The nucleotide structure ,consists of
the nitrogenous base ,attached to the 1’ carbon of deoxyribose
,
the phosphate group attached to the 5’ carbon of deoxyribose
,
a free hydroxyl group (-OH) ,at the 3’ carbon of deoxyribose,1. DNA HELICASES,
to separate the strand,
2. GYRASE (Topoisomerases),
unwind the supercoil,
3. Single strand binding protein (SSBP)
, activity of helicase,
keep two strand separate,
protect DNA from nuclease degradation,
release after replication,
The following slides contains a brief comparison of the different forms of the DNA. It includes A-DNA, B-DNA , and Z-DNA.
It also briefs about the conditions that would favor the transition from one form to the another
DNA Replication In Eukaryotes (Bsc.Zoology)DebaPrakash2
This Slide Is explanation of Mechanism of DNA Replication In Eukaryotes.
As we know we all have DNA as the genetic material and So we should know how this DNA getting Duplicated so that it'll pass to daughter cells.
The following slides contains a brief comparison of the different forms of the DNA. It includes A-DNA, B-DNA , and Z-DNA.
It also briefs about the conditions that would favor the transition from one form to the another
DNA Replication In Eukaryotes (Bsc.Zoology)DebaPrakash2
This Slide Is explanation of Mechanism of DNA Replication In Eukaryotes.
As we know we all have DNA as the genetic material and So we should know how this DNA getting Duplicated so that it'll pass to daughter cells.
Eukaryotic DNA replication is a conserved mechanism that restricts DNA replication to once per cell cycle. Eukaryotic DNA replication of chromosomal DNA is central for the duplication of a cell and is necessary for the maintenance of the eukaryotic genome.
DNA replication in eukaryotes occurs in three stages: initiation, elongation, and termination, which are aided by several enzymes. Because eukaryotic genomes are quite
complex, DNA replication is a very complicated process that involves several enzymes and other proteins. It occurs in three main stages: initiation, elongation, and termination.
Genetic Codon The Three nucleotide base sequence in mRNA that act as code words for amino acids in protein constitute the genetic code or codons.
There are 64 different combinations of three base codons composed of Adenine (A), Guanine (G), Cytosine (C) and Uracil (U).
Written from the 5-’ end to 3’ end.
UAA,UAG & UGA do not code for amino acid. They are called as stop codon or non sense codon.
Characteristics of Genetic Code are:
University: same codon for same amino acid in all living organism.
Specificity: A particular codon will code for the same amino acid,highly specific or unambiguous.
Non overlapping : read from a fixed point as a continuous base sequence.
Degenerate: Most of the amino acids have more than one codon. 61 codons available to code for only 20 amino acids.
DNA :DNA stands for Deoxy Ribonucleic acid.
It’s the genetic code that determines all the characteristics of living organism.
DNA is a double stranded molecule, made up of two chains of nucleotides. Nucleotides consist of three subunits : a sugar, a phosphate group and a nitrogen base pair.
Sugar present is Deoxyribose and Nitrogen bases are :
Adenine (A)
Guanine (G)
Cytosine (C)
Thymine (T)
Structure of DNA : Double helical structure of DNA was proposed by James Watson and Francis Crick in 1953.
Features of model of DNA are:
DNA is a right handed double helix, have two polydeoxyribonucleotide chains twisted around each other on a common axis.
Two strands are antiparallel i.e., one strand runs in the 5’ to 3’ direction while the other in 3’ to 5’ direction.
The diameter of helix is 20 A° (2nm).
Each turn of the helix is 34 A° (3.4 nm) with 10 pairs of nucleotides, each pair placed at a distance of about 3.4 A°.
The two strands are held together by Hydrogen bonds formed by complementary base pairs. The A-T pair has 2 hydrogen bonds while G-C pair has 3 hydrogen bonds.
The complementary base pairing in DNA helix proves Chargaff’s rule. The content of adenine equals to that of thymine (A=T) and guanine equals to that of the cytosine (G≡C).
Function of DNA
RNA
DNA replication
Transcription
Translation
Actual base excess is the concentration of titratable base when the blood is titrated with a strong base or acid to a plasma pH of 7.40 at a pCO2 of 40 mmHg (5.3 kPa) and 37 °C at the actual oxygen saturation.
“ Base excess” is the absolute deviation (in mmol/L) of the buffer base amount from the normal level in blood.
