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Cẩm nang tự ôn luyện thi đại học môn Sinh học cực hay - Phùng Duy ĐổngA : T : G : X = a : a : b : b hoac ,,,.,.,-,,.,,„,„,,„,,,.., a 1. Tir cac v i dii cu the hay khai quat va cho biel: V i d u : A : G - 3 : 1 ^ A : T : G : X = 3 : 3 : I : 1. Co 4 loai nucleotit, neu to hdp bo 1, bo 2, bo 3,..., bo n thl se tao ra bao nhicu to help. 2. Neu chi c6 3 loai nucleotit A , X , G to hdp bo ma, se ma hoa di/dc bao nhieu axit amin. D i e u nay trong thifc te CO .xiiy ra khong? 3. Se CO bao nhieu id hdp cac bi) ba c6 chii'a it nha't 1 ribonucleotit loai A (DS: 37). 4. So to hdp cac bo ba chiVa 2A va 1U (DS: 8). 5. Co bao nhieu cac to hdp bo ba khong chiJa X (DS: 27). Gdi y trii Icfi: Lap biing to hc.Jp de tim hoac suy ra iCl' cong thu'c to hdp. a b b 2a + 2b N N Do do: A = T = — X 3; G = X =— x 1 ( N la long so nucleotit) 8 8 - So lien ket hidro - 2 A + 3G = 2T + 3G - 2A + 3X = 2T + 3 X . - So lien ket hoa tri trong 1 mach dcJn = N - 1 va trong phan tii" A D N = 2N - 2 (giiira axil va diTcJng). - So lien ke't hoa trj giffa cac nucleotit trong A D N = N - 2. - 'iv^j j.,^,,., . . So nucleotit trong mot vong xoan = 20 nucleotit. b) Can cii" vao mdi lien he giffa khdi lifclng phan tvf ( M ) , sd' Ming nucleotit (N), so lu'dng ribonucledtit (Nn,). so lu'dng axit amin (aa) va chieu dai (D) ciia cac phan tOr c6 the dien la mdi lien he do qua sd do sau: - ' • • 29 Cam luygn thi Sinh lioc - I'liung Duy D6ng nang ttj 6n Cty TIMHH MTV M(j,en) > < Chia 300 Nhan 300 Chia 300 N(gcn) < . • , Chia 110 Nhan 120 l-'(Chuoi poiipcptil) • Hoac Suy \ Nhan 300 N{mARN) M ( C h u o i polipcpltl) - so'nucleotit c u a mot m a c h r a : A + X = 1500 Giai la 1500. C ( p h U d n g t r i n h thi? h a i ) h e phu'dng trinh i A + X = 1500l A = 600=T > A=600 X=900 = G J DVVH Khang Vi?t yidu 2: Tim so' nucle6tit cua gen bie't so' lien kct hidro ciia g e n do la 3900. Va s6' lien ke't hoa trj giiJa cac nucleotit trong mot mach ddn lii 1499. Chia 2 nhan 3,4 Nhan 3,4 Chia 3, 4 nhan 2 Chia 3,4 Nhan 3 HUihig ddn Chia 3 A Doc de ta tha'y ngay 2 dieu kien, can ci'r vao mot dieu kien ta lap mot phi/dng trinh. Giai he phu'dng trinh bac nha't 2 an so ta c6 ngay dap an. ¥ T ^(gcn) MmARN) L(Chiioi IDlipcplil) Theo s d do tren khi dau bai cho bie't ba't ki mot yeu to niio Irong bang ta c6 the suy ra ta't ca cac yeu to khac trong bang. c) Can cu" vao mo'i quan he giiJa gen va mARN A, T, G, X, T . A2 X2 G2 Bie't so hen kct hidro bang 3900 ^ 2A + 3G = 3900 (1) Bie't so hen ke't hoa tri bang 1499 -> A + G = 1500 (2) Giai he phuTdng trinh niiy ta du'dc: , . , ,, / ' X =: G = 900 va A = T = 600 , Loai 5: Tim so' % moi loai ddn phan Cach giai nhu'ng bai toan thuoc loai nay cung tiTdng ti; nhiT each giai toan loai gen 4 da de cap tren. ' ' >• Can luu y: mARN •A(m) U ( m ) + De bai khong can cho biet 2 dieu kien nhiT d dang toan loai 4 ma chi can X(m) ^(m)(m) cho bie't mot dieu kien la du, vi mot dieu kien tat yeu da bie't la tong so % cac loai Til" mo'i quan he tren suy ra: A = T = A(n,) + U ( | „ ) . G nucleotit bang 100% ^ A % + X % = A % +G % = T % + G = X = G(n,) + A | = T 2 = A(m). T i = A 2 = U ( m ) . G| = X 2 Loai 4: Tim so l i f d n g moi loai ddn phan G(m). X| = G 2 = X(m). - Co 4 loai nucleotil