BAB III Gntk Kromosom 2016 2 Send

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Genetika

Transcript of BAB III Gntk Kromosom 2016 2 Send

  • BAB III. Genetika Kromosom

    novrinila@yahoo.com

  • Struktur dan Bentuk KromosomKromosom: gen Protein ---- histon

    Gen: urutan tertentu dari asam deoksiribonukleat (DNA) yang menentukan pembentukan protein, diantaranya enzim dan dapat diwariskan ---- fungsi protein??? (minimal 5)

    Genom: Himpunan gen yang lengkap yang dimiliki oleh suatu organisma dalam mengendalikan seluruh proses metabolisma dalam suatu organisme sehingga dapat hidup sempurna

    Jumlah gen dalam genom berbeda untuk setiap organisma yang berlainan.

  • Pregnancy Loss and Chromosome Testing for MiscarriagesTypes of chromosome aberrations in human lymphocytes.

  • Sex DeterminationAsexual organism are those for which no evidence of sexual reproduction is known. Organism which has alternate between short periods of sexual production and prolonged period of sexual reproduction. In diploid eukaryote organism, sexual reproduction is the only natural mechanism resulting in new members of species.Multicellular origanisms has primary sexual differentiation: only gonads to produce gametes secondary sexual differentiation : involves other organs, such as mammary glands and external genitalia.

  • euchromatic regions that contain functional genes and heterochomatic region that lack genes Pseudoautosomal Region(PAR) is; - homology with region on the X chromosome , - synapse and recombine with it (X) during meiosis, - critical to the segregation of the X and Y chromosomes during male gametogenesis. Non Recombining Region of the Y (NRY) called as male-specific region of the Y (MSY).Sex-Determined Region Y (SRY) is critical genes that control male sexual development

  • In plants and animal unisexual, dioecious, and gonochoric are equivalent ----; individual containing only male or female reproductive organs. bisexual, monoecious, and hermaphroditic refer ----- individual containing both male and female reproductive organs. This later group of organisms can produce fertile gametes for both sexes. intersex ----- individuals of intermediate sexual differentiation, who are most often steril.

  • Linkage is the condition where two or more nonallelic genes tend to be inherited together. Linked genes have their loci along the same chromosome; they do not assort independently but can be separated by crossing over.

  • Linkage and Crossing Over

  • Sex-linked Genes (X-linked genes)Sex Chromosom in Human and Drosophila: X and Y- Sex chromosome X : in femaleSex chromosome Y : in male * region of pairing homology with the X chromosome (synapse and segregate during meiosis, PAR) * male-specific region of the Y (MSY) considered to be relatively inert genetically.

  • X-Linked in Humangenes present on the X chromosome exhibit unique patterns of inheritance in comparison with autosomal genes. A. Hemofilia: - Suffers from bleeding because of slow clotting blood. The recessive gene (h), links to the sex chromosome-X - All male offspring from a mother with hemophilia will suffer from hemophilia because they inherit one sex chromosome-X from their mother. - female offspring are not necessarily to be hemophilia because the allele may be heterozygous Hh, except if the father is also hemophilia.

  • B. Collor BlindnessThe allele for color blindness c (recessive) is linked to the sex chromosome-X Most of the sufferer of color blindness is male.

  • ConditionCharacteristicsColor blindness type:a. deutan typeInsensitivity to green lightb. protan typeInsensitivity to red lightFabry diseaseDeficiency of galactosidase A: Heart and kidney defects, early death.G-6-PD deficiencyDeficiency of glucose-6-phosphate dehydrogenase, severe anemic reaction following intake of primaquines in drugs and certain foods, including fava beans.Hemophilia AClassical form of clothing deficiency, absence of clothing factor VIIIHemophilia BChristmas disease, absence of clothing factor IXHunter SyndromeMucopolarysaccharide storage disease resulting from iduronate sulfatase enzyme deficiency, short stature, clawlike fingers, coarse facial features, slow mental deterioration, and deafness.IchtyosisDeficiency of steroid sulfatase enzyme, scaly dry skin, particularly on extremities. Lesch-Nyhan SyndromDeficiency of hypoxanthine-guanine phosphorybosyl transferase enxyme (HGPRT) leading to motor and mental retardation, self mutilation, and early death.Duchene Muscular DysstrophyProgressive, life-shortening disorder characterized by muscle degeneration and weakness, sometimes associated with mental retardation, absence of protein dystrophin.

  • X-linked in Drosophila Thomas H MorganWhite eyes (mutant, recessive) vs. red eye (wild-type, dominant) mutant wild-type

  • Crossing Over Linked genes have their loci along the same chromosome; they do not assort independently but can be separated by crossing over. Crossing over is the exchange of chromosomal material (parts of chromosomal arms) between homolog chromosomes by breakage and reunion. The exchange of material between nonsister chromatids during meiosis is the basis of genetic recombination.

