Question

What would happen to a protein like signal peptidase if you removed its signal peptide but added a nuclear localization signal (NLS)?

		It would end up in the nucleus.
		It would end up in the cytoplasm
		It would be secreted
		None of the above

What would happen to a secreted protein (e.g. insulin) if you produced it from an mRNA missing the sequence encoding the signal peptide?

		It would be properly secreted, though it might not fold correctly.
		It would get translated in the cytoplasm and remain there.
		It would get trapped in the ER.
		It would get transported to the plasma membrane and become embedded there.

Which of these amino acids would you predict are most likely to rely on wobble (in other words, which is coded for by the largest number of codons?

		Alanine (Ala)
		Arginine (Arg)
		Aspartic acid (Asp)
		Asparagine (Asn)

Please explain!

Answer 1

1) a) it will end up in nucleus

Explanation - nuclear localisation signal is a sequence tag that facilitates transportation of proteins to nucleus. So, yes loss of signal peptide and addition of NLS will led protein to be in nucleus.

2) c) it would get trapped in ER

Explanation- signal peptide are sequences present in proteins which are in organelles such as ER, golgi and destined to be secreted. So, due to loss of signal peptide protein will not be able to translocate.

3) b) arginine (Arg)

Explanation- There main two reasons for a amino acid to have more codons in comparison to others i.e amino acid is used frequently in cell function and second to reduce effect of mutation. Extensive translation of a amino acid in a protein prone it to get mutation. So, different codons for same amino acid residues this effect.

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