nhu'ng vi A = T, G = X nen ta chi can tim so" lu'dng cua 2 loai nucleotit khong bo sung vdi nhau se bie't du'dc so lu'dng cua 4 loai. - Nhu" vay nhflng bai toiin ihuoc loai nay c6 2 an so, buoc de phiii c6 2 dieu kien. - Can cH vao moi dieu kien trong de bai ta lap mot phu'dng trinh bac nha't mot an so'. Giai he phu'dng trinh bac nhii't 2 an so ta se tim ngay ra dap an. Vidu 1: Bie't chicu dai cua gen la 0,51|jm gen co .so'nucleotit loai A - 600. Tim so'nucleotit moi loai cua gen do. HU('mg ddn - Theo de bai ta CO ngay phuTdng trinh 1 la: A = 600 - Bie't A = 600 T = 600. Nhu- vay an so thiJ hai phai tim la so loai nucleotil khong bo sung vdi A. Do la G hoac X. - Dieu kien thi? hai trong de bai khong noi ro so' nucleotit nhu'ng can cu" vao mo'i lien he giffa chicu dai gen (L gen) vdi so nucleotit ciia gen (N gen) trong bang he thong d muc 2 ta bie't ngay so'nucleotit cua gen la: 0,51x10^ A 3,4 30 = 1500x2. = T % + X % = 50% X(m). (c6 nghia la to'ng % cua 2 loai nucleotit khong bd sung nhau bang 50%) - Vi du: Bai loan cho bie't A = 20%. ta c6 ngay he A + X=50%1 A=20% phu'dng t r i n h : A = T = 20% J^X=G=30% Dieu kien cho bie't c6 the la mot trong 9 yeu to Irong bang he tho'ng (2) da trinh bay d tren. Tijr dieu kien do co suy dieu kien la can. + Hoc sinh thiTdng nham Ian khi tim so' lifdng moi loai nucleotit vdi so % m6i loai khi cho bie't so lieu trong moi mach ddn. Vidu: • A =3001 ' = > A = A , + A , - 3 0 0 + 200=500 A2=200j ' ^ A|=iO%l _ A | % + A 2 % 10+30 Nhu'ng ^=>A%=—! ^ =—-—=20% ^A2=30%j 2 2 ' i >' ChiJ khong phai A % = 10% + 30% = 40% (vi so vdi so Idn gap doi thi so %' giam21an). Loai 6: Toan ve c d che nhan doi cua A D N \ Muo'n giai loai loan nay can nam vilng: 1. Mot vongxoan dai 34A" CO 10 cap nucleotil. , 31 Cty TNHH MTV DVVH Khang Vigt Ca'm nang ti; 6n va luygn thi Sinh hgc - Phung Duy DO'ng d) Co bao nhieu lu'dl lARN du'dc dieu den de giai ma cho mARN? 2. Phan tu" ADN c6 2 mach ngiMc chieu nhau, mach ma goc c6 chicii 3' —> 5' e) Co bao nhieu axil amin duTdc lien ket vao cac phan luT protein de thifc hien va mach bd sung c6 chieu 5' 3'. Mach 5' ^ 3' la mach c6 lien ke'l hoa lri bill chiltnang? _ a'>;i;'f''v dau liY C so 5 (5') ciia nucleolil ihi? nha'l va kel ihi'ic cJ' C so 3 (3') ciia nucleolil Hiidng dan cuo'i Cling. - Tir chieu dai cua gen la 0,51 jam c6 the tinh diTdc so nucleotit cua gen la: 3. Ci? moi nucleolil c6 mol lien kel hoa lri giiJa diftJng c) vi tri C so'5 vdi axit pholphoric ciia nucleolil do (5' - P). ^ : ^ x 2 = 3000 ' • 3,4 4. Ciic nucleolil ke liep nhau trong moi mach ddn lien ket vcli nhau bhng lien A = 28% 1 A=T=28% kel hoa tri (con goi la lien ke'l phosphodiesle) gii^a C so 3 (3' - OH) cua - Giai he phiTdng trinh: ^=> _ nucleolil nay vd\l ciia nucleolil ben canh. ^ A + X=50%J G = X = 22% •, , . 5. Ciic nucleolil giiJa 2 mach dOn lien kel vcfi nhau bang lien kel hidro iheo Tiir do suy ra so'nucleotit moi loai: \< i . • nguyen utc bo sung. Do do: 98 22 - So lien kel hoa tri giffa cac nucleotit trong ADN biing N - 2 (N: long so A = T = 3000x—=840; G = X = 3000x -660 nucleolil trong ADN). 