Ribosomes

[dreambig]

Just a general question that has been bugging me about ribosomes:
If they are not membrane bound what keeps ribosomes in shape?

[alondouek]

Through covalent bonds. Ribosomes are rRNA (ribosomal ribonucleic acid) - they maintain their structure much the same way that any other RNA strand does.

EDIT: Forgot to mention that the ribosome consists of both rRNA complexes and proteins - it is a ribonucleoprotein.

[Yacoubb]

EDIT: Forgot to mention that the ribosome consists of both rRNA complexes and proteins - it is a ribonucleoprotein.

Hence, a conjugated protein

[alondouek]

Hence, a conjugated protein

I wouldn't classify a ribosome as a conjugated protein, seeing as its structure is primarily ribonucleic acid-based.

Haemoglobin is a conjugated protein, in that it is primarily a protein in structure but has heme groups. Following the definition of a conjugated protein, it can only be a protein that functions in conjugation with other chemical groups.

[Yacoubb]

I wouldn't classify a ribosome as a conjugated protein, seeing as its structure is primarily ribonucleic acid-based.

Haemoglobin is a conjugated protein, in that it is primarily a protein in structure but has heme groups. Following the definition of a conjugated protein, it can only be a protein that functions in conjugation with other chemical groups.

Yeah I guess that's valid. So really I think knowing that ribosomes are made primarily of RNA (rRNA) would be important, and knowing that ribosomes remain compact because of the bonds between the RNA nucleotides!

^ It is probably a segment of learning about the 3 types of RNA:
a)mRNA (messenger RNA)
b)tRNA (transfer RNA)
c)rRNA (ribosomal RNA).

[Yacoubb]

Just something handy to remember when you're looking at protein synthesis. The context of a SAC/exam question would lead you to making an accurate judgement as to where a particular protein is actually synthesised. The formal way VCAA actually wants your response to be is the following:

* Any proteins synthesised within a cell and are utilised within the intracellular environment (e.g. lysozame for intracellular digestion is lysosomes),  are said to be synthesised in free ribosomes.

*Any proteins that are synthesised and then secreted outside the cell into the extracellular environment of a cell (e.g. insulin hormone for blood glucose regulation), are said to be synthesised in the Rough Endoplasmic Reticulum.

Just a handy insight. Also, make sure you never write ER.. always say Endoplasmic Reticulum, because ER is not universally recognised as meaning Endoplasmic Reticulum.