Pokretljivost

Pokretljivost je sposobnost organizama da se samostalno kreće, koristeći metaboličku energiju. Ovaj tgermin uključuje i pokretljivost unutarćelijskih struktura i organela.

Definicije uredi

Pokretljivosti može se suprotstaviti sesilnost, stanje organizama koji ne posjeduju sredstva za samopokretljivost i koji su obično nepokretni. Pokretljivost se razlikuje od kretanja, sposobnosti nečega da se premjesti sa jednog na drugo mjesto. Termin pokretljivost uključuje i pokretljivost i kretanje; sesilni organizmi, uključujući biljke i gljive, često imaju pokretne dijelove poput plodova, sjemena ili spora koje mogu raspršiti drugi agensi poput vjetra, vode ili drugih organizama.^[2]

Pokretljivost je genetički određena,^[3] ali mogu uticati i okolinski faktori, kao što su toksini. Nervni i mišićnoskeletni sistem omogučavaju glavninu pokretljivosti sisara.^[4]^[5]^[6]

Pored životinjske lokomocije, većina životinja su pokretne, mada su neke i skretanja, opisano kao da imaju pasivnu pokretljivost. Mnoge bakterije i drugi mikroorganizmi i višećelijski organizmi su pokretni; neki mehanizmi protoka tečnosti u višećelijskim organima i tkivima takođe se smatraju primerima pokretljivosti, kao i kod peristaltičke pokretljivosti gastrointestinalnog trakta. Pokretne morske životinje obično se nazivaju slobodno plivajućim,^[7]^[8]^[9] a pokretni neparazitski organizmi nazivaju se slobodno živećim.^[10]

Ćelijska razina uredi

Eukariotski citoskeleti podstiču ćelije da se kreću kroz tečnost i preko površina, dijele se u nove ćelije, a citoskelet vrši transport organela unutar ćelije.
Ovaj video snima obojene citoskelete iz presjeka lista Arabidopsis thaliana .^[11]

Na ćelijskom nivou postoje različiti načini kretanja:

pokretljivost bičevima, pokreti slični plivanju ( naprimjer kod Spermatozoa, podstaknuto redovitim mahanjem njihovih bičeva, ili kod bakterije E. coli, koja pliva okrećući spiralni prokariotski bič)
ameboidni pokret, pokret poput puzanja, koji također omogućava plivanje ^[12]^[13]
klizanje
ronjenje
trzanje, oblik pokretljivosti koji bakterije koriste za puzanje po površinama pomoću grabljastih filamenata pod nazivom pili tip IV.
filopodije, omogućava kretanje aksonskih konusa rasta .^[14]

Mnoge ćelije nisu pokretne na 37 °C, naprimjer kod Klebsiella pneumoniae i Shigella ili pod određenim okolnostima kao što je Yersinia pestis.

Pokreti uredi

Vidi: Taksija

Aktivnostu koje se percipiraju kao pokreti mogu biti:

duž hemijskog gradijenta (hemotaksija)
duž gradijenta temperature (termotaksija)
duž svjetlosnog gradijenta (fototaksija)
duž linije magnetnog polja (magnetotaksija)
duž električnog polja (galvanotaksija)
duž pravca gravitaciijske sile (gravitaksija)
duž gradijenta krutosti (vidi durotaksija)
duž gradijenta ćelijskih mjesta prijanjanja (haptotaksija)
duž ostalih ćelija ili biopolimera

Mišići daju sposobnost voljnog i nehotičnog kretanja kao pri mišićnim, spazmima i refleksnim radnjama. Na nivou mišićnog sistema, pokretljivost je sinonim za kretanje životinja.^[15]^[16]
Većina spermatozoida ima jedan bič koji im pomaže u plivanju. Obloge grlića maternice, maternica i jajovodi ženskog reproduktivnog sistema imaju važniju ulogu u transportu sperme do jajne ćelije.
Rekordne brzine koje postižu, gepardi duguju u velikoj mjeri pokretljivosti njihovih mišića.
Izdanci biljaka se kreću rastući prema svjetlosti. Ovo je poznato kao pozitivni fototropizam. Korijeni rastu dalje od svetlosti. Ovo je poznato kao negativni fototropizam.
Monociti i makrofagi imunskog sistema gutaju bakterije širenjem pseudopodija. Ovaj crtani film nije tačan prikaz fagocitoze.
Pokretljivost na potćelijskom nivou. Prikaz translacije – pokretni molekulski nanoskopski proces pomoću dinamike proteina.