“Buffer base” , represents the , blood’s total buffer capacity, comprising the bicarbonate, hemoglobin, plasma protein, and ,phosphate buffer systems ,normal buffer base level
,Infectious disease , involving mainly the , inflammation of , leptomeninges (aracnoid-piamater)
If , infection spread to brain parenchyma , it is meningoencephalitis ,
It may be caused by bacteria, virus, fungi, parasites
Pyrexia,
Headache,
Meningism,
Photophobia,
Kernig’s sign ,
Brudunski’s sign ,,
Lactate dehydrogenase: ,
the sensitivity and specificity 70-85% depending on the cutoff value. As with ,lactate LD activity ,is also significantly higher in ,bacterial meningitis ,than in ,aseptic meningitis.,
CSF lysozyme, activity is significantly increased in patients with both bacterial and , tuberculous meningitis.
Hypersensitivity, or allergy,
* An immune response results in exaggerated reactions harmful to the host ,
* There are four types of hypersensitivity reactions ,
Type I, Type II, Type III, Type IV ,
* Types I, II and III are antibody mediated ,
* Type IV is cell mediated,
An antigen reacts with cell fixed antibody , (Ig E) ,
leading to release of soluble molecules,
An antigen (allergen) ,
soluble molecules (mediators) ,
* Soluble molecules cause the manifestation of disease,
* Systemic life threatening, anaphylactic shock ,
* Local atopic allergies , bronchial asthma,
and food allergies
cerebrovascular disease , denotes any abnormality of the brain caused by a, pathologic process, involving , blood vessels.
The three basic processes are
thrombotic occlusion of vessels,
(2) embolic occlusion of vessels,
(3) vascular rupture.
Cerebrovascular diseases include the three major categories:
1.Thrombosis, 2.Embolism, and 3.Hemorrhage.
. Vasculitis, major cause of thrombosis
APOPTOSIS , DESCRIPTION, CELL INJURY,
Cell injury that damage DNA ,
loss of growth factors. ,
Direct action of cytokines (e.g., tumor necrosis factor) ,
Immune system action (e.g., natural killer cells or cytotoxic T lymphocytes).
Viral infection (eg HIV, Hepatitis)
, Sublethal damage to the cells , by ionizing radiation, hyperthermia, toxins
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.
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.
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.
263778731218 Abortion Clinic /Pills In Harare ,sisternakatoto
263778731218 Abortion Clinic /Pills In Harare ,ABORTION WOMEN’S CLINIC +27730423979 IN women clinic we believe that every woman should be able to make choices in her pregnancy. Our job is to provide compassionate care, safety,affordable and confidential services. That’s why we have won the trust from all generations of women all over the world. we use non surgical method(Abortion pills) to terminate…Dr.LISA +27730423979women Clinic is committed to providing the highest quality of obstetrical and gynecological care to women of all ages. Our dedicated staff aim to treat each patient and her health concerns with compassion and respect.Our dedicated group ABORTION WOMEN’S CLINIC +27730423979 IN women clinic we believe that every woman should be able to make choices in her pregnancy. Our job is to provide compassionate care, safety,affordable and confidential services. That’s why we have won the trust from all generations of women all over the world. we use non surgical method(Abortion pills) to terminate…Dr.LISA +27730423979women Clinic is committed to providing the highest quality of obstetrical and gynecological care to women of all ages. Our dedicated staff aim to treat each patient and her health concerns with compassion and respect.Our dedicated group of receptionists, nurses, and physicians have worked together as a teamof receptionists, nurses, and physicians have worked together as a team wwww.lisywomensclinic.co.za/
The prostate is an exocrine gland of the male mammalian reproductive system
It is a walnut-sized gland that forms part of the male reproductive system and is located in front of the rectum and just below the urinary bladder
Function is to store and secrete a clear, slightly alkaline fluid that constitutes 10-30% of the volume of the seminal fluid that along with the spermatozoa, constitutes semen
A healthy human prostate measures (4cm-vertical, by 3cm-horizontal, 2cm ant-post ).
It surrounds the urethra just below the urinary bladder. It has anterior, median, posterior and two lateral lobes
It’s work is regulated by androgens which are responsible for male sex characteristics
Generalised disease of the prostate due to hormonal derangement which leads to non malignant enlargement of the gland (increase in the number of epithelial cells and stromal tissue)to cause compression of the urethra leading to symptoms (LUTS
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.
