RNA and Protein Synthesis
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Transcript of RNA and Protein Synthesis
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RNA & Protein Synthesis
Uracil
Hydrogen bonds
Adenine
RiboseRNA
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Basic components of RNA
Ribonucleic acid consists of following basic components
1- Ribose sugar 2- Phosphate in
diester linkage 4-Nitrogenous base
pairs- Purines- adenine,
guanine Pyrimidines- cytocine,
uracil
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Primary structure of RNA
Although there are multiple types of RNA molecules, the basic structure of all RNA is similar.
Each kind of RNA is a polymeric molecule made by stringing together individual ribonucleotides, always by adding the 5'-phosphate group of one nucleotide onto the 3'-hydroxyl group of the previous nucleotide.
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Secondary structure of RNA
Single-stranded RNA can also form many secondary structures in which a single RNA molecule folds over and forms hairpin loops, stabilized by intramolecular hydrogen bonds between complementary bases.
Such base-pairing of RNA is critical for many RNA functions, such as the ability of tRNA to bind to the correct sequence of mRNA during translation
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DNA can replicate or undergo transcription
Replication-it is process by which DNA copies itself to produce identical daughter molecules of DNA. DNA is the reserve bank of genetic information.
Transcription-transcription results in the formation of one single-stranded RNA molecule.
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DNA RNA
Structure Double Stranded
Single Stranded
Bases- Purines Adenine (A) Adenine (A)
Guanine (G) Guanine (G)
Bases - Pyrimidines
Cytosine (C) Cytosine (C)
Thymine (T) Uracil (U)
Sugar Deoxyribose Ribose
Differences between DNA and RNA:
RNA’s JOB= Make Proteins!!
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Types of RNA
1) messenger RNA (mRNA)- carries instructions from the DNA in the nucleus to the ribosome
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Types of RNA
2) ribosomal RNA (rRNA)- combines with proteins to form the ribosome (proteins made here)
3) transfer RNA (tRNA)- transfers each amino acid to the ribosome as it is specified by coded messages in mRNA during the construction of a protein
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Types of RNA
4 ) snRNA – small nuclear RNA
5) snoRNA- small nucleolar RNA
6) scRNA- small cytoplasmic RNA
7) micro- RNAs,miRNA, small interfering RNAs
Present in eukaryotes only.
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Protein Synthesis Overview
There are two steps to making proteins (protein synthesis):
1) Transcription (nucleus)
DNA RNA
2) Translation (cytoplasm)
RNA protein
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DNA
Transcription
RNA
Translation
Protein
Conventional concept
Genome
Transcription
Transcriptome
Translation
Proteome
Current concept, Bioinformatics era
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Proteins.
Everything a cell is or does depends on the proteins it contains.
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From genes to proteins.
Two steps – Transcription , Translation.
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Transcription
RNADNA
RNApolymerase
Adenine (DNA and RNA)Cytosine (DNA and RNA)Guanine(DNA and RNA)Thymine (DNA only)Uracil (RNA only)
Nucleus
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TRANSCRIPTION
It is a process by which RNA is synthesize from DNA. The genetic information stored in DNA is expressed through RNA.
One of the two strands of DNA serves as Template and produces working copies of RNA molecules. The other DNA strand which does not participate in in transcription is referred to as coding strand or sense strand or non-template strand.
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Transcription RNA Editing: Before the mRNA leaves the
nucleus, it is called pre-mRNA or (hnRNA) heterogeneous nuclear RNA and it gets “edited.” Parts of the pre-mRNA that are not involved in coding for proteins are called introns and are cut out. The remaining mRNA pieces are called exons (because they are expressed) and are spliced back together to form the mRNA.
Then the final mRNA leaves the nucleus through the nuclear pores and enters the cytoplasm headed to the ribosome.
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Transcription 1) Transcription begins when the
enzyme RNA polymerase binds to DNA at a promoter region.
