For MBBS, BDS and General Biochemistry students, coding strand, sense strand, anti-sense strand, promoter, enhancers, silencers, TATA box, Goldberg Hogness box, alternative spilicing, post-transcriptional modification
it describes transcription with simple diagram and animation. its steps and inhibitors are described for both eukaryotes and prokaryotes. it will be easily understood by UG students . post transcriptional modification of all the RNA are also described with diagrams.
it describes transcription with simple diagram and animation. its steps and inhibitors are described for both eukaryotes and prokaryotes. it will be easily understood by UG students . post transcriptional modification of all the RNA are also described with diagrams.
Structure and function of Messenger RNA (mRNA )ICHHA PURAK
This presentation of 42 slides delivers information about structure,function synthesis , life span of both prokaryotic and eukaryotic messenger RNA also about role in protein sorting and targetting
This presentation explains the fundamentals of Genetic Code, Protein synthesis mechanism and Antibiotics that inhibits at various stages of Translation.
Eukaryotic transcription is the elaborate process that eukaryotic cells use to copy genetic information stored in DNA into units of RNA replica.- Source: Wikipedia
Transcription in eukaryotes: A brief view
Transcription is the process by which single stranded RNA is synthesized by double stranded DNA. Transcription in eukaryotes and prokaryotes has many similarities while at the same time both showing their individual characteristics due to the differences in organization. RNA Polymerase (RNAP or RNA Pol) is different in prokaryotes and eukaryotes. Coupled transcription is seen in prokaryotes but not in Eukaryotes. In eukaryotes the pre-RNA should be spliced first to be translated.
In Eukaryotic transcription, synthesis of RNA occurs in the 3’→5’ direction. The 3’ end is more reactive due to the hydroxide group. 5’ end containing phosphate groups meanwhile, is not very reactive when it comes to adding new nucleotides. In Eukaryotes, the whole genome is not transcribed at once. Only a part of the genome is transcribed which also acts as the first, principle stage of genetic regulation.
Eukaryotes have five nuclear polymerases:
• RNA Polymerase I: This produces rRNA (23S, 5.8S, and 18S) which are the major components in a ribosome. This also produces pre-rRNA in yeasts.
• RNA Polymerase II: Helps in the production of mRNA (messenger RNA), snRNA (small, nuclear RNA), miRNA. This is the most studied type and requires several transcription factors for its binding
• RNA Polymerase III: This synthesizes tRNA (transfer RNA), 5S rRNA and other small RNAs required in the cytosol and nucleus.
• RNA Polymerase IV: Synthesizes siRNA (small interfering RNA) in plants.
• RNA Polymerase V: This is the least studied polymerase and synthesizes siRNA-directed heterochromatin in plants.
Eukaryotic transcription can be broadly divided into 4 stages:
• Pre-Initiation
• Initiation
• Elongation
• Termination
Transcription is an elaborate process which cells use to copy the genetic information stored in DNA into RNA. This pre-RNA is modified into mRNA before being transcribed to proteins. Transcription is the first step to utilizing the genetic information in a cell. Both Eukaryotes and Prokaryotes employ this process with the basic phases remaining the same. However eukaryotic transcription is more complex indicating the changes transcription has undergone towards perfection during evolution.
Transcription is the process by which the information in a strand of DNA is copied into a new molecule of messenger RNA (mRNA).Transcription is carried out by an enzyme called RNA polymerase and a number of accessory proteins called transcription factors.
Structure and function of Messenger RNA (mRNA )ICHHA PURAK
This presentation of 42 slides delivers information about structure,function synthesis , life span of both prokaryotic and eukaryotic messenger RNA also about role in protein sorting and targetting
This presentation explains the fundamentals of Genetic Code, Protein synthesis mechanism and Antibiotics that inhibits at various stages of Translation.
