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7/28/2019 Pp Ribosome
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RIBOSOME AND PROTEIN
SYNTHESIS
By : Delfi Zurita
NIM : RSA1C411009
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A.Definition Ribosome
Ribosomes are the components of cells that make proteins from all amino acids. Ribosomes also
referred to as molecular machines inside cells that make proteins from amino acids in a process called
translation, the ribosome "translates" the genetic information from RNA to protein. It binds messenger
ribonucleic acid (mRNA) and read the information contain in the mRNA nucleotide sequence.
The ribosome construct proteins from the genetic instructions held within messenger RNA.
Suspended free ribosomes in the cytosol (the semi-fluid cytoplasm), and the other attached to the rough
endoplasmic reticulum, thus giving the appearance of roughness, the other steps in the synthesis of proteins
(such as translocation) is caused by changes in protein conformation.
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B. Structure of RibosomeRibosomes consist of ribonucleic acid (RNA abbreviated) and protein, in nearly equal numbers.
Ribonucleic acid derived from the nucleolus, where ribosomes are synthesized in the cell. A simple
prokaryotic cell (ex, bacteria) consisting of several thousands of ribosomes, while very advanced
eukaryotic cells (ex, human cells) have several millions of ribosomes. Prokaryotic ribosomes are smaller
in size compared to eukaryotic.
Beside, Ribosomes also consists of two parts, called subunits. Ribosomes size stated on the
basis of deposition rate during centrifugation as a unit called the Svedberg unit (S). In most prokaryotes
have 70S ribosomes size, where as in eukaryotes usually about 80S.Setiap subunit consists of both
protein and ribonucleic acid (RNA) components
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Of the structure of the ribosome have the following properties:
1. The shape is universal, the elliptical longitudinal section.
2. On the negative staining technique, it appears that there is a transverse
groove, perpendicular to the axis, is divided into two sub-units that have
different dimensions.
3. Each sub-unit is characterized by a sedimentation coefficient expressed in
Svedberg units (S). So that the sedimentation coefficient of 70S for
prokaryotes is a whole ribosome (50S sub-unit for large and for small 30S).
For eukaryotic ribosome is 80S for the whole (60S to 40S subunits to large
and small).
4. The dimensions of the ribosome and the form of a variable. In prokaryotes,
the ribosome is 29 nm in length with a large 21 nm. And eukaryotes, a large
size of 32 nm with 22 nm.
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5. In prokaryotes sub-units are small, elongated, curved shape with 2
limbs, features 3 digitized, like a chair. In eukaryotes, the subunits form
resemble the ribosomes of E. coli
On the surface of ribosomes, granular nucleoprotein has two
distribution layout. Nucleoprotein granules scattered freely in the
cytoplasm called a ribosome-free. Meanwhile, the nucleoprotein
granules attached to the surface of the endoplasmic reticulum called the
ribosome bound. Free ribosomes play a role in the synthesis of the
enzyme. Enzymes are produced serve as a catalyst in the liquid cytosol.
Ribosomes certainly be useful in the synthesis of proteins.
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C. The Function of Ribosome
The function of the ribosome, they play assembling amino
acids to form specific proteins, which in turn is essential to carry out
the cell. As we all have a fair idea about the production of proteins,deoxyribonucleic acid (DNA) was first produced RNA (messenger
RNA or mRNA) by DNA transcription process, after which the
genetic message from the mRNA is translated into proteins during
translation of DNA.
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D. The CompositionChemishtry of Ribosome
The composition of the ribosome is:
1. Ribosomal Nucleic Acid
a) large subunits composed of protein and RNA in the quantity of a balanced,
containing two types of rRNA, namely:
-The 28S rRNA
- The SS rRNA
b) small subunit-containing RNA 18s . It known that, in the absence of RNA 185, the
sub-unit can not associate small subunit. While the 28s RNA allows the association.SS RNA attached to the nucleic acid sequences are tRNA. When reading the tRNA
attached to the sites that are part of the RNA 285. Displacement of the tRNA molecule
attached to the mRNA causing translational motion of the corresponding mRNA.
