*Genetika Mendel

*Gregor Mendel (1822-1884)Menemukan hukum pewarisan suatu sifat

*Gregor Johann MendelSeorang pendeta bangsa AustriaMeneliti pewarisan sifat pada tanaman arcis (pea)Menghasilkan Hukum Sistem pewarisanTemuan Mendel tak diterima sampai menjelang abad ke 20

*Gregor Johann MendelAntara 1856 and 1863, Mendel menanam dan menguji 28,000 tanaman arcisDia mencatat bahwa selama penelitian sifat induk tetap muncul pada anak Dijuluki Father of Genetics"

*Site of Gregor Mendels experimental garden in the Czech Republic

*Genetic TerminologyTrait - any characteristic that can be passed from parent to offspring Heredity - passing of traits from parent to offspring

*1). ISTILAH-2 DASAR TERKAIT PEWARISAN SIFATa. GEN ALEL Gb. Kromosom mengandung Gen-2GEN: FAKTOR GENETIK PENGATUR SIFAT Contoh: gen M mengatur sifat warna bunga, gen K mengatur sifat warna bijiALEL: BENTUK ALTERNATIF SUATU GEN Contoh: Gen M (pengatur warna bunga) mempunyai 2 alel: alel M menyebabkan bunga berwarna merah alel m menyebabkan bunga berwarna putih Contoh: Gen K mengatur sifat warna biji mempunyai 2 alel: Alel K menyebabkan biji berwarna kuningAlel k menyebabkan biji berwarna hijau

*b. GENOTIPE GENOTIPE (G): susunan genetik (gen-2) organismeGen-2 berpasangan (dari tetua jantan dan tetua betina)Contoh: Genotipe organisme berdasar 3 pasang gen (Gambar) mempunyai genotipe: MM KK BbPASANGAN GEN/ALEL dibedakan atas:HOMOZIGOT: mempunyai alel sama, contoh: MM, KKHETEROZIGOT: mempunyai alel tidak sama, contoh: Bb

*c. FENOTIPE

*

M

M

MM

x

mm

m

m

M

m

F1: Mm

(M dg m alelik)

(M dominan

thd m)

F1 : keturunan pertama hsl. persil.

F2 : keturunan kedua hsl persilang.

(hasil selfing antara individu F1)

Homosigot: individu dg. 2 alel sama,

MM / mm

Heterosigot: indv. dg 2 alel berbeda,

Mm

*Mendels Pea Plant Experiments

*Mengapa arcis, Pisum sativum?Dapat ditanam ditempat sempit Menghasilkan banyak keturunan Menghasilkan tanaman homozigot jika menyerbuk sendiri Mudah menyilangkan

*Reproduksi pada tanamanPollen contains spermProduced by the stamenOvary contains eggsFound inside the flower

Pollen membawa sperm ke egg untuk fertilisasiSelf-fertilization terjadi pada bunga yg samaCross-fertilization terjadi antara bunga berbeda

*Mendels Experimental MethodsMendel hand-pollinated flowers using a paintbrushHe could snip the stamens to prevent self-pollinationHe traced traits through the several generations

*

*Percobaan Mendel Mendel membuat tanaman homozigot dengan membiarkannya menyerbuk sendiri beberapa generasi

*Delapan sifat arcisSeed shape --- Round (R) or Wrinkled (r)Seed Color ---- Yellow (Y) or Green (y)Pod Shape --- Smooth (S) or wrinkled (s)Pod Color --- Green (G) or Yellow (g)Seed Coat Color ---Gray (G) or White (g)Flower position---Axial (A) or Terminal (a)Plant Height --- Tall (T) or Short (t)Flower color --- Purple (P) or white (p)

*

*

*Mendels Experimental Results

*Rasio Pengamatan Vs rasio teoritisRasio teoritis tanaman berbiji bundar (round) atau kisut (wrinkled) adalah 3 round : 1 wrinkledRasio yang diamati Mendel adalah 2.96:1Perbedaan disebabkan kesalahan statistik (statistical error)Semakin besar sample semakin mendekati rasio teoritis