Tom Selleck Health: A Comprehensive Look at the Iconic Actor’s Wellness Journeygreendigital
Tom Selleck, an enduring figure in Hollywood. has captivated audiences for decades with his rugged charm, iconic moustache. and memorable roles in television and film. From his breakout role as Thomas Magnum in Magnum P.I. to his current portrayal of Frank Reagan in Blue Bloods. Selleck's career has spanned over 50 years. But beyond his professional achievements. fans have often been curious about Tom Selleck Health. especially as he has aged in the public eye.
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Introduction
Many have been interested in Tom Selleck health. not only because of his enduring presence on screen but also because of the challenges. and lifestyle choices he has faced and made over the years. This article delves into the various aspects of Tom Selleck health. exploring his fitness regimen, diet, mental health. and the challenges he has encountered as he ages. We'll look at how he maintains his well-being. the health issues he has faced, and his approach to ageing .
Early Life and Career
Childhood and Athletic Beginnings
Tom Selleck was born on January 29, 1945, in Detroit, Michigan, and grew up in Sherman Oaks, California. From an early age, he was involved in sports, particularly basketball. which played a significant role in his physical development. His athletic pursuits continued into college. where he attended the University of Southern California (USC) on a basketball scholarship. This early involvement in sports laid a strong foundation for his physical health and disciplined lifestyle.
Transition to Acting
Selleck's transition from an athlete to an actor came with its physical demands. His first significant role in "Magnum P.I." required him to perform various stunts and maintain a fit appearance. This role, which he played from 1980 to 1988. necessitated a rigorous fitness routine to meet the show's demands. setting the stage for his long-term commitment to health and wellness.
Fitness Regimen
Workout Routine
Tom Selleck health and fitness regimen has evolved. adapting to his changing roles and age. During his "Magnum, P.I." days. Selleck's workouts were intense and focused on building and maintaining muscle mass. His routine included weightlifting, cardiovascular exercises. and specific training for the stunts he performed on the show.
Selleck adjusted his fitness routine as he aged to suit his body's needs. Today, his workouts focus on maintaining flexibility, strength, and cardiovascular health. He incorporates low-impact exercises such as swimming, walking, and light weightlifting. This balanced approach helps him stay fit without putting undue strain on his joints and muscles.
Importance of Flexibility and Mobility
In recent years, Selleck has emphasized the importance of flexibility and mobility in his fitness regimen. Understanding the natural decline in muscle mass and joint flexibility with age. he includes stretching and yoga in his routine. These practices help prevent injuries, improve posture, and maintain mobilit
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
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
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
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.
Ethanol (CH3CH2OH), or beverage alcohol, is a two-carbon alcohol
that is rapidly distributed in the body and brain. Ethanol alters many
neurochemical systems and has rewarding and addictive properties. It
is the oldest recreational drug and likely contributes to more morbidity,
mortality, and public health costs than all illicit drugs combined. The
5th edition of the Diagnostic and Statistical Manual of Mental Disorders
(DSM-5) integrates alcohol abuse and alcohol dependence into a single
disorder called alcohol use disorder (AUD), with mild, moderate,
and severe subclassifications (American Psychiatric Association, 2013).
In the DSM-5, all types of substance abuse and dependence have been
combined into a single substance use disorder (SUD) on a continuum
from mild to severe. A diagnosis of AUD requires that at least two of
the 11 DSM-5 behaviors be present within a 12-month period (mild
AUD: 2–3 criteria; moderate AUD: 4–5 criteria; severe AUD: 6–11 criteria).
The four main behavioral effects of AUD are impaired control over
drinking, negative social consequences, risky use, and altered physiological
effects (tolerance, withdrawal). This chapter presents an overview
of the prevalence and harmful consequences of AUD in the U.S.,
the systemic nature of the disease, neurocircuitry and stages of AUD,
comorbidities, fetal alcohol spectrum disorders, genetic risk factors, and
pharmacotherapies for AUD.
Acute scrotum is a general term referring to an emergency condition affecting the contents or the wall of the scrotum.
There are a number of conditions that present acutely, predominantly with pain and/or swelling
A careful and detailed history and examination, and in some cases, investigations allow differentiation between these diagnoses. A prompt diagnosis is essential as the patient may require urgent surgical intervention
Testicular torsion refers to twisting of the spermatic cord, causing ischaemia of the testicle.
Testicular torsion results from inadequate fixation of the testis to the tunica vaginalis producing ischemia from reduced arterial inflow and venous outflow obstruction.