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2. Ribosomal Protein
a. Small subunit(30S prokaryotic): 21 proteins are described respectively by the
letter S and a number between 1 and 21 (S1, S2, S21). Weight moleku130.000 -
40,000 Dalton. Located on the surface of the ribosome, rRNA surrounds. Proteins
act as receptors for transducti elongation factor while the other controls.
b. Major subunit: 33 proteins known as Li to L33. Involved in Translocation by
the presence of GTP (ribosam attached) which provides energy to move the
release of tRNA and acetyl inRNA.
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E. The Process ProteinSynthesis
Protein synthesis is the process of the formation of proteins in the cell, which
is inseparable from the role and workings of DNA that make up RNA through
RNA transcription process it will control the synthesis of proteins in the cell
cytoplasm.
Than Protein is a macromolecule composed by various amino acids, and enzymes
are proteins that act as catalysts for biochemical reactions in cell metabolism.
Enzymes characters (protein) as a control and the farmers mortal determined by
the number and type of amino acid sequence of the translated genes for protein
synthesis.
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The components of protein synthesis
Components that play a role in protein synthesis is the cell nucleus, rough endoplasmic reticulum,
ribosomes rRNA, mRNA, tRNA, and RNA polymerase
a. The cell nucleus
Genetic cell nucleus resource location, namely DNA. So, the information is translated as the synthesis of
protein from the cell nucleus
b. RE rude and Ribosome (rRNA)
RE rough is the site where ribosomes attached. In addition, rRNA or site RNAmerupakan Ribosomal
protein synthesis
c. tRNA (transfer RNA)
tRNA is one type of RNA that serves to bind the amino acids from amino acids sitoplasmadan
combine with another at the stage of protein synthesis
d. RNA polymerase
RNA polymerase is an enzyme that plays a role in coupling DNA molecules and RNA molecules
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Protein synthesis can be divided into two main phases, namely the process of
making mRNA molecules in the cell nucleus (transcription) and mRNA translation
process by coupling rRNA and amino acids (translation) ribosome
1. Transcription
Transcription occurs in the cell nucleus. In this phase, RNA polymerase chain adhere to
open-chain DNA. One of the DNA to be translated (DNA template / rantaisense) obtained
initiate partner base, so as to create the chain of complement. Complementary chain then
go into mRNA (messenger RNA).
2. Translation
Translation stage is the stage in which the mature mRNA from the nucleus of cells that
had been transferred to the cytoplasm, particularly in the ribosome, immediately
translated.Translation itself consists of three stages, is initiation, elongation and
termination
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a. Initiation
At the mRNA reaches the ribosome, the first time that happened was initiation. Namely the
introduction of codons (3 couples code:. Ex UAA, AUG), which is a synthesis from beginnercodon (start codon), which is an amino acid Methionine, code-codon read After August, the
first amino acid of ribosomes would be combined with an acid amino next. Free amino acids
in the cytoplasm and carried to the ribosome by transfer RNA or tRNA.
b. ElongationElongation is a continuation of the process of initiation. At this stage, the codons will keep
reading and tRNA will continue to bring amino acids to the ribosome as it is the extension to
mRNA.Pada codon, the ribosome will usually be in the position of aggregates or bundles.
Two ribosomal mRNA or more be attached to chain together so it looks like to assemble.
This phenomenon is called ribosomes that group polisom and its function is to accelerate the
process of protein synthesis.
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c. Termination
Termination is the last of the translational process. This process begins when the codons are
read codons coding for termination of protein synthesis. Codon called a stop codon, which
consists of three codons are UAA, UAG, and UGA. When someone reads a codon, will
dismiss the process of releasing factor amino. Process acid synthesis termination chain ends
with the formation of chains of amino acids that are very long, or more commonly called a
polypeptide chain. The name is based on the bond between one amino acid with another
amino acid called peptide bonds. Polypeptide chain is what we call a protein, instead of the
primary. Protein or polypeptide chains of protein synthesis is the primary protein chain.
Protein has been modified for use in the body. The process modifications will be made in the
body after the transfer of Golgi reticulum endoplasm
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Thanks For YoursAttention