Difference between revisions of "Ribosomes"

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ribosomes
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=== Definition ===
  
''noun, plural of [[ribosome]]''
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'''noun'''
  
Small round particles in a [[cell]] made up of [[RNA]] and [[protein]] that are primarily involved in the assembly of proteins by translating [[messenger RNA]] (a process called [[translation]]).
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''singular: ribosome''
  
Ribosomes, being entirely [[particulate]], are not considered [[organelles]] when the term organelle is strictly used to refer to [[membraned]] structures. Although in some literature they are referred to as "non-membranous organelles".
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Plural form of '''[[ribosome]]''', i.e. any of the small round particles in a cell made up of RNA and protein that are primarily involved in the assembly of proteins by translating messenger RNA (a process called translation)
Ribosomes are typically composed of two [[subunits]]: the large and small [[subunits]]. They join as one during [[translation]]; together, they [[catalyze]] the [[translation]] of [[mRNA]] into a [[polypeptide chain]] during [[protein synthesis]], and since their [[active site]]s are made of [[RNA]], ribosomes are also referred to as "[[ribozymes]]."
 
  
Ribosomes are formed in the [[cytoplasm]] of [[prokaryotic cell]]s. In [[eukaryotic cell]]s, they are formed most often in the [[nucleolus]]. Another difference between ribosomes of [[prokaryotes]] and [[eukaryotes]] is the structure of the ribosomes. [[Prokaryotes]] have [[70S ribosome]]s, each consisting of a small (30S) and a large (50S) [[subunit]]. Eukaryotes have [[80S ribosome]]s, each consisting of a small (40S) and large (60S) [[subunit]]. However, the [[organelles]] like [[chloroplasts]] and [[mitochondria]] that are present only in [[eukaryotic cell]]s also consist of [[70S ribosome]]s resembling those in [[prokaryotes]] (e.g. [[bacteria]]), indicating that these [[eukaryotic]] [[organelles]] have descended from their ancestral [[bacteria]] (see [[Endosymbiotic theory]]).
 
  
In [[eukaryotes]], the ribosomes may be classified as either ‘free’ or ‘bound’. [[Free ribosome]]s may be found suspended in the [[cytosol]] whereas [[bound ribosome]]s are attached to [[endoplasmic reticulum]] (as such called [[rough endoplasmic reticulum]]). Free ribosomes are involved in the [[synthesis]] of [[proteins]] that will function in the [[cytosol]] while bound ribosomes in the [[synthesis]] of [[proteins]] that are to be exported or used within the [[cell membrane]]. The two types of ribosomes have similar function and structure, and in fact, are interchangeable.
 
  
Word origin: from ribonucleic acid and Greek: ''soma'' (meaning body)
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=== See: [[Ribosome]] for further information. ===

Latest revision as of 00:04, 18 August 2019

Definition

noun

singular: ribosome

Plural form of ribosome, i.e. any of the small round particles in a cell made up of RNA and protein that are primarily involved in the assembly of proteins by translating messenger RNA (a process called translation)


See: Ribosome for further information.