The document discusses the translation of mRNA into proteins. It begins by introducing the process of translation and its key components. It then discusses early studies that linked genes to proteins, including the work of Garrod on alkaptonuria and Beadle and Tatum's one gene-one enzyme hypothesis. The genetic code is explained, with each mRNA codon corresponding to a specific amino acid. There are four levels of structure in proteins, with primary structure being the amino acid sequence encoded by the gene.
In molecular biology and genetics, translation is the process in which ribosomes in the cytoplasm or ER synthesize proteins after the process of transcription of DNA to RNA in the cell's nucleus. The entire process is called gene expression.
In molecular biology and genetics, translation is the process in which ribosomes in the cytoplasm or ER synthesize proteins after the process of transcription of DNA to RNA in the cell's nucleus. The entire process is called gene expression.
Name- Date- Parlod- Monster Synthesis Activity Eurpase To examine how.pdfactexerode
Name: Date: Parlod: Monster Synthesis Activity Eurpase To examine how an organism's DNA
determines their phenotypes. Backerouni. Information: Your unique body tharacteristics (tralts),
such as hair color or blood typo, are deternined by the proteins your body producex. Protrins are
the building block of life - in fact, about 45% of the human body is made of preterin. These
orkanic macremelecules perform a wide range of functions including body repatr, regulaten, and
protection. Proteins are created by bonding groups of amino aclds that are coded for by the
nucleotide base sequences ( A , T , G , and C ) in your DNA DNA is trapped in the nucleus
because it is too wide to escape through the small nuclear pores in the nuclear niemtrane This is a
big isnue for the cell, since proteins are made outside the nucleus in the cytoplasm. For dis
reason, a yrocess called transeription occurs. DNA passes on its nucleotide base sequences, or
code, to a singlestranded molecule called mRNA (messenger). mRNA then carries the code ouf
to the cyaplasin to the ribosomes, the site where proteins are made. When the miNA reaches the
ribosome, the code in the mRNA nucisotides are read in groups of three basos, or codons. It
takes three bases to code for a single amino acid. Each codon signals another type of RNA,
called thWA (transfee), to carry a specific amino acld into the ribosome. As amino acids
continue to bond to one another it forms a polypeptide chain that eventually results in a protein.
This process is known as translation. In thit ectiliv, woe will simulate protefn synthesis by
transerlbing the DNA and translating the mRNA of the imagiy ry UID Ol. monster You will
decode each gene to determinc the phenotgple expression of the cinvil? inaticic'a ONA, and then
draw the monster based on your resulte 1. Pick a, DNA anand fir MAIH: COMaE. Alele It TAC
ATA CGC GEC NTT Alieke 1 s. Tac HAT cod tea NTE Allele 7: taC ARA CEC GIA Nit.
Aleierlintuc tat cece areate Allele 3. TAC GCG CCC ANA ATt Mirir ia tive pur cie Gesta Arce.
Allele d- Fhe bCC Cif TTH Ats Alleie 13 TNe filt cors of ktes 2. Pick a DNA strand for EiY
ReOLD. k. rik a bSil strand far rum Tyy? Allele II TAC ATA CCC GGO ATT Allele 24 TAE
ATN CEC GIA AIT Alele 3: TAE GGGCEC A AL ATT: Allele 4r TAC fGe CnT TTI AIT 7.
Hirk mikh mrand for Howis 3. Pirk a DNA strand fot H4s Dsirt Mllele 5: TAC A.AA TIT gCC
ATL Aliele be IAC CAA CAT EAI ARC Alleit 7t JAC GTA GTE CET ATE 4. Pick a DNh
strand for Fatri STI Aliele 5- TACAAA TTT COC ETL Aliele fitTC CAS CAT CASATC Aliele
7 fAC A QTO GCT ATE 5. Plick a DNA moand for bifus Allele fi TAC ATI ERA TMA ATE
Alele LUTAENTA CRE CICNTT Instructions: 1. Pick out a DNA strand for each category a.
