{"id":90,"date":"2014-07-31T12:52:13","date_gmt":"2014-07-31T12:52:13","guid":{"rendered":"http:\/\/carnea.cz\/?p=90"},"modified":"2014-07-31T12:52:13","modified_gmt":"2014-07-31T12:52:13","slug":"genetika-barev-dil-i","status":"publish","type":"post","link":"https:\/\/carnea.cz\/?p=90","title":{"rendered":"Genetika barev d\u00edl I."},"content":{"rendered":"

Tak\u017ee jako prvn\u00ed si d\u00e1me pojem GENETIKA<\/strong> – no, to je p\u0159ece v\u011bda :-), tak\u017ee se honem za\u010dn\u011bte tv\u00e1\u0159it n\u00e1le\u017eit\u011b v\u011bdecky! Ale bez srandi\u010dek, je to v\u011bdn\u00ed obor zab\u00fdvaj\u00edc\u00ed se d\u011bdi\u010dnost\u00ed znak\u016f a vlastnost\u00ed u organism\u016f. Genetika v sou\u010dasnosti um\u00ed spoustu fantastick\u00fdch v\u011bc\u00ed – s jej\u00ed pomoc\u00ed lze u je\u0161t\u011b nenarozen\u00fdch d\u011bt\u00ed diagnostikovat z\u00e1va\u017en\u00e9 poruchy na chromozomech – nejzn\u00e1m\u011bj\u0161\u00ed z nich je asi Down\u016fv syndom. \u017de je mo\u017en\u00e9 si nechat zhotovit test paternity (otcovstv\u00ed), to u\u017e dneska v\u00ed taky snad ka\u017ed\u00fd ta\u0165ka. Ov\u0161em do takhle slo\u017eit\u00fdch z\u00e1le\u017eitost\u00ed zab\u00edhat nebudu, to slibuju. Pro pochopen\u00ed d\u011bdi\u010dnosti barev u mor\u010dat vysta\u010d\u00edme s cca 10 z\u00e1kladn\u00edmi pojmy, kter\u00e9 je ov\u0161em t\u0159eba si d\u016fkladn\u011b v\u0161t\u00edpit do pam\u011bti, p\u00e1\u010d jinak to prost\u011b nep\u016fjde. Tak d\u00e1vat pozor, za\u010d\u00edn\u00e1me!<\/p>\n

Na za\u010d\u00e1tek si pov\u00edme poh\u00e1dku, zn\u00e1 j\u00ed ka\u017ed\u00e9 mal\u00e9 d\u00edt\u011b, ale p\u0159esto j\u00ed pro jistotu p\u0159ipomenu. Byl jednou jeden dome\u010dek, v tom dome\u010dku stole\u010dek, na stole\u010dku misti\u010dka v t\u00e9 misti\u010dce vodi\u010dka a bla a bla a bla. To zn\u00e1te. A te\u010f si pov\u00edme podobnou poh\u00e1dku. Bylo jedno zvi\u0159\u00e1tko, \u0159\u00edkali mu mor\u010d\u00e1tko, v tom mor\u010d\u00e1tku v\u011bci\u010dky, jmenuj\u00ed se bun\u011b\u010dky, v t\u011bch bun\u011b\u010dk\u00e1ch jad\u00fdrka, v t\u011bch jad\u00fdrk\u00e1ch zamotan\u00e9 ma\u0161li\u010dky a t\u011bm ma\u0161li\u010dk\u00e1m se \u0159\u00edk\u00e1 CHROMOZ\u00d3MY<\/strong>. Po\u010det chromoz\u00f3m\u016f je dan\u00fd a nem\u011bnn\u00fd v\u017edy pro ur\u010dit\u00fd zv\u00ed\u0159ec\u00ed druh. No a na t\u011bch chromoz\u00f3mech je zapsan\u00e1 spousta informac\u00ed \u2013 jsou to genetick\u00e9 informace, prost\u011b je tam naps\u00e1no v\u0161echno o (nejen) t\u011bch barvi\u010dk\u00e1ch srsti, co n\u00e1m n\u011bkdy d\u00e1vaj\u00ed tak zabrat. Ve zkratce se informac\u00edm z t\u011bch sakramentskejch za\u0161modrchanejch ma\u0161l\u00ed \u0159\u00edk\u00e1 GENY<\/strong>. A proto\u017ee tohle je moc jednoduch\u00e9, tak te\u010f to tro\u0161ku zkomplikuju. \u017d\u00e1dn\u00fd gen nen\u00ed jen v jedn\u00e9 jedin\u00e9 form\u011b, p\u00e1\u010d jak \u0159\u00edk\u00e1m, bylo by to v\u0161echno moc jednoduch\u00e9, ale m\u00e1 v\u00edce forem a t\u011bm se \u0159\u00edk\u00e1 ALELY<\/strong>. N\u00e1zorn\u011b vysv\u011btl\u00edm na p\u0159\u00edkladu ze sv\u011bta lid\u00ed \u2013 gen pro barvu o\u010d\u00ed m\u00e1 u lid\u00ed zjednodu\u0161en\u011b dv\u011b alely \u2013 jedna alela je pro modrou barvu o\u010d\u00ed (k modr\u00e9 se \u0159ad\u00ed t\u00e9\u017e \u0161ed\u00e1 a zelen\u00e1) a druh\u00e1 alela je pro hn\u011bdou barvu o\u010d\u00ed. V\u00fdsledkem p\u016fsoben\u00ed t\u011bchto dvou alel v populaci je, \u017ee n\u00e1m po sv\u011bt\u011b b\u011bhaj\u00ed lidi\u010dky modrooc\u00ed a hn\u011bdooc\u00ed.<\/p>\n

