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RIBOSOM
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RIBOSOM
Ribosom merupakan organel yangberukuran ultra mikroskopis, berbentuk
butiran, kecil, bulat, padat dan terdiri
dari ribonukleoprotein
Dijumpai pada sel eukariot ataupun
prokariot
Ribosom berfungsi dalam sintesa
protein
Ribosom dapat dipisahkan dari sel
dengan menggunakan alat sentrifuge2
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Ribosomes
- The ribosome is an organelle thatultra-microscopic size, grain shape,
small, round, dense and consists of
ribonukleoprotein- Found in prokaryotic or eukaryotic cell
- Ribosomes function in protein
synthesis- Ribosomes can be separated from
cells by using centrifuges3
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Tipe ribosom dapat dikelompokkan
berdasarkan ukuran dan berat molekul
pada proses sedimentasi yang
dilakukan untuk mengisolasinya
Koefisien sedimentasi dinyatakan
sebagai S unit/Swedberg/ Syedberg unit
didasarkan pada ukuran dan berat
molekul
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Type of ribosomes can be grouped by
size and molecular weight on thesedimentation process undertaken to
isolate
Sedimentation coefficient S isexpressed as units / Swedberg /
Syedberg unit is based on the size
and molecular weight
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Tipe-tipe ribosom :
Berdasarkan ukuran dan koefisien pengendapannya (S), dikenal
ribosom dengan tipe :
1. Ribosom 55S ; 60S dan 77S
55S : pada ribosom mitokondria mamalia
60S : pada sel mitokondria hewan
77S : pada sel jamur
2. Ribosom 70S
dapat ditemukan pada sel prokariot, blue green algae,
bakteri, khloroplast, Mitokondria
3. Ribosom 80S ditemukan pada sel-sel eukariot baik pada
tanaman maupun hewan
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types of ribosomes:
Based on the size and deposition coefficient (S),
known as the ribosome by type:
1. 55S ribosome: 60S and 77S
55S: the mammalian mitochondrial ribosome
60s: the mitochondria of animal cells
77S: in the yeast cells
2. 70S ribosomal
can be found in prokaryotes, blue green algae
, bacteria, khloroplast, Mitochondria
3. 80s ribosomes found in eukaryotic cells in both
plants and animals7
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Struktur Ribosom
Ribosom yang komplit disusun oleh dua sub unityang dimiliki oleh masing-masing type yang berbeda
ukuran maupun koefisien sedimentasinya
Contohnya : Ribosom 55S terdiri atas 2 sub unit yaitu : 35S
dan 25S
Ribosom 70S terdiri atas 2 sub unit yaitu : 50S
dan 30S Ribosom 80S terdiri atas 2 sub unit yaitu : 60S
dan 40S
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Ribosome structure
Complete ribosomes composed by two subunits owned by each different type or size of
the coefficient sedimentasi
For example:
- 55S ribosome consists of two sub units
namely: 35S and 25s
- 70S ribosome consists of two sub unitsnamely: 50S and 30S
- 80s ribosome consists of two sub units
namely: 60S and 40S 9
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Komposisi Kimia Ribosom
Ribosom secara kimiawi disusun oleh rRNA, protein, lemak dan
ion logam tertentu
1. RNA Ribosom (rRNA)
Ribosom 70S terdiri atas 3 type rRNA yaitu : 23S rRNA, 16S
rRNA, 5S rRNA
23S rRNA dan 5S rRNA terdapat pada sub unit yang besar
(50S), sedangkan 16S rRNA terdapat dalam sub unit
ribosom yang lebih kecil (30S)
Ribosom 80S juga terdiri dari 3 type rRNA, yaitu : 28S
rRNA, 18S rRNA, 5S rRNA
. Ratio antara rRNA dan protein pada kedua tipe tersebut tidak
selalu sama 10
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Chemical Composition of Ribosomes
Ribosomes are chemically prepared by rRNA, proteins, fats and
certain metal ions
1. The ribosome RNA (rRNA)
70S ribosome consists of three types of rRNA are: 23S rRNA,
16S rRNA, 5S rRNA
23S rRNA and 5S rRNA present in the large subunit
(50S), whereas the 16S rRNA contained in the sub-units
smaller ribosomes (30S)
80s Ribosomes also consists of three types of rRNA, namely:
28S rRNA, 18S rRNA, 5S rRNA
ratio between rRNA and proteins in both types are not
always the same
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Contoh :
Ribosom 70S : mengandung rRNA
lebih besar dibandingkan dengan
protein, yaitu rRNA 60-64%, protein 36-
37% ;