100 100 - 'Sau 5 ddt nhan doi lien tiep so lifdng nucleotit moi loai can cung ca'p la: - So lien ket hoa lri giiJa axil pholphoric va difc^ng deoxiribozd Irong ca A = T = (2' - 1) X 840 = 26040 nucleolil r ,r phan liVla 2N - 2. G = X = (2^ 1) X 660 = 20460 nucleolil - So lien ket hidro trong ADN la: 2A + 3G = 2A + 3X = 2T + 3G = 2T + 3X - So lien ket hidro bj pha v3: (2' - 1)[( 840 x 2) + (660 x 3)] = 113460 - Sau moi Ian tai sinh so lien ket hidro bi pha hi'iy bang 1/2 so hen ket hidro - So' lien ket hoa tri diTdc hinh thanh (phan tu" A D N dau lien khong phai du'dc tai lap, so lien kel hoa tri du"* lhanh lap bang so lien ket hoa lri cua ADN me. - Sau n Ian Uii sinh lien tiep ciia mot phan tiJ ADN se lao thanh 2" phan tufhinh thanh): (2' - 1)(3000 - 2) = 92938 ADN nhiTng nguyen lieu chi can cung cap cho 2" - 1 phan ti;'!" ADN difc/c lao - So lu-dng mARN du'dc long hdp tir cac gen con: 2^x3 = 96 mARN ^^^^^^^ - Tong so'ribonucleolil moi tru'dng cung ca'p: 96x1500 = 144000 lhanh (suy tii" nguyen tile bitn bao ton). 9 - So' lu'dt lARN can du'dc dieu de to'ng hdp mot chuoi polipeplit la: Logi 7: Toiin ve dich mil. • i ^ - 1 = 4 9 9 liTdt (VI ma ket thuc khong can tARN) '* 1. So niiich polipeplit diMc tiio ihiinh phu Ihuoc so'Ian sao mil (so mARN) va so riboxom irirdt Iren mot philn tu" mARN. Bai 2: Mot gen c6 chieu dai 0,408|jm. Hieu so nucleotit loai A vdi loai nucleotit 2. Xiic dinh thcfi gian long hrip chuoi polipeplit: khac la 240. Khi gen nhan doi, thdi gian tiep nhan va gan cac nucleotit loai A mat 15 giay. Th(ti gian long hilp 1 chuoi polipeplit bang Mli gian litp riip moi axil amin a) Tinh thdi gian can thiet de gen tif nhan doi mot Ian, biet rang thdi gian nhan vdi so axil amin du^dc lap rap. Hoac bang do dai phan tu" mARN chia cho tiep nhan va lap rap moi nucleotit deu nhu' nhau. van toe cua riboxom. b) Ne'u thdi gian hoan thanh long hdp 1 mARN tren gen mat 30 giay, tinh 3. Xac dinh van toe riboxom: Viin toe cua riboxom bang do dai phan HJ" van to'c sao ma (theo ribonucleotil/giay) mARN chia cho thcii gian riboxom Iru'Ot Iron mARN. c) Ne'u tren moi mARN c6 6 riboxom trUdt qua thdi gian giai ma 1 axit amin 4. Xiic dinh chieu diii cua mARN, ciia gen bang lich Viin toe ciia riboxom vdi tna:' t 0,2 giay. Khoang each thdi gian giffa 2 riboxom ke tiep nhau 1,4 giay. Cac thdi gian tr^dt ciia no Iren mARN,... riboxom chuyen dpng deu va each deu nhau. ^ .iv B A I T A P VAN D V N G - Tim van to'c cua riboxom? Bai 1: Mot gen eo chieu dai (),51|jm. Co A = 28% so' nucleotit cua gen. Gen • nhan doi 5 liin lien tiep Ifio ra cac gen con. Moi gen sao mii 3 liin, moi m;~i sao cho 5 riboxom Iru'dl qua khong Ird h i . a) Tinh so lu'dng moi loiii nucleolil moi tru'dng cung ca'p cho gen nhan doi? b) Trong qua Irinh nhan doi do gen can phii vd bao nhieu lien kel hidro, hinh thanh them bao nhieu lien ke'l hoa trj givta ciic nucleolil? c) Tong so'ribonucleolil moi lru"cfng ciin cung cap cho cttc gen con sao ma? 32 - Thdi gian cua qua trinh long hdp protein? ^, ^ HUcfng dan • Tir chieu dai cua gen bang 0,408 \im -> so" nucleotit cua gen la 2400 => A + G = 1200. A--G = 240 1 A = T = 7 2 0 Giai he phifdng trinh: A + G = 1200j G=X=480 ^3 Cty TNHH MTV DVVH Khang Vigt Ca'm nang ti; 6n va luygn thi Sinh hpc - Phiing Duy Pgng Thdi gian ticp nhan va gan cac nucleotit loai G (hay X) vao mach mdi bang: , 480x15 Thdi gian can thie't de gen tiT nhan doi 1 Ian: 10 giay + 15 giay = 25 giay , ^ _ 1200rib6nucle6tit ... Van toe sao ma: = 40 ribonucleotit/giay 30giay Thdi gian Ccin thiet de tdng help 1 chuoi polipeptit: 1200 — ^ X 0,2 giay = 8 giay - Van toe trifdt cua riboxom: (1200 x 3,4 A") : 80 giay = 51 A"/giay. - Thdi gian tiep xuc cham cua riboxom tren mARN: 1,4 giay x 5 = 7 giay - Thdi gian ca qua trinh tdng hdp protein: 80 giay + 7 giay = 87 giay Bai 3: Ba doan gen deu c6 600 nucleotit: , . AG + TX 1 2 Doan gen 1 CO 3:ti le A + T=—. G+X 3 G+X 2 Cho biet trong 3Adoan + T=gen , . do thi moi doan c6 bao nhieu Hen ke't hidro. Doan gen 2: 1 Dap so': Doan gen 1: 800 lien ke't hidro. ' Doan ge.n 2: 750 lien ket hidro. Doan gen 3: 780 hen ket hidro. A+T Bai 4: Neu 2 gen c6 cung so lien ket hidro la 1300, gen c6 ti le = 1, con G+X gen 2 CO ti le A—+ Tc 2h o bie't gen nao c6 so liTdng nucleotit nhieu hdn va ^ Z CO 11 ~• G + X ^ 3 ; nhieu hdn bao nhieu? Dap so': - Sdlufdng nucleotit cua gen 1: 1040 - So liTdng nucleotit cua gen 2: 1000 - So liTdng nucleotit gen 1 nhieu hdn gen 2 la 40. Bai 5: Mot gen c6 chicu dai 0,255|jm, c6 hieu sdgiiJa T vdi loai nucleotit khong bd sung bang 30% so nucleotit cua gen: mARN diTdc tdng hdp tijf gen do c6 U = 60% so ribonucleotit tren mot mach ddn cua gen c6 G = 14% so nucleotit cua mach va A b^ng 450 nucleotit. 1. So'lUdng nucleotit cua gen va cua tijrng mach ddn cua gen. 2. SdlUdng va ti le % tijfng loai ribonucleotit. ^ •* 3. So' lu'dng axit amin can cung cap cho qua trinh tdng hdp protein. Ne'u gen sao ma 4 Ian, trung binh moi mARN c6 8 riboxom trufdt khong lap lai. 4. Tinh khoang each deu giiJa cac riboxom (theo A"). Ne'u bie't thdi gian de tdng hdp xong mot phan tiir protein la 125 giay, thdi gian tiep xuc ciia mARN vdi 8 riboxom het 153 giay, cac riboxom each deu nhau khi trU'dt tren mARN. Dap so: . .....i . ,„.:v,...„^:''^';-v.i..„ t-.. - Sdnucleotit cua gen: 1500 . . - So liTdng nucleotit tiifng loai: A = T = 600. G = X = 150 - So liTdng ribonucleotit tren mARN: G(m) = 45. X(m) = 150. U(m) = 450. A(m) = 150 - So'axit amin cung cap: 7968 - Khoang each giffa cac riboxom: 81,6 A" Bai 6: Khi cho tdng hdp mot phan tijT mARN gen pha di?t 3600 lien ket hidro. Moi tru'dng te'bao cung cap 155G va 445X. Gen do sao ma khong vu'dt qua 4 Ian da can tdi 1500 ribonucleotit loai U. Sau do do nhu cau can tdng hdp them, protein gen lai tiep luc sao ma (tdng hdp mARN) va tao nen cac mARN mdi lai cantdi2625U. 1. Chieu dai cua gen v^ so lu'dng nucleotit cua gen. 2. So' lu'dng tiJCng loai ribonucleotit tren moi phan tuC mARN. 3. Vdi gia thie't neu tren ma so ma sao tao ra td'i da, moi ma sao (mARN) cho 5 riboxom tnfdt mot Ian thi moi tnldng npi bao phai cung cap cho bao nhieu axit amin. Co bao nhieu lU'dt tARN mang axit amin tdi giai ma? Dap so': - Chieu dai gen: 5 lOOA". - So liTdng nucleotit moi loai: A = T = 900. G = X = 600. ;' - G„, = 155, Xn, = 445, A„ = 525, = 375. , , ^ .^JM^Q^ - So axit amin cung ca'p: 27445. ' s"' - So' liTdt tARN tiTdng i^ng vdi so axit amin cung cap: 27445. ' Bai 7: Mot gen c6 hieu so % nucleotit loai G vdi nucleotit khong bd sung vdi no b^ng 20% va G = 1050 nucleotit. Tren mach ddn thii'nha't cua gen c6 A, + Gi = 600. Xi - Ti = 300. Khi tdng hdp mARN moi triTdng da cung cap 1350 ribonucleotit loai X. Moi phan tuf mARN c6 6 riboxom trU'dt qua mot Ian de tdng hdp protein. 