Promoters are signals in DNA that indicate to the enzyme where to bind to make RNA.
2) The enzyme separates the DNA strands by breaking the hydrogen bonds, and then uses one strand of DNA as a template from which nucleotides are assembled into a strand of RNA.
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Transcription
3) RNA polymerase pairs up free floating RNA nucleotides with DNA template and joins the nucleotides together to form the backbone of the new mRNA strand.
4) When mRNA hits a termination sequence, it separates from the DNA
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Steps of transcription
Initiation
Elongation
Termination
post – transcriptional modifications
The RNAs produced during transcription are called primary mRNA transcripts. They undergo many alterations- terminal base additions, base modifications, splicing etc. This process is required to convert RNA into active form. Enzyme involved mainly is - ribonucleases.
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Cell
Nucleus
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Cell
Nucleus
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Nucleus
Chromosome
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Key
= Phosphate
= Sugar
= Uracil
= Adenine
= Guanine
= Cytosine
RNA Polymerase
3’ 5’
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Key
= Phosphate
= Sugar
= Uracil
= Adenine
= Guanine
= Cytosine
RNA Polymerase
3’ 5’
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Key
= Phosphate
= Sugar
= Uracil
= Adenine
= Guanine
= Cytosine
RNA Polymerase
3’ 5’
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Key
= Phosphate
= Sugar
= Uracil
= Adenine
= Guanine
= Cytosine
RNA Polymerase =
3’ 5’
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Key
= Phosphate
= Sugar
= Uracil
= Adenine
= Guanine
= Cytosine
RNA Polymerase =
3’ 5’
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Key
= Phosphate
= Sugar
= Uracil
= Adenine
= Guanine
= Cytosine
RNA Polymerase =
3’ 5’
mRNA Strand =
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Key
= Phosphate
= Sugar
= Uracil
= Adenine
= Guanine
= Cytosine
RNA Polymerase =mRNA Strand =
3’ 5’
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On average rate of RNA synthesis is about 43 nucleotides per second .
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TRANSCRIPTION-COMPLIMENTARY BASE PAIR RELATIONSHIP
DNA 5’ A T G C A T G G C A 3’ CODING STRAND
3’ T A C G T A C C G T 5’ TEMPLATE STRAND
RNA 5’ …....A U G C A U G G C A………3’
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The conventional numbering system of promoters
Bases preceding this are numbered
in a negative direction
There is no base numbered 0
Bases to the right are numbered in a
positive direction
Most of the promoter region is labeled with negative numbers
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Promoter sites
In eukaryotes promoter DNA bases sequences known as HOGNESS BOX or TATA BOX located on the left about 25 nucleotides away(upstream) from the starting site of mRNA synthesis. Second site of recognition between 70 to 80 nucleotides upstream known as CAAT BOX.
Coding strand 5’ GGCCAATC ATATAA 3’
Template strand 3’ 5’
-70 bases -25 bases (coding region)
Start of transcription
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Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display
Eukaryotic promoter sequences are more variable and often much more complex than those of bacteria
For structural genes, at least three features are found in most promoters Regulatory elements TATA box (present in ~20 % of our genes) and other
short sequences in TATA-promoters that have a similar function
Transcriptional start site
Sequences of Eukaryotic Structural Genes
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Factors that control gene expression can be divided into two types, based on their “location”
cis-acting elements DNA sequences that exert their effect only over a
particular gene Example: TATA box
trans-acting elements Regulatory proteins that bind to such DNA sequences
Sequences of Eukaryotic Structural Genes
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Signals the end of protein synthesis
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Usually an
adenine
The core promoter is relatively short It consists of the TATA box
Important in determining the precise start point for transcription
The core promoter by itself produces a low level of transcription This is termed basal transcription
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Regulatory elements affect the binding of RNA polymerase to the promoter They are of two types
Enhancers Stimulate transcription
Silencers Inhibit transcription
They vary widely in their locations, from –50 to –100 region
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RNA polymerases
RNA polymerase I- synthesis of precursors of large ribosomal RNAs.
