Mendelian Genetics Gregor Mendel is father of genetics. recognized as the Mendel, who was not scientifically trained, developed his theories in the 1850 s and 1860 s, without any knowledge of cell biology or the science of inheritance. Photo courtesy of Wikipedia. In later years, genes, chromosomes, and DNA were discovered and people began to understand how and why Mendel s theories worked.
Robert Bakewell 1700s English Breeder of: Shire horses Leicester sheep Longhorn cattle Used inbreeding progeny testing Gregor Mendel basic genetic principles used pea plants not well understood during his life Mendel, G. 1866. Experiments on Plant Hybridization. Transactions of the Brünn Natural History Society.
Topic of Discussion :Genetics of Animal 1 Introduction: History and Development of Genetics. 2. Mendelism :Monohibryd and dihibryd Inheritance, 3. Exception of Mendelsm : intermedier, linkage,, sex limited, sex inlfluenced 4. Genetic Material I: Chromosome, DNA and Gen, Abberation 5. Multiple Allel 6. Class Discusion: Proup of 5: Paper and PPT, Presentation. Topic 1-5. 7. Class Discusion: Proup of 5: Paper and PPT, Presentation. Topic 1-5. 8. MIDTEST
9. Probability in Genetics Inheritance 10. Sex Determination, linked and crossing over 11. Introduction to Genetics Population 12. Factors influencen in Population 13. Introduction to Genetics Engineering 14. Class Discusion: Proup of 5: Paper and PPT, Presentation. Topic 1-5. 15. Class Discusion: Proup of 5: Paper and PPT, Presentation. Topic 1-5. 16 FINAL TEST
Mendel s experiments dealt with the relationship between an organism s genotype and its phenotype. Genotype the genetic composition of an organism. Phenotype the observable or measurable characteristics (called traits) of that organism. The relationship between phenotype and genotype is expressed as the following equation: P = G + E P = phenotype, G = genotype, and E = environment.
To understand Mendel s principles and the relationships between phenotype and genotype, it is necessary to understand what makes up the genetic material of animals and how this is transferred from one generation to the next. 1. Nucleolus 5. Rough Endoplasmic Reticulum 9. Mitochondria 2. Nucleus 6. Golgi Aparatus 10. Vacuole 3. Ribosome 7. Cytoskeleton 11. Cytoplasm 4. Vesicle 8. Smooth Endoplasmic Reticulum 12. Lysosome 13. Centrioles
Genetics Vocabulary Homozygous- when both alleles of a pair are the same for a gene Homozygouse Dominant- PP Homozygous Recessive- pp Heterozygous- when the 2 alleles in the pair are different for a gene Heterozygous for flower color: Pp
Fertilization Takes place when a sperm cell from a male reaches the egg cell of a female The two haploid cells (the sperm and the egg) unite and form one complete cell or zygote Zygote is diploid, it has a full set of chromosome pairs This results in many different combinations of traits in offspring
Chromosomes Occur in pairs in the nucleus of all body cells except the sperm and ovum Each parent contributes to one-half of the pair The number of pairs of chromosomes is called the diploid number The diploid number varies species to species but is constant for each species of animal Common Livestock Diploid Number Cattle 30, Swine 19, Sheep 27, Goat 30, Horse 32, Donkey 31, Chicken 39, Rabbit 22
MENDELISME Mendel proposed three principles to describe the transfer of genetic material from one generation to the next. The Principle of Dominance : in a heterozygous organism, one allele may conceal the presence of another allele. The Principle of Segregation: in a heterozygote, two different alleles segregate from each other during the formation The Principle of Independent Assortment : the alleles of different genes segregate, or assort, independently of each other. Later studies have shown that there are some important exceptions to Mendel s Principle of Independent Assortment, but otherwise, these principles are recognized as the basis of inheritance.