1. Tinh khdi liTdng phan til cua gen? 2. Chieu dai gen? 3. So Irfdng va ti le % moi loai ribonucleotit cua mARN. ' 4. Tdng so axit amin diTdc lien ke't tren cac phan tuT protein de thifc hi6n chtfc iiang sinh hoc. Cty TNHH MTV DVVH Khang Vi?t ca'm nang t\) 6n va luy$n thi Sinh hpc - PhCing Duy flB'ng 5. Thdi gian cua qua trinh tong hOp protein va khoang each deu ve do dai giu"a cac riboxom tren mARN? , Bie't rang thdi gian tong hdp protein deu ma't 1 phiit 40 giay. Khoang each ve thdi gian giffa 2 riboxom la 1,4 giay. Bai todn nay c6 2 each ^idi: Cdch nidi tM nhcit: Can ciJ vao dieu kien cua bai loan ta lap he phUdng trinh bac nha't CO 2 an so': T + X=50%' . >A=T-13,7%; G-X=36,3% T = 13,7% Dap so': - Kho'i lu'dng phan tuf cua gen 9.10'dvc • - Chieu dai gen: 0,51 |Lim . A = T = 15% = 450. G = X = 35% = 1050 - A„ = 300. Un, = 150. Gn, = 600. X^, = 450. - So'axit amin: 8964 - Thdi gian cua qua trinh to'ng hdp protein: 107 giay; khoang each giiJa cac Cdch fiidi tM hai: Khong can giai ma loai bo cac dap an khong dung vdi dieu ; kien cua bai toan: •-•-M^ ' ' ' "• Bai toan tim ti le phan tram ti^ng loai nucleotit bao gid cung phai phii hdp vdi dieu kien: A riboxom la 71,4 A". < % + X % = A % + G %) = T % + X %. = T % + G % = ^ = 50%) 2 Ta tha'y ngay cac dap an A , C, D deu khong phii hdp vdi dieu kien nay. Do Bai 8: Mot gen khi tong hdp 1 phan tij" mARN da lam dut 3450 hen ket hidro. do dap an phai la B. Trong gen hieu so' % loai A vdi loai khong bo sung vdi no bang 20% tong so Bai 2: Gen dai 3005,6A", C6 hieu giffa nucleotit loai T vdi loai nucleotit khac la nucleotit cua gen. Tren mARN so'ribonucleotit loai 0 = 300, loai A = 600. 272. So'lu'dng nucleotit moi loai ciia gen tren la: 1. Tinh so'lu'dng nucleotit moi loai cua gen? A) A = T = 289;G = X - 1 5 3 2. Chieu dai gen va kho'i lu'dng phan tu" cua gen? C) A = T=:578;G = X = 306 3. So lu'dng ribonucleotit moi loai tren mARN? B) A = T = 153; G = X =: 289 - D) A = T = 306; G = X = 578 HUdng ddn 4. Neu gen noi tren nhan doi lien ticp 5 ddt thi moi tru'dng noi bao da cung V i A = T va G = X nen chi can tim 2 loai nucleotit khong bo' sung nhau, nghla cap them moi loai nucleotit la bao nhieu? Trong qua trinh do c6 bao nhieu lien la bai toan chi c6 2 an so'. Do do can giai he phu'dng trinh bac nha't c6 2 an so'. ket hidro bi pha huy? Bao nhieu lien ket hoa tri difdc hinh thanh giiJa cac nucleotit? Phu'dng trinh thiJ nha't c6 the tha'y ngay la T - X = 272 con phu'dng trinh thiJ hai 5. Ne'u moi gen con tao ra sao ma 3 Ian, moi ma sao (mARN) cho 5 riboxom khong CO trong de bai toan. De chi cho biet chieu dai gen la 3005,6 A " vay thi tru'dt qua khong trd lai thi moi tru'dng da cung cap bao nhieu axit amin? Trong so' phu'dng trinh thiJ hai chac chan phai suy ra tCf dieu kien nay. That vay, chieu dai do CO bao nhieu axit amin du'dc lien ket vao cac phan tuf protein. Khi chung thi/c cua gen la 3005,6 A " ma moi nucleotit dai 3,4 A " . Nen so' nucleotit moi mach hien cac chut nang sinh hoc. Ne'u cho biet moi phan ttJf protein la mot chuoi polipeptit. Dap so': - A = T = 1050; G = X = 450 - 5100 A". 