BIOB10H3 Study Guide - Midterm Guide: Thylakoid, Signal Peptide, Intermembrane Space
Document Summary
Originated as cyanobacteria lived as symbionts within eukaryotic cells through phagocytosis. Many similarities with cyanobacteria: similar photosynthetic machinery; divide by binary fission. Contains porin proteins (large channels): allows large molecules to get in & out. Membrane has 75% protein: 25% lipid ratio. Lumen = the space that thylakoid sacs encloses. Stroma = space enclosed by inner envelope membrane (contains grana & stroma lamellae) Stroma lamellae = flattened membranes that connect thylakoids from different grana. The space within the chloroplast enclosed by the inner envelope membrane. 90% of the chloroplast proteins are imported into the organelle (similar to mitochondria) Most chloroplast proteins are translated on free ribosomes in the cytosol. Chloroplast transit peptide: targeting signal that direct them to chloroplasts (located at the n-terminus of protein) Stroma targeting domain: stroma proteins have this as part of the transit peptide. Thylakoid transfer domain: thylakoid proteins have this located downstream of stroma targeting domain.