The prevalence of testicular torsion in adult patients hospitalized with acute scrotal pain is approximately 25 to 50 percent
2. DNA Structure
DNA is a nucleic acid
The building blocks of DNA are nucleotides, each composed of:
A 5-carbon sugar called deoxyribose
A phosphate group (PO4)
A nitrogenous base
Adenine, Thymine, Cytosine, Guanine
3. The nucleotide structure consists of
the nitrogenous base attached to the 1’
carbon of deoxyribose
the phosphate group attached to the 5’
carbon of deoxyribose
a free hydroxyl group (-OH) at the 3’
carbon of deoxyribose
4.
5. Nucleotides are connected to each other to form a long chain
phosphodiester bond: bond between adjacent nucleotides
formed between the phosphate group of one nucleotide and the 3’ –OH of
the next nucleotide
The chain of nucleotides has a 5’ to 3’ Orientation
7. Determining the 3-dimmensional structure of DNA
involved the work of a few scientists
Erwin Chargaff determined that
amount of adenine = amount of thymine
amount of cytosine = amount of guanine
This is known as Chargaff’s Rules
8. James Watson and Francis Crick, 1953
deduced the structure of DNA using
evidence from Chargaff, Franklin, and
others
proposed a double helix structure
9. The double helix consists of:
2 sugar-phosphate backbones
nitrogenous bases toward the interior of the
molecule
bases form hydrogen bonds with
complementary bases on the opposite
sugar-phosphate backbone
10. The two strands of nucleotides are antiparallel to each other
one is oriented 5’ to 3’, the other 3’ to
5’
The two strands wrap around each other to create the helical shape of
the molecule
11.
12. In these grooves,
proteins can interact
specifically with
exposed atoms of the
nucleotides (usually by
H bonding) and
thereby recognize and
bind to specific
nucleotide sequences
without disrupting the
base pairing of the
double-helical DNA
molecule
13.
14. A B Z
Shape Broadest Intermedi
ate
Narrowest
Rise per
base pair
2.3 Å 3.4 Å 3.8 Å
Screw
sense
Right
handed
Right
handed
Left handed
Base per
turn
11 10.4 12
Glycosidic
Bond
Anti Anti Alternating Anti
and syn
Comparison of A , B and Z forms of DNA
15. STEPS INVOLVED IN DNA REPLICATION
1. Identification of the origins of replication
2. Unwinding (denaturation) of dsDNA to provide an
ssDNA template
3. Formation of the replication fork; synthesis of RNA
primer
4. Initiation of DNA synthesis and elongation
5. Formation of replication bubbles with ligation of the
newly synthesized DNA segments
6. Reconstitution of chromatin structutre
15
16. DNA replication is the process
where an entire double-stranded
DNA is copied to produce a
second, identical DNA double
helix
Meselson and Stahl concluded
that the mechanism of DNA
replication is the semiconservative
model
Each strand of DNA acts as a
template for the synthesis of a
new strand
16
Q. During which phase
of the cell cycle
does DNA replicate?
17. FACTORS NEEDED FOR REPLICATION
1. DNA HELICASES
to separate the strand
2. GYRASE (Topoisomerases)
unwind the supercoil
3. Single strand binding protein (SSBP)
activity of helicase
keep two strand separate
protect DNA from nuclease degradation
release after replication
17
18. 4. PRIMOSOME
Complex Protein (contains)
primase
helicase (dna B)
act as primer for DNA synthesis
removed by polymerase I
18
19. 5. DNA SYNTHESIS CATALYZED BY DNA POLYMERASE
III
New strand synthesis is catalyzed by DNA poly III
5' 3' direction
Antiparallel to parent template
dNTPs are added one after another to 3‘
Newly synthesized strand nucleotide is
complementary to parent DNA strand
19
20. 6. DNA LIGASE:
It catalyses the formation of phosphodiester linkage
between small fragment of DNA
7. TERMINATION
Termination utilization sub (Tus) protein binds to
termination sequence prevent helicase (dna B)
protein
Unwinding of DNA helix is stopped
20
21. Initiation of Replication
Initiation starts at a site called origin of replication
The origin of replication in E. coli is termed oriC
origin of Chromosomal replication
Important DNA sequences in oriC
AT-rich region
DnaA protein binds with the site of origin causing the double
stranded DNA to separate
The dsDNA is unwound by Helicase (DnaB)
This generates positive supercoiling ahead of each replication
fork
21
22. Initiation of Replication
DNA gyrase: relieves tension from the unwinding of
the DNA strands during bacterial replication
It cuts nicks in both strands of DNA, allowing them to
swivel around one another and then resealing the cut
strands
The single stranded binding proteins (SSBs) bind to
the exposed bases to prevent them from annealing