Eukaryotic transcription is the elaborate process that eukaryotic cells use to copy genetic information stored in DNA into units of RNA replica.- Source: Wikipedia
Transcription in eukaryotes: A brief view
Transcription is the process by which single stranded RNA is synthesized by double stranded DNA. Transcription in eukaryotes and prokaryotes has many similarities while at the same time both showing their individual characteristics due to the differences in organization. RNA Polymerase (RNAP or RNA Pol) is different in prokaryotes and eukaryotes. Coupled transcription is seen in prokaryotes but not in Eukaryotes. In eukaryotes the pre-RNA should be spliced first to be translated.
In Eukaryotic transcription, synthesis of RNA occurs in the 3’→5’ direction. The 3’ end is more reactive due to the hydroxide group. 5’ end containing phosphate groups meanwhile, is not very reactive when it comes to adding new nucleotides. In Eukaryotes, the whole genome is not transcribed at once. Only a part of the genome is transcribed which also acts as the first, principle stage of genetic regulation.
Eukaryotes have five nuclear polymerases:
• RNA Polymerase I: This produces rRNA (23S, 5.8S, and 18S) which are the major components in a ribosome. This also produces pre-rRNA in yeasts.
• RNA Polymerase II: Helps in the production of mRNA (messenger RNA), snRNA (small, nuclear RNA), miRNA. This is the most studied type and requires several transcription factors for its binding
• RNA Polymerase III: This synthesizes tRNA (transfer RNA), 5S rRNA and other small RNAs required in the cytosol and nucleus.
• RNA Polymerase IV: Synthesizes siRNA (small interfering RNA) in plants.
• RNA Polymerase V: This is the least studied polymerase and synthesizes siRNA-directed heterochromatin in plants.
Eukaryotic transcription can be broadly divided into 4 stages:
• Pre-Initiation
• Initiation
• Elongation
• Termination
Transcription is an elaborate process which cells use to copy the genetic information stored in DNA into RNA. This pre-RNA is modified into mRNA before being transcribed to proteins. Transcription is the first step to utilizing the genetic information in a cell. Both Eukaryotes and Prokaryotes employ this process with the basic phases remaining the same. However eukaryotic transcription is more complex indicating the changes transcription has undergone towards perfection during evolution.
Transcription is the process by which the information in a strand of DNA is copied into a new molecule of messenger RNA (mRNA).Transcription is carried out by an enzyme called RNA polymerase and a number of accessory proteins called transcription factors.
dna transcription is a important topic for biology student. this presentation may be helpful for student of biology.it is useful for all types of courses as like M.Sc, B.Sc, 11th and 12th standard.
The process by which an RNA copy of a gene is made or it’s a DNA dependent RNA synthesis.
Transcription resembles replication
In its fundamental chemical mechanism
Its polarity (direction of synthesis)
Its use of a template
Transcription differs from replication
It does not requires a primer
It involves only limited segments of a DNA molecule
Within transcribed segments only one DNA strand serves as a template for synthesis of RNA.
This presentation is targeted for MBBS, MD and BDS students that describes briefly about aetiopathogenesis, tumour markers, anti cancer agents, apoptosis
Glycine is an aliphatic amino acid which gives rise to many vital derivatives. This is a non-essential amino acid. This presentation is targeted for MBBS, MD, BDS and general Biochemistry students.
it is about how ammonia is detoxified to urea and its biomedical significance. This PPT can be used by students of MBBS, MD, BDS and general Biochemistry students
Overview of amino acid anabolism and catabolism and fate of ammonia in amino acid metabolism. This is targeted for MBBS, MD, BDS and general Biochemistry students
Title: Sense of Smell
Presenter: Dr. Faiza, Assistant Professor of Physiology
Qualifications:
MBBS (Best Graduate, AIMC Lahore)
FCPS Physiology
ICMT, CHPE, DHPE (STMU)
MPH (GC University, Faisalabad)
MBA (Virtual University of Pakistan)
Learning Objectives:
Describe the primary categories of smells and the concept of odor blindness.
Explain the structure and location of the olfactory membrane and mucosa, including the types and roles of cells involved in olfaction.
Describe the pathway and mechanisms of olfactory signal transmission from the olfactory receptors to the brain.
