence that
serve as the recognition point for binding of
RNA polymerase.
Located immediately adjacent to the genes
they regulate.
11. 2.1: Promoters
Promoters
ďProkaryotes - There are two promoter elements or
DNA sequences which are 35 and 10 base pairs in
length and seated upstream to the transcriptional
initiation sites.
ďThe consensus sequence present at
ď-35 position is TTGACA
ď-10 position is TATAAT. This is also termed as Pribnow-
box.
ďEukaryotes â There are two types of promoters
which are:
ďBasal promoters
ďUpstream promoters
11
12. 2.2: Promoters
ď Basal promoter or core promoter -These promoters
reside within 40bp upstream of the start site. These
promoters are seen in all protein coding genes.
Examples are CCAAT-boxes and TATA-boxes
1. TATA box
ď The consensus sequence for TATA box is
TATAT/AAT/A
ď It resides 20 to 30 bases upstream of the
transcriptional start site
ď This is similar in sequence to the prokaryotic
Pribnow-box
ď Proteins like TFIIA, B, C interact with this TATA box
12
13. 2.3: Promoters
2. CCAAT-box
ď The consensus sequence for this is
GGT/CCAATCT
ď It resides 50 to 130 bases upstream of the
transcriptional start site
ď Protein named as C/EBP (CCAAT-box/Enhancer
Binding Protein) binds this box
ď Upstream promoters - These promoters may lie up to
200bp upstream of the transcriptional initiation site. The
structure of this promoter and the associated binding
factors keeps varying from gene to gene
13
14. Promoters
Promoters for RNA polymerase II
include:
TATA box,
CAAT box,
GC box,
& Octamer box.
Site Structure Importance
TATA box -25 30bp upstream
)from the initial
point of
transcription
8bp sequences
composed only of
T=A pairs.
Mutations in this
sequence greatly
reduce transcription
)Loosing the ability
to bind to
transcription
factors(
CAAT box -70 80bp upstream
)from the initial
point of
transcription
CAAT or CCAAT
sequence.
Mutations in this
sequence greatly
reduce transcription
GC box 110bp upstream
)from the initial
point of
transcription
GGGCGG sequence,
often present in
multiple copies.
Documented by
mutational analysis
Octamer box -120 130bp
upstream
)from the initial
point of
transcription
ATTTGCAT
sequence.
Affects the
efficiency of
promoter in
initiating
transcription.
15. 3. Enhancers
DNA sequences interact with regulatory proteins
increase the efficiency of initiation
of transcription
increase its rate.
16. 3.1:Enhancers:
1. Large ) up to several hundred bp long).
2. Tissue- specific ( stimulate transcription
only in certain tissues).
17. 3.2: Enhancers
ď Enhancers
ďEnhancers can be located upstream, downstream or
within the gene that is transcribed
ďThe binding of these enhancers with enhancer
binding proteins (transcription factors) increases the
rate of transcription of that gene to a greater extent.
ďPromoters are capable of initiating lower levels of
transcription.
ďEnhancers are responsible for the cell or tissue
specific transcription.
ďEach enhancer has its own transcription factor that it
binds to.
17
18. 3.3: Enhancers
1. The proteins that bind to enhancers affect the activity of
proteins that bind to promoters.
2. Enhancers may allow RNA polymerase to bind to DNA and
move along the chromosome till it reaches a promoter site.
3. May respond to molecules outside the cell ( e.g : steroid
hormones).
4. May respond to molecules inside the cell ( e.g : during
development thus the gene participates in cell
differentiation).
19. 3.4:How enhancers can control transcription
although they are located away from the
transcription site.
Enhancers bind to transcription factors by at
Least 20 different proteins
Form a complex
change the configuration of the chromatin
folding, bending or looping of DNA.
20. 3.5:Action of an enhancer
ď â An enhancer binding protein has two binding
sites
ďBinds DNA
ďBinds the transcription factors that are bound to the
promoter
20
23. DNA looping will bring the distal enhancers
close to the promoter site to form
activated transcription complexes,
then the transcription is activated,
increasing the overall rate of RNA synthesis.
3.6:Enhancers:
24.
25. 4.Transcription factors
â Are the proteins that are essential for
initiation of the transcription, but they are
not part of RNA polymerase molecule that
carry out the transcription processâ.