RNA polymerases II- synthesizes the precursors for mRNAs and small rRNAs.
RNA polymerases III- formation of tRNAs and small rRNAs.
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Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display
Three categories of proteins are required for basal transcription to occur at the promoter
RNA polymerase II six different proteins called general transcription factors
(GTFs or TFs) . They are- TFIID, TFIIA,TFIIB,TFIIF,TFIIE, TFIIH.
A protein complex called mediator.
RNA Polymerase II and its Transcription Factors
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Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display
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A closed complex
Released after the
open complex is formed
RNA poly II can now proceed to the elongation
stage
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12-23Figure 12.7
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12-26
Similar to the synthesis of DNA
via DNA polymerase
Figure 12.8
On average, the rate of RNA synthesis is about 43 nucleotides per second!
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‘promoter’ Protein coding
Difference in gene structure between
- prokaryote
- eukaryotecore
‘promoter’
An important difference between prokaryotes and eukaryotes is that eukaryotes’ genes are not split into intons and exons. In eukaryotes is the DNA coding protein are, Therefore, exons eventually end up in the mRNA
intron
exons
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Pre-mRNA
Transcription start, elongation, termination and RNA processing in eukaryotes
: coding protein: non-coding protein: ‘leader’ and ‘trailer’
CAP
CAP (poly A tail)
The longest gene in human genome is more than 1.500.000 base pares (bp) and the mRNA is ~ 7000 nt.
‘promoter’
intron
exons
GENE
mRNA AAAAAAAAAAAAAAn
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TERMINATION Transcription stops by termination signals. Two
types of termination identified.
Rho depended- specific protein Rho factor, binds to the growing RNA, acts as ATPase and terminates transcription and releases RNA.
Rho independent – formation of hairpins of newly synthesized RNA.this occurs due to presence of palindromes. It is word that reads alike forward and backwards, like madam, motor. Presence of palindromes in DNA base sequence work as termination zone. Newly synthesize RNA folds to form hairpins due to complimentary base pairing, and termination occurs.
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coding sequences, called exons, are interrupted by intervening sequences or introns
Transcription produces the entire gene product Introns are later removed or excised Exons are connected together or spliced
This phenomenon is termed RNA splicing It is a common genetic phenomenon in eukaryotes Occurs occasionally in bacteria as well
post transcriptional RNA modification
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Aside from splicing, RNA transcripts can be modified in several ways
For example
Trimming of rRNA and tRNA transcripts
5’ Capping and 3’ polyA tailing of mRNA transcripts
y
RNA MODIFICATION
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RNA Editing
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Introns are removed and extrons are spliced
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The spliceosome is a large complex that splices pre-mRNA
It is composed of several subunits known as snRNPs (pronounced “snurps”) Each snRNP contains small nuclear RNA and a set of
proteins. Or small nuclear ribonucloprotein particle. Types of snRNPs are U1,U2,U3,U4,U5,U6.
Pre-mRNA Splicing
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The subunits of a spliceosome carry out several functions
1. Bind to an intron sequence and precisely recognize the intron-exon boundaries
2. Hold the pre-mRNA in the correct configuration
3. Catalyze the chemical reactions that remove introns and covalently link exons
Pre-mRNA Splicing
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Intron loops out and exons brought closer
together
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Intron will be degraded and the snRNPs used again
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One benefit of genes with introns is a phenomenon called alternative splicing
A pre-mRNA with multiple introns can be spliced in different ways This will generate mature mRNAs with different
combinations of exons
This variation in splicing can occur in different cell types or during different stages of development
Intron Advantage?
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The biological advantage of alternative splicing is that two (or more) polypeptides can be derived from a single gene
This allows an organism to carry fewer genes in its genome
Intron Advantage?