Illustrate the biochemical cascade triggered by odorant binding to olfactory receptors, including the role of G-proteins and second messengers in generating an action potential.
Identify different types of olfactory disorders such as anosmia, hyposmia, hyperosmia, and dysosmia, including their potential causes.
Key Topics:
Olfactory Genes:
3% of the human genome accounts for olfactory genes.
400 genes for odorant receptors.
Olfactory Membrane:
Located in the superior part of the nasal cavity.
Medially: Folds downward along the superior septum.
Laterally: Folds over the superior turbinate and upper surface of the middle turbinate.
Total surface area: 5-10 square centimeters.
Olfactory Mucosa:
Olfactory Cells: Bipolar nerve cells derived from the CNS (100 million), with 4-25 olfactory cilia per cell.
Sustentacular Cells: Produce mucus and maintain ionic and molecular environment.
Basal Cells: Replace worn-out olfactory cells with an average lifespan of 1-2 months.
Bowman’s Gland: Secretes mucus.
Stimulation of Olfactory Cells:
Odorant dissolves in mucus and attaches to receptors on olfactory cilia.
Involves a cascade effect through G-proteins and second messengers, leading to depolarization and action potential generation in the olfactory nerve.
Quality of a Good Odorant:
Small (3-20 Carbon atoms), volatile, water-soluble, and lipid-soluble.
Facilitated by odorant-binding proteins in mucus.
Membrane Potential and Action Potential:
Resting membrane potential: -55mV.
Action potential frequency in the olfactory nerve increases with odorant strength.
Adaptation Towards the Sense of Smell:
Rapid adaptation within the first second, with further slow adaptation.
Psychological adaptation greater than receptor adaptation, involving feedback inhibition from the central nervous system.
Primary Sensations of Smell:
Camphoraceous, Musky, Floral, Pepperminty, Ethereal, Pungent, Putrid.
Odor Detection Threshold:
Examples: Hydrogen sulfide (0.0005 ppm), Methyl-mercaptan (0.002 ppm).
Some toxic substances are odorless at lethal concentrations.
Characteristics of Smell:
Odor blindness for single substances due to lack of appropriate receptor protein.
Behavioral and emotional influences of smell.
Transmission of Olfactory Signals:
From olfactory cells to glomeruli in the olfactory bulb, involving lateral inhibition.
Primitive, less old, and new olfactory systems with different path
Lung Cancer: Artificial Intelligence, Synergetics, Complex System Analysis, S...Oleg Kshivets
RESULTS: Overall life span (LS) was 2252.1±1742.5 days and cumulative 5-year survival (5YS) reached 73.2%, 10 years – 64.8%, 20 years – 42.5%. 513 LCP lived more than 5 years (LS=3124.6±1525.6 days), 148 LCP – more than 10 years (LS=5054.4±1504.1 days).199 LCP died because of LC (LS=562.7±374.5 days). 5YS of LCP after bi/lobectomies was significantly superior in comparison with LCP after pneumonectomies (78.1% vs.63.7%, P=0.00001 by log-rank test). AT significantly improved 5YS (66.3% vs. 34.8%) (P=0.00000 by log-rank test) only for LCP with N1-2. Cox modeling displayed that 5YS of LCP significantly depended on: phase transition (PT) early-invasive LC in terms of synergetics, PT N0—N12, cell ratio factors (ratio between cancer cells- CC and blood cells subpopulations), G1-3, histology, glucose, AT, blood cell circuit, prothrombin index, heparin tolerance, recalcification time (P=0.000-0.038). Neural networks, genetic algorithm selection and bootstrap simulation revealed relationships between 5YS and PT early-invasive LC (rank=1), PT N0—N12 (rank=2), thrombocytes/CC (3), erythrocytes/CC (4), eosinophils/CC (5), healthy cells/CC (6), lymphocytes/CC (7), segmented neutrophils/CC (8), stick neutrophils/CC (9), monocytes/CC (10); leucocytes/CC (11). Correct prediction of 5YS was 100% by neural networks computing (area under ROC curve=1.0; error=0.0).
