Mendel & HereditaryMendels law & the deviations

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MENDEL & HEREDITARY

Based on

Mendels 1st law

Mendels 2nd law

Monohybrid Inheritance pattern Non mendelian inheritance Gene linkage Sex linkage

Dihybrid

Cross over

Epistasis & hypostasis Cryptomere Polygenic Gene interaction

Sex determination

Lethal gene

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GLOSSARY Terms MeaningPhenotype Genotype Pure Line Dominant Recessive Gametes Allele Homozygote Heterozygote Monohybrid Dihybrid Epistasis

Mendel & Hereditary9 Hipostasis

MENDEL & HEREDITARYA monk from Austria, named Gregor Mendel, towards by the end of the 19th century conducted a series of crossover experiments on garden pea (Pisum sativum). The experiments he had done for many years, Mendel discovered the principles of heredity, which then become the main foundation for the development of genetics as a branch of science. By his work, Mendel is regarded as the Father of Genetics. Mendel chose peas as his experiments material, because:

Many hybrids have been produced before so it was is expected the characteristic separation occured Having a lot of varieties from the pure line Small and easy to breed and have a short life time Sexual organs are in flowers so self-fertilization or autogami able to occur

MENDELS EXPERIMENT

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P : Purple (PP) x white (pp) Gamete: P p F1 = Purple (Pp)

Gamete A Gamete B P p

P PP (purple) Pp (purple)

p Pp (purple) pp (putih)

self fertilization (Pp x Pp) F2 :

Purple : white = 3 : 1 TERMINOLOGYThere are several terms that need to know to explain the principles of inheritance.

P is the elder individual (parental) F 1 is the first offspring F 2 is the second offspring Gene P is said to be a gene or dominant allele, while gene p is a gene or a recessive allele. Alleles are alternative forms of a gene contained in the particular locus (place) Dd is called heterozygous individual , DD and dd are each called as dominant homozygous and recessive homozygous individuals. The properties that can be directly observed in individuals, ie, tall or short, called the phenotype. Thus, the phenotype is the expression of genes that can directly be observed as a trait in an individual. Meanwhile, the underlying genetic makeup the appearance of a trait called genotypes Crossing which concerns only one trait inheritance pattern is named Mendel monohybrid crosses. Example: flower color (purple-white), cotyledon color (green-yellow). Dihybrid the crosses involving two different traits. For example crossing a pure line between yellow-soft soybean seeds with green-wrinkle seeded

Segregation Law During gamete formation there occurs the process of segregation or segregation of heredity factors randomly

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The law of independent assortment During gamerte formation, each allele assorts independently From the diagram aboveP= ggww Yellow,smooth green,wrinkled F1= GgWw (yellow,smooth)gW Gw GW Gw GGWw ( yellow,smoot h) GGww ( yellow,wrinkl ed ) GgWw ( yellow,smoot h) Ggww ( yellow,wrinkl ed ) gW GgWW ( yellow,smooth ) GgWw ( yellow,smooth ) ggWW ( green,smooth ) ggWw ( green,smooth ) gw GgWw ( yellow,smoot h) Ggww ( yellow,wrinkl ed ) ggWw ( green,smoot h) ggww ( green,wrinkle d)

GGWW

x

GW

GGWW (yellow,smoot h) GGWw ( yellow,smoot h) GgWW ( yellow,smoot h) GgWw ( yellow,smoot h)

gw

dihybrid cross can be seen that the phenotype of F 2 has ratio of 9: 3: 3: 1 as a result of the segregation of genes G and W independently. Thus, the gametes are formed may contain a combination of dominant gene with a dominant gene (GW), a dominant gene with a recessive gene (Gw and gW), as well as the recessive gene with recessive gene (I). This is what came to be known as the law of independent assortment or Mendel's 2nd law.

Back cross and Test crossBack cross is a cross between an individual with one the parent. For example, Aa individual from crosses between AA and aa can be backcrossed with both AA and aa. Cross-forth between the Aa and AA will result in a range of phenotypes, namely A-, or two kinds of genotypes, namely AA and Aa with a ratio of 1: 1. Meanwhile, back cross between Aa and aa will produce two kinds of phenotypes, namely A-and aa with a ratio of 1: 1, or two kinds of genotypes, is Aa and aa with a ratio of 1: 1. Test cross is the cross between an unknown organism with recessive homozygous organism. In order to test the hypothesis on allele segregation which stated that F1 was heterozygous, Mendel crossed F1 generation with homozygous recessive plant.

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INHERITANCE

PATTERN

I. Non-Mendelian Inheritance 1. Epistasis & hypostasisEpistasis dan Hipostasis Ada 2 gen sama-sama dominan dan terletak pada lokus yang berbeda. Sifat yang ditentukan itu adalah warna kulit biji gandum Gen yang satu bersifat menghalangi (epistasis) sedangkan yang lain bersifat dihalangi (hipostasis) Kehadiran kedua gen dominan tersebut akan memunculkan fenotipe dari gen yang epistasis biasa Ketidakhadiran dari kedua gen dominan akan memunculkan fenotipe baru yaitu putih. Contoh: Induk : HHkk >< hhKK (hitam) (kuning) Gamet : Hk dan hK F1 : HhKk (hitam) F1 x F1: HhKk >< HhKk F2 : Game HK Hk hK Hk t HK HHKK HHKk HhKK HhKk Hk HHKk HHkk HhKk Hhkk hK HhKK HhKk hhKK hhKk hk HhKk Hhkk hhKk Hhkk Perbandingan keturunan = hitam : kuning : putih = 12 : 3 : 1

2. Interaction of genes

Mendel & Hereditary13Apparent deviation of Mendel's laws that do not involve the modification phenotype ratio, but make new phenotypes which is the result of cooperation or interaction of two pairs of non-allele genes. For example the inheritance pattern of the chicken comb

single

walnu t

rose

pea

Crosses between roses peal chicken and pea peal chicken produce offspring walnutshaped peal. Furthermore, if walnut peal chicken crossed with another walnut, then the F 2 generation obtained by the ratio of phenotypes walnut: roses: pea: single = 9: 3: 3: 1.This indicates the involvement of two pairs of non-allele genes that interact to produce a phenotype.

P:

RRpp rose

x

rrPP pea

F1 : F2 : 9 R-P3 R-pp 3 rrP1 rrpp

RrPp walnut walnut rose pea single walnut : rose : pea : single = 9 : 3 : 3 : 1

3. Polygenic (15 : 1)Deviations occur because of the nature of many genes is controlled. example: feathers on the legs of poultry P : FFHH x ffhh (feathered) (not feathered) F1 : FfHh (feathered) P2 : FfHh (feathered) x FfHh (feathered) F2 : : 9 F H : feathered 