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Most mature mRNAs have a 7-methyl guanosine covalently attached at their 5’ end This event is known as capping
Capping occurs as the pre-mRNA is being synthesized by RNA pol II Usually when the transcript is only 20 to 25 bases long
Capping: marking 5’ends of mRNAs
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The 7-methylguanosine cap structure is recognized by cap-binding proteins
Cap-binding proteins play roles in the
Movement of some RNAs into the cytoplasm Early stages of translation Splicing of introns
Function of Capping
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Most mature mRNAs have a string of adenine nucleotides at their 3’ ends This is termed the polyA tail
The polyA tail is not encoded in the gene sequence It is added enzymatically after the gene is completely
transcribed
The 3’ end of a mRNA: Tailing
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Cell
Nucleus
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Cell
Nucleus
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RNAPolymerase
RNA Polymerase binds and unwinds the DNA double helix.
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RNA Polymerase binds and unwinds the DNA double helix.
RNAPolymerase
Guanine
Cytosine
Thymine
Adenine
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RNA Polymerase binds and unwinds the DNA double helix.
RNAPolymerase
Guanine
Cytosine
Thymine
Adenine
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RNA Polymerase binds and unwinds the DNA
double helix.
RNAPolymerase
Guanine
Cytosine
Thymine
Adenine
![Page 79: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/79.jpg)
RNA Polymerase binds and unwinds the DNA double
helix.
RNAPolymerase
Guanine
Cytosine
Thymine
Adenine
![Page 80: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/80.jpg)
RNA Polymerase binds and unwinds the DNA double
helix.
RNAPolymerase
![Page 81: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/81.jpg)
RNA Polymerase binds and unwinds the DNA double
helix.
RNAPolymerase
![Page 82: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/82.jpg)
RNA Polymerase binds to the promoter region.
RNAPolymerase
![Page 83: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/83.jpg)
RNA Polymerase binds to the promoter region.
RNAPolymerase
![Page 84: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/84.jpg)
RNA Polymerase binds to the promoter region.
RNAPolymerase
![Page 85: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/85.jpg)
RNA Polymerase binds to the promoter region.
RNAPolymerase
![Page 86: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/86.jpg)
RNA Polymerase binds to the promoter region.
RNAPolymerase
![Page 87: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/87.jpg)
RNA Polymerase binds to the promoter region.
RNAPolymerase
Guanine
Cytosine
Thymine
Adenine
![Page 88: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/88.jpg)
RNA Polymerase reads the DNA and creates the mRNA strand.
RNAPolymerase
Guanine
Cytosine
Thymine
AdenineUracil
Start Codon Coding Region
![Page 89: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/89.jpg)
RNA Polymerase reads the DNA and creates the mRNA strand.
RNAPolymerase
Guanine
Cytosine
Thymine
AdenineUracil
Start Codon Coding Region
mRNA Strand
![Page 90: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/90.jpg)
RNA Polymerase reads the DNA and creates the mRNA strand.
RNAPolymerase
Guanine
Cytosine
Thymine
AdenineUracil
Start Codon Coding Region
mRNA Strand
![Page 91: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/91.jpg)
RNA Polymerase reads the DNA and creates the mRNA strand.
RNAPolymerase
Guanine
Cytosine
Thymine
AdenineUracil
Start Codon Coding Region
mRNA Strand
![Page 92: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/92.jpg)
RNA Polymerase reads the DNA and creates the mRNA strand.
RNAPolymerase
Guanine
Cytosine
Thymine
AdenineUracil
Start Codon Coding Region
mRNA Strand
![Page 93: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/93.jpg)
RNA Polymerase reads the DNA and creates the mRNA strand.
RNAPolymerase
Guanine
Cytosine
Thymine
AdenineUracil
Start Codon Coding Region
mRNA Strand
![Page 94: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/94.jpg)
RNA Polymerase reads the DNA and creates the mRNA strand.
RNAPolymerase
Guanine
Cytosine
Thymine
AdenineUracil
Start Codon Coding Region
mRNA Strand
![Page 95: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/95.jpg)
RNA Polymerase reads the DNA and creates the mRNA strand.