9x10'dvC. - Gm = 300; X „ = 150; An, = 600; U „ = 450. - A = T = 32550. G = X = 13950; 106950 hen ket hidro, 92938 hen ket hoa tri. - So axit amin cung cap: 239520, so' lu'dng axit amin lien ke't thiTc hien chiJc ddn la: ^ ^^^' ^ = 884 nucleotit. So' nucleotit trong mach bang tong so' nucleotit cua gen. Do do: T + X = 884 nang: 239040. T - X = 272l Giai he phi/dne trinh: •' ^ T + X = 884j A - T = 578 G = X = 306 • ^ - ; Vdi bai toan nay chi can can ciJ vao dieu kien hieu giifa T vdi loai nucleotit khac la 272 (T - X = 272) ta tha'y ngay dap so' la C vi tat ca cac dap so khac deu khong phii hdp vdi dieu kien cua de bai. V. B A I T A P T R A C N G H I E M Bai 3: Mot gen c6 tich giiJa 2 loai nucleotit khong bo sung bang 6%, ti le tifng Bai 1: Gen c6 so' nucleotit loai Timin bang 13,7% to'ng so' nucleotit, ti le phan tram tijfng loai nucleotit ciia gen tren la: A) A = T = 13,7%. G = X = 8,73% B) A = T = 13,7%. G = X = 36,3% C ) A = T = G = X = 13,7% D ) A = T = G = X = 36,3% loai nucleotit cua gen la: A) A = T = 30%. G = X = 20%. B) A = T = 35%.. G = X = 15%. C) A = T = 40%. G = X = 15%. D) A = T = 15%. G = X = 40%. 37 Cam nang tg 6n va luyen Ihi S i n h hoc - Phung Duy Ddng Hudng ddn Vi tdng so % cua 2 loai nucleotit khong bd sung nhau phai bang 50% nen chi CO 2 dap an A va B la phu hOp (loai dtfOc 2 dap an) tie'p tuc xet den dieu kien tich giffa 2 loai khong bd sung bang 6% ta loai them dtfOc dap an B. Vay con lai dap an A la dung. Bai 4: Mot gen c6 ti le giffa cac loai nucleotit la tirong quan ve gia tri G+X 7 giffa cac loai nucleotit tinh theo ti le phan tram la: i A) A = T = 35%;G = X = 15% \ B) (G + T ) % = (A + X ) % = 50% ,^ , v,,^ , C) A G = A X = T G = T X = 5,25% D) Ca A, B va C deu dung. HUclngddn Yi bai toan tim ti le % moi loai nucleotit chi can biet mot dieu kien la du, vi tdng ti le % cua 2 loai nucleotit khong bd sung bao gid cQng bang 50%. NhiT vay ta thay ngay dap an B la dung. Can ci? vao dieu kien de bai phai c6 ^^-5^1=1. Tu" dieu kien nay ta biet them G+X 7 dap an A ciing dung. Tir dap an A ta CO the suy ra ngay dap an C ciing dung. Nhu" vay c6 3 dap an diing. Bai 5: Mot gen c6 tdng so 2 loai nucleotit la 90%. Ti le phan tram tifng loai nucleotit cua gen tren la: A) A = T = 45%; G = X = 5% B) A = T = 5%; G = X = 45% C) A = T = 40%; G = X = 50% D) A va B diing. HUdng ddn Ddi chieu vdi dieu kien cua bai toan la tdng so 2 loai nucleotit la 90% thi dap an D va C la sai, 2 dap an con lai A, B deu diing. Khi xet den dieu kien tat ye'u phai c6 la tdng so % 2 loai nucleotit khong bd sung vcti nhau la 50% (dieu kien nay khong can c6 trong de bai) thi dap an D va C cung sai, con dap an A va B deu dung. Tai sao nhu^ vay? Vi dieu kien de bai cho biet tdng 2 loai nucleotit chicm 90% thi c6 the xay ra 2 tru^dng hc^p A + T = 90% hoac G + X = 90%. Do do bai toan c6 2 dap so: tog v6i tru-dng hdp A + T = 90% thi c6 dap so la A. Lfng vdi tru-dng hop G + X = 90% thi c6 dap an B. Bai 6: Gen c6 T > X va T ' + X' = 0,065. Gia tri nao la diing? A) A = T = 10%; G = X = 40% B) T^ = 5%; X^ = 1,5% D) G^ = 3,5%; T^ = 3% 38 C) A^ = 0,04; G-^ = 0,025 X X X X Cty TNHH MTV DVVH Khang Vi^t HUdng ddn Ta thay ngay de bai khong the giai du^dc bang each giai phu-Ong trinh (vi thieu dieu kien). Nhtf vay chi c6 the giai bang phiTdng phap loai trif. Vi T > X nen ca 3 d^p an B, C, D deu sai. Vay con lai dap an A la dung. De khang dinh A la