*Macam GenerasiInduk (Parental) P1 = generasi induk dalam suatu percobaan genetika

Generasi F1 = Generasi turunan pertama (1st filial generation) dalam suatu percobaan genetika

Generasi F2 = Generation turunan kedua generation dalam suatu percobaan genetika. (2nd filial generation)

*Following the GenerationsPersilangan 2 induk homozigot TT x ttHasilnya semua Hybrids TtPersilangan 2 Hybrid menghasilkan 3 Tinggi & 1 pendek TT, Tt, tt

*Monohybrid

*a). Hk. MENDEL I (Hukum Segregasi/Pemisahan Pasangan Gen/Alel):Pada pembentukan gamet*), ALEL DARI PASANGAN-2 GEN AKAN MEMISAH (BERSEGREGASI) ke dalam Gamet-gamet yg dibentuk*) Perbiakan generatif melibatkan:Pembentukan gamet-2 Penyatuan gamet

*Sifat: bentuk biji (Seed Shape)Alleles: R Roundr WrinkledCross: Round seeds x Wrinkled seedsRR x rrP1 Monohybrid CrossRRrrRrRrRrRrGenotype: RrPhenotype: RoundGenotypic Ratio: Semua samaPhenotypic Ratio: Semua sama

*Homozygous dominant x Homozygous recessiveKeturunan semua Heterozygot (hybrids)Keturunan disebut generasi F1 Rasio Genotip & Phenotip sama semua

*Trait: Bentuk bijiAlleles: R bundarr KisutCross: Biji Bundar x biji BundarRr x RrPersilangan F1 Monohybrid RrrRRRrrRrRrGenotip: RR, Rr, rrPhenotip: Bundar & kisutRasio Gntp: 1:2:1Rasio Pntp: 3:1

*Heterozygot x heterozygot Keturunan (Offspring): 25% Dominan Homozygot RR 50% Heterozygot Rr 25% Recessif Homozygous rrOffspring disebut F2 generationRasio Genotyp adalah 1:2:1Rasio Phenotyp adalah 3:1

*Bentuk Biji Yang kelihatan

*Uji Silang (Test Cross)Mendel menyilangkan homozigot & hybrida dari generasi F2Dua kemungkinan test cross: Homozygot dominant x Hybrid Homozygot recessive x Hybrid

*Trait: Seed ShapeAlleles: R Bundarr KisutCross: Biji Bundar x Biji Bundar RR x RrF2 Monohybrid Cross (1st)RRrRRRRrRRRrGenotip: RR, RrPhenotip: BundarRasio Genotip: 1:1Rasio Phenotip: Semua sama Bundar

*Trait: Seed ShapeAlleles: R Bundarr KisutCross: Biji Kisut x Biji Bundar rr x RrF2 Monohybrid CrossrrrRRrrrRrrrGenotip: Rr, rrPhenotip: Bundar & Kisut Rasio Gntp: 1:1Rasio pntp: 1:1

*F2 Monohybrid Cross ReviewHomozygot x heterozygot Keturunan: 50% Homozygot RR or rr 50% Heterozygot RrRasio Phenotip adalah 1:1

*Practice Your CrossesWork the P1, F1, and both F2 Crosses for each of the other Seven Pea Plant Traits

*Tugas :Buat Persilangan :Antara Homozigot x Homozigot : (tiga macam)Antara Homozigot x Heterozigot : (tiga macam)Antara Heterozigot x Heterozigot (1 macam)

Buat lengkap dengan skema, perbandingan genotipe dan fenotipe yang dihasilkan baik pada F1 dan F2

*Mendels Laws

*Results of Monohybrid CrossesInheritable factors or genes are responsible for all heritable characteristics Phenotype is based on Genotype Each trait is based on two genes, one from the mother and the other from the father True-breeding individuals are homozygous ( both alleles) are the same

*Law of Dominance

In a cross of parents that are pure for contrasting traits, only one form of the trait will appear in the next generation.All the offspring will be heterozygous and express only the dominant trait.RR x rr yields all Rr (round seeds)

*Law of Dominance

*Law of SegregationDuring the formation of gametes (eggs or sperm), the two alleles responsible for a trait separate from each other.Alleles for a trait are then "recombined" at fertilization, producing the genotype for the traits of the offspring.