RNAPolymerase
Guanine
Cytosine
Thymine
AdenineUracil
Start Codon Coding Region
mRNA Strand
![Page 96: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/96.jpg)
RNA Polymerase reads the DNA and creates the mRNA strand.
RNAPolymerase
Guanine
Cytosine
Thymine
AdenineUracil
Start Codon Coding Region
mRNA Strand
![Page 97: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/97.jpg)
RNA Polymerase reads the DNA and creates the mRNA strand.
RNAPolymerase
Guanine
Cytosine
Thymine
AdenineUracil
Start Codon Coding Region
mRNA Strand
![Page 98: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/98.jpg)
RNA Polymerase reads the DNA and creates the mRNA strand.
RNAPolymerase
Guanine
Cytosine
Thymine
AdenineUracil
Start Codon Coding Region
mRNA Strand
![Page 99: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/99.jpg)
mRNA leaves the nucleus and enters the cytoplasm.
RNAPolymerase
Guanine
Cytosine
Thymine
AdenineUracil
Start Codon Stop CodonCoding Region
mRNA Strand
Termination Sequence
![Page 100: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/100.jpg)
mRNA leaves the nucleus and enters the cytoplasm.
![Page 101: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/101.jpg)
mRNA leaves the nucleus and enters the cytoplasm.
Nuclear Pore
![Page 102: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/102.jpg)
mRNA leaves the nucleus and enters the cytoplasm.
Nuclear Pore
![Page 103: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/103.jpg)
mRNA leaves the nucleus and enters the cytoplasm.
Nuclear Pore
![Page 104: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/104.jpg)
mRNA leaves the nucleus and enters the cytoplasm.
Nuclear Pore
![Page 105: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/105.jpg)
mRNA leaves the nucleus and enters the cytoplasm.
Nuclear Pore
![Page 106: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/106.jpg)
mRNA leaves the nucleus and enters the cytoplasm.
Nuclear Pore
![Page 107: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/107.jpg)
mRNA leaves the nucleus and enters the cytoplasm.
![Page 108: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/108.jpg)
The Genetic CodeProteins (polypeptides) are long chains of amino acids that
are joined together.
There are 20 different amino acids.
The structure and function of proteins are determined by the order in which different amino acids are joined together to produce them.
The four bases (letters) of mRNA (A, U, G, and C) are read three letters at a time (and translated) to determine the order in which amino acids are added to a protein.
![Page 109: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/109.jpg)
AMINO ACIDS
Amino acids are organic solvents.
Have two functional groups –NH₂ and
-COOH group.
The amino group is basic while carboxylic group is acidic in nature.
Soluble in water but insoluble in organic solvents e.g. chloroform,acetone,ether,etc.
All amino acids which make up proteins are L-α-aminoacids.
![Page 110: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/110.jpg)
![Page 111: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/111.jpg)
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Semi-essential aminoacids.
These include Arginine and Histidine.These are growth promoting factors since they are not synthesized in sufficient quantity during growth.
SELENOCYSTEINE- the 21st amino acid.
![Page 115: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/115.jpg)
The Genetic Code
A codon consists of three consecutive nucleotides that specify a single amino acid that is to be added to the polypeptide (protein).
![Page 116: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/116.jpg)
The Codon Table
Sixty-four combinations are possible when a sequence of three bases are used; thus, 64 different mRNA codons are in the genetic code.
![Page 117: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/117.jpg)
Some codons do not code for amino acids; they provide instructions for making the protein.
More than one codon can code for the same amino acid.
![Page 118: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/118.jpg)
All organisms use the same genetic code (A,T,C,G). This provides evidence that all
life on Earth evolved from a common origin.
![Page 119: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/119.jpg)
![Page 120: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/120.jpg)
Cracking the Code This picture shows the amino
acid to which each of the 64 possible codons corresponds.
