PINDAH SILANG.ppt

PINDAH SILANG (CROSSING OVER)

PINDAH SILANG (CROSSING OVER)

Contoh : (1) Pada tan. Ercis (susunan “sis”)Gen-gen terangkai : + (M) = bunga ungu m = bunga merah + (B) = serbuk sari panjang b = serbuk sari bulat

P1 : + + x m b + + m b ungu, serbuksari panjang merah, bulatF1 : + + m b ungu, panjang Test cross : + + (M B) x m b m b m b m b F2 : Kalau Test Cross pada Dihibrid ??

M B

M B

bm

bm

F2 : 192 tan berbunga ungu, serbuk sari panjang 23 tan berbunga ungu, serbuk sari bulat 30 tan berbunga merah, serbuk sari panjang 182 tan berbunga merah, serbuk sari bulat

Gamet-gamet yang tidak mengalami pindah silang : gamet + + (M B) dan gamet m bGamet-gamet yang gen-gennya mengalami pindah

silang : gamet + b (M b) dan gamet m + (m B)

F2 :

Genotif

Fenotif Banyaknya Frekuensi

Tipe

M Bm b

Ungu, panjang

192 (192/427) x 100 %

Parental

M bm b

Ungu, bulat

23 Rekombinan

m Bmb

Merah, panjang

30 Rekombinan

m bm b

Merah, bulat

182 Parental

Prosentase Rekombinasi : 23 + 30 x 100 % = 12,41 % 427 Tipe parentalnya : 100 % - 12,41 % = 87,59

%

(2) Pada tan. Ercis (susunan “trans”)

P : + b x m + + b m +Atau P : M b x m B M b m B

Ungu, bulat merah, panjang

Tentukan gamet, F1 ?

F2 : (hasil uji silang) 14 tan berbunga ungu, serbuk sari panjang

178 tan berbunga ungu, serbuk sari bulat 160 tan berbunga merah, serbuk sari panjang 18 tan berbunga merah, serbuk sari bulat

Gamet-gamet yang tidak mengalami pindah silang : .........

Gamet-gamet yang gen-gennya mengalami pindah silang : ......

F2 :

Berapa prosentase rekombinasi ?

Genotif

Fenotif Banyaknya Frekuensi

Tipe

??? ???

Ringkasan :1. Gen-gen tidak terangkai : a. perkawinan dihibrid (AaBb x AaBb), keturunan 9 :

3 : 3 : 1 b. Uji silang dihibrida (AaBb x aabb), keturunan 1 : 1 :

1 : 12. Gen-gen terangkai sempurna : a. Perkawinan dihibrid, gen-gen terangkai sis (A B x A B), keturunan 3 : 0 : 0 : 1 atau 3 : 1 a b ab b. Perkawinan dihibrid, gen-gen terangkai trans : ( A b x A b ), keturunan 2 : 1 : 1 : 0 atau 2 : 1 : 1 a B a B

3. Gen-gen terangkai tak sempurna a. Uji silang dihibrid, gen terangkai sis .......... b. Uji silang dihibrid, gen terangkai trans

Recombination Occurs Less Frequently Between Closely Linked Genes

Physical crossing over is a normal meiosis event

Crossing-over pertukaran segmen dari kromatid-kromatid bukan non-sister kromatid dari sepasang kromosom homolog

The term used to describe crossing over is recombination

Recombination can occur between any two genes on a chromosome

The farther apart the two genes the more crossing over

Pindah silang dibedakan atas :1.Pindah silang tunggal2.Pindah silang ganda

Pindah silang tunggal

Berapakah NPSnya?

NILAI PINDAH SILANG (NPS)

NPS ADALAH ANGKA YANG MENUNJUKKAN BESARNYA PERSENTASE KOMBINASI BARU YANG DIHASILKAN AKIBAT TERJADINYA PINDAH SILANG

Jawaban

NPS = 16 + 22 x100% = 38 x100%

382+16+22+35 773= 4,92%

Faktor-faktor yang mempengaruhi pindah silang :

1.TEMPERATUR, temperatur kurang atau melebihi temperatur biasa dapat memperbesar kemungkinan pindah silang

2.UMUR, makin tua suatu individu makin kurang mengalami pindah silang

3.ZAT KIMIA tertentu dapat memperbesar kemungkinan terjadinya pindah silang

4.PENYINARAN SINAR X dapat memperbesar kemungkinan pindah silang

5.JARAK ANTAR GEN YANG TERANGKAI, makin jauh letak satu gen dengan gen lainnya, makin besar kemungkinan pindah silang

6.JENIS KELAMIN, umumnya jantan atau betina dapat mengalami pindah silang. Namun pada ulat sutera betina dan Drosophila jantan tidak pernah terjadi pindah silang

PETA KROMOSOM

(CHROMOSOME

MAPPING)

© 2005 Prentice Hall Inc. / A Pearson Education Company / Upper Saddle River, New Jersey 07458