A proto\u017ee p\u0159\u00edroda je je\u0161t\u011b chyt\u0159ej\u0161\u00ed a v\u016fbec nejrad\u0161i m\u00e1 nejr\u016fzn\u011bj\u0161\u00ed vychyt\u00e1vky, jednu takovou si te\u010f nast\u00edn\u00edme. Vychyt\u00e1vka zn\u00ed \u2013 chromoz\u00f3my se v oby\u010dejn\u00fdch t\u011bln\u00edch bu\u0148k\u00e1ch nach\u00e1zej\u00ed v sad\u011b \u2013 \u010dili jaksi v p\u00e1ru po dvou. Ale v pohlavn\u00edch bu\u0148k\u00e1ch to tak nen\u00ed, tam je v\u017edy jen jeden chromoz\u00f3m z dan\u00e9ho p\u00e1ru. A kdopak v\u00ed, pro\u010d to tak je? No p\u0159eci proto, \u017ee a\u017e n\u00e1m p\u0159i roozmno\u017eov\u00e1n\u00ed splyne bu\u0148ka sami\u010d\u00ed s bu\u0148kou sam\u010d\u00ed, tak n\u00e1m vzniknou nejen miminka, ale zase taky norm\u00e1ln\u00ed bu\u0148ky s p\u00e1rem chromoz\u00f3m\u016f. Jeden mimin\u010d\u00ed chromoz\u00f3m tedy poch\u00e1z\u00ed od maminky (po n\u011bm jsou mimi kr\u00e1sn\u00e1 a hodn\u00e1 a chytr\u00e1 a tak) a druh\u00fd mimin\u010d\u00ed chromoz\u00f3m poch\u00e1z\u00ed od tat\u00ednka (tady si dopl\u0148te, co uzn\u00e1te za vhodn\u00e9 :-)). P\u0159\u00edroda n\u00e1m tak hezky zajistila tzv. genetickou variabilitu populace.<\/p>\n

Tak a te\u010f se dost\u00e1v\u00e1me k pojm\u016fm pon\u011bkud slo\u017eit\u011bj\u0161\u00edm. Otev\u0159te si na sebe okno, a\u0165 v\u00e1m to l\u00e9pe mysl\u00ed, dejte si kousek \u010dokol\u00e1dy a \u010dt\u011bte d\u00e1l :-). Vysv\u011btl\u00edme si pojem dominance x recesivita a homozygot x heterozygot.<\/p>\n

