Difference between 70S and 80S Ribosomes (Prokaryotic vs Eukaryotic ribosomes)

Difference between 70S and 80S Ribosomes (Prokaryotic vs Eukaryotic ribosomes)


hi friends welcome to biologyexams4u.com. Today the topic of our discussion is difference between 70s and
80s ribosomes. Ribosomes are extremely small protein synthesizing nano machines
that is present in all types of cells. These nano machines are responsible for
the production of all types of proteins inside the cell. Ribosomes consist of rRNA, ribosomal proteins and divalent ions like magnesium that is meant for
dissociation and Association of ribosomal subunits or it can be called
as ribonucleoprotein complex and the function is protein synthesis. and we’ll
be discussing in detail the difference between 70s and 80s ribosomes. First of
all starting with the occurrence 80s ribosomes are present in all eukaryotic
cells and are also called as eukaryotic ribosomes that is present in plants
animals fungus etc. Whereas 70s ribosomes that are present in prokaryotes like
bacterium also semi-autonomous organelles like mitochondria and
chloroplasts poses this 70s ribosome. it is called as prokaryotic ribosomes as it
is present in bacterium or prokaryotes. Difference number two. 80S ribosome
occurs free ribosomes in cytoplasm it can be seen bound to RER and also
outer nuclear membrane where its role is protein synthesis, rough endoplasmic
reticulum (RER) is involved in the synthesis of proteins that are excretory or
secretory proteins whereas outer nuclear membrane is also having ribosomes that
may be involved in protein synthesis. Whereas 70s ribosomes as they are occur freely
in cytoplasm as there is no covered nuclear membrane in the case of
prokaryotes it is seen free in cytoplasm as a free ribosomes. This is also present in
mitochondria and chloroplasts of eukaryotic cells. Difference number 3. regarding the
subunits. 80s ribosome consists of two subunits
a 60S subunit and a 40S smaller subunit and the unit is Swedberg unit
and it is used as a measuring unit for sedimentation speed during ultra
centrifugation. 80s ribosome consists of a 60S larger subunit and a 40S
smaller subunit and combined to form a 80S ribosome as
addition of two three-dimensional structures always reduce the size or
volume of the resulting structure. That’s why this 80S. Whereas prokaryotic
ribosomes consist of two subunits a larger subunit which is 50s and a
smaller sub unit which is 30s and forming a ribosome that is 70S.
For the Association and dissociation of these subunits, magnesium ions are
essential. Difference number four. it is regarding the sub units the 60S
subunit consists of 5.8 s 5s and 28s rRNA complex with approximately 49
proteins that constitute 60s. Whereas 40s consists of 18s rRNA and
approximately 33 proteins making it 40s Whereas in the case of 70S subunits
the 50s subunit contains two rrnas that is 23S and 5S approximately 34
proteins forming the 50s at larger subunit whereas a smaller subunit 30s
consist of 16s rRNA and 21 proteins Difference number five. The 80s ribosomes
are composed of 40% RNA and 60% protein and this is actually protein rich where
a 70s ribosomes are RNA rich consists of 60% RNA and 40% proteins and
these are the basic difference between 70s and 80s ribosomes. Thankyou so much
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28 Replies to “Difference between 70S and 80S Ribosomes (Prokaryotic vs Eukaryotic ribosomes)”

  1. Ribosomes are the sites for protein synthesis in cells. Most of you ( like myself ) are wondering what was the "S" next to the number or why the subunits dont add up to the total number..here is the answer:
    1.- The approx size of ribosomes and other cellular structures are expressed in Svedbers ( Theodor Svedberg a novel price winner and the inventor of the ultra centrifuge )
    2.-Ribosomes are "measure" by their sedimentation rate ( how fast they settle down) to the bottom of ta test tube during centrifugation
    3.- Small, loosely packed, or light ones take a little longer to settle so therefore they are assigned a lower number , which is the case of Prokarytoic (bacterium) ribosomes with 70S (svedberg)
    4.-large , compacts , heavy particles sediment faster than small ones and their sediment rate is higher which is the case in Eukaryotic ribosomes with 80S (svedberg)
    5.- Prokaryotic ribomosomes 70S and Eukaryotic Ribosomes 80S have subunits ( when you add them up the will not add up to the total of units)
    NOW.. here is the key to this.. it took me a while to understand ( LOL )
    6.- All ribosomes have 2 subunits , each is composed of polypeptides and molecules of RNA ( also called rRNA-ribosomal RNA) .
    -Prokaryotic(bacterium ) Ribosomes =70S Ribosomes = 30S smaller subunits and 50S larger Subunits
    30S smaller subunits contain polypeptides and a SINGLE rRNA molecule
    50S larger subunits contain polypeptides and TWO rRNA molecules
    -Eukaryotic Ribosomes= 80S Ribosomes= 40 smaller subunits and 60 larger subunits
    40S smaller subunit contain a SINGLE rRNA molecule
    60S larger subunit contains TWO rRNA molecules and a polypeptide

    Because sedimentation rates are depended not only on ass and size but also on shape, the sedimentation rates of subunits do not add up to the sedimentation rate of a whole ribosome.

    …this is what i got from my microbio lecture ( Nursing student )

  2. Your are listing down differences, exclude their similarities, it started with DIFFERENCE NO.2 and I stopped watching. I Appreciate the effort, though.

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