Then short (5 to 50 nucleotides) RNA primers are
synthesized by primase
22
23. These short RNA strands start, or prime DNA synthesis
DNA polymerases can synthesize DNA only in the 5’ to 3’
direction
DNA synthesis is semidiscontinuous and bidirectional
On the leading strand the DNA synthesis is
continuous
On the lagging strand the DNA synthesis is discontinuous
DNA polymerase III adds complimentary nucleotides
(deoxyribonucleoside triphosphates) in the 5’ to 3’ direction, using
RNA points
The segments arprimers as starting e called Okazaki fragments
23
24. Building Complimentary
Strands In prokaryotes, there are 3
enzymes known to function in
replication & repair
DNA polymerase I, II & III
In eukaryotes, there are 5
enzymes known to function
in replication & repair
DNA pol α, β, γ, δ,ε
24
26. Building Complimentary Strands in
prokaryotes
RNA primers are synthesized by primase and are temporary
The leading strand (uses 3’-5’ template) is synthesized
continuously
The lagging strand (uses 5’-3’ template) is synthesized
discontinuously in short fragments
26
27. Building Complimentary Strands in
prokaryotes
DNA polymerase I removes the RNA primers from
the leading strand and fragments from the lagging
strand and replaces them with the appropriate
deoxyribonucleotides
27
29. Building Complimentary Strands in
prokaryotes
DNA ligase joins the Okazaki fragments into one
strand on the lagging strand of DNA through the
formation of a phosphodiester bond
29
31. Building Complimentary
Strands in prokaryotes
As the 2 new strands of DNA are
synthesized, 2 double stranded DNA
molecules are produced that automatically
twist into a helix
31
32. PROOF READING
Fidelity of replication is important is done by DNA Polymerase II
DNA Polymerase III – beside synthesis also perform proof reading activity
(3’ 5’ exonuclease activity)
Check during synthesis
Correction
32
33. PROCESSIVITY
The average number of nucleotides added before a polymerase
dissociates defines its processivity
DNA polymerases vary greatly in processivity; some add just a few
nucleotides before dissociating, others add many thousands
33
34. EUKARYOTIC REPLICATION
Multiple origin site
Multiple replication bubbles
Enzymes – 5 types
DNA polymerase - , , , and
DNA Poly = Synthesis of RNA primer (both strand)
Responsible for initiation
Poly = Repair of DNA
Poly = Replication of mitochondrial DNA
Poly = Replication of leading & lagging strand
Proof reading
Poly = Lagging strand
34
35. Transcription
RNA synthesis, or transcription, is the process of transcribing DNA
nucleotide sequence information into RNA sequence information.
RNA synthesis is catalyzed by a large enzyme called RNA polymerase.
It takes place in three stages: initiation, elongation, and termination.
36. RNA polymerase performs multiple
functions in transcription
1.It searches DNA for initiation sites, also called promoter sites.
2.It unwinds a short stretch of double-helical DNA to produce a single-
stranded DNA template from which it takes instructions.
3.It selects the correct ribonucleoside triphosphate and catalyzes the
formation of a phosphodiester bond.
4.It detects termination signals that specify where a transcript ends.
5.It interacts with activator and repressor proteins that modulate the rate
of transcription initiation over a wide dynamic range.
37. Transcription cycle
(1) Template binding: RNA polymerase (RNAP) binds to DNA
and locates a promoter (P) melts the two DNA strands to
form a preinitiation complex (PIC).
(2) Chain initiation: RNAP holoenzyme (core + one of multiple
sigma factors) catalyzes the coupling of the first base
(usually ATP or GTP) to a second ribonucleoside
triphosphate to form a dinucleotide.
(3) Chain elongation: The fundamental reaction of RNA
synthesis is the formation of a phosphodiester bond. The 3 -
hydroxyl group of the last nucleotide in the chain
nucleophilically attacks the phosphate group of the incoming
nucleoside triphosphate with the concomitant release of a
pyrophosphate
(4) Chain termination and release: The completed RNA chain
and RNAP are released from the template. The RNAP
holoenzyme re-forms, finds a promoter, and the cycle is
repeated.
39. The strand that is transcribed or copied into an RNA
molecule is referred to as the template strand of the
DNA.
The other DNA strand is frequently referred to as the
coding strand of that gene.
40. Transcription starts at promoters on the DNA template.
Promoters are sequences of DNA that direct the RNA
polymerase to the proper initiation site for
transcription.