CONCLUSIONS: 5YS of LCP after radical procedures significantly depended on: 1) PT early-invasive cancer; 2) PT N0--N12; 3) cell ratio factors; 4) blood cell circuit; 5) biochemical factors; 6) hemostasis system; 7) AT; 8) LC characteristics; 9) LC cell dynamics; 10) surgery type: lobectomy/pneumonectomy; 11) anthropometric data. Optimal diagnosis and treatment strategies for LC are: 1) screening and early detection of LC; 2) availability of experienced thoracic surgeons because of complexity of radical procedures; 3) aggressive en block surgery and adequate lymph node dissection for completeness; 4) precise prediction; 5) adjuvant chemoimmunoradiotherapy for LCP with unfavorable prognosis.
TEST BANK for Operations Management, 14th Edition by William J. Stevenson, Ve...kevinkariuki227
TEST BANK for Operations Management, 14th Edition by William J. Stevenson, Verified Chapters 1 - 19, Complete Newest Version.pdf
TEST BANK for Operations Management, 14th Edition by William J. Stevenson, Verified Chapters 1 - 19, Complete Newest Version.pdf
Couples presenting to the infertility clinic- Do they really have infertility...Sujoy Dasgupta
Dr Sujoy Dasgupta presented the study on "Couples presenting to the infertility clinic- Do they really have infertility? – The unexplored stories of non-consummation" in the 13th Congress of the Asia Pacific Initiative on Reproduction (ASPIRE 2024) at Manila on 24 May, 2024.
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These simplified slides by Dr. Sidra Arshad present an overview of the non-respiratory functions of the respiratory tract.
Learning objectives:
1. Enlist the non-respiratory functions of the respiratory tract
2. Briefly explain how these functions are carried out
3. Discuss the significance of dead space
4. Differentiate between minute ventilation and alveolar ventilation
5. Describe the cough and sneeze reflexes
Study Resources:
1. Chapter 39, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 34, Ganong’s Review of Medical Physiology, 26th edition
3. Chapter 17, Human Physiology by Lauralee Sherwood, 9th edition
4. Non-respiratory functions of the lungs https://academic.oup.com/bjaed/article/13/3/98/278874
Ozempic: Preoperative Management of Patients on GLP-1 Receptor Agonists Saeid Safari
Preoperative Management of Patients on GLP-1 Receptor Agonists like Ozempic and Semiglutide
ASA GUIDELINE
NYSORA Guideline
2 Case Reports of Gastric Ultrasound
micro teaching on communication m.sc nursing.pdfAnurag Sharma
Microteaching is a unique model of practice teaching. It is a viable instrument for the. desired change in the teaching behavior or the behavior potential which, in specified types of real. classroom situations, tends to facilitate the achievement of specified types of objectives.
ARTIFICIAL INTELLIGENCE IN HEALTHCARE.pdfAnujkumaranit
Artificial intelligence (AI) refers to the simulation of human intelligence processes by machines, especially computer systems. It encompasses tasks such as learning, reasoning, problem-solving, perception, and language understanding. AI technologies are revolutionizing various fields, from healthcare to finance, by enabling machines to perform tasks that typically require human intelligence.
NVBDCP.pptx Nation vector borne disease control programSapna Thakur
NVBDCP was launched in 2003-2004 . Vector-Borne Disease: Disease that results from an infection transmitted to humans and other animals by blood-feeding arthropods, such as mosquitoes, ticks, and fleas. Examples of vector-borne diseases include Dengue fever, West Nile Virus, Lyme disease, and malaria.
These lecture slides, by Dr Sidra Arshad, offer a quick overview of physiological basis of a normal electrocardiogram.
