Question: where does the electron transport chain pumps protons
[{'answer': 'across a membrane', 'provenance': [{'wikipedia_id': '92236', 'title': 'Electron transport chain', 'start_paragraph_id': 1, 'start_character': 276, 'end_paragraph_id': 1, 'end_character': 293, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'answer': 'mitochondrial membrane', 'provenance': [{'wikipedia_id': '92236', 'title': 'Electron transport chain', 'start_paragraph_id': 2, 'start_character': 258, 'end_paragraph_id': 2, 'end_character': 280, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '92236', 'title': 'Electron transport chain', 'start_paragraph_id': 0, 'start_character': 0, 'end_paragraph_id': 0, 'end_character': 0, 'bleu_score': 1.0, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 3208113499940348235}, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '92236', 'title': 'Electron transport chain', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 796, 'bleu_score': 0.9829771687435411, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 3208113499940348235}, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '92236', 'title': 'Electron transport chain', 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 541, 'bleu_score': 0.9458134147569861, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 3208113499940348235}, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '92236', 'title': 'Electron transport chain', 'start_paragraph_id': 9, 'start_character': 0, 'end_paragraph_id': 9, 'end_character': 1085, 'bleu_score': 0.972403621987549, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 3208113499940348235}, 'section': 'Section::::In mitochondria.\n'}]}, {'provenance': [{'wikipedia_id': '92441', 'title': 'Proton pump', 'section': 'Section::::Function.\n', 'start_paragraph_id': 7, 'end_paragraph_id': 7, 'meta': {'evidence_span': ['In cell respiration, the proton pump uses energy to transport protons from the matrix of the mitochondrion to the inter-membrane space.', 'In cell respiration, the proton pump uses energy to transport protons from the matrix of the mitochondrion to the inter-membrane space. It is an active pump that generates a proton concentration gradient across the inner mitochondrial membrane because there are more protons outside the matrix than inside.']}}]}]