Two common motifs are present on the 5 (upstream)
side of the start site.
They are known as the -10 sequence and the -35
sequence because they are centered at about 10 and
35 nucleotides upstream of the start site.
47. Translation
The four letter alphabet of nucleic acid is
translated into entirely different 20 alphabets of
proteins
48. Translation Requirements
mRNA- Template
tRNA- Adaptor molecule
Ribosome- Molecular machinery
Amino acids- Precursors of protein
Enzyme and translation factors
Energy- ATP and GTP
49. mRNA
Template
Nucleotides are arranged in triplet
of bases – Codons
Protein coding region of each
mRNA is composed of a
contiguous, non-overlapping
string of codons called an
opening reading frame (ORF)
Begins with start codon and end with stop codon
51. Activation of tRNA
Some tRNA recognize more than one codon
Codon-anticodon interaction – Complementary base pairing and
antiparallel
First two bases of codon and anticodon pair in standard
way
Codon differ in 1st two bases are read by different tRNA
Eg. UUA and CUA – Leucine
1st base of anticodon determine number of codon read by
one tRNA
C or A – One
U or G – Two Eg. UUA & UUG and UUU & UUC
I – three Eg. GCU, GCC, GCA (Ala)
52. rRNA
Molecular machinery- Protein
Synthesis
Ribonucleoprotein assemblies
2/3rd of mass rRNA
Recognition of start signal –
16SrRNA
Peptidyl transferase – 23SrRNA
56. Activation
Activation of amino acids
Amino-acyl tRNA synthetases, ATP and tRNA
Form ester with either 3’-OH or 2’-OH of terminal
Adenine residue of tRNA
Two equivalent ~P used
Ester linkage and drive the reaction
Aminoacyl-tRNA synthatases belong to 2
Classess
Class I acylate at 2’-OH and for Larger and more
hydropobic amino acid
Class II acylate at 3’-OH (Except Phe-tRNA)
58. In prokaryotes, Shine-
Dalgarno sequences
recognized by an initiation
complex
consisting of a Met amino-
acyl tRNA,
Initiation Factors (IFs) and
the small ribosomal subunit
59. GTP hydrolysis by IF2 coincident
with release of the IFs and binding
of the large ribosomal subunit
leads to formation of a complete
ribosome, on the mRNA and ready
to translate.
60. Nucleotide sequence in mRNA signal where to start
protein synthesis
The translation of an mRNA begins with codon AUG.
In eukaryotes cap and in prokaryotes Shine - Dalgarno
sequence tell ribosome where to begin searching for
the start of translation
61. A U G G G C U U AAA G C A G U G C A C G U U
A ribosome on the rough endoplasmic
reticulum attaches to the mRNA molecule.
ribosome
62. A U G G G C U U AAA G C A G U G C A C G U U
It brings an amino acid to the first three
bases (codon) on the mRNA.
Amino acid
tRNA molecule
anticodon
U A C
A transfer RNA molecule arrives.
The three unpaired bases (anticodon)
on the tRNA link up with the codon.
63. A U G G G C U U AAA G C A G U G C A C G U U
Another tRNA molecule comes into
place, bringing a second amino acid.
U A C
Its anticodon links up with the second
codon on the mRNA.
64. A U G G G C U U AAA G C A G U G C A C G U U
A peptide bond forms between the
two amino acids.
Peptide bond
65. A U G G G C U U AAA G C A G U G C A C G U U
The first tRNA molecule releases its amino
acid and moves off into the cytoplasm.
66. A U G G G C U U AAA G C A G U G C A C G U U
The ribosome moves along the mRNA to
the next codon.
67. A U G G G C U U AAA G C A G U G C A C G U U
Another tRNA molecule brings
the next amino acid into place.
68. A U G G G C U U AAA G C A G U G C A C G U U
A peptide bond joins the second
and third amino acids to form a
polypeptide chain.
69. A U G G G C U U AAA G C A G U G C A C G U U
The polypeptide chain gets longer.
The process continues.
This continues until a termination
(stop) codon is reached.
The polypeptide is then complete.
71. mRNA
Contains initiation and termination signal
Collection of codons – Genetic code
Degeneracy
Unambiguous
Non overlapping
No punctuation
Nearly Universal
Synonyms
Codons decode the same amino acids
UUU and UUC – codon for Phe
AUG – Met and UGG- Trp
Two (rest), Three (Ile), Four (TGVPA) and Six
Codons (SLR)
72. XYU and XYC always code same amino acid
XYA and XYG usually code same amino acid
