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1. Science
(Project Based Assessment)
By- Vansh Verma
Class 8th B
By – vansh verma

2. .
Topic
TYPES OF CELL –
ANIMALS/PLANTS
(RIBOSOME)
By – vansh verma

3. Introduction
.
 It is large and complex molecule .
 Found in all living cells prokaryote &
eukaryote .
 That serves as the primary site of
Biological protein synthesis .
 In 1995 , George E .Palade Discovered
ribosomes and described them as a
small particles in the cytoplasm
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4.  It is without cell membrane
 Two subunits are attach by
different angles,
 Large subunit
 Small subunit
Structure
 The subunits of the ribosome are
synthesized by the nucleolus
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5.  A ribosome has two main constituent
elements
 Protein = 25-40%
Structure
 RNA = 37-62%
 Consists of two RNA
strands
 Strands are dotted
with protein coats
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6.  Quantity of ribosomes vary depend upon
the type of cell e.g.,
 Bacteria = 20,000
Quantity
 Yeast = 200,000
 Quantity depends upon the physiological
ability of cell to produce proteins
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7.  Main function of ribosomes is the
translation of genetic information
encoded in nucleotide bases of DNA into
amino acid sequence of proteins.
Functions
 This is also known as “gene expression”
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8.  The two ribosomal subunits join to
translate the mRNA into proteins.
Translation
 Following are the steps of translation:
Initiation
Elongation
Termination”
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9.  To begin initiation, the
small subunit of a
ribosome attaches to the
mRNA..
Initiation
 The small subunit then moves
along the mRNA until it reaches
the first readable Codon. This
codon always codes for the
amino acid methionine.
 The tRNA molecules are the
next to enter. These charged
molecules of RNA bring the
amino acids to the ribosome.
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10.  Each tRNA has a triplet coding
sequence that corresponds with
the amino acid it carries along.
Initiation
 The triplet sequence of the
tRNA is complementary to the
triplet codon sequence in the
mRNA.
 Each triplet codon sequence in
the mRNA and the tRNA
corresponds to a specific amino
acid.
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11.  After the first tRNA moves into
place, the large subunit of the
ribosome attaches to the small
subunit..
Initiation
 The complete ribosome consists
of two sites: petidyl (left)
andaminoacyl (right).
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12.  After the first tRNA has
attached to the peptidyl site, a
second tRNA enters the
complete ribosome and
attaches to its complementary
mRNA codon in
the aminoacyl site.
Elongation
 With the two tRNA in place, the
amino acid from
the peptidyl tRNA, moves and
attaches to the tRNA in
the aminoacyl site
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13.  The peptide chain is released
from the tRNA and leaves the
ribosome.
Elongation
 Protein synthesis is now
complete. The peptide chain is
ready to act as a protein or be
combined with other chains to
form larger, polypeptide proteins
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14.  During overburdening or stress condition
of endoplasmic reticulum and thus
ribosomes present on them function
improperly
Ribosome associated
diseases:
 This improper functioning is
characterized by improper folding of
proteins
 Some of such diseases are:
Diabetes
Cystic fibrosis
Neurodegenerative disorders
And other conformational disorders
By – vansh verma

15. Thanku For Reading
Give Your Feedback !
For more suggestions or feedback mail to vansh.ve@khaitanpublicschool.com