Write dowa the DNA strand and allele number on your "Monster Synthesis Data Sheet" b.
Transcribe each DNA strand into mRNA. c. Trenslate the mRNA strand into an ainino acld
sequence using the grnetic codan chart d. Write down the physiaial appearance (phenotype)
based on the amino ac.
Adv. biopharm. APPLICATION OF PHARMACOKINETICS : TARGETED DRUG DELIVERY SYSTEMSAkankshaAshtankar
MIP 201T & MPH 202T
ADVANCED BIOPHARMACEUTICS & PHARMACOKINETICS : UNIT 5
APPLICATION OF PHARMACOKINETICS : TARGETED DRUG DELIVERY SYSTEMS By - AKANKSHA ASHTANKAR
Name- Date- Parlod- Monster Synthesis Activity Eurpase To examine how.pdfactexerode
Name: Date: Parlod: Monster Synthesis Activity Eurpase To examine how an organism's DNA
determines their phenotypes. Backerouni. Information: Your unique body tharacteristics (tralts),
such as hair color or blood typo, are deternined by the proteins your body producex. Protrins are
the building block of life - in fact, about 45% of the human body is made of preterin. These
orkanic macremelecules perform a wide range of functions including body repatr, regulaten, and
protection. Proteins are created by bonding groups of amino aclds that are coded for by the
nucleotide base sequences ( A , T , G , and C ) in your DNA DNA is trapped in the nucleus
because it is too wide to escape through the small nuclear pores in the nuclear niemtrane This is a
big isnue for the cell, since proteins are made outside the nucleus in the cytoplasm. For dis
reason, a yrocess called transeription occurs. DNA passes on its nucleotide base sequences, or
code, to a singlestranded molecule called mRNA (messenger). mRNA then carries the code ouf
to the cyaplasin to the ribosomes, the site where proteins are made. When the miNA reaches the
ribosome, the code in the mRNA nucisotides are read in groups of three basos, or codons. It
takes three bases to code for a single amino acid. Each codon signals another type of RNA,
called thWA (transfee), to carry a specific amino acld into the ribosome. As amino acids
continue to bond to one another it forms a polypeptide chain that eventually results in a protein.
This process is known as translation. In thit ectiliv, woe will simulate protefn synthesis by
transerlbing the DNA and translating the mRNA of the imagiy ry UID Ol. monster You will
decode each gene to determinc the phenotgple expression of the cinvil? inaticic'a ONA, and then
draw the monster based on your resulte 1. Pick a, DNA anand fir MAIH: COMaE. Alele It TAC
ATA CGC GEC NTT Alieke 1 s. Tac HAT cod tea NTE Allele 7: taC ARA CEC GIA Nit.
Aleierlintuc tat cece areate Allele 3. TAC GCG CCC ANA ATt Mirir ia tive pur cie Gesta Arce.
Allele d- Fhe bCC Cif TTH Ats Alleie 13 TNe filt cors of ktes 2. Pick a DNA strand for EiY
ReOLD. k. rik a bSil strand far rum Tyy? Allele II TAC ATA CCC GGO ATT Allele 24 TAE
ATN CEC GIA AIT Alele 3: TAE GGGCEC A AL ATT: Allele 4r TAC fGe CnT TTI AIT 7.
Hirk mikh mrand for Howis 3. Pirk a DNA strand fot H4s Dsirt Mllele 5: TAC A.AA TIT gCC
ATL Aliele be IAC CAA CAT EAI ARC Alleit 7t JAC GTA GTE CET ATE 4. Pick a DNh
strand for Fatri STI Aliele 5- TACAAA TTT COC ETL Aliele fitTC CAS CAT CASATC Aliele
7 fAC A QTO GCT ATE 5. Plick a DNA moand for bifus Allele fi TAC ATI ERA TMA ATE
Alele LUTAENTA CRE CICNTT Instructions: 1. Pick out a DNA strand for each category a.
Write dowa the DNA strand and allele number on your "Monster Synthesis Data Sheet" b.
