Remember Chromosomes occur in pairs homologous pairs the

Remember: Chromosomes occur in pairs. (homologous pairs) the different alleles of a gene occupy the same positions on each chromosome

• About 30% of the genes in humans are di-allelic, that is they exist in two forms, (they have two alleles) • About 70% are mono-allelic, they only exist in one form and they show no variation • A very few are poly-allelic having more than two forms The ABO blood system • • This is a controlled by a tri-allelic gene It can generate 6 genotypes • The alleles control the production of antigens on the surface of the red blood cells Two of the alleles are codominant to one another and both are dominant over the third • • © 2007 Paul Billiet ODWS Allele IA produces antigen A Allele IB produces antigen B Allele i produces no antigen

BASIC: ALEL DAN GEN GANDA Mono. Hibrid pada Hewan: Warna Rambut Hitam: (gen A): AA (hitam) x aa (albino) Aa (Hitam) However, it is possible to have several different allele possibilities for one gene. Multiple alleles is when there are more than two allele possibilities for a gene. Gen A: 1 Kali mutasi : -- >alel a Gen Ganda: Bbrp kali mutasi---) bbrp alel: a 1, a 2, a 3, dst

A L E L G A N D A Pengertian: Gen (virgin) kalau bermutasi membentuk Alel ( A -- a) Banyak Gen mengalami mutasi berulang-ulang, menimbulkan banyak macam alel (lebih dari 2, disebut alel Ganda) ontoh: Gen pigmentasi bulu kelinci (Gen C, pigmentasi hitam), memiliki 3 alel: . c : albino (tak ada pigmentasi). cch: pigmentasi terang, bulu pigmentasi gelap pada ujung (Chinchilla). ch: pigmentasi bagian ujung-ujung tubuh, bagian lain putih (H= himalaya) Urutan dominasi alel : C>cch>ch>c

Certain types of rabbits… …can either be brown, white, have a chinchilla pattern, or have a himalayan pattern C causes fully brown coat cc causes albino (white) cch causes a chinchilla pattern ch causes a Himalayan pattern The alleles are arranged in the following pattern C > cch > c • • Himalayan rabbit – color in certain parts of the body; dominant only to c; chc or chch Albino rabbit – no color – allele is recessive to all other alleles; cc Full color rabbit – alleles are dominant to all others; CC, Ccch, Cch, or Cc Chinchilla rabbit – partial defect in pigmentation cch allele dominant to all other alleles except C; cchch, cchcch, or cchc

Kelinci Gelap: Kelinci lebih terang; Chinchila: CC, Ccch, Cch cchh; cch, ch; ccchc Kelinci Himalaya: c h ch; ch, c Kelinci Albino: cc P; Cch X Ch Ch P ; CC x Cch F 1: Cch Ch X Cch Ch F 1 : C Cch x c c F 2: Cch F 2: Cc Cch Ch Cch c Cch Ch Ch

Multiple alleles dominance Each gene locus can have more than 2 alleles. An may be dominant to some alleles but recessive to others. sexallele linkage This situation produces more than 2 different phenotypes. multiple alleles Each individual has 2 alleles present in their cells at any one time. d BB or Bbl bb or bbl blbl

Multiple gene inheritance Cat colour is the result of the inheritance of a large number of different genes.

In this case both A and B are dominant to O (recessive). A and B are codominant (both expressed) So. . . there are four human blood types AA, AO A blood type BB , BO B blood type AB blood type or OO O blood type Genotypes Phenotypes (Blood types) IA I A A IA I B AB IAi A IB I B B IB i B ii O

Sistem Golongan Darah A-B-O. (K. Landsteiner, 1868 – 1943) Gen Asli I (Isoagglutinogen), : 1. Alelnya : Ia, Ib, I 2. Urutan dominan: Ia = Ib >i Golongan (Fenotip) Genotip A Ia Ia atau Ia i B Ib Ib; atau Ib i Contoh: Gol A x Gol B (Ia Ia; Ia I) x ( Ib Ib; Ib I) AB Ia Ib O ii 1. Ia Ia x Ib Ib AB 2. Ia Ia x Ib I AB; A 3. Ia I x Ib I AB; B 4. Ia I x Ib I AB; A, B, O

Donor-recipient compatibility Recipient Type A B AB O A Donor B AB O = Agglutination = Safe transfusion © 2007 Paul Billiet ODWS Note: • Type O blood may be transfused into all the other types = the universal donor. • Type AB blood can receive blood from all the other blood types = the universal recipient.

Crossing Over dan Rekombinan • Sometimes in meiosis, homologous chromosomes exchange parts in a process called crossing-over. • New combinations are obtained, called the crossover products.

Structure of Chromosomes – Homologous chromosomes are identical pairs of chromosomes. – One inherited from mother and one from father – made up of sister chromatids joined at the centromere. Copyright © Mc. Graw-Hill Companies Permission required for reproduction or display

MEIOSIS AND CROSSING OVER Chromosomes are matched in homologous pairs • Each synapsis is made up of 2 pairs of sister chromatids • This matched set of 4 chromatids is called a tetrad Chromosomes Centromere Sister chromatids Figure 8. 12

Crossing Over Basics • Occurs at One or More Points Along Adjacent Homologues • Points contact each other • DNA is Exchanged • Menaikkan var. Genetik http: //waynesword. palomar. edu/images/cross 3. jpg 21 Apr 2002 16

Crossing over further increases genetic variability • Crossing over is the exchange of corresponding segments between two nonsister chromatids of homologous chromosomes • Genetic recombination results from crossing over during prophase I of meiosis – This increases variation further

Recombination During Meiosis Recombinant gametes

Two Loci Inheritance A A B B a a 2 b b 1 A a B b A a b b Recombinant 4 3 5 6 A a B b a a b b

Coat-color genes • How crossing over leads to genetic recombination • Nonsister chromatids break in two at the same spot • The 2 broken chromatids join together in a new way Eye-color genes Tetrad (homologous pair of chromosomes in synapsis) 1 Breakage of homologous chromatids 2 Joining of homologous chromatids Chiasma 3 Separation of homologous chromosomes at anaphase I 4 Separation of chromatids at anaphase II and completion of meiosis Parental type of chromosome Recombinant chromosome Parental type of chromosome Gametes of four genetic types

• A segment of one chromatid has changed places with the equivalent segment of its nonsister homologue • If there were no crossing over meiosis could only produce 2 types of gametes Coat-color genes Eye-color genes Tetrad (homologous pair of chromosomes in synapsis) 1 Breakage of homologous chromatids 2 Joining of homologous chromatids Chiasma 3 Separation of homologous chromosomes at anaphase I 4 Separation of chromatids at anaphase II and completion of meiosis Parental type of chromosome Recombinant chromosome Parental type of chromosome Gametes of four genetic types