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Gated transportNucleus and peroxisomesFully folded proteins pass through a large pore (nuclear pore)(Dr. Susan Wente will present lectures on nuclear import) TranslocationER, mitochondria and chloroplastsUnfolded proteins are threaded through a small pore (translocon)Membrane remains impermeable to small molecules Vesicular transport (Dr. Jim Goldenring)Secretory and endocytic pathwaysProteins move between organelles without crossing a membraneCarried by small membrane-bound vesicles.
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21. Difference between a signal peptide and transmembrane segment The primary difference is degree of hydrophobicity.
Signal peptides usually have 8-10 consecutive hydrophobic amino acids.
Transmembrane segments usually have at least 18 consecutive hydrophobic amino acids.