Transcribe each DNA strand into mRNA. c. Trenslate the mRNA strand into an ainino acld
sequence using the grnetic codan chart d. Write down the physiaial appearance (phenotype)
based on the amino ac.
Adv. biopharm. APPLICATION OF PHARMACOKINETICS : TARGETED DRUG DELIVERY SYSTEMSAkankshaAshtankar
MIP 201T & MPH 202T
ADVANCED BIOPHARMACEUTICS & PHARMACOKINETICS : UNIT 5
APPLICATION OF PHARMACOKINETICS : TARGETED DRUG DELIVERY SYSTEMS By - AKANKSHA ASHTANKAR
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
NVBDCP.pptx Nation vector borne disease control programSapna Thakur
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Muktapishti is a traditional Ayurvedic preparation made from Shoditha Mukta (Purified Pearl), is believed to help regulate thyroid function and reduce symptoms of hyperthyroidism due to its cooling and balancing properties. Clinical evidence on its efficacy remains limited, necessitating further research to validate its therapeutic benefits.
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.
The Gram stain is a fundamental technique in microbiology used to classify bacteria based on their cell wall structure. It provides a quick and simple method to distinguish between Gram-positive and Gram-negative bacteria, which have different susceptibilities to antibiotics
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New Drug Discovery and Development .....NEHA GUPTA
The "New Drug Discovery and Development" process involves the identification, design, testing, and manufacturing of novel pharmaceutical compounds with the aim of introducing new and improved treatments for various medical conditions. This comprehensive endeavor encompasses various stages, including target identification, preclinical studies, clinical trials, regulatory approval, and post-market surveillance. It involves multidisciplinary collaboration among scientists, researchers, clinicians, regulatory experts, and pharmaceutical companies to bring innovative therapies to market and address unmet medical needs.
Flu Vaccine Alert in Bangalore Karnatakaaddon Scans
As flu season approaches, health officials in Bangalore, Karnataka, are urging residents to get their flu vaccinations. The seasonal flu, while common, can lead to severe health complications, particularly for vulnerable populations such as young children, the elderly, and those with underlying health conditions.
Dr. Vidisha Kumari, a leading epidemiologist in Bangalore, emphasizes the importance of getting vaccinated. "The flu vaccine is our best defense against the influenza virus. It not only protects individuals but also helps prevent the spread of the virus in our communities," he says.
This year, the flu season is expected to coincide with a potential increase in other respiratory illnesses. The Karnataka Health Department has launched an awareness campaign highlighting the significance of flu vaccinations. They have set up multiple vaccination centers across Bangalore, making it convenient for residents to receive their shots.
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Protect yourself and your loved ones by getting vaccinated. Together, we can help keep Bangalore healthy and safe this flu season. For more information on vaccination centers and schedules, residents can visit the Karnataka Health Department’s official website or follow their social media pages.
Stay informed, stay safe, and get your flu shot today!
2. INTRODUCTION
The translation of the mRNA codons into amino
acid sequences leads to the synthesis of proteins
A variety of cellular components play important
roles in translation
These include proteins, RNAs and small molecules
In this chapter we will discuss the current state of
knowledge regarding the molecular features of
mRNA translation
2
3. Proteins are the active participants in cell
structure and function
Genes that encode polypeptides are termed
structural genes
These are transcribed into messenger RNA (mRNA)
The main function of the genetic material is to
encode the production of cellular proteins
In the correct cell, at the proper time, and in suitable
amounts
13.1 THE GENETIC BASIS FOR
PROTEIN SYNTHESIS
3
5. First to propose (at the beginning of the 20th
century) a relationship between genes and
protein production
Garrod studied patients who had defects in their
ability to metabolize certain compounds
Urine chemist
He was particularly interested in alkaptonuria
Patients bodies accumulate abnormal levels of
homogentisic acid (alkapton)
Disease characterized by
Black urine and bluish black discoloration of cartilage and skin
Archibald Garrod
5
7. He proposed that alkaptonuria was due to a
missing enzyme, namely homogentisic acid
oxidase
Garrod also knew that alkaptonuria follows an
autosomal recessive pattern of inheritance
He proposed that a relationship exists between
the inheritance of the trait and the inheritance
of a defective enzyme
Archibald Garrod
7
10. In the early 1940s, George Beadle and Edward
Tatum were also interested in the relationship
between genes, enzymes and traits
Experiments supported Garrod’s idea that each gene =
one enzyme
Their genetic model was Neurospora crassa (a
common bread mold)
Their studies involved the analysis of simple nutritional
requirements
Beadle and Tatum’s Experiments
10
11. They analyzed more than 2,000 strains that had
been irradiated to produce mutations
At this point, DNA identified as probable carrier of genetic
information
Does DNA somehow “code” for enzymes?