Također pogledajte uredi

Reference uredi

^ Clegg, Chris (2008). "3.2 Cells make organisms". Edexcel biology for AS (6th izd.). London: Hodder Murray. str. 111. ISBN 978-0-340-96623-5.
^ "Botanical Nerd Word: Vagile". torontobotanicalgarden.ca/. Pristupljeno 29. 9. 2020.
^ Nüsslein-Volhard, Christiane (2006). "6 Form and Form Changes". Coming to life: how genes drive development. San Diego, California: Kales Press. str. 75. ISBN 978-0979845604. During development, any change in cell shape is preceded by a change in gene activity. The cell's origin and environment that determine which transcription factors are active within a cell, and, hence, which genes are turned on, and which proteins are produced.
^ Fullick, Ann (2009). "7.1". Edexcel A2-level biology. Harlow: Pearson. str. 138. ISBN 978-1-4082-0602-7.
^ Fullick, Ann (2009). "6.1". Edexcel A2-level biology. Harlow: Pearson. str. 67. ISBN 978-1-4082-0602-7.
^ E. Cooper, Chris; C. Brown, Guy (oktobar 2008). "The inhibition of mitochondrial cytochrome oxidase by the gases carbon monoxide, nitric oxide, hydrogen cyanide and hydrogen sulfide: chemical mechanism and physiological significance". Journal of Bioenergetics and Biomembranes. 40 (5): 533–539. doi:10.1007/s10863-008-9166-6. PMID 18839291.
^ Krohn, Martha M.; Boisdair, Daniel (maj 1994). "Use of a Stereo-video System to Estimate the Energy Expenditure of Free-swimming Fish". Canadian Journal of Fisheries and Aquatic Sciences. 51 (5): 1119–1127. doi:10.1139/f94-111.
^ Cooke, Steven J.; Thorstad, Eva B.; Hinch, Scott G. (mart 2004). "Activity and energetics of free-swimming fish: insights from electromyogram telemetry". Fish and Fisheries. 5 (1): 21–52. doi:10.1111/j.1467-2960.2004.00136.x. We encourage the continued development and refinement of devices for monitoring the activity and energetics of free-swimming fish
^ Carey, Francis G.; Lawson, Kenneth D. (februar 1973). "Temperature regulation in free-swimming bluefin tuna". Comparative Biochemistry and Physiology A. 44 (2): 375–392. doi:10.1016/0300-9629(73)90490-8. PMID 4145757. Acoustic telemetry was used to monitor ambient water temperature and tissue temperature in free-swimming bluefin tuna (Thunnus thynnus Linneaus [sic], 1758) over periods ranging from a few hours to several days.
^ "About Parasites". Centers for Disease Control. Pristupljeno 29. 9. 2020. Protozoa are microscopic, one-celled organisms that can be free-living or parasitic in nature.
^ Alberts, Bruce; Johnson, Alexander; Lewis, Juian; Raff, Martin; Roberts, Keith; Walter, Peter (2008). "16". Molecular biology of the cell (5th izd.). New York: Garland Science. str. 965. ISBN 978-0-8153-4106-2. For cells to function properly, they must organize themselves in space and interact mechanically with their environment... Eucaryotic cells have developed... the cytoskeleton... pulls the chromosomes apart at mitosis and then splits the dividing cell into two... drives and guides intracellular traffic of organelles... enables cells such as sperm to swim and others, such as fibroblasts and white blood cells, to crawl across surfaces. It exhibits wide range of movement
^ Van Haastert, Peter J. M. (2011). "Amoeboid Cells Use Protrusions for Walking, Gliding and Swimming". PLOS ONE. 6 (11): e27532. Bibcode:2011PLoSO...627532V. doi:10.1371/journal.pone.0027532. PMC 3212573. PMID 22096590.
^ Bae, A. J.; Bodenschatz, E. (2010). "On the swimming of Dictyostelium amoebae". Proceedings of the National Academy of Sciences. 107 (44): E165–6. arXiv:1008.3709. Bibcode:2010PNAS..107E.165B. doi:10.1073/pnas.1011900107. PMC 2973909. PMID 20921382.
^ Gilbert, Scott (2006). Developmental biology (8th. izd.). Sunderland, Mass.: Sinauer Associates, Inc. Publishers. str. 395. ISBN 9780878932504.
^ Parsons, Richard (2009). "Unit 5 Section 1". A2-level biology : the revision guide : exam board: Edexcel. Broughton-in-Furness: Coordination Group Publications. str. 50. ISBN 978-1-84762-264-8. Skeletal muscle is the type of muscle you use to move, e.g. the bicep and triceps move the lower arm. Skeletal muscles are attached to bones by tendons. Ligaments attach bones to other bones, to hold them together. Skeletal muscles contract and relax to move bones at a joint.
^ Vannini, Vanio; Jolly, Richard T.; Pogliani, Giuliano (1994). The new atlas of the human body : a full color guide to the structure of the body. London: Chancellor Press. str. 25. ISBN 978-1-85152-984-1. The muscle mass is not just concerned with locomotion. It assists in the circulation of blood and protects and confines the visceral organs. It also provides the main shaping component of the human form.

[1] Clegg, Chris (2008). "3.2 Cells make organisms". Edexcel biology for AS (6th izd.). London: Hodder Murray. str. 111. ISBN 978-0-340-96623-5.

