Submitted to : Submitted by:

Dr. Mithilesh Kumar Vishnu Kumar

Dr. Vipul Jha AB & MB

Questions & Facts 1. Why are eukaryotic ribosomes 80S when prokaryotic ribosomes

are 70S?

2. Are there functional differences between free ribosomes and

endoplasmic reticulum ribosomes?

3. In the text it says: " In the nucleolus, new ribosomal RNA is

transcribed from the DNA, and it combines with proteins from

the cytoplasm to form the subunits of the ribosome. Where they

can combine to form ribosomes and carry out their job of making

proteins.

4. How we can say that ribosome work as enzyme?

5. Hibernating 100S ribosomes help bacteria survive (SLU

Scientist: Disrupting staph's naps may lead to new antibiotics.

Ribosome Macromolecular structures of rRNA + rProtein, is called

( Ribonucleoprotein).

Protein producing structure organelles

Site of origin nucleolus

Large amount requirement for protein synthesis.

Some eukaryotic organisms contains up to four nucleoli

Nucleoli are site specific genetic loci called nucleolar

organizing regions (NORs)

NORs contain tandem repeats of rRNA genes

Human genome contains more than 200 clustered copies of

the rRNA gene on five different chromosome(13, 14, 15,

21, 22).

It is a large & complex molecule.

Found in all living cells prokaryote & eukaryote.

That serves as the primary site of biological protein

synthesis.

Ribosome was first observed in 1953s by romanian

cell biologist george emil palade using a electrone

microscope.

In prokaryote free form in cytoplasm & protoplasm.

In eukaryote free in cytoplasm inside the cell attach to

the outer membrane in endoplasmic reticulum

Discovery

Ribosomes were first observed in the mid-1950s

by Romanian-American cell biologist George Emil

Palade, using an electron microscope, as dense particles

or granules.

The term "ribosome" was proposed by scientist

Richard B. Roberts in the end of 1950s.

In prokaryote free form in cytoplasm & protoplasm.

In eukaryote free in cytoplasm inside the cell attach to

the outer membrane in endoplasmic reticulum

Structure

Structure of 16s RNA

BIOGENESIS OF rRNA

1. Prokaryotic cell 3 rRNA in e.coli are transcribed from a single gene. 7 copies of gene occur in genome. A single transcript is produced in mature rRNA.processing of RNA folding, attachment of rProtein, methylation of bases & cleavage by Ribonuclease.

2. Eukaryotic cell

single gene arranged in multiple copies as clusters series.Transcribed in nucleolus by polymerase-I. 5S rRNA is transcribed in cytoplasm by polymerase III.