M\u00e1-li jedinec alely na obou chromoz\u00f3mech stejn\u00e9, \u0159\u00edk\u00e1 se mu HOMOZYGOT<\/strong>, nem\u00e1-li je stejn\u00e9, \u0159\u00edk\u00e1 se mu HETEROZYGOT<\/strong>. Nejsou to \u017e\u00e1dn\u00e1 sprost\u00e1 slova, ale v\u011bdeck\u00fd \u017earg\u00f3n :-). T\u00e9 alele, kter\u00e1 jaksi p\u0159evl\u00e1dne nad svou druhou soudru\u017ekou v p\u00e1ru se \u0159\u00edk\u00e1 DOMINANTN\u00cd<\/strong>. T\u00e9 chud\u011b\u0159e druh\u00e9 um\u00e1\u010dknut\u00e9, co se nem\u016f\u017ee projevit jak se j\u00ed zachce, ale jen kdy\u017e jej\u00ed dominantn\u00ed k\u00e1mo\u0161ka zmiz\u00ed, se \u0159\u00edk\u00e1 RECESIVN\u00cd<\/strong>. U barvy lidsk\u00fdch o\u010d\u00ed je modr\u00e1 barva recesivn\u00ed, hn\u011bd\u00e1 dominantn\u00ed. Modrook\u00fd \u010dlov\u00ed\u010dek je tedy homozygotem, a to recesivn\u00edm homozygotem. Hn\u011bdook\u00fd \u010dlov\u00ed\u010dek je pak bu\u010f dominantn\u00edm homozygotem nebo heterozygotem. Tak\u017ee kdy\u017e uvid\u00edte n\u011bjak\u00e9ho modrook\u00e9ho fe\u0161\u00e1ka nebo fe\u0161andu, hned v\u00edte, jak je to s n\u00edm. Kde\u017eto kdy\u017e uvid\u00edte n\u011bjak\u00e9ho hn\u011bdook\u00e9ho Vinnetoua, tak v\u00edte prd. A tady nar\u00e1\u017e\u00edme na dal\u0161\u00ed dva pojmy \u2013 FENOTYP<\/strong> a GENOTYP<\/strong>. Genotyp je soubor v\u0161ech gen\u016f, kter\u00e9 organismus m\u00e1 v sob\u011b schovan\u00e9. Fenotyp je pak to, co vid\u00edme na mor\u010d\u00e1kovi jaksi zvenku \u2013 o\u010dima. Zat\u00edmco podle genotypu lze zcela jasn\u011b \u0159\u00edci, jak m\u00e1 doty\u010dn\u00e9 zv\u00ed\u0159e vypadat ani\u017e byste ho kdy vid\u011bli, podle fenotypu je mo\u017en\u00e9 genotyp ur\u010dit pouze sp\u00ed\u0161e orienta\u010dn\u011b \u2013 n\u011bco lze ur\u010dit dob\u0159e, n\u011bco h\u016f\u0159 a n\u011bco v\u016fbec.<\/p>\n

Pro lep\u0161\u00ed pochopen\u00ed si te\u010f vyrob\u00edme p\u00e1r p\u0159\u00edklad\u016f – z\u016fstaneme u modr\u00fdch a hn\u011bd\u00fdch o\u010d\u00ed.<\/p>\n

Alelu pro modrou barvu o\u010d\u00ed ozna\u010d\u00edme o<\/strong>, alelu pro hn\u011bdou barvu pak O<\/strong>.<\/p>\n

PS: p\u0159i ozna\u010dov\u00e1n\u00ed alel se pou\u017e\u00edv\u00e1 mal\u00fdch p\u00edsmen pro alely recesivn\u00ed, velk\u00fdch p\u00edsmen pro alely dominantn\u00ed.<\/p>\n

