Yeej yog dab tsi?
Ib lub noob yog ib ntu ntawm nucleotides ntawm deoxyribonucleic acid, nyob rau hauv cov ntaub ntawv genetic encoded (cov ntaub ntawv hais txog cov qauv tseem ceeb ntawm cov protein molecules). DNA molecule yog ob zaug tso tseg. Txhua ntawm cov chains nqa ib ntu ntawm nucleotides. Cov qauv tseem ceeb ntawm cov protein, uas yog tus naj npawb thiab cov kab ke ntawm cov amino acids, ua lub luag haujlwm txiav txim siab hauv keeb kwm yav dhau los. Txhawm rau kom cov ntaub ntawv encoded nyeem kom raug thiab tsis tu ncua, cov noob yuav tsum muaj qhov pib codon, txiav tawm codon, thiab kev nkag siab codons uas ncaj qha encode qhov tsim nyog amino acid ib ntus. Codons yog peb sib law liag nucleotides uas code rau ib qho amino acid. Codons UAA, UAG, UGA yog khoob thiab tsis code rau ib qho ntawm cov amino acids uas twb muaj lawm; thaum lawv nyeem, cov txheej txheem replication nres. Qhov seem codons (hauv61 daim) code rau amino acids.
cais cov noob tseem ceeb thiab rov ua dua tshiab. Cov noob tseem ceeb yog cov kab ke ntawm nucleotides uas ua kom pom qhov tshwm sim ntawm ib qho tshwj xeeb (tsis hais seb hom gene twg yog nyob rau hauv tib khub (txhais tau tias yog cov noob caj noob ces)). Ib tug recessive noob yog ib theem ntawm nucleotides nyob rau hauv uas qhov tshwm sim ntawm ib tug zoo nyob rau hauv lub phenotype yog ua tau tsuas yog yog hais tias tib recessive noob nyob rau hauv ib tug khub.
Cov ntaub ntawv no tsuas yog cov ntaub ntawv caj ces uas tuaj yeem dhau los ntawm ib tiam dhau ib tiam. Txawm li cas los xij, qhov tshwm sim ntawm ib lossis lwm qhov zoo nyob tsuas yog nyob ntawm qhov sib txawv ntawm kev sib xyaw ntawm cov noob. Yog hais tias muaj ib tug recessive thiab dominant noob nyob rau hauv cov khub, ces cov cuab yeej encoded los ntawm tus tseem ceeb ib tug yuav phenotypically manifest nws tus kheej. Thiab tsuas yog nyob rau hauv cov ntaub ntawv ntawm ib tug ua ke ntawm ob recessive noob, lawv cov ntaub ntawv tshwm. Ntawd yog, cov noob tseem ceeb suppresses tus recessive.
cov noob tuaj qhov twg?
Cov ntaub ntawv uas peb noob neej nqa los ntawm peb cov poj koob yawm txwv. Cov no suav nrog tsis yog niam txiv nkaus xwb, tab sis kuj yog niam tais yawm txiv thiab lwm cov txheeb ze. Ib tus neeg txheej ntawm cov noob yog tsim los ntawm kev sib xyaw ntawm cov spermatozoon thiab qe, los yog, los ntawm kev sib xyaw ntawm X thiab Y chromosomes, los yog ob X chromosomes. Ob leeg X thiab Y chromosomes tuaj yeem nqa cov ntaub ntawv los ntawm leej txiv, thaum tsuas yog X chromosome tuaj yeem nqa cov ntaub ntawv los ntawm leej niam.
Nws paub tias X chromosome muaj cov ntaub ntawv ntau ntxiv, yog li cov poj niam tiv taus ntau dua rau cov kab mobtxawv qhov txawv ntawm cov txiv neej. Nyob rau hauv txoj kev xav, tus naj npawb ntawm cov tub thiab ntxhais yug tshiab yuav tsum sib npaug, tab sis nyob rau hauv kev xyaum cov tub yog yug los. Raws li qhov tshwm sim, raws li ob qhov tseeb no, muaj qhov sib npaug ntawm ob qho kev sib deev. Kev yug me nyuam ntau dua ntawm cov txiv neej cov pej xeem raug cuam tshuam los ntawm kev tiv thaiv ntau dua rau ntau hom kev cuam tshuam ntawm cov poj niam.
Gene engineering
Tam sim no, kev tshawb fawb hnyav ntawm cov khoom siv caj ces tab tom pib. Cov txheej txheem rau kev sib cais, cloning thiab hybridization ntawm tus kheej cov noob tau tsim. Nov yog kauj ruam tseem ceeb tshaj plaws hauv kev tsim lub neej yav tom ntej. Xws li kev mloog zoo rau qhov teeb meem no ua rau ntau qhov kev xav thiab kev cia siab. Tom qab tag nrho, kev tshawb fawb ntxaws tuaj yeem tso cai rau tib neeg los npaj cov khoom thiab cov yam ntxwv ntawm lub neej yav tom ntej, zam ntau yam kab mob thiab loj hlob hauv nruab nrog cev thiab lawv cov kab ke rau kev hloov pauv.