To decode a codon, start at the middle of the circle and move outward.
Ex: CGA
Arginine
Ex: GAU
Aspartic Acid
![Page 121: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/121.jpg)
Translation
Translation takes place on ribosomes, in the cytoplasm.
The cell uses information from messenger RNA (mRNA) to produce proteins, by decoding the mRNA message into a polypeptide chain (protein).
![Page 122: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/122.jpg)
Stapes of protein synthesis
1) requirements of the components- amino acids, ribosome, mRNA,tRNA, ATP
2)activation of amino acids
3)protein synthesis proper
4) chaperones and protein folding
5) post – translational modifications.
![Page 123: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/123.jpg)
Source: http://www.coolschool.ca/lor/BI12/unit6/U06L01.htm
![Page 124: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/124.jpg)
Key
= Uracil
= Adenine
= Guanine
= Cytosine
Cytoplasm
![Page 125: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/125.jpg)
Key
= Uracil
= Adenine
= Guanine
= Cytosine
Start Codon Codon Codon Codon Stop Codon
![Page 126: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/126.jpg)
Key
= Uracil
= Adenine
= Guanine
= Cytosine
Start Codon Codon Codon Codon Stop Codon
![Page 127: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/127.jpg)
Key
= Uracil
= Adenine
= Guanine
= Cytosine
Start Codon Codon Codon Codon Stop Codon
![Page 128: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/128.jpg)
Key
= Uracil
= Adenine
= Guanine
= Cytosine
Start Codon Codon Codon Codon Stop Codon
Ribosome
Anticodon
Amino AcidtRNA
![Page 129: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/129.jpg)
Key
= Uracil
= Adenine
= Guanine
= Cytosine
Start Codon Codon Codon Codon Stop Codon
Ribosome
Anticodon
Amino AcidtRNA
![Page 130: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/130.jpg)
Key
= Uracil
= Adenine
= Guanine
= Cytosine
Start Codon Codon Codon Codon Stop Codon
Ribosome
Anticodon
Amino AcidtRNA
![Page 131: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/131.jpg)
Key
= Uracil
= Adenine
= Guanine
= Cytosine
Start Codon Codon Codon Codon Stop Codon
Ribosome
Anticodon
Amino AcidtRNA
![Page 132: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/132.jpg)
Key
= Uracil
= Adenine
= Guanine
= Cytosine
Start Codon Codon Codon Codon Stop Codon
Ribosome
Anticodon
Amino AcidtRNA
![Page 133: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/133.jpg)
Key
= Uracil
= Adenine
= Guanine
= Cytosine
Start Codon Codon Codon Codon Stop Codon
Ribosome
Anticodon
Amino AcidtRNA
![Page 134: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/134.jpg)
Key
= Uracil
= Adenine
= Guanine
= Cytosine
Start Codon Codon Codon Codon Stop Codon
Ribosome
Anticodon
Amino AcidtRNA
![Page 135: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/135.jpg)
Key
= Uracil
= Adenine
= Guanine
= Cytosine
Start Codon Codon Codon Codon Stop Codon
Ribosome
Anticodon
Amino AcidtRNA
![Page 136: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/136.jpg)
Key
= Uracil
= Adenine
= Guanine
= Cytosine
Start Codon Codon Codon Codon Stop Codon
Ribosome
Anticodon
Amino AcidtRNA
Polypeptide Chain
Peptide Bond
![Page 137: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/137.jpg)
Key
= Uracil
= Adenine
= Guanine
= Cytosine
Start Codon Codon Codon Codon Stop Codon
Ribosome
Anticodon
Amino AcidtRNA
Polypeptide Chain
Peptide Bond
![Page 138: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/138.jpg)
Key
= Uracil
= Adenine
= Guanine
= Cytosine
Start Codon Codon Codon Codon Stop Codon
Ribosome
Anticodon
Amino AcidtRNA
Polypeptide Chain
Peptide Bond
![Page 139: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/139.jpg)