They analyzed enzyme pathways for synthesis of
vitamins and amino acids
Figure 13.2 shows an example of their findings on
the synthesis of the amino acid methionine
Beadle and Tatum’s Experiments
11
14. Beadle and Tatum’s conclusion: A single “gene” in
DNA controls the synthesis of a single enzyme
This was referred to as the one gene–one enzyme
hypothesis
14
15. In later decades, this theory was progressively
modified by new research
1. Enzymes are only one category of proteins
2. Some proteins are composed of two or more different
polypeptides
The term polypeptide denotes structure
The term protein denotes function
So it is more accurate to say a structural gene encodes a
polypeptide
In eukaryotes, alternative splicing means that a structural gene
can encode many different polypeptides
3. Many genes have been identified that do not encode
polypeptides
For instance, functional RNA molecules (tRNA, rRNA, etc.)
15
16. Degenerate: (Adj) Having declined or become
less specialized
Adaptor (Noun) A device that converts attributes
of one device or system to those of an otherwise
incompatible device or system.
Charge (Verb) To give a task to something or
someone (Last slide Quiz 6, Sec 7)
16
17. Translation involves an interpretation of one
language into another
In genetics, the nucleotide language of mRNA is
translated into the amino acid language of proteins
Translation relies on the genetic code
Refer to Table 13.1
The genetic information is coded within mRNA in
groups of three nucleotides known as codons
The Genetic Code (first slide quiz
8, Sec 7)
17
18. Triplet codons correspond to a
specific amino acid
Multiple codons may encode
the same amino acid.
These are known as
synonymous codons
Three codons do not encode an
amino acid. These are read
as STOP signals for
translation
18
19. Special codons:
AUG (which specifies methionine) = start codon
This defines the reading frame for all following codons
AUG specifies additional methionines within the coding sequence
UAA, UAG and UGA = termination, or stop, codons
The code is degenerate
More than one codon can specify the same amino acid
For example: GGU, GGC, GGA and GGG all code for glycine
In most instances, the third base is the variable base
It is sometime referred to as the wobble base
The code is nearly universal
Only a few rare exceptions have been noted
Refer to Table 13.3
19
21. Sample Problem
(only one answer is correct)
A tRNA has the anticodon 5’-CAU-3’. What amino acid does it carry?