[nerd_word-2] "Botanical Nerd Word: Vagile". torontobotanicalgarden.ca/. Pristupljeno 29. 9. 2020.

[3] Nüsslein-Volhard, Christiane (2006). "6 Form and Form Changes". Coming to life: how genes drive development. San Diego, California: Kales Press. str. 75. ISBN 978-0979845604. During development, any change in cell shape is preceded by a change in gene activity. The cell's origin and environment that determine which transcription factors are active within a cell, and, hence, which genes are turned on, and which proteins are produced.

[4] Fullick, Ann (2009). "7.1". Edexcel A2-level biology. Harlow: Pearson. str. 138. ISBN 978-1-4082-0602-7.

[5] Fullick, Ann (2009). "6.1". Edexcel A2-level biology. Harlow: Pearson. str. 67. ISBN 978-1-4082-0602-7.

[6] E. Cooper, Chris; C. Brown, Guy (oktobar 2008). "The inhibition of mitochondrial cytochrome oxidase by the gases carbon monoxide, nitric oxide, hydrogen cyanide and hydrogen sulfide: chemical mechanism and physiological significance". Journal of Bioenergetics and Biomembranes. 40 (5): 533–539. doi:10.1007/s10863-008-9166-6. PMID 18839291.

[7] Krohn, Martha M.; Boisdair, Daniel (maj 1994). "Use of a Stereo-video System to Estimate the Energy Expenditure of Free-swimming Fish". Canadian Journal of Fisheries and Aquatic Sciences. 51 (5): 1119–1127. doi:10.1139/f94-111.

[8] Cooke, Steven J.; Thorstad, Eva B.; Hinch, Scott G. (mart 2004). "Activity and energetics of free-swimming fish: insights from electromyogram telemetry". Fish and Fisheries. 5 (1): 21–52. doi:10.1111/j.1467-2960.2004.00136.x. We encourage the continued development and refinement of devices for monitoring the activity and energetics of free-swimming fish

[9] Carey, Francis G.; Lawson, Kenneth D. (februar 1973). "Temperature regulation in free-swimming bluefin tuna". Comparative Biochemistry and Physiology A. 44 (2): 375–392. doi:10.1016/0300-9629(73)90490-8. PMID 4145757. Acoustic telemetry was used to monitor ambient water temperature and tissue temperature in free-swimming bluefin tuna (Thunnus thynnus Linneaus [sic], 1758) over periods ranging from a few hours to several days.

[10] "About Parasites". Centers for Disease Control. Pristupljeno 29. 9. 2020. Protozoa are microscopic, one-celled organisms that can be free-living or parasitic in nature.

[11] Alberts, Bruce; Johnson, Alexander; Lewis, Juian; Raff, Martin; Roberts, Keith; Walter, Peter (2008). "16". Molecular biology of the cell (5th izd.). New York: Garland Science. str. 965. ISBN 978-0-8153-4106-2. For cells to function properly, they must organize themselves in space and interact mechanically with their environment... Eucaryotic cells have developed... the cytoskeleton... pulls the chromosomes apart at mitosis and then splits the dividing cell into two... drives and guides intracellular traffic of organelles... enables cells such as sperm to swim and others, such as fibroblasts and white blood cells, to crawl across surfaces. It exhibits wide range of movement

[12] Van Haastert, Peter J. M. (2011). "Amoeboid Cells Use Protrusions for Walking, Gliding and Swimming". PLOS ONE. 6 (11): e27532. Bibcode:2011PLoSO...627532V. doi:10.1371/journal.pone.0027532. PMC 3212573. PMID 22096590.

[13] Bae, A. J.; Bodenschatz, E. (2010). "On the swimming of Dictyostelium amoebae". Proceedings of the National Academy of Sciences. 107 (44): E165–6. arXiv:1008.3709. Bibcode:2010PNAS..107E.165B. doi:10.1073/pnas.1011900107. PMC 2973909. PMID 20921382.

[Gilbert-14] Gilbert, Scott (2006). Developmental biology (8th. izd.). Sunderland, Mass.: Sinauer Associates, Inc. Publishers. str. 395. ISBN 9780878932504.

[15] Parsons, Richard (2009). "Unit 5 Section 1". A2-level biology : the revision guide : exam board: Edexcel. Broughton-in-Furness: Coordination Group Publications. str. 50. ISBN 978-1-84762-264-8. Skeletal muscle is the type of muscle you use to move, e.g. the bicep and triceps move the lower arm. Skeletal muscles are attached to bones by tendons. Ligaments attach bones to other bones, to hold them together. Skeletal muscles contract and relax to move bones at a joint.

[16] Vannini, Vanio; Jolly, Richard T.; Pogliani, Giuliano (1994). The new atlas of the human body : a full color guide to the structure of the body. London: Chancellor Press. str. 25. ISBN 978-1-85152-984-1. The muscle mass is not just concerned with locomotion. It assists in the circulation of blood and protects and confines the visceral organs. It also provides the main shaping component of the human form.

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