Mapping IMapping is

identifying relationships between genes on chromosomesJust as a road map

shows relationships between towns on highway: fine maps

Two types of mapping: genetic and physical

Mapping II Genetic mapping

Based on differences in recombination frequency between genetic loci: meiosis

Physical mapping Based on actual distances in base pairs

between specific sequences found on the chromosome

Most powerful when genetic and physical mapping are combined

Genetic mapping IBased on recombination frequencies

The further away two points are on a chromosome, the more recombination there is between them

Because recombination frequencies vary along a chromosome, we can obtain a relative position for the loci

Distance between the markers

Genetic mapping IIGenetic mapping requires that a cross be

performed between two related organisms The organism should have phenotypic

differences (contrasting characters like red and white or tall and short etc) resulting from allele differences at two or more loci

The frequency of recombination is determined by counting the F2 progeny with each phenotype

Genetic mapping example IGenes on two

different chromosomesIndependent

assortment during meiosis (Mendel)

No linkageDihybrid ratio

F1

9 : 3 : 3 : 1

F2

P

Genetic mapping example IIGenes very close

together on same chromosomeWill usually end up

together after meiosis

Tightly linked

F1

1 : 2 : 1

F2

P

Genetic mapping example IIIGenes on same

chromosome, but not very close togetherRecombination will

occur Frequency of

recombination proportional to distance between genes

Measured in centiMorgans =cM Recombinants

Non-parental features

One map unit = one centimorgan (cM) = 1% recombination between loci

Membuat Peta Kromosom :Peta Kromosom adalah : gambar skema

sebuah kromosom yang dinyatakan sebagai sebuah garis lurus dimana diperlihatkan lokus setiap gen yang terletak pada kromosom tsb.

Sentromer dari kromosom biasanya dianggap sbg pangkal, maka diberi tanda angka 0

Pada lokus setiap gen dibubuhkan angka yang menunjukkan jarak antara gen itu dengan sentromer atau jarak antara satu gen dengan gen yang lain.

Peta relatif : peta kromosom tanpa menunjukkan letak sentromer

0 p q

26,2

17,713

10

6,2

ab c

Jarak Peta ????

By definition, one map unit is equal to

one percent recombinant gametes or phenotypes

In honor of Morgan, one map unit is also called one centimorgan (cM)

1 mu = 1% = 1 cM

To determine the distance between two genes, divide the number of recombinant gametes by the total number of gametes

Formula :

Number of recombinants x 100% Total Number

Contoh 1 : Coupling Data F1 Gamete Testcross Distribution Gamete Type

pr+ vg+ 1339 Parental

pr+ vg   151 Recombinant

pr vg+   154 Recombinant

pr vg 1195 Parental

pr vg distance = ((151 +154)/2839)*100% = 10.7 m.u

= 10.7 cM

Contoh 2 : Repulsion Data F1 Gamete Testcross Distribution Gamete Type

pr+ vg+   157 Recombinant

pr+ vg   965 Parental

pr vg+ 1067 Parental

pr vg   146 Recombinant pr vg distance = ((157 + 146)/2335)*100% = 13.0

cM

Jarak Gen

Coupling : pr vg 10,7 cM

Repulsion : pr vg

13,0 cM

Linkage maps estimate distances between genes.

The closer together two genes are, the more likely they will be inherited together.

Cross-over frequencies are related to distances between genes.The higher the frequency, the further the genes are apart

Linkage maps show the relative locations of genes.

• Cross-over frequencies can be converted into map units.

• Ex: A 5% cross-over frequency equals 5 map units.

– gene A and gene B cross over 6.0 percent of the time

– gene B and gene C cross over 12.5 percent of the time

– gene A and gene C cross over 18.5 percent of the time

Draw a linkage map based on the following cross over percentages:

A – B = 8%B – C = 10%A – C = 2%

Draw a linkage map based on the following cross over percentages:

A – B = 8%B – C = 10%A – C = 2%

8.0 2.0

B A C

8.0 + 2.0 = 10.0

Remember these are estimates; the differences between the two estimates reflect random deviation

Neither estimate is incorrect; repeated experimentation would give a more accurate estimate

Figure 3.18 Genomes 3 (© Garland Science 2007)

cM or centimorgan

1% Recombination = 1 cM

Membuat peta kromosom dengan gen rangkap tiga : Deriving Linkage Distance And Gene Order From Three-Point Crosses

Analyzing three genes allows us to determine gene order as well as linkage distance

Need to create a F1 and follow deviation from a 1:1:1:1:1:1:1:1 ratio What are the expected gametes when three linked genes are

considered?

Analyzing Three-Point Test Cross Data

Genotype Observed

ABC    390

abc    374

AbC     27

aBc     30

ABc       5

abC       8

Abc     81

aBC     85

Total 1000

What are the parental genotypes?

What is the gene order?

What are the linkage distances?

What are the parental genotypes?

The genotypes most frequently found are the parental genotypes

ABC and abc are the parental genotypes

Menentukan urutan gen :Tipe tetua = paling banyak (n.c.o)Tipe crossing over ganda = paling sedikit

(d.c.o) Dua gen pada tipe tetua = dua gen pada

tipe d.co, yang tidak sama terletak di tengah

What is the gene order?

