BiotechHiranyagarbha · Class 11-12
Double helix se germplasm tak: DNA ki banavat, allele aur kismon ka bachaav
Priya ki dadi har saal apni potli se dhaan ke beej nikaal kar Odisha ke apne khet mein boti hain. School trip mein Priya ne gene bank ka thanda kamra dekha, jahan beej 'surakshit' rakhe the — jabki dadi ke khet ka wahi beej har saal thoda badal raha hai. Usne socha: sanrakshan ka sahi tareeka kaunsa — thanda kamra ya kisaan ka khet?
Socho pehle… phir dekho jawab
Priya ne dono tasveerein milayi aur jawab mila: dono, kyunki dono alag cheez bachaate hain. Bank us pal ka genotype jama rakhta hai (ex-situ); khet mein kism mausam aur rog ke saath vikasit hoti rehti hai aur naye allele bhi ubharte hain (in-situ). Jad ek hi hai: DNA ka kram aur uski vividhata.
Gene bank ki scientist Dr. Mohanty ne neev se shuru kiya. Banavat: DNA ek dohri seedhi (double helix, Watson-Crick model) hai — do polynucleotide ladiyaan, sugar-phosphate ki reedh, aur beech mein base jodi: A=T (do hydrogen bond), G≡C (teen). Ladiyaan antiparallel (5'→3' aur 3'→5'). Priya ne poocha, 'Toh nakal kaise banti hai?' Replication semi-conservative: har nayi DNA mein ek purani aur ek nayi ladi — isliye nakal mein galti kam, aur har cell ko poori kitaab.
'Aur kram se dhaan ka gun kaise banta hai?' Dr. Mohanty ne central dogma samjhaya: gene ka kram mRNA mein likha jaata hai (transcription), ribosome usse protein banata hai (translation). Ek nucleotide ka badlav (mutation) protein badal sakta hai: kabhi haani, kabhi naya hunar. Ek gene ke alag roop = allele; aabaadi mein jitne zyada allele, utni genetic diversity, utna hi badalte mausam ya naye rog ka jawab dene ka mauka. Priya ko dadi ki potli yaad aayi — usmein kitne allele chhupe honge!
Phir Dr. Mohanty ne Priya ke apne Odisha ki kahani sunayi. Kism ka matlab: ek landrace peedhiyon ke kisaan-chunaav se bani allele ki ek khaas pool hai. Udaharan (IRRI): Odisha ki kam upaj wali FR13A mein SUB1A gene ka woh allele tha jo doobne par paudhe ki badhat rok kar urja bachata hai — 14 din tak paani mein jeevit. Marker-assisted backcrossing se yeh allele zyada upaj wali Swarna mein laaya gaya (Swarna-Sub1) — bina transgenic banaye. Priya ne kadi likhi: ek landrace bachi, phir uska allele pehchana gaya, phir marker se sahi santaan chuni gayi, isliye baadh-prabhavit kheton ko kism mili. 'Purani dhaan ne nayi dhaan ko tairna sikhaya!' woh boli.
Ab Priya ka asli sawaal. Dr. Mohanty ne germplasm sanrakshan ke do raaste aur unka trade-off gine. Ex-situ: gene bank mein beej kam nami par −18°C ke aas-paas dashakon tak; cryopreservation (−196°C, liquid nitrogen) un fasalon ke liye jinke beej sookhte nahi; tissue culture. Faayda — surakshit, soochibaddh, sabke liye uplabdh; seema — vikas ruk jaata hai, aur bank mein rakha beej kisi ek pal ka namuna hai. In-situ: kisaan ke khet aur samudayik beej-bank; faayda — kism mausam ke saath dhalti rehti hai aur gyaan (kab bona, kaise pakana) saath bachta hai; seema — ek buri fasal ya bazaar ka dabaav kism ko mita sakta hai. Isliye neeti dono ko jodti hai.
Ghar lautkar Priya ne project ki shuruaat Bharat ki jad se ki: Chandogya Upanishad 6.12 — Uddalaka Shvetaketu se bargad ka beej tudwaate hain: 'kya dikhta hai?' 'Kuch nahi.' 'Jo sookshm tumhe nahi dikhta, usi se yeh vishaal bargad hai.' Ek vyakhya mein yeh sookshm-se-vishaal ki baat DNA ki samajh ka sabse purana roop hai. Priya ne apne project mein isi vaakya se shuru karke FR13A tak ki kadi likhi.
Tum Priya hoti toh dadi ki potli ke beej gene bank mein bachaati ya khet mein — aur kyun?
Humne kya kiya :- Double helix aur central dogma se allele aur genetic diversity tak pahunch kar in-situ/ex-situ ke trade-off ko FR13A → Swarna-Sub1 se parkha.
Isse kya hua :- Samjhe ki kism = allele ki ek khaas pool; bank us pal ko bachata hai, khet uske bhavishya ko; aur ek 'bekaar' kism ka ek allele laakhon kheton ka jawab ho sakta hai.
Ghar pe try karo
Ek 24-nucleotide DNA ladi likho; uski antiparallel jodi ladi banao (A=T, G≡C); phir use mRNA mein likho (T ki jagah U) aur codon table se protein ke pehle 4 amino acid nikaalo. Ab ek nucleotide badal kar dekho: amino acid badla ya nahi (silent vs missense)? Ek para: 'Ek allele ka farak kisaan ke liye kya ho sakta hai?'
Wow!
Swarna-Sub1 ko transgenic banaye bina banaya gaya — ek desi kism ka allele DNA marker ki madad se chun-chun kar nayi kism mein laaya gaya; purani dhaan ne nayi dhaan ko tairna sikhaya!
3 sawaal
- DNA replication 'semi-conservative' kyun kehlaati hai?
Jawab dekho
Har nayi DNA mein ek purani, ek nayi ladi hoti hai. Dohri seedhi khulti hai aur har purani ladi par nayi jodi ladi banti hai.
- Allele kya hai?
Jawab dekho
Ek hi gene ke alag roop. Ek gene ke alag kram = allele; aabaadi mein allele ki sankhya genetic diversity hai.
- Cryopreservation kis taapmaan par hoti hai?
Jawab dekho
−196°C (liquid nitrogen). Liquid nitrogen mein −196°C par cells aur bhroon dashakon tak surakshit rehte hain; aam beej bank −18°C ke aas-paas.
NCERT se jodo: NCERT Class 12 Biology — molecular basis of inheritance: DNA ki banavat, replication, central dogma; biodiversity and conservation: in-situ aur ex-situ (idea in words)