*Applying the Law of Segregation

*Law of Independent Assortment

Alleles for different traits are distributed to sex cells (& offspring) independently of one another. This law can be illustrated using dihybrid crosses.

*Dihybrid CrossA breeding experiment that tracks the inheritance of two traits.Mendels Law of Independent Assortmenta. Each pair of alleles segregates independently during gamete formationb. Formula: 2n (n = # of heterozygotes)

*Question:How many gametes will be produced for the following allele arrangements?

Remember: 2n (n = # of heterozygotes)

1.RrYy

2.AaBbCCDd

3.MmNnOoPPQQRrssTtQq

*Answer:1. RrYy: 2n = 22 = 4 gametesRY Ry rY ry

2. AaBbCCDd: 2n = 23 = 8 gametesABCD ABCd AbCD AbCdaBCD aBCd abCD abCD

3. MmNnOoPPQQRrssTtQq: 2n = 26 = 64 gametes

*Dihybrid CrossTraits: Seed shape & Seed colorAlleles: R round r wrinkled Y yellow y green

RrYy x RrYyRY Ry rY ryRY Ry rY ryAll possible gamete combinations

*Dihybrid Cross

*Dihybrid Cross

*Dihybrid CrossRound/Yellow: 9 Round/green: 3 wrinkled/Yellow: 3 wrinkled/green: 19:3:3:1

*Test CrossA mating between an individual of unknown genotype and a homozygous recessive individual.Example: bbC__ x bbcc

BB = brown eyesBb = brown eyesbb = blue eyes

CC = curly hairCc = curly haircc = straight hair

*Test CrossPossible results:

*Summary of Mendels laws

*Incomplete DominanceandCodominance

*Incomplete DominanceF1 hybrids have an appearance somewhat in between the phenotypes of the two parental varieties.Example: snapdragons (flower)red (RR) x white (rr)

RR = red flowerrr = white flower

*Incomplete Dominancer

*Incomplete Dominance

*CodominanceTwo alleles are expressed (multiple alleles) in heterozygous individuals.Example: blood type

1.type A= IAIA or IAi2.type B= IBIB or IBi3.type AB= IAIB4.type O= ii

*Codominance ProblemExample:homozygous male Type B (IBIB)x heterozygous female Type A (IAi)

*Another Codominance ProblemExample: male Type O (ii) x female type AB (IAIB)

*CodominanceQuestion: If a boy has a blood type O and his sister has blood type AB, what are the genotypes and phenotypes of their parents?

boy - type O (ii) X girl - type AB (IAIB)

*CodominanceAnswer:Parents:genotypes = IAi and IBiphenotypes = A and B

*Sex-linked TraitsTraits (genes) located on the sex chromosomesSex chromosomes are X and YXX genotype for femalesXY genotype for malesMany sex-linked traits carried on X chromosome

*Sex-linked TraitsSex ChromosomesExample: Eye color in fruit flies

*Sex-linked Trait ProblemExample: Eye color in fruit flies (red-eyed male) x (white-eyed female) XRY x XrXrRemember: the Y chromosome in males does not carry traits.RR = red eyedRr = red eyedrr = white eyedXY = maleXX = female

*Sex-linked Trait Solution:50% red eyed female50% white eyed male

*Female Carriers

*Genetic Practice Problems

*Breed the P1 generationtall (TT) x dwarf (tt) pea plants

*Solution:tall (TT) vs. dwarf (tt) pea plants

*Breed the F1 generationtall (Tt) vs. tall (Tt) pea plants

*Solution:tall (Tt) x tall (Tt) pea plants

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