Learning objectives:
1. Define an electrocardiogram (ECG) and electrocardiography
2. Describe how dipoles generated by the heart produce the waveforms of the ECG
3. Describe the components of a normal electrocardiogram of a typical bipolar leads (limb II)
4. Differentiate between intervals and segments
5. Enlist some common indications for obtaining an ECG
Study Resources:
1. Chapter 11, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 9, Human Physiology - From Cells to Systems, Lauralee Sherwood, 9th edition
3. Chapter 29, Ganong’s Review of Medical Physiology, 26th edition
4. Electrocardiogram, StatPearls - https://www.ncbi.nlm.nih.gov/books/NBK549803/
5. ECG in Medical Practice by ABM Abdullah, 4th edition
6. ECG Basics, http://www.nataliescasebook.com/tag/e-c-g-basics
Prix Galien International 2024 Forum ProgramLevi Shapiro
June 20, 2024, Prix Galien International and Jerusalem Ethics Forum in ROME. Detailed agenda including panels:
- ADVANCES IN CARDIOLOGY: A NEW PARADIGM IS COMING
- WOMEN’S HEALTH: FERTILITY PRESERVATION
- WHAT’S NEW IN THE TREATMENT OF INFECTIOUS,
ONCOLOGICAL AND INFLAMMATORY SKIN DISEASES?
- ARTIFICIAL INTELLIGENCE AND ETHICS
- GENE THERAPY
- BEYOND BORDERS: GLOBAL INITIATIVES FOR DEMOCRATIZING LIFE SCIENCE TECHNOLOGIES AND PROMOTING ACCESS TO HEALTHCARE
- ETHICAL CHALLENGES IN LIFE SCIENCES
- Prix Galien International Awards Ceremony
- Video recording of this lecture in English language: https://youtu.be/lK81BzxMqdo
- Video recording of this lecture in Arabic language: https://youtu.be/Ve4P0COk9OI
- Link to download the book free: https://nephrotube.blogspot.com/p/nephrotube-nephrology-books.html
- Link to NephroTube website: www.NephroTube.com
- Link to NephroTube social media accounts: https://nephrotube.blogspot.com/p/join-nephrotube-on-social-media.html
Title: Sense of Taste
Presenter: Dr. Faiza, Assistant Professor of Physiology
Qualifications:
MBBS (Best Graduate, AIMC Lahore)
FCPS Physiology
ICMT, CHPE, DHPE (STMU)
MPH (GC University, Faisalabad)
MBA (Virtual University of Pakistan)
Learning Objectives:
Describe the structure and function of taste buds.
Describe the relationship between the taste threshold and taste index of common substances.
Explain the chemical basis and signal transduction of taste perception for each type of primary taste sensation.
Recognize different abnormalities of taste perception and their causes.
Key Topics:
Significance of Taste Sensation:
Differentiation between pleasant and harmful food
Influence on behavior
Selection of food based on metabolic needs
Receptors of Taste:
Taste buds on the tongue
Influence of sense of smell, texture of food, and pain stimulation (e.g., by pepper)
Primary and Secondary Taste Sensations:
Primary taste sensations: Sweet, Sour, Salty, Bitter, Umami
Chemical basis and signal transduction mechanisms for each taste
Taste Threshold and Index:
Taste threshold values for Sweet (sucrose), Salty (NaCl), Sour (HCl), and Bitter (Quinine)
Taste index relationship: Inversely proportional to taste threshold
Taste Blindness:
Inability to taste certain substances, particularly thiourea compounds
Example: Phenylthiocarbamide
Structure and Function of Taste Buds:
Composition: Epithelial cells, Sustentacular/Supporting cells, Taste cells, Basal cells
Features: Taste pores, Taste hairs/microvilli, and Taste nerve fibers
Location of Taste Buds:
Found in papillae of the tongue (Fungiform, Circumvallate, Foliate)
Also present on the palate, tonsillar pillars, epiglottis, and proximal esophagus
Mechanism of Taste Stimulation:
Interaction of taste substances with receptors on microvilli
Signal transduction pathways for Umami, Sweet, Bitter, Sour, and Salty tastes
Taste Sensitivity and Adaptation:
Decrease in sensitivity with age
Rapid adaptation of taste sensation
Role of Saliva in Taste:
Dissolution of tastants to reach receptors
Washing away the stimulus
Taste Preferences and Aversions:
Mechanisms behind taste preference and aversion
Influence of receptors and neural pathways
Impact of Sensory Nerve Damage:
Degeneration of taste buds if the sensory nerve fiber is cut
Abnormalities of Taste Detection:
Conditions: Ageusia, Hypogeusia, Dysgeusia (parageusia)
Causes: Nerve damage, neurological disorders, infections, poor oral hygiene, adverse drug effects, deficiencies, aging, tobacco use, altered neurotransmitter levels
Neurotransmitters and Taste Threshold:
Effects of serotonin (5-HT) and norepinephrine (NE) on taste sensitivity
Supertasters:
25% of the population with heightened sensitivity to taste, especially bitterness
Increased number of fungiform papillae
Knee anatomy and clinical tests 2024.pdfvimalpl1234
This includes all relevant anatomy and clinical tests compiled from standard textbooks, Campbell,netter etc..It is comprehensive and best suited for orthopaedicians and orthopaedic residents.