E. coli : rRNA = 63%,
protein =37%
Ribosom 80S : mempunyai rRNA lebih
sedikit dibanding protein, yaitu rRNA
40-44%, protein 56-60%
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example:
70S ribosomes: rRNA containinglarger than the protein, namely rRNA
60-64%, 36-37% protein;
E. coli: rRNA = 63%,
protein = 37%
80s ribosomes: rRNA have fewer than
proteins, namely rRNA 40-44%, 56-60%
protein
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2. Protein Ribosom
Pada sel prokariot ribosom type 70S mengandung
55 protein ribosom, yang terdiri dari : 34 protein pada
sub unit 50S, 21 protein pada sub unit 30S
Analisis kimia dari sub unit ribosom memberikan hasil
Sel prokariot :
sub unit > mengandung 2 molekul rRNA masing-
masing 23S dan 5S mengandung 31-34 jenis
protein
sub unit < hanya mengandung sebuah rRNA dengan
koefisien sedimentasi 16S 21 jenis protein
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2. proteins Ribosomes
In prokaryotes type 70S ribosome contains 55ribosomal proteins, which consists of: 34 proteins
in 50S subunits, 21 proteins in the 30S subunit
Chemical analysis of the ribosomal subunits provideresults Prokaryotes:
sub-unit> containing two molecules each of the 23S
rRNA and 5S contains 31-34 types of proteins
sub-unit
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Sel eukariot :
terdiri dari 2 sub unit, masing-masing memiliki
koefisien sedimentasi 60S dan 40S
sub unit > mempunyai 3 buah rRNA masing-
masing dengan koefisien sedimentasi 28S ;5,8S dan 5S 45-49 jenis protein
sub unit < mempunyai 1 buah rRNA koefisien
sedimentasi 18S 33 jenis protein
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eukaryotes:
consists of two sub-units, each has asedimentation coefficient of 60S and 40S
sub-unit> has 3 pieces each with its own
rRNA sedimentation coefficient of 28S; 5.8 Sand 5S 45-49 types of proteins
sub-unit
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Biologi Umum 18
Composition
of eukaryotic
andprokaryotic
ribosomes
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3. Protein Enzimatik Ribosom
Protein ribosom kebanyakan bertindak sebagai
enzim, yang mengkatalisis proses-proses pada
sintesis protein.
a. Protein transfer factor (faktor G dan faktor Ts)
diperlukan untuk melakukan translokasi ribosom pada mRNA,
untuk menstransfer tRNA pada ribosom dari satu tempat ketempat lainnya, untuk mengikat tRNA yang membawa asam
amino pada mRNA selama proses sintesis protein.
b. Protein initiation factor (F1, F2 )
protein yang memulai terjadinya proses sintesis proteinc. Protein termination factor (R1 dan R2)
protein yang mengakhiri dan melepaskan rantai polipeptida
yang telah selesai dibuat dari ribosom.
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3. Enzymatic Protein Ribosome
Ribosomal proteins mostly act as enzymes, which catalyze
the process of protein synthesis.
a. Protein transfer factor (G factor and factor Ts)
required to perform the ribosome on the mRNA translocation,
to menstransfer tRNA on the ribosome from one place to
elsewhere, to bind the tRNA that carries acid
amino on the mRNA during protein synthesis process.b. Protein initiation factor (F1, F2)
proteins that initiate the process of protein synthesis
c. Termination of protein factor (R1 and R2)
proteins that terminate and release the polypeptide chain
which has been created from the ribosome.
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4. Ion MetalikTerdiri dari ion Mg++ ,Ca2+, Mn+
Kedua sub unit ribosom tetap merupakan satu
kesatuan karena pengaruh konsentrasi ion
magnesium ( Mg++) . Bila konsentrasi ion
magnesium cukup tinggi maka kedua subunit
ribosom akan bersatu membentuk suatu kesatuanyang disebut dimer
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4. Metallic ion
Consisting of Mg ++ ions, Ca2 +,Mn +
Both ribosomal subunits remains a
single entity because of the influence ofthe concentration of magnesium ions
(Mg + +). If the magnesium ion
concentration is high enough then thetwo ribosomal subunits will unite to form
a union called the dimer
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Cryoelectron microscopy based image
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Biologi Umum 25
Cryoelectron microscopybased imageof the E. co li ribosome at ~25
resolution.