Key
= Uracil
= Adenine
= Guanine
= Cytosine
Start Codon Codon Codon Codon Stop Codon
Ribosome
Anticodon
Amino AcidtRNA
Polypeptide Chain
Peptide Bond
![Page 140: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/140.jpg)
Key
= Uracil
= Adenine
= Guanine
= Cytosine
Codon Codon Codon Stop Codon
Ribosome
Anticodon
Amino AcidtRNA
Polypeptide Chain
Peptide Bond
![Page 141: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/141.jpg)
Key
= Uracil
= Adenine
= Guanine
= Cytosine
Codon Codon Stop Codon
Ribosome
Anticodon
Amino AcidtRNA
Polypeptide Chain
Peptide Bond
![Page 142: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/142.jpg)
Key
= Uracil
= Adenine
= Guanine
= Cytosine
Codon Codon Stop Codon
Ribosome
Anticodon
Amino AcidtRNA
Polypeptide Chain
Peptide Bond
![Page 143: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/143.jpg)
Key
= Uracil
= Adenine
= Guanine
= Cytosine
Codon Stop Codon
Ribosome
Anticodon
Amino AcidtRNA
Polypeptide Chain
Peptide Bond
![Page 144: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/144.jpg)
Key
= Uracil
= Adenine
= Guanine
= Cytosine
Codon Stop Codon
Ribosome
Anticodon
Amino AcidtRNA
Polypeptide Chain
Peptide Bond
![Page 145: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/145.jpg)
Key
= Uracil
= Adenine
= Guanine
= Cytosine
Ribosome
Anticodon
Amino AcidtRNA
Polypeptide Chain
Peptide Bond
Amino Acid Chain
![Page 146: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/146.jpg)
Key
= Uracil
= Adenine
= Guanine
= Cytosine
Ribosome
Anticodon
Amino AcidtRNA
Polypeptide Chain
Peptide Bond
Final Protein in Tertiary Structure
![Page 147: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/147.jpg)
translation
Initiation codon
AUG
Termination codons or non-sense codons or stop signals
UAA
UAG
UGA
![Page 148: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/148.jpg)
Messenger RNA (mRNA)
1) The mRNA that was transcribed from DNA during transcription, leaves the cell’s nucleus and enters the cytoplasm.
![Page 149: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/149.jpg)
Transfer RNA(tRNA) 2) The mRNA enters the cytoplasm and attaches to a ribosome at the
AUG, which is the start codon. This begins translation.
3) The transfer RNA (tRNA) bonds with the correct amino acid and becomes “charged.” (in the cytoplasm)
4) The tRNA carries the amino acid to the ribosome. Each tRNA has an anticodon whose bases are complementary to a
codon on the mRNA strand. (The tRNA brings the correct amino acid to the ribosome.)
Ex: The ribosome positions the start codon to attract its anticodon, which is part of the tRNA that binds methionine.
The ribosome also binds the next codon and its anticodon.
![Page 150: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/150.jpg)
The Polypeptide “Assembly Line”
5) The ribosome moves along the mRNA and adds more amino acids to the growing polypeptide or protein
The tRNA floats away, allowing the ribosome to bind to another tRNA.
The ribosome moves along the mRNA, attaching new tRNA molecules and amino acids.
![Page 151: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/151.jpg)
Completing the Polypeptide6) The process continues
until the ribosome reaches one of the three stop codons on the mRNA, and then the ribosome falls off the mRNA.
7) The result is a polypeptide chain or protein that is ready for use in the cell.
![Page 152: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/152.jpg)
mRNA binds to the ribosome and the code is read.
![Page 153: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/153.jpg)
mRNA binds to the ribosome and the code is read.
![Page 154: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/154.jpg)
tRNA has the anticodon and amino acid attaches.
