Editing Active transport (section)

==Bulk transport==
{{Main|Endocytosis|Exocytosis}}

[[Endocytosis]] and [[exocytosis]] are both forms of [[Solvent drag|bulk transport]] that move materials into and out of cells, respectively, via [[Vesicle (biology and chemistry)|vesicles]].<ref>{{Cite book|title=Tenth Addition Campbell Biology|last1=Reece|first1=Jane|last2=Urry|first2=Lisa|last3=Cain|first3=Michael|last4=Wasserman|first4=Steven|last5=Minorsky|first5=Peter|last6=Jackson|first6=Robert|publisher=Pearson Education, Inc|year=2014|isbn=978-0-321-77565-8|location=United States of America|pages=137|edition=Tenth Addition}}</ref> In the case of endocytosis, the cellular membrane folds around the desired materials outside the cell.<ref>[https://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=mboc4&part=A2383 Transport into the Cell from the Plasma Membrane: Endocytosis – Molecular Biology of the Cell – NCBI Bookshelf]. Ncbi.nlm.nih.gov (2011-10-03). Retrieved on 2011-12-05.</ref> The ingested particle becomes trapped within a pouch, known as a vesicle, inside the [[cytoplasm]]. Often enzymes from [[lysosome]]s are then used to digest the molecules absorbed by this process. Substances that enter the cell via signal mediated electrolysis include proteins, hormones and growth and stabilization factors.<ref>Paston, Ira; Willingham, Mark C. (1985). Endocytosis. Springer, Boston, MA. pp 1–44. doi: 10.1007/978-1-4615-6904-6_1. {{ISBN|9781461569060}}.</ref> Viruses enter cells through a form of endocytosis that involves their outer membrane fusing with the membrane of the cell. This forces the viral DNA into the host cell.<ref>{{Cite journal|last1=Jahn|first1=Reinhard|last2=Südhof|first2=Thomas C.|date=1999|title=Membrane Fusion and Exocytosis|journal=Annual Review of Biochemistry|language=en|volume=68|issue=1|pages=863–911|doi=10.1146/annurev.biochem.68.1.863|pmid=10872468|issn=0066-4154}}</ref>

Biologists distinguish two main types of endocytosis: [[pinocytosis]] and [[phagocytosis]].<ref>[http://www.takdangaralin.com/science/biology-science/cell-two-major-process-in-exchange-of-materials-between-cell-and-environment/ Cell : Two Major Process in Exchange Of Materials Between Cell And Environment] {{webarchive|url=https://web.archive.org/web/20100811173330/http://www.takdangaralin.com/science/biology-science/cell-two-major-process-in-exchange-of-materials-between-cell-and-environment/|date=August 11, 2010}}. Takdang Aralin (2009-10-26). Retrieved on 2011-12-05.</ref>
* In pinocytosis, cells engulf liquid particles (in humans this process occurs in the small intestine, where cells engulf fat droplets).<ref>[http://www.biology-online.org/dictionary/Pinocytosis Pinocytosis: Definition]. biology-online.org</ref>
* In phagocytosis, cells engulf solid particles.<ref>[http://courses.washington.edu/conj/bloodcells/phagocytosis.htm Phagocytosis]. Courses.washington.edu. Retrieved on 2011-12-05.</ref>

Exocytosis involves the removal of substances through the fusion of the outer cell membrane and a vesicle membrane.<ref name="annualreviews.org">{{cite journal|doi=10.1146/annurev.biochem.68.1.863|title=Membrane Fusion and Exocytosis|year=1999|last1=Jahn|first1=Reinhard|last2=Südhof|first2=Thomas C.|journal=Annual Review of Biochemistry|volume=68|pages=863–911|pmid=10872468}}</ref> An example of exocytosis would be the transmission of neurotransmitters across a synapse between brain cells.