Ribosome-Peroxisomes-Glyoxysome | Notes-by-UK-Sir | Cell-Bio-11

CELL    (Ribosome-Peroxisosomes-Glyoxysome)

 

Ribosome

Want to Know about Lysosome and Cytoskeleton:

https://uksirnotes.blogspot.com/2021/07/Lysosome-cytoskeleton-uksirnotes.html

Want to Know about Cytoplasm, RER, SER:

https://uksirnotes.blogspot.com/2021/07/Cytoplasm-ER-Golgi-complex.html

Want to Know about Mitochondria and chloroplast:

https://uksirnotes.blogspot.com/2021/07/Mitochondria-Plastid-Chloroplast-uksirnotes.html

Ribosome

Palade particle/ protein factories

 

•      Discovered by Robinson and Brown 1953 (in plant)

•      By Palade (1955) in animal cell - also term the coin.

•      E coli cell contain- 20,000-30,000 ribosomes.

•      A typical Plant cell contain – up to 5,00,000.

•      Present in all eukaryotes- except mammal RBC.

•      These are Ribo nucleo proteins and Naked protoplasmic particles.

•      Size- length 200-340A⁰, diameter – 170-240 A⁰

•      It is the Site of protein synthesis- for which called as protein factories.

Ribosome

•      Contain 2 sub units-

•       Larger Sub unit- dome shape, where as Smaller sub unit – ellipsoid.

•      L.S.U.- contain Protuberance, ridge  and stalk.

•      S.S.U. –contain  Platform, cleft,  head and base.

•      Ribosome needs Mg ²⁺ for binding of both units.

•      They may occur in single or in polysome form.

•      Poly some connected to m RNA.

•      May be of two type: Organelle ribosome and cytoplasmic ribosome.

•      Cytoplasmic- free in cytoplasm or attached to the ER by large sub unit (helped by special Ribophorin or SRP protein)

•      Organelle ribosome present in plastid (PlastidoRibosome) and mitochondria (Mitoriboosome)

•      Bounded Ribosome transfer protein through the ER.

•      The newly formed Protein folded and transferred by specific proteins, called as Chaperones.

•      S means Svedberg Unit (S= 1×10 -13 sec) or sedimentation coefficient in centrifuge

•      80 S = 340× 240A⁰ (Mass= 4.5 million Dalton)

•      70s = 290 ×210 A⁰  (Mass = 3.0 million Dalton)

 

Composition

•      Chemically – Ribosomes are = Protein and rRNA. (RibonucleoProtein)

•      The protein are both structural and enzymes.

•      Ribosome of liver cell may contain lipid up to 10%.

 

Function

•      Perform Protein synthesis.

•      It also helps in Enzyme synthesis.

•      R RNA present in Ribosome – act as attachment point for mRNA and t RNA.

•      Gives protection to newly synthesized Proteins.

 

Micro bodies

•      These are small cell organelles.

•      Single cell membrane present.

•      Mostly Absorb oxygen and take part in oxidation.

•      These are of 2 type- Peroxisome and Glyoxysomes.

Peroxisomes:

•      These microbodies Contain Enzymes for Peroxide Biosynthesis.

•      Discovered by- J. Rhodin 1954, described as organelle by De Duve et al (1965).

•      Term Coined by De Duve 1969, detail study by Tolbert- 1969.

•      Present in both plant and animal.

•      In Photosynthetic cell- 70-100 in number.

•      More in liver and kidney cell.

•      Present near ER, mitochondria and Chloroplast.

•      They develop from ER.

•      Diameter is 0.5- 1.0 μm.

•      A special Protein group present – peroxins.

•      Covered by single membrane.

•      Matrix is granular or may be fibrils arranged.

•      Contain Enzymes- urate oxidase, amino acid oxidase, Hydroxy acid oxidase, catalase etc.

•      Take O₂- form Hydrogen peroxide (H₂O₂ ) act as scavanging molecule.

Function:

•      De-toxification of alcohol (25%).

•      Unusual substance or Xenobiotics (e.g- some A.A. , alkanes etc)- broken inside peroxisome.

•      Urate is nutralized in side peroxisome to allatonin.

•      F.A chain broken down by Peroxisome (to form Prosta glandin).

•      Involved in Photorespiration process in plants.

•      In root nodules- fixed nitrogen to ureids- help for transport.

Glyoxysome

•      By-discovered Beevers in 1961 and studiedd by  Briedenbach in 1967.

•      Contain enzyme for B-Oxydation of F.A. and for Glyoxylate Pathway.

•      Also called Special – peroxisome.

•      After completing their function they change to Peroxisome.

•      Present in germinating oil seed and in some fungi.

•      Contain enzyme rich matrix and colloidal core.

Function:

•      Produce Acetyl CoA, during Beta-Oxydation of F.A.

•      Acetyl CoA- help in producing ATP.

•      Reappear in Senescent part of plant for degradation of Lipid and to re metabolize the product.

Sphaerosomes or Oleosome :

•      Single membrane bound small spherical vesicles. (Store and synthesis of  Lipid)

•      Develop from ER.

•      Discovered by Perner in 1953.

•      Spherical structure of 0.5-0.1 μm diameter.

•      Maximum lipid contain – 98%  + protein (very few).

•      Found in huge amount in endosperm of oily seed, maize root tip.

•      Also contain Enzymes for Lipid synthesis.

Hydrolytic enzyme also present believed to have the lysosomal activity in plant cell.

Want to Know about Lysosome and Cytoskeleton:

https://uksirnotes.blogspot.com/2021/07/Lysosome-cytoskeleton-uksirnotes.html

Want to Know about Cytoplasm, RER, SER:

https://uksirnotes.blogspot.com/2021/07/Cytoplasm-ER-Golgi-complex.html

Want to Know about Transport in  Membrane:

https://uksirnotes.blogspot.com/2021/07/Membrane-transport-system-UKsir.html

That's all about Ribosome-Peroxisosomes-Glyoxysome . Feel free to ask doubts in comment section.. uksir.