Guanine
Cytosine Adenine
Uracil
tRNA
anticod
on
amino
acid
Met
start
codon
![Page 155: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/155.jpg)
Amino acids bind to each other through peptide bonds.
Guanine
Cytosine Adenine
Uracil
tRNA
anticod
on
amino
acid
peptide bondLeuArg
start
codon
![Page 156: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/156.jpg)
Amino acids bind to each other through peptide bonds.
Guanine
Cytosine Adenine
Uracil
tRNA
anticod
on
amino
acid
peptide bondLeuArgLeu
start
codon
![Page 157: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/157.jpg)
Amino acids bind to each other through peptide bonds.
Guanine
Cytosine Adenine
Uracil
tRNA
anticod
on
amino
acid
peptide bondLeuArgLeuThr
start
codon
![Page 158: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/158.jpg)
Amino acids bind to each other through peptide bonds.
Guanine
Cytosine Adenine
Uracil
tRNA
anticod
on
amino
acid
peptide bondLeuArgLeuThrGlu
start
codon
![Page 159: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/159.jpg)
Amino acids bind to each other through peptide bonds.
Guanine
Cytosine Adenine
Uracil
tRNA
anticod
on
amino
acid
peptide bondLeuArgLeuThrGluThr
start
codon
![Page 160: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/160.jpg)
Amino acids bind to each other through peptide bonds.
Guanine
Cytosine Adenine
Uracil
tRNA
anticod
on
amino
acid
peptide bondLeuArgLeuThrGluThrAsp
start
codon
![Page 161: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/161.jpg)
Amino acids bind to each other through peptide bonds.
Guanine
Cytosine Adenine
Uracil
tRNA
anticod
on
amino
acid
peptide bondLeuArgLeuThrGluThrAspCys
start
codon
![Page 162: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/162.jpg)
Amino acids bind to each other through peptide bonds.
Guanine
Cytosine Adenine
Uracil
tRNA
anticodon
amino
acid
peptide bondLeuArgLeuThrGluThrAspCysLeu
start
codon
![Page 163: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/163.jpg)
Amino acids bind to each other through peptide bonds.
Guanine
Cytosine Adenine
Uracil
tRNA
anticodon
amino
acid
peptide bondLeuArgLeuThrGluThrAspCysLeuThr
start
codon
![Page 164: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/164.jpg)
Amino acids bind to each other through peptide bonds.
Guanine
Cytosine Adenine
Uracil
tRNA
anticodon
amino
acid
peptide bondLeuArgLeuThrGluThrAspCysLeuThrSTOP
start
codon
![Page 165: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/165.jpg)
Ribosome hits the stop codon, and protein synthesis is complete.
Guanine
Cytosine Adenine
Uracil
amino
acid
chain
peptide bondLeuArgLeuThrGluThrAspCysLeuThrAsp
Stop Codon
CompletedProtein
start
codon
![Page 166: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/166.jpg)
Ribosome hits the stop codon, and protein synthesis is complete.
Guanine
Cytosine Adenine
Uracil
amino
acid
chain
peptide bondLeuArgLeuThrGluThrAspCysLeuThrAsp
Stop Codon
CompletedProtein
![Page 167: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/167.jpg)
Ribosome hits the stop codon, and protein synthesis is complete.
Guanine
Cytosine Adenine
Uracil
amino
acid
chain
peptide bondLeuArgLeuThrGluThrAspCysLeuThrAsp
Stop Codon
CompletedProtein
![Page 168: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/168.jpg)
Amino acid chain coils into a complete protein.
CompletedProtein
![Page 169: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/169.jpg)
Amino acid chain coils into a complete protein.
CompletedProtein
![Page 170: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/170.jpg)
Source: http://www.biochem.arizona.edu/classes/bioc471/pages/Lecture1/Lecture1.html
![Page 171: RNA and Protein Synthesis](https://reader038.fdocuments.us/reader038/viewer/2022102419/554e7fdbb4c905f66a8b5405/html5/thumbnails/171.jpg)