26. Function:
Each RNA polymerase requires a number of
transcription factors which help in:
1. Binding of the enzyme to DNA template.
2. Initiation and maintenance of
transcription.
3. Control the rate of gene expression.
Transcription factors
27. Structure & Mechanism of action
These proteins contain 2 functional domains, that
perform specific function.
1. DBD: DNA binding domain: binds to DNA sequences
present in regulatory regions (e.g : TATA
binding protein).
2. AD: Transcriptional activating domain: activate
transcription via protein-protein interaction
28.
29. Types of transcription factors:
1. Basal transcription factors:
The initiation of transcription by RNA polymerase
II requires the assistance of several basal
transcription factors.
Each of these proteins binds to a sequence
within the promoter to facilitate the proper
alignment of RNA polymerase on the template
strand of DNA.
30. The basal TFs must interact with the
promoters in the correct sequence to initiate
transcription effectively.
TFIID is the 1st
basal TF that interact with the
promoter ; it contains TATA- Binding Protein.
Followed by TFII B, F, E, H & J.
Types of transcription factors:
31.
32. 2. Special TFs:
Involved in regulation of heat, light, and hormone inducible
genes.
They bind to:
a. enhancers.
b. Basal TFs.
c. RNA polymerase that bind to the gene promoter.
Therefore, special TFs can regulate the transcriptional activity
of the gene.
Types of transcription factors:
33. How is the gene transcription controlled
at this point
⢠The unique combination of the promoter
sites, transcription factors and enhancers
chosen ultimately decides which gene
gets switched on and which one gets
switched off.
33
34. 5.Regulation of RNA
Processing
ď RNA processing involves
ďAddition of 5' cap
ďAddition of a 3' poly (A) tail
ďRemoval of introns
ď The RNAs which get translated to proteins are
transported out from the nucleus to cytoplasm.
ď Depending on the final combination of exons after
splicing different kinds of proteins are obtained
which can perform different functions in the cell.
34
35. 5.1:Exon Shuffling
⢠The functions of two proteins synthesized from the same
mRNA are different in different cells as different
combination of exons exist in different cells.
35
36. 6.Regulation of RNA Transport
⢠Only some RNAs function within the
nucleus whereas all other RNAs which are
meant for protein synthesis have to be
transported from the nucleus to the
cytoplasm via nuclear pores.
36
37. 6.1:Regulation of RNA Longevity
⢠mRNAs from different genes have
different life spans.
⢠The information of the life span of mRNA
is found in the 3' UTR(Un-translated
Reagion).
⢠The sequence AUUUA within 3' UTR acts
as a signal for early degradation.
⢠More the number of times the sequence is
repeated ď Shorter the lifespan of mRNA
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39. 6.Regulation of Translation
ďTranslational initiation
ďThe expression of a gene product also depends
on the ability of the ribosome to recognize the
correct AUG codon out of the multiple methionine
codons present in the mRNA.
ďControl of translational process
ďIn many animals large amounts of mRNAs are
produced by the eggs but all of them do not get
translated until the egg is fertilized.
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40. 7.Post Translational Control Points
ďPost translational modifications
ďFunctional state of protein depends on
modifications like glycosylation, acetylation, fatty
acylation, disulfide bond formations.
ďChaperons
ďProtein transport
ďTransportation to the site of action also regulate
gene expression.
ďProtein stability
ďThe lifespan of a protein depends on the specific
amino acid sequence present within them
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41. Summary of the Class
⢠The expression of genes is controlled at various levels in
eukaryotes.
⢠At the chromatin stage the level of condensation
determines whether the genes will remain
transcriptionally active or not.
⢠The unique combination of the promoter sites,
transcription factors and enhancers regulates the
transcriptional rate of a gene.
⢠After transcription the gene expression is controlled by
RNA processing.
⢠The expression of gene is also controlled at the level of
translation and after translation.
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DNA acetylation refers to the addition of an acetyl (CH3CO) group to one of the histone proteins that help hold DNA in its tightly wound configuration. When histones are altered by this change, the binding between histones and DNA is relaxed. This promotes transcription in eukaryotic cells. Read more: http://www.answers.com/topic/what-is-dna-acetylation#ixzz2OxwGU1Nx