dung ta thay ke't qua phii hdp vdi nguyen tac bd sung: A + G = T + X = 50%. Bai 7: Gen c6 96 chu ki xoan va ti le giiJa cac loai nucleotit la A = - G. So Wdng ti^ng loai nucleotit cua gen la: A) A = T = 120; G = X = 360. B) A = T = 240; G = X = 720. , C) A = T = 360; G = X = 120. D) A = T = 720; G = X = 240. HUdng ddn De bai co 2 dieu kien, du de lap he phu-dng trinh bac nhat 2 an so. Nhtfug khong can thiet, ta thay ngay dap an C va D khong dung vi khong phii hdp vdi dieu kien A = G. Con dap an A khong diing vi khong hdp vdi dieu kien con lai cua de bai la gen c6 96 chu ki xoan. Vay B la dap an cua bai toan. Bai 8: Gen dai 4080A", so lien ket hidro trong doan tiT (2700 - 3000) va c6 tich giii-a 2 loai nucleotit khong bd sung la 5,25%. Ti le phan tram va so lien ket hidrd cua gen la: A) A = T = 35%; G = X = 15% va 2700. B) A = T = 15%; G = X = 35% va 2760. ' C) A = T = 35%; G = X = 15% va 3240. D) A - T = 35%; G = X = 15% va 2760. HUdng ddn - Vi ca 4 dap an deu dung vdi dieu kien tich giffa 2 loai nucleotit khong bo sung la 5,25% va dung vdi nguyen tac bd sung. NhiT vay chi con mot each giai duy nha't la can ciJ vao dieu kien gen dai 4080A" de suy luan tiep. Nhu^ng tir chieu dai ciia gen de suy ra tdng so 2 loai nucleotit, khong the suy du"dc so lien ket hidrd. Vi vay, khong the suy luan bang phtfdng phap loai trij", ma phai giai bkng phu"dng phap lap he phu'dng trinh nhU sau: Gen dai 4080A" ^ A + X = 1200 (1) Theo de bai lai c6: A x X = 5,25% (2) ^ So lien ket hidro la 2760. Nhu" vay dap an A va D dung (vi deu c6 lien ket hidrd 2760) nhifng giai PhiTdng trinh cho thay A > X. Do do chi D dung. BAITAP VANDVNG Mgt mach ddn cua gen c6 1799 lien ket hoa tri giffa axit vd dUifng vd gen c6 2030 lien kit hidro. Hay suf dung cac di?kien tren tra Idi cac bai trac nghiem so 9, 10. fiai 9: Gen c6 khdi lu-dng: A) 540300 dvC B) 1080600 dvC C) 540000 dvc D) 1080000 dvC : 39 Cty TIMHH MTV DVVH Khang Vi^t ca'm nang ti; 6n va luyjn thi Sinh hgc - Phiing Duy D6ng C) Bai 10: So' li/dng tiifng loai nucleotit cua gen la: A ) A = T = 270. G = X = 630 B) A = T = 670. G = X = 230 C) A = T = 230. G = X = 670 D ) A = T = 1340. G = X = 460 a::^ loai nucleotit khdc Id 10%. ,. A ) 1147,5 A " B) 4590 A " C ) 2295 A " D)9180A". B) A = T = 405. G = X = 270 A, B) A, C) A, A) = 240; T, = 600; G| = 240; X| = 120. = 200; T , = 500; G, = 300; X , = 200. • = 300; T i = 200; G, = 300; X , = 400. ' C) A = T = 540. G = X = 810 D ) A = T - 810. G - X = 540 A) ket hidro cua gen vdi lien ket hoa tri trong niQt mach dcfn cua C) A A " • " ' , , = T = 1050; G = X = 450 B) A = T = 1050; G = X = 500 = T = 1050; G = X = 480 D) A = T - 1050; G = X = 405 Bai 21: Chieu dai cua gen la: A)0,51|jm. hidro cua gen la 2551. B)0,48|jm. C ) 0,498Mm. D ) 0,480|jm. Bai 22: So liTdng ribonucleotit tren m A R N l a : Surdung cac d i ^ k i e n tren, tra 151 cac bai tap 13, 14. Bai 13: So lien ket hidro va lien ke'l hoa tri giffa axit va diTdng trong gen tren la: A ) 4050 va 2998 B) 4050 va 5998 C ) 5998 va 4050 Bai 14: T i le % tiTng loai nucleotit cua gen la: D ) 4050 va 5998 0 2400. B) 1200. D) 1800. B)500. C ) 600. D) 400. Bai 24: M o t gen c6 A^ - G^ = 5% gia t r i nao sau day dung? B) A = T = 2 0 % ; G = X = 15% C) A = T = 15%; G = X = 3 5 % D) A = T = 3 