Dominant and Recessive Genes In a heterozygous pair the dominant gene hides the effect of its allele The hidden allele is called a recessive gene When working problems involving genetic inheritance the dominant gene is usually written as a capital letter and the recessive gene is written as a lowercase letter (PP,pp,pp) Black is dominant to red in cattle White face is dominant to color face in cattle Black is dominant to brown in horses Color is dominant to albinism Rose comb is dominant to single comb (chicken) Pea comb in chickens is dominant to single comb Barred feather pattern in chickens is dominant to nonbarred feather the dominant gene is also sex-linked Normal size in cattle is dominant to snorter dwarfism
Teories of Inheritance (Conventional) Ovisma: pemilik sifat keturunan adalah ovum ( ), fungsi jantan menghasilkan cairan untuk perkembangan ovum Animalkulisma: pada cairan jantan ditemukan hewan2 kecil (Spz), sbg pembawa sifat keturunan Preformasi: Loewenhook: (mikroskop) ada MH kecil dalam spermatozoa atau ada manusia kecil dlm ovum Epigenesis: Ovum terfertilisasi oleh Spz, kmd. tumbuh sedikir demi sedikit Pangenesis (Darwin): dalam sel kelamin terdapat tunas 2 tumbuh menjadi MH baru setelah fertilisasi Plasma benih (Weisman): Gamet dibentuk oleh jar.khusus, bukan jar. tubuh
Penelitian dan Peneliti Genetika Mendel: From Result of Mendel Then, What Is Genetic Factor? Genetic Materials? W. ROUX (1883): Cromosome T. Bovery (1902): Gen bagian dari kromosom Faktor Penentu (Gen/Kromosom) di wariskan lewat GAMET (pada Anafase Meiosis I saat Separasi Kromosom homolog) HIPOTESA SUTTON-T. BOVERY
HIPOTESA WS SUTTON-T. BOVERY: Animal Chromosomes 1. Gen dibawa oleh kromosom 2. Satu pasang kromosom asal maternal+paternal 3. Pemindahan 1 ps kromosom saat meiosis 4. Sel benih mengandung kombinasi gen jantan dan betina 5. Kromosom homolog secara genetis berbeda, sehingga sel benih scr genetis berbeda 6. Tiap kromosome terdiri lebih dari 1 gen, gen-gen dalam kromosom pindah bersama-sama
TEORI : DOMONANSI-RESESIF Sifat Tinggi : Dominan (gen T) Sifat rendah/kerdil: Resesif (gen t) Parents (P) TT Gamet:T X tt Gamet: t Monohibrid: 1 sifat beda Di hibrid : 2 sifat beda Filial 1 (F1) Tri hibrid : 3 sifat beda Tt HIBRIDA Fenotip: 3:1 Genotip : 1 : 2: 1 tt: homosigot F2? F2 / T t T TT Tt t Tt tt TT: homosigot Tt: heterosigot HK.MENDEL I: Pemisahan Gen se alel
Dominansi penuh dan semi dominant Dominansi Penuh Semi Dominant: Bunga pk 4. Parents (P) TT X tt Merah X Putih Gamet:T Gamet: t Merah Muda (Tinggi) (rendah) Filial 1 (F1) Tt Kodominan (Tinggi) RR x rr Merah putih Bedanya??? Rr Roan/coklat
MONOHIBRID HEWAN Warna rambut hitam (gen dominan A, pigmentasi melanin) F1 AA Hitam X Aa aa albino Pada F2: Fenotip : 3: 1 Genotip : 1 : 2 : 1 Hitam 1.Resiprok: Kebalikan / HH x hh Macam sistim Persilangan 2. Back cross: 3. Test Cross: Hh Hasil sama F1 dng parent / Hasil: Fenotip/genotip ttt. F1 dng P resesif Pembuktian F1 homosigot /heterosigot
Pada marmot: Dihidrid pada hewan Rambut Hitam (gen H) vs putih (gen h) Rambut Kasar (gen K) vs rambut halus (gen h) F2 HH KK x hh kk Gamet HK Gamet : hk F1: Hh Kk x Hh Kk Gamet HK Hk hk kk HK * * * * Hk * + * + hk * * = = kk * + = O Rasio fenotip : 9 : 3 : 3 : 1
Perhitungan Matematis (Rumus estimasi) Juml. Sifat beda Macam gamet F1 Kombi nasi F2 Fenotip F2 Kombi nasi F1 Kombi nasi homosi got n 2 n (2 n ) 2 2 n 2 n 2 n 3 n 1 2 4 2 2 2 3 2 4 16 4 4 4 9 3 8 64 8 8 8 27 Genoti p F2 Macam Gamet: Monohibrid (Aa) : 2 n = 2 1 = 2 = (A/a) Dihibrid (AaBb) = 2 2 = 4 = (AB, Ab, ab, ab) Tri hibrid (AaBbCc) 2 3 = 8 = (ABC,.., abc) Kombinasi: Mono hibrid : (AaxAa)=(2 1 ) 2 =4 = (AA,Aa,Aa,aa) Dihibrid (AaBbxAaBb) = (2 2 ) 2 = 16
Perkawinan Intermedier (Dominansi tak sempurna) Pd Mirabilis jalapa P mm X MM putih merah Mm X Mm Merah muda ( pink) MM 1 Mm Mm 2 mm 1 Perkawinan Kodominan (dominansi parsial) Pada sapi Shorthorn P : RR X rr Merah putih Rr X Rr Coklat RR 1 Rr Rr 2 rr 1
Implementasinya pada ternak: Jika jumlah gamet (gen) sama dengan jumlah kromosom Maka Kombinasinya* Sapi 2 n = 2 30 kombinasi gamet = 1.07 x 10 9 Kuda 2 n = 2 32 kombinasi gamet = 4.29 x 10 9 Manusia 2 n = 2 23 kombinasi gamet = 8.3 x 10 6 Note : More than a 100 or 1000 gens/ Chromosome So, What is the conclussion: -
S u m m a r y Gregor Mendel is considered the father of genetics The amount of difference between parents and offspring is caused by genetics and the environment P= G+ E Fertilization occurs when the sperm cell penetrates the egg and the chromosome pairs are formed again when fertilization takes place Genes control an animals traits Some genes are dominant and some are recessive Animals may carry two dominant or two recessive genes for a trait. They are called homozygous pairs Animals may also carry a dominant and recessive gene pair. They are called heterozygous pairs Livestock improvement is the result of using the principles of genetics