Prvn\u00ed tabulka ukazuje k\u0159\u00ed\u017een\u00ed dvou recesivn\u00edch homozygot\u016f – v praxi jsou maminka i tat\u00ednek modrooc\u00ed – oo<\/strong>. V\u00fdsledkem jsou d\u011bti\u010dky pouze modrook\u00e9 bez vlohy pro jakoukoliv jinou barvu. Zde lze podle fenotypu zcela jasn\u011b ur\u010dit genotyp, co\u017e ov\u0161em neb\u00fdv\u00e1 pravidlem, naopak je to sp\u00ed\u0161e v\u00fdjimkou.<\/p>\n\n\n\n\n\n
o<\/strong><\/td>\no<\/strong><\/td>\n<\/tr>\n
o<\/strong><\/td>\noo<\/strong><\/td>\noo<\/strong><\/td>\n<\/tr>\n
o<\/strong><\/td>\noo<\/strong><\/td>\noo<\/strong><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Druh\u00e1 tabulka ukazuje k\u0159\u00ed\u017een\u00ed dvou dominantn\u00edch homozygot\u016f – v praxi jsou maminka i tat\u00ednek hn\u011bdooc\u00ed OO<\/strong>. V\u00fdsledkem jsou d\u011bti\u010dky pouze hn\u011bdook\u00e9 bez vlohy pro jakoukoliv jinou barvu. Zde podle fenotypu nelze ur\u010dit genotyp – proto\u017ee prost\u011b jaksi dovnit\u0159 zv\u00ed\u0159at nevid\u00edme a ji\u017e jedin\u00e1 alela O <\/strong>sta\u010d\u00ed, aby o\u010di byly hn\u011bd\u00e9, tak\u017ee na pohled nev\u00edme, zda se jedn\u00e1 o homozygoty nebo heterozygoty.<\/p>\n\n\n\n\n\n
O<\/strong><\/td>\nO<\/strong><\/td>\n<\/tr>\n
O<\/strong><\/td>\nOO<\/strong><\/td>\nOO<\/strong><\/td>\n<\/tr>\n
O<\/strong><\/td>\nOO<\/strong><\/td>\nOO<\/strong><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

T\u0159et\u00ed tabulka ukazuje k\u0159\u00ed\u017een\u00ed recesivn\u00edho a dominantn\u00edho homozygota – v praxi je maminka modrook\u00e1 oo<\/strong> a tat\u00ednek hn\u011bdook\u00fd OO<\/strong> – nem\u00e1 vlohu pro modrou barvu.<\/p>\n

V\u00fdsledkem jsou d\u011bti\u010dky pouze hn\u011bdook\u00e9, ale v\u0161echny maj\u00ed vlohu pro modrou barvu o\u010d\u00ed. Zde op\u011bt nelze podle fenotypu nelze ur\u010dit genotyp – proto\u017ee prost\u011b jaksi dovnit\u0159 zv\u00ed\u0159at nevid\u00edme a ji\u017e jedin\u00e1 alela O <\/strong>sta\u010d\u00ed, aby o\u010di byly hn\u011bd\u00e9.<\/p>\n\n\n\n\n\n
o<\/strong><\/td>\no<\/strong><\/td>\n<\/tr>\n
O<\/strong><\/td>\nO<\/strong>o<\/strong><\/td>\nO<\/strong>o<\/strong><\/td>\n<\/tr>\n
O<\/strong><\/td>\nO<\/strong>o<\/strong><\/td>\nO<\/strong>o<\/strong><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

\u010ctvrt\u00e1 tabulka ukazuje k\u0159\u00ed\u017een\u00ed heterozygot\u016f – v praxi je maminka hn\u011bdook\u00e1 O<\/strong>o<\/strong> a tat\u00ednek hn\u011bdook\u00fd O<\/strong>o <\/strong>– oba maj\u00ed vlohu pro modrou barvu.<\/p>\n