What is the gene order?

* Menentukan susunan gen dengan memperhatikan Tipe Parental dan Tipe DCO

Pada Tipe Parental di-DCO-kan dan dibandingkan dengan hasil DCO pengamatan

The double crossover moves a non-parental allele of the central gene between two parental alleles

Gene C is between genes A and B (gene order = A C B)

Analyzing Three-Point Test Cross Data

Genotype Observed Type of Gamete

ACB    390 Parental

acb    374 Parental

ACb     27 Single-crossover between genes C and B

acB     30 Single-crossover between genes C and B

AcB       5 Double-crossover

aCb       8 Double-crossover

Acb     81 Single-crossover between genes A and C

aCB     85 Single-crossover between genes A and C

Total 1000

What are the linkage distances? Linkage distance equals the sum of the

appropriate single cross plus all double crosses divided by total number of gametes

Formula :Jarak = SCO + DCO x 100%

Jumlah Total

*Jarak A - C = ((81+85+5+8)/1000)*100 = 17.9 cM

*Jarak C - B = ((27+30+5+8)/1000)*100 = 7.0 cM

A C B17,9 cM 7,0 cM

*Jarak A - C = ((81+85+5+8)/1000)*100 = 17.9 cM

*Jarak C - B = ((27+30+5+8)/1000)*100 = 7.0 cM

A C B17,9 cM 7,0 cM

Interference Interference - the reduction in the expected

number of crossovers at two adjacent genetic intervals

Interferensi – interaksi antar pindah silangPindah silang pada tempat tertentu mengurangi

kemungkinan terjadinya pindah silang pada daerah didekatnya.

Pindah silang di daerah I mengurangi terjadinya pindah silang pada daerah II

Mengakibatkan frekuensi pindah silang ganda lebih kecil dari yang diharapkan

coefficient of coincidence (c.o.c.) = ratio of observed to expected double crossovers

Koefisien koinsidensi adalah ukuran dari kekuatan interferensi dan merupakan nisbah antara frekuensi pindah silang ganda yang diamati dan frekuensi pindah silang ganda yang diharapkan

Rumus

atauKK = Banyaknya pindah silang ganda (DCO) yang

sesungguhnya

Banyaknya pindah silang ganda (DCO) yang diharapkan

Interferensi = 1 - KK

Apabila interferensi sempurna (1,0) maka tidak ada pindah silang ganda yang dapat diamati

Apabila semua pindah silang ganda yang diharapkan dapat diamati maka interferensinya nol (0)

Misalnya diketahui data sebagai berikut:

Genotipe gamet Jumlah Fenotipe

Dari F1 heterosigot individu

V Gl Va 235 normal

v gl va 270 mengkilat, steril sebagian, pucat

V gl Va 7 mengkilat

v Gl va 4 steril sebagian, pucat

V gl va 62 mengkilat, steril sebagian

v Gl Va 60 pucat

V Gl va 40 steril sebagian

v gl Va 48 mengkilat, pucat

726

Misalnya :

Diketahui peta kromosom :V Gl Va 18,3 13,6

31,9

SCO-1 (V-Gl) : 18,3%SCO-2 (Gl-Va) : 13,6%Pindah silang ganda yang diharapkan = SCO-1 x

SCO-2 = 0,183 x 0,136 = 0,025 = 2,5%

Pindah silang ganda yang sebenarnya :7+4 = 1,5%726

Sehingga Koefisien Koinsidensinya :KK = 1,5% = 0,6

2,5%

Jadi Interferensinya : I = 1-KK = 1 – 0,6 = 0,4 = 40%

1. In human pedigree below where the male parent does not appear, it is assumed that he is phenotypically normal. Both hemophilia (h) and color blindness (c) are sex linked recessives. In so far as possible, determine the genotype for each invidual in the pedigree ?

I 1 2 2 3 II 1 2 3 4 5 6 7III 1 2 3

= hemophilia = color blind =

hemophilia-colorblind

PR

2. Pada tanaman jagung (Zea mays) dikenal gen-gen yang terangkai yaitu :Bm = tulang daun hijau (normal)bm = tulang daun coklat

Pr = biji kuning (normal) pr = biji merah V = daun hijau (normal) v = daun hijau pucat

Uji silang tanaman trihibrid : Bm Pr V X bm pr v bm pr v bm pr v

Menghasilkan keturunan sebagai berikut :

a.Gambarkan peta kromosom relatif dimana gen-gen iti terangkai ?

b.Tuliskan genotif dari tanaman parental ?c.Berapakan inferensinya ? Apa maknanya ?

Bm pr v bm pr v

57 tanaman

bm pr v 434 tanaman

bm Pr V 60 tanaman

Bm Pr V 441 tanaman

bm Pr v 2 tanaaman

Bm Pr v 1 tanaman

Bm pr V 3 tanaman

bm pr V 2 tanaman

2.