a. Histidine
b. Methionine
c. Phenyalanine
d. Valine
e. None of the above
21
22. Polypeptide synthesis has a directionality that
parallels the 5’ to 3’ orientation of mRNA
During each cycle of elongation, a peptide bond is
formed between the carboxyl group of the last amino
acid in the polypeptide chain and the amino group in
the amino acid being added
The first amino acid has an exposed amino group
Said to be N-terminal or amino terminal end
The last amino acid has an exposed carboxyl group
Said to be C-terminal or carboxy terminal end
Refer to Figure 13.6
A Polypeptide Chain Has Directionality
22
26. There are four levels of structure in proteins
1. Primary
2. Secondary
3. Tertiary
4. Quaternary
A protein’s primary structure is its amino acid
sequence
Refer to Figure 13.8
Levels of Structure in Proteins
26
28. The primary structure of a protein folds to form
regular, repeating shapes known as secondary
structures
There are two types of secondary structures
a helix
b sheet
Certain amino acids are good candidates for each structure
These secondary structures are stabilized by the
formation of hydrogen bonds between atoms located in
the polypeptide backbone
Refer to Figure 13.9
Levels of Structures in Proteins
28
29. The short regions of secondary structure in a protein
fold into a three-dimensional tertiary structure
Refer to Figure 13.9
This is the final conformation of proteins that are
composed of a single polypeptide
Structure determined by hydrophobic and ionic interactions as well as
hydrogen bonds and Van der Waals interactions
Proteins made up of two or more polypeptides have
a quaternary structure
This is formed when the various polypeptides associate
with one another to make a functional protein
Refer to Figure 13.9
Levels of Structures in Proteins
29
31. To a great extent, the characteristics of a cell depend on the
types of proteins its makes
Proteins can perform a variety of functions
Refer to Table 13.5
A key category of proteins are enzymes
Accelerate chemical reactions within a cell
Can be divided into two main categories
Anabolic enzymes Synthesize molecules and macromolecules
Catabolic enzymes Break down large molecules into small ones
Important in generating cellular energy
Functions of Proteins
31
33. In the 1950s, Francis Crick and Mahon Hoagland
proposed the adaptor hypothesis
tRNAs play a direct role in the recognition of codons in
the mRNA
In particular, the hypothesis proposed that tRNA
has two functions
1. Recognizing a 3-base codon in mRNA
2. Carrying an amino acid that is specific for that codon
13.2 STRUCTURE AND
FUNCTION OF tRNA
33
35. The secondary structure of tRNAs exhibits a
cloverleaf pattern
It contains
Three stem-loop structures
A few variable sites
An acceptor stem with a 3’ single strand region
The actual three-dimensional or tertiary structure
involves additional folding
In addition to the normal A, U, G and C nucleotides,
tRNAs commonly contain modified nucleotides
More than 80 of these can occur
tRNAs Share Common Structural
Features
35
37. The enzymes that attach amino acids to tRNAs are
known as aminoacyl-tRNA synthetases
There are 20 types
One for each amino acid
Aminoacyl-tRNA synthetases catalyze a two-step
reaction involving three different molecules
Amino acid, tRNA and ATP
Refer to Figure 13.13
Charging of tRNAs
37
38. The aminoacyl-tRNA synthetases are responsible
for the “second genetic code”
The selection of the correct amino acid must be highly
accurate or the polypeptides may be nonfunctional
Error rate is less than one in every 100,000
Sequences throughout the tRNA including but not limited
to the anticodon are used as recognition sites
Modified bases may affect
translation rates
recognition by aminoacyl-tRNA synthetases
Codon-anticodon recognition
Charging of tRNAs
38
40. 40
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41. As mentioned earlier, the genetic code is degenerate
With the exception of serine, arginine and leucine, this
degeneracy always occurs at the codon’s third position
To explain this pattern of degeneracy, Francis Crick
proposed in 1966 the wobble hypothesis
In the codon-anticodon recognition process, the first two
positions pair strictly according to the A – U /G – C rule
However, the third position can actually “wobble” or move a
bit
Thus tolerating certain types of mismatches
tRNAs and the Wobble Rule
41
43. Translation occurs on the surface of a large
macromolecular complex termed the ribosome
Bacterial cells have one type of ribosome
Found in their cytoplasm
Eukaryotic cells have two types of ribosomes
One type is found in the cytoplasm
The other is found in organelles
Mitochondria ; Chloroplasts
13.3 RIBOSOME STRUCTURE
AND ASSEMBLY
43
44. Unless otherwise noted the term eukaryotic
ribosome refers to the ribosomes in the cytosol
A ribosome is composed of structures called the
large and small subunits
Each subunit is formed from the assembly of
Proteins
rRNA
Table 13.6 presents the composition of bacterial and
eukaryotic ribosomes
13.3 RIBOSOME STRUCTURE
AND ASSEMBLY
44
46. During bacterial translation, the mRNA lies on the
surface of the 30S subunit
As a polypeptide is being synthesized, it exits through a
channel within the 50S subunit
Ribosomes contain three discrete sites
Peptidyl site (P site)
Aminoacyl site (A site)
Exit site (E site)
Ribosomal structure is shown in Figure 13.15
Functional Sites of Ribosomes
46
48. Translation can be viewed as occurring in three
stages
Initiation
Elongation
Termination
Refer to 13.16 for an overview of translation
13.4 STAGES OF
TRANSLATION
48
50. The mRNA, initiator tRNA, and ribosomal subunits
associate to form an initiation complex
This process requires three Initiation Factors
The initiator tRNA recognizes the start codon in
mRNA
In bacteria, this tRNA is designated tRNAfmet
It carries a methionine that has been covalently modified to
N-formylmethionine
The start codon is AUG, but in some cases GUG or UUG
In all three cases, the first amino acid is N-formylmethionine
The Translation Initiation Stage
50
53. Figure 13.17
70S initiation
complex
This marks the
end of the
initiation
stage
IF1 and IF3 are released.