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PROTEIN
SYNTHESIS
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Protein Synthesis The production (synthesis)of polypeptide chains
(proteins) Two phases:
Transcription & Translation
mRNA must be processedbefore it leaves the nucleus
of eukaryotic cells
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Transcription
Translation
DNA
mRNA
Ribosome
Protein
Prokaryotic Cell
DNA RNA Protein
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DNA RNA Protein
Nuclearmembrane
Transcription
RNA Processing
Translation
DNA
Pre-mRNA
mRNA
Ribosome
Protein
EukaryoticCell
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Pathway to Making a
ProteinDNA
mRNA
tRNA (ribosomes)
Protein
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Nucleic Acids
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DNA or Protein?Walter Sutton discoveredchromosomes were made of
DNA and ProteinHowever, scientists wereNOTsure which one (protein
or DNA) was the actualgenetic material of the cell
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DNA! Frederick Griffithin 1928 showed the
DNAwas the cellsgenetic material
Watson & Crickinthe 1950s built the1stmodel of DNA
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Structure of DNA DNA is made of subunits callednucleotides
DNA nucleotides are composedof a phosphate, deoxyribosesugar, and a nitrogen-containingbase
The 4 bases in DNA are:adenine (A), thymine (T),
guanine (G),and cytosine (C)
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DNA Nucleotide
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Base Pairing Rule Watson and Crick showed that DNAis a double helix
A(adenine) pairs with T(thymine)
C(cytosine) pairs with G(guanine)
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Nitrogen Rings Purineshave single rings ofcarbon-nitrogen (G, A)
Pyrimidineshave double carbon-nitrogen rings (C, T) This is called complementary
base pairingbecause a purineisalways paired with a pyrimidine
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.
5 to 3 SugarsWhen the DNA double helixunwinds, it resembles a ladderThe sidesof the ladder arethe sugar-phosphatebackbonesThe rungsof the ladder arethe complementary paired
basesThe two DNA strands areanti-parallel (they run in
opposite directions)
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Anti-Parallel
Strandsof DNA
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DNA
Replication
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Steps in DNA Replication
Occurs when chromosomes duplicate(make copies)An exact copyof the DNA is producedwith the aid of the enzyme DNA
polymeraseHydrogen bondsbetween bases breakand enzymes unzip the moleculeEach old strandof nucleotides serves
as a templatefor each new strandNew nucleotidesmove intocomplementary positions are joined byDNA polymerase
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Two New,IdenticalDNA
StrandsResultfrom
Replication
A th Vi f R li ti
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Another View of Replication
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RNA
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RNA Differs from DNA1. RNAhas a sugar ribose
DNAhas a sugar deoxyribose
2. RNAcontains the base uracil (U)
DNAhas thymine (T)3. RNAmolecule is single-stranded
DNAis double-stranded
f
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Structure of RNA
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.
Three Types of RNA Messenger RNA (mRNA)carriesgenetic information to theribosomes
Ribosomal RNA (rRNA),alongwith protein, makes up theribosomes
Transfer RNA (tRNA)transfersamino acids to the ribosomeswhere proteins are synthesized
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Making a
Protein
G n s & P t ins
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Genes & Proteins
Proteinsare made of aminoacidslinked together by peptidebonds
20different amino acids exist
Amino acids chains are calledpolypeptides
Segment of DNA that codes forthe amino acid sequence in aprotein are called genes
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Two Parts of Protein
Synthesis Transcriptionmakes an RNAmolecule complementary to a
portion of DNA Translationoccurs when thesequence of bases of mRNADIRECTSthe sequence of aminoacidsin a polypeptide
G i C d
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Genetic Code DNA contains a triplet code Every three bases on DNA standsfor ONE amino acid
Each three-letter unit on mRNAis
called a codon Most amino acids have more thanone codon!
There are 20 amino acidswith a
possible 64 different triplets The code is nearly universal amongliving organisms
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Transcription
Translation
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Overview of Transcription
During transcriptionin thenucleus, a segment of DNAunwinds and unzips, and the
DNA serves as atemplate formRNA formation
RNA polymerasejoins the RNAnucleotides so that the codonsin mRNA are complementarytothe triplet code in DNA
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Steps in Transcription
The transfer of information in thenucleusfrom a DNAmolecule to anRNAmolecule
Only 1 DNAstrand serves as thetemplate
Starts at promoter DNA(TATA box)
Ends at terminator DNA(stop) When complete, pre-RNAmolecule isreleased
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Transcription
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What is theenzyme
responsible for
the production ofthe mRNA
molecule?
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RNA Polymerase
Enzymefound in the nucleus
Separates the two DNA
strands by breaking thehydrogen bondsbetween thebases
Then moves along one of theDNA strands and links RNAnucleotidestogether
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DNA
pre-mRNA
RNA Polymerase
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Question:
What would be thecomplementary RNA strand
for the following DNAsequence?
