Proteins have two basic secondary structure forms - beta strand and alpha helix. Do these depend on the organism or do the two forms exist for every protein?

For tertiary and quaternary structure: do such motifs depend on the position or does each organism have a specific form of protein structure?

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    $\begingroup$ Welcome to Biology SE. However I am afraid your question is too general and at a very basic level. You can learn about proteins by carefully reading information available on the internet, for example sections such as this in Berg et al. or the entry in Wikipedia. If, after studying the examples there you are still confused, come back with a well-formed question. $\endgroup$ – David Jul 26 '16 at 21:29
  • $\begingroup$ The OP asks what is the relation between levels of protein folding and phylogeny. It's a good question, I think it could be rephrased with the aid of a native speaker. $\endgroup$ – Rodrigo Jul 27 '16 at 1:10
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    $\begingroup$ I agree with @David - this question is exceedingly basic and should be understandable by reading textbooks, websites, etc - it is not a very well-formed question. $\endgroup$ – Vance L Albaugh Jul 27 '16 at 1:15
  • $\begingroup$ @Rodrigo Although I tend to agree with David on this, and I think you re being generous in assuming it's about folding and phylogeny, it is possible the question is good. $\endgroup$ – gilleain Jul 27 '16 at 8:58
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    $\begingroup$ @Muna Ar : What do you mean by 'depend on the position'? $\endgroup$ – gilleain Jul 27 '16 at 8:58

Beta sheets and alpha helix are secondary structures that are simply very common to proteins. Their formation depends on the Amino acids that make up particular stretch in the primary sequence. For example alanines in a row will naturally tend to twist up into a alpha helix in water (medium matters). There are no hard and set rules to determine Tert. Structure or quart (aside from modeling but you have to validate in the end so its not entire end case)

  • $\begingroup$ So the tertiary and the quarternary depend on the protein , it could have a tertiary or quart as it could not right ? $\endgroup$ – Muna Ar Jul 28 '16 at 20:00
  • $\begingroup$ Tert depends on primary sequence and environnment. Quart depends on some level of symmetry in tert structure that allows for optimal contact between subunits $\endgroup$ – SciEnt Jul 29 '16 at 5:13

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