IF2 hydrolyzes its GTP and is released.
The 50S subunit associates.
tRNAfMet
IF2
GTP
E A
P
3′
5′
3′
5′
70S
initiation
complex
IF1
IF3
Initiator tRNA
tRNAfMet
53
54. 54
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and playing each animation. Most
animations will require the latest
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55. In eukaryotes, the assembly of the initiation complex
is similar to that in bacteria
However, additional factors are required
Note that eukaryotic Initiation Factors are denoted eIF
Refer to Table 13.7
The initiator tRNA is designated tRNAmet
It carries a methionine rather than a formylmethionine
The Translation Initiation Stage
55
56. The start codon for eukaryotic translation is AUG
Ribosome scans from the 5’ end of mRNA until it finds
the AUG start codon (not all AUGs can act as a start)
The consensus sequence for optimal start codon
recognition is show here
Start codon
G C C (A/G) C C A U G G
-6 -5 -4 -3 -2 -1 +1 +2 +3 +4
Most important positions for codon selection
These rules are called Kozak’s rules
After Marilyn Kozak who first proposed them
With that in mind, the start codon for eukaryotic
translation is usually the first AUG after the 5’ Cap!
56
57. Translational initiation in eukaryotes can be
summarized as such:
An initiation factor protein complex (eIF4) binds to the 5’
cap in mRNA
These are joined by a complex consisting of the 40S
subunit, tRNAmet, and other initiation factors
The entire assembly moves along the mRNA scanning
for the right start codon
Once it finds this AUG, the 40S subunit binds to it
The 60S subunit joins
This forms the 80S initiation complex
57
58. During this stage, amino acids are added to the
polypeptide chain, one at a time
The addition of each amino acid occurs via a series
of steps outlined in Figure 13.19
This process, though complex, can occur at a
remarkable rate
In bacteria 15-20 amino acids per second
In eukaryotes 2-6 amino acids per second
The Translation Elongation Stage
58
61. 61
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62. The final stage occurs when a stop codon is
reached in the mRNA
In most species there are three stop or nonsense codons
UAG
UAA
UGA
These codons are not recognized by tRNAs, but by
proteins called release factors
Indeed, the 3-D structure of release factors mimics that of tRNAs
The Translation Termination Stage
62
63. Bacteria have three release factors
RF1, which recognizes UAA and UAG
RF2, which recognizes UAA and UGA
RF3, which does not recognize any of the three codons
It binds GTP and helps facilitate the termination process
Eukaryotes only have one release factor
eRF, which recognizes all three stop codons
The Translation Termination Stage
63
65. 65
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animations will not appear until the
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and playing each animation. Most
animations will require the latest
version of the Flash Player, which is
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67. Bacteria lack a nucleus
Therefore, both transcription and translation occur in the cytoplasm
As soon an mRNA strand is long enough, a ribosome will
attach to its 5’ end
So translation begins before transcription ends
This phenomenon is termed coupling
Refer to Figure 13.21
Bacterial Translation Can Begin
Before Transcription Is Completed
67