DNA 5-GCGTATG-3
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Answer:
DNA 5-GCGTATG-3
RNA 3-CGCAUAC-5
P P RN
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Processing Pre-mRNA
Also occurs in the nucleus
Pre-mRNA made up of segmentscalled introns & exons
Exons code for proteins, whileintrons do NOT!
Introns spliced out by splicesome-enzymeand exons re-join
End product is a mature RNAmolecule that leaves the nucleus tothe cytoplasm
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RNA Processing
pre-RNA molecule
intron intronexon exon exon
exon
exon exon
Mature RNA molecule
exon exon exon
intron intron
splicesome splicesome
M RNA ( RNA)
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Messenger RNA (mRNA)
Carries the information for aspecific protein
Made up of 500 to 1000
nucleotides long Sequence of 3 bases called codon
AUGmethionine or start codon UAA, UAG, or UGAstopcodons
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Messenger RNA (mRNA)
methionine glycine serine isoleucine glycine alanine stopcodon
protein
A U G G G C U C C A U C G G C G C A U A AmRNA
startcodon
Primary structure of a protein
aa1 aa2 aa3 aa4 aa5 aa6
peptide bonds
codon 2 codon 3 codon 4 codon 5 codon 6 codon 7codon 1
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Transfer RNA (tRNA)
amino acidattachment site
U A C
anticodon
methionine amino acid
Rib l RNA ( RNA)
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Ribosomal RNA (rRNA)
Made up of rRNAis 100 to 3000nucleotideslong
Made inside thenucleusof a cell
Associates withproteins to formribosomes
b
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Ribosomes
Made of a large and smallsubunit
Composed of rRNA (40%)andproteins (60%)
Have two sitesfor tRNA
attachment --- P and A
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Ribosomes
PSite ASite
Largesubunit
Small
subunit
mRNA
A U G C U A C U U C G
T l
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Translation
Synthesis of proteinsin thecytoplasm
Involves the following:1. mRNA (codons)
2. tRNA (anticodons)3. ribosomes
4. amino acids
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Translation
Three steps:
1. initiation: start codon (AUG)
2. elongation: amino acids linked3. termination: stop codon(UAG, UAA, or UGA).
Lets Make a Protein !
mRNA Codons Join the
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mRNA Codons Join theRibosome
PSite ASite
Largesubunit
Small subunit
mRNA
A U G C U A C U U C G
Initiation
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Initiation
mRNA
A U G C U A C U U C G
2-tRNA
G
aa2
A U
A
1-tRNA
U A C
aa1
anticodon
hydrogenbonds codon
Elongation
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A U G C U A C U U C G
1-tRNA 2-tRNA
U A C G
aa1 aa2
A UA
anticodon
hydrogenbonds codon
peptide bond
3-tRNA
G A A
aa3
Elongation
aa1 peptide bond
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mRNA
A U G C U A C U U C G
1-tRNA
2-tRNA
U A C
G
aa1
aa2
A UA
peptide bond
3-tRNA
G A A
aa3
Ribosomes move over one codon
(leaves)
aa1peptide bonds
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mRNA
A U G C U A C U U C G
2-tRNA
G
aa1
aa2
A UA
3-tRNA
G A A
aa3
4-tRNA
G C U
aa4
A C U
aa1peptide bonds
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mRNA
A U G C U A C U U C G
2-tRNA
G
aa1aa2
A U
A
3-tRNA
G A A
aa3
4-tRNA
G C U
aa4
A C U
(leaves)
Ribosomes move over one codon
aa1peptide bonds aa5
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mRNA
G C U A C U U C G
aa1aa2
A
3-tRNA
G A A
aa3
4-tRNA
G C U
aa4
A C U
U G A
5-tRNA
aa1 peptide bonds aa5
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mRNA
G C U A C U U C G
aa2
A
3-tRNA
G A A
aa3
4-tRNA
G C U
aa4
A C U
U G A
5-tRNA
Ribosomes move over one codon
aa4aa5
199
T i ti
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mRNA
A C A U G U
aa1
aa2
U
primarystructureof a protein
aa3
200-tRNA
aa4
U A GC U
aa200
aa199
terminatoror stop
codon
Termination
End Product The Protein!
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End Product The Protein! The end products of proteinsynthesis is a primary structureofa protein
A sequence of amino acidbonded
together by peptide bonds
aa1
aa2 aa3aa4
aa5
aa200
aa199
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TERIMA KASIH