V\u00fdsledkem jsou d\u011bti\u010dky hn\u011bdook\u00e9 – jaksi po rodi\u010d\u00edch, ale m\u00e1me t\u00e9\u017e d\u011bti modrook\u00e9. Po\u010det hn\u011bdook\u00fdch d\u011bt\u00ed je statisticky 75% (25% dominantn\u00ed homozygoti, 50% heterozygoti), modrook\u00fdch d\u011bt\u00ed je statisticky 25%. Zde lze u modrook\u00fdch d\u011bt\u00ed dle fenotypu ur\u010dit genotyp\u00a0u hn\u011bdook\u00fdch toto nelze – proto\u017ee prost\u011b jaksi dovnit\u0159 zv\u00ed\u0159at nevid\u00edme a ji\u017e jedin\u00e1 alela O <\/strong>sta\u010d\u00ed, aby o\u010di byly hn\u011bd\u00e9.<\/p>\n\n\n\n\n\n
O<\/strong><\/td>\no<\/strong><\/td>\n<\/tr>\n
o<\/strong><\/td>\nO<\/strong>o<\/strong><\/td>\noo<\/strong><\/td>\n<\/tr>\n
O<\/strong><\/td>\nOO<\/strong><\/td>\nO<\/strong>o<\/strong><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

V k\u0159\u00ed\u017een\u00ed bychom mohli d\u00e1le pokra\u010dovat, ale mysl\u00edm, \u017ee p\u0159\u00edklady sta\u010d\u00ed. Z\u00e1v\u011br z tohoto je tento – modrook\u00fd \u010dlov\u011bk nese genotyp oo<\/strong> a se stejn\u00fdm modrook\u00fdm partnerem nemohou zplodit jin\u00e9 potomky ne\u017e modrook\u00e9. Tuto informaci zjist\u00edme na prvn\u00ed pohled. Hn\u011bdook\u00fd \u010dlov\u011bk nese genotyp OO<\/strong> nebo O<\/strong>o<\/strong>, m\u016f\u017ee zplodit s druh\u00fdm hn\u011bdook\u00fdm partnerem potomky bu\u010f modrook\u00e9 nebo hn\u011bdook\u00e9 a podle pohledu toto nem\u016f\u017eeme ur\u010dit, a\u0165 kouk\u00e1me sebel\u00edp. M\u00e1me- li jednoho z rodi\u010d\u016f modrook\u00e9ho a jednoho hn\u011bdook\u00e9ho, pak m\u016f\u017eeme m\u00edt d\u011bti pouze hn\u011bdook\u00e9 nebo hn\u011bdook\u00e9 i modrook\u00e9, z\u00e1le\u017e\u00ed na tom, zda hn\u011bdook\u00fd partner je homozygot nebo heterozygot – zda tedy nese nebo nenese vlohu pro modrou barvu.<\/p>\n

T\u00edmto zat\u00edm kon\u010d\u00edme a v p\u0159\u00ed\u0161t\u00edm d\u00edle u\u017e se vrhneme na mor\u010diska a probereme si prvn\u00ed gen – A – tzv. aguti faktor.<\/p>\n

 <\/p>\n","protected":false},"excerpt":{"rendered":"

Tak\u017ee jako prvn\u00ed si d\u00e1me pojem GENETIKA – no, to je p\u0159ece v\u011bda :-), tak\u017ee se honem za\u010dn\u011bte tv\u00e1\u0159it n\u00e1le\u017eit\u011b v\u011bdecky! Ale bez srandi\u010dek, je…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[9],"tags":[],"class_list":["post-90","post","type-post","status-publish","format-standard","hentry","category-genetika-barev"],"_links":{"self":[{"href":"https:\/\/carnea.cz\/index.php?rest_route=\/wp\/v2\/posts\/90","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/carnea.cz\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/carnea.cz\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/carnea.cz\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/carnea.cz\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=90"}],"version-history":[{"count":1,"href":"https:\/\/carnea.cz\/index.php?rest_route=\/wp\/v2\/posts\/90\/revisions"}],"predecessor-version":[{"id":91,"href":"https:\/\/carnea.cz\/index.php?rest_route=\/wp\/v2\/posts\/90\/revisions\/91"}],"wp:attachment":[{"href":"https:\/\/carnea.cz\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=90"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/carnea.cz\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=90"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/carnea.cz\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=90"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}