Ribosom and Protein Synthesis

8/13/2019 Ribosom and Protein Synthesis

1/84

1

RIBOSOM


2/84

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


3/84

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


4/84

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

4


5/84

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

5


6/84

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

6


7/84

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


8/84

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

8


9/84

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


10/84

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


11/84

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

11


12/84

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%

12


13/84

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

13


14/84

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

14


15/84

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


16/84

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

16


17/84

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


18/84

Biologi Umum 18

Composition

of eukaryotic

andprokaryotic

ribosomes


19/84

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.

19


20/84

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.

20


21/84

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

21


22/84

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

22


23/84

23


24/84

Cryoelectron microscopy based image


25/84

Biologi Umum 25

Cryoelectron microscopybased imageof the E. co li ribosome at ~25

resolution.


26/84

26

PROTEIN

SYNTHESIS


27/84

27

Protein Synthesis The production (synthesis)of polypeptide chains

(proteins) Two phases:

Transcription & Translation

mRNA must be processedbefore it leaves the nucleus

of eukaryotic cells


28/84

28

Transcription

Translation

DNA

mRNA

Ribosome

Protein

Prokaryotic Cell

DNA RNA Protein


29/84

29

DNA RNA Protein

Nuclearmembrane

Transcription

RNA Processing

Translation

DNA

Pre-mRNA

mRNA

Ribosome

Protein

EukaryoticCell


30/84

30

Pathway to Making a

ProteinDNA

mRNA

tRNA (ribosomes)

Protein


31/84

31

Nucleic Acids


32/84

32

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


33/84

33

DNA! Frederick Griffithin 1928 showed the

DNAwas the cellsgenetic material

Watson & Crickinthe 1950s built the1stmodel of DNA


34/84

34

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)


35/84

35

DNA Nucleotide


36/84

36

Base Pairing Rule Watson and Crick showed that DNAis a double helix

A(adenine) pairs with T(thymine)

C(cytosine) pairs with G(guanine)


37/84

37

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


38/84

38

.

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)


39/84

39

Anti-Parallel

Strandsof DNA


40/84

40

DNA

Replication


41/84

41

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


42/84

42

Two New,IdenticalDNA

StrandsResultfrom

Replication

A th Vi f R li ti


43/84

43

Another View of Replication


44/84

44

RNA


45/84

45

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


46/84

46

Structure of RNA


47/84

47

.

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


48/84

48

Making a

Protein

G n s & P t ins


49/84

49

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


50/84

50

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


51/84

51

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


52/84

52


53/84

53

Transcription

Translation


54/84

54

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


55/84

55

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


56/84

56

Transcription


57/84

57


58/84

58

What is theenzyme

responsible for

the production ofthe mRNA

molecule?


59/84

59

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


60/84

60

DNA

pre-mRNA

RNA Polymerase


61/84

61

Question:

What would be thecomplementary RNA strand

for the following DNAsequence?

DNA 5-GCGTATG-3


62/84

62

Answer:

DNA 5-GCGTATG-3

RNA 3-CGCAUAC-5

P P RN


63/84

63

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


64/84

64

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)


65/84

65

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


66/84

66

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


67/84


68/84

68

Transfer RNA (tRNA)

amino acidattachment site

U A C

anticodon

methionine amino acid

Rib l RNA ( RNA)


69/84

69

Ribosomal RNA (rRNA)

Made up of rRNAis 100 to 3000nucleotideslong

Made inside thenucleusof a cell

Associates withproteins to formribosomes

b


70/84

70

Ribosomes

Made of a large and smallsubunit

Composed of rRNA (40%)andproteins (60%)

Have two sitesfor tRNA

attachment --- P and A


71/84

71

Ribosomes

PSite ASite

Largesubunit

Small

subunit

mRNA

A U G C U A C U U C G

T l


72/84

72

Translation

Synthesis of proteinsin thecytoplasm

Involves the following:1. mRNA (codons)

2. tRNA (anticodons)3. ribosomes

4. amino acids


73/84

73

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


74/84

74

mRNA Codons Join theRibosome

PSite ASite

Largesubunit

Small subunit

mRNA


Initiation


75/84

75

Initiation

mRNA


2-tRNA

G

aa2

A U

A

1-tRNA

U A C

aa1

anticodon

hydrogenbonds codon

Elongation


76/84

76mRNA


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


77/84

77

mRNA


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


78/84

78

mRNA


2-tRNA

G

aa1

aa2

A UA

3-tRNA

G A A

aa3

4-tRNA

G C U

aa4

A C U

aa1peptide bonds


79/84

79

mRNA


2-tRNA

G

aa1aa2

A U

A

3-tRNA

G A A

aa3

4-tRNA

G C U

aa4

A C U

(leaves)


aa1peptide bonds aa5


80/84

80

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


81/84

81

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


aa4aa5

199

T i ti


82/84

82

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!


83/84

83

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


84/84

TERIMA KASIH

Documents

Ribosom and Protein Synthesis