5 % ; G = X = 15% Mot gen CO 120 chu ki xoan. Hieu so % nucleotit loai A v6i nucleotit A) 1500. Bai 23: Gen tren m a hoa du'dc mot chuoi polipeptit gom bao nhieu axit amin? A ) 498. A) A = T = 3 0 % ; G = X = 20% A) khong bo sung v&i no bang 20%. Tren phdn tv[ mARN tdng hcfp tU gen do c6 X,„ = 120 ribonucledtit. A' D)Ca3dapandeudi]ng. Bai 25: M o t gen c6 A > G v a A H G^ = 17%. Gia t r i nao sau day diing? A D ) Ca 2 cau A v a B deu dtlng. Mach thii nhat ciia gen dai 0,2448 |im. d mach dm tint hai c6 ti le cac loai fi A ) A = T = 3 5 % ; G = X = 15% B) A = T = 4 0 % ; G = X = 10% C) A = T = 3 0 % ; G = X = 2 0 % D ) A = T = 25%; G = X = 40% nucleotit A, T, G, X idn iMt la 1: 7: 4: 8. SuT dung cac du" k i e n tren de l a m bai so" 26, 27, 28. Bai 16: So'liTcing m o i loai nucleotit cua gen do la: Bai 26: T i le % tufng loai nucleotit A, T, G, X tren mach dcfn thtf nhat Ian liTdt la: A ) A = T = 8 4 0 ; G = X = 360 B) A = T = 800; G = X = 400 A ) 5%, 2 0 % , 3 5 % , 4 0 % . B) 4 0 % , 3 5 % , 2 0 % , 5%. C) A = T = 6 0 0 ; G = X = 400 D ) A = T = 700; G = X = 500 C) 4 0 % , 2 0 % , 3 5 % , 5%. D ) 3 5 % , 5%, 4 0 % , 2 0 % . Bai 17: T i le m oi loai ribonucleotit tren m A R N la: Bai 27: So liTdng tufng loai nucleotit A, T , G, X tren mach thu" h a i Ian lifdt la: A ) A „ = 2 0 % ; G „ = 2 0 % ; X^, = 10%; U „ = 5 0 % . A ) 36, 252, 288, 140 B) A „ = 10%; G^ = 2 0 % ; Xn, = 3 0 % ; U „ = 4 0 % . 0 C) A „ = 3 0 % ; G „ = 10%; X„, = 2 0 % ; U^, = 4 0 % . , B) A = T = 2 0 % = 288 240; X^, = 120. ' " D ) 3 6 , 2 5 2 , 144,288. , , ' ,. v a G = X = 30% = 432 C) A = T = 1 2 , 5 % = 1 8 0 v a G = X = 37,5% = 540 ' B) A „ = 200; U „ = 500; G „ = 400; X ^ = 100. , , 252,36,288,144 A > A = T = 3 0 % = 4 3 2 v a G = X = 2 0 % = 288 Bai 18: So lifdng m o i loai ribonucleotit tren m A R N la: ,40.,, , B) 288, 144, 252, 36 Bai 28: T i le % v a so liTdng tiTng loai nucleotit trong gen tren la: • D ) A „ = 2 0 % ; Gn, = 3 0 % ; X,„ = 15%; U „ = 35%. = 600; G„, ^ B) T + X = A + G = 5 0 % . = T = 4 0 % . G = X = 10% C) A^ = 10%. G^ = 7%. Bai 15: T i le % m o i loai nucleotit cua gen la: ' '^ ' B) A - G = 10%. = 2 5 % . G^ = 2 0 % . C) A = T = 3 0 % . C = X = 2 0 % . A) Hay su-dung cac d f f k i e n tren tra Idi cac bai so 15, 16, 17, 18, 19. A ) A „ = 240; - Bai 20: So lU'dng m o i loai nucleotit cua gen: gen Id 5549. Trong do lien ket hoa tri trong mgt match dm it hm so lien ket * = 240; U„, = 120; G„, = 600; X„, = 240. Hay surdung d i ^ k i e n tren tra Idi cac bai so 20, 2 1 , 22, 23. A ) A = T = 270. G - X = 405 " Mgt gen c6 khdi lU0ig phdn tiC 9.10^ dvC, trong d6A = 1050 nucleotit. Bai 12: So'lu'cfng tilfng loai nucleotit cua gen tren la: Tdng so'lien ::i D ) A i = 400; T, = 300; G, = 200; X , = 300. Bai 11: Chicu dai cua g e n t r e n la: : = 300; U „ = 200; G^ = 240; X „ = 260. Bai 19: So'liTdng m o i loai nucleotit trong mot mach cua gen la: MQtgen chvta 1755 lien ket hidro va c6 hieu so'giffa nucleotit loai X vdi mot S u r d u n g d f f k i e n t r a I d i c a c b a i 11, 12. D) A^ A^ ,, . D ) A = T = G = X = 2 5 % = 360. 41
9 7602 58
358 7027 142
169 6489 70
183 5766 72
297 5747 120
466 5226 114
71 4971 100
186 3827 65
468 3672 107
273 3357 70
71 3157 90
327 2902 83
36 2790 137
5 2733 117
409 2578 123