4. Decoding DNA:
DNA→ RNA → PROTEIN
Two separate processes involved:
Transcription – DNA used as the template
to make RNA
Translation – RNA serves as the template
for the sequence of amino
acids in a protein
5. The first step in expressing a gene
Occurs in the nucleus
DNA-directed RNA synthesis
An RNA copy of DNA is made.
This RNA serves as a messenger
between the nucleus and the
cytoplasm (mRNA).
6. How big part of human transcribed RNA
results in proteins?
Of all RNA, transcribed in higher
eukaryotes, 98% are never translated into
proteins
• Of those 98%, about 50-70% are introns
• 4% of total RNA is made of coding RNA
• The rest originate from non-protein genes,
including rRNA, tRNA and a vast number
of other non-coding RNAs (ncRNAs)
8. Similarities with replication
Involves general steps of initiation,
elongation and termination
5’→3’ polarity
Large, multicomplex initiation
complex
Adherence to Watson-Crick base
pairing rule
9. Differences between replication and
transcription
Ribonucleotides
U in place of T
Primer not involved
Very small portion of the
genome is transcribed
No proofreading function of
transcription
Doesn’t stop at one cycle
14. Prokaryotic RNAP
Single RNAP transcribing all 3 RNAs– mRNA,
rRNA & tRNA
5 subunits-- 2α, β, β’,ω--E
Sigma (σ)– 5th factor– helps in binding of RNAP to
specific promoter region of DNA template
E σ- Holoenzyme
RNAP- Metallozyme– Zn
β- binds to Mg++
15. Eukaryotic RNAP
3 RNAP
molecule location product
RNA polymerase I nucleolus 28S, 18S
5.8s rRNA
RNA polymerase II nucleus hnRNA,
mRNA,
some snRNAs
RNA polymerase III nucleus tRNA, 5S rRNA,
some snRNAs
16. Recognition of the promoter
region
Melting of DNA (Helicase +
Topoisomerase)
RNA Priming (Primase)
RNA Polymerization
Recognition of terminator
sequence
19. Initiation (Prokaryotic)
Promoter region recognised and sigma
factor binds to it
Proteins called transcription factors
bind to the promoter region of a gene
If the appropriate transcription factors
are present, RNA polymerase binds to
form an initiation complex
RNA polymerase melts the DNA at the
transcription start site
Polymerization of RNA begins
22. Prokaryotic promoters
TATA box/ Prinbow box– conserved
sequence on coding strand
-10 bp– 5’TATAAT’3 sequence
-35 bp– 5’TGTTGACA3’ sequence
RNAP binds here to form closed
complexes
AT rich regions– easily melted
23. Eukaryotic promoters
Each type of RNAP uses a different
promoter
Promoters used by RNAP I & II– same as
prokaryotic– upstream
Promoter used by RNAP III– downstream
Goldberg- Hogness box-- -25 to -30 bp
TATAAA sequence
CAAT box-- -70 to -80 bp
Eukaryotic initiation complex is very
complex
26. Elongation
RNAP binds at promoter site– Preinitiation
complex ↓
Conformational change in RNAP
↓
1st nucleotide (almost always a purine)
associates on β-subunit of the enzyme
↓
RNAP catalyses formation of a phosphodiester
bond in presence of appropriate nucleotide
↓
Elongation of RNA in 5’→3’ direction
27. Promoter clearance
In eukaryotes- a transition phase
Just before Elongation proper
After initial synthesis of 10-20
nucleotides have been
polymerized, RNAP physically
moves away from the promoter
down the transcription unit
30. Termination
Rho dependent requires a protein called Rho,
that binds to and slides along the RNA transcript.