  • During the first meiotic prophase, when homolog are paired or synapsed, a reciprocal exchange of chromosome segments can take place. This crossing over result in the reshuffling, or recombination, of the alleles between homolog and always occurs during the tetrad stage.

  • A simplified overview of the contrast among the meiotic consequences of

  • Linkage RatioDrosophilabw+ = red eyes, wild type, dominantbw = brown eyes, mutant, recessivehv+ = thin vein, wild type, dominanthv = heavy vein, mutant, recessive

  • Crossover Linkagey = yellow body, mutant, recessivey+ = grey body, wild type, dominantw = white eyes, mutant, recessivew+ = red eyes, wild type, d ominantm = miniature wing, mutant, recessivem+ = normal wing, mutant, dominant

  • Phenotype progeny F21) yellow - white 0,5 %2) white - miniature 34,5 % 3) yellow - miniature 35,4 %0,534,535,4ywm

  • Single Crossover

    Crossover can occur between two sister or non-sister chromatids and between two-genes that arelinked or not linked to each other. between two sister chromatids or between not linked genes ---- No recombinant gamete produced between two non-sister chromatids and linked genes ---- Recombinant gamete produced. The ratio of the recombinant chromosome and parental chromosomes produced = 1 : 1.

  • 50% of the potential gametes formed are recombinant

  • Multiple CrossoverIn one tetrad are more than 2 crossovers (CO). Frequency CO among linked genes is highly affected by the distance among genes. For example: recombinant gametes of single crossover (SCO) between gene A and gene B = 20% between gene B and gene C = 30% Therefore, double crossover (DCO) between gene A and gene C is (0,20) x (0,30) = 6% (0,06). So the probability DCO < SCO

  • Pemetaan kromosom

    2 hipotesis yang diajukan morgan tentang pindah silang.1. Gen-gen dalam suatu organisme tersusun secara linier sepanjang kromosom.2. Frekuensi turunan yang menunjukkan fenotip rekombinan/pindah silang dapat digunakan untuk menentukan letak relatif gen-gen terpaut di dalam satu kromosom.

  • Contoh: alel sifat menurun (inheritance) bentuk dan warna sayap yang diamati pada persilangan Drosophila adalah sebagai berikut: B = sayap kelabuV = sayap panjangb = sayap hitamv = sayap kisut

    Persilangan drosophila dengan sifat sifat :BetinaJantanSayap kelabu panjangxSayap hitam kisut (BBVV)(bbvv)

    F1 : Semua betina bersayap hitam dan kisut (bbvv) Semua jantan bersayap kelabu panjang (B-V-)

  • F2 : hasil persilangan antara turunan F1 komposisi turunan(filial) F2

    Fenotip warna dan Bentuk SayapGenotipJumlah(ekor)Tipekelabu dan panjang B-V-822parentalkelabu dan kisutB-vv130rekombinanhitam dan panjangbbV-161rekombinanhitam dan kisutbbvv652parentalJumlah1765

  • Sturtevant dan pemetaan kromosomTemuan dan hipotesis morgan digunakan Sturtevant untuk membuat 2 hipotesis dalam menentukan jarak antar gen. 1. jarak antara gen-gen yang terpaut dalam satu kromosom.2. Distribusi linier gen sepanjang kromosom dapat digunakan sebagai dasar untuk menentukan peta kromosom

    Kesimpulan: * Frekuensi pindah silang gen kecil ---- jarak antar gen-gen terpaut dekat * Frekuensi pindah silang gen besar ---- jarak antar gen-gen terpaut jauh

  • Frekuensi pindah silang (PS) = nilai pindah silang (NPS) NPS = turunan tipe rekombinan turunan

    Jadi berdasarkan data hasil persilangan di atas maka : NPS = 130 + 161/ 1765 = 16.15% Jarak antara alel untuk bentuk dan warna sayap dalam kromosom adalah16.5 unit

  • Tiga titik dalam pemetaan kromosom Drosophila 1. Pindah silang antar gen-gen yang berdampingan baru bisa berlangsung bila jarak antara gen tersebut > 5 unit peta 2. Bila jarak antara 2 gen yang berdekatan sangat besar, misal 17 unit, maka diantara dua gen tersebut dapat terjadi multipel pindah silang.

    Multiple pindah silang selalu memberikan hasil yang berbeda padaturunannya karena selalu terbentuk turunan tipe rekombinan bila terjadidiantara lebih dari 2 gen yang berdampingan (lebih dari 2 titik). Jadi minimal harus terjadi pada 3 titik peta (3