The terminator sequence slows down the
elongation complex, Rho catches up and knocks it
off the DNA
Bacterial RNAP sometimes recognizes the DNA
encoded termination signals and dislodges
Rho independent termination
2nd GC-rich region that likes to form stem loop
structure
Stem loop forms, pulling mRNA from template
31. Rho – ATP-dependent RNA stimulated helicase that
disrupts the nascent RNA-DNA complex
Terminator
RNA
Pol.
5’
RNA
r
RNA
Pol.
5’
RNA
Help, rho
hit me!
r
RNA
Pol.
5’
RNA
33. Eukaryotic termination
Less well defined
May be similar to Rho-independent
type
RNA processing, termination and
polyadenylation proteins appear to
load onto RNAP-II soon after initiation
34. Differences between eukaryotic and
prokaryotic transcription
Eukaryotes– different
compartments for transcription
and translation.
Prokaryotes– translation starts
without undergoing processing
Promoter sites
35. Eukaryotic transcription
TATA box is bound by 34kDa protein TATA
binding protein (TBP)
TBP + TAF (TBP associated factor)
↓
TF II D
↓
1st step of formation of transcription
complex
↓
Other factors attach
Enhancers and silencers
38. Endonuclease cleavage
Poly-A tailing (20-250 A)
5’ capping– 7-methyl GTP
Methylation- Methylations of N6 of
Adenine residue and 2’-OH group
of ribose- done in cytoplasm
Removal of introns
Splicing of exons
39. Prokaryotes- translation starts
even before mRNA is completely
synthesised
t-RNA and r-RNA also undergo
post-transcriptional modification
40. Removal of introns
Exons– expressed regions
hn-RNA– M.W. 107 ; mature RNA 1-
2×106
Introns removed and exons are
spliced (joined) together
Energy requiring process
Takes place in nucleus
41.
42. SnRNA (Small nuclear)
90-300 nucleotides
U1,U2,U4,U5,U6 &U7
Uracil-rich
Present in nucleus
SnRNA+ specific proteins=SNURP
(small nuclear ribonuclear protein
particles)
Form spliceosomes (SnRNP +hnRNA at
exon -intron junction)
Spliceosomes contain Ribozymes
44. Alternative splicing leads to differential
expression and certain diseases
Beta thalassaemia- a mutation in an
intron- exon junction- absent beta
chain synthesis
Glucokinase is expressed differently
in liver and pancreas due to different
promoters- Differential splicing
45. Alternate editing
ApoB gene generates ApoB100 in liver
and in intestine ApoB48
In intestine same primary transcript is
formed but a cytidine deaminase
converts a CAA codon into UAA-
produces a 49kDa protein- ApoB48
46.
47. Inhibitors of Transcription
Inhibitor Source Mode of action
Actinomycin-D Antibiotics from
streptomyces
Insertion of
phenoxazone ring
between two G-C bp
of DNA
Rifampin Rifamycin Binds to β-subunit
of RNAP
α-Amanitin Mushroom RNAP II
inactivated
3’-deoxyadenosine Synthetic analogue Incorrect entry
into chain causing
chain termination
49. mi-RNA
Derived from large primary transcripts
through specific nucleolytic processing
Transcribed by RNAP-II
Genes located independently or within the
intronic DNA
Comes out to cytoplasm- acted upon by a
dicer nuclease and gets incorporated into
RISC (RNA induced silencing complex)
50.
51. For more ppt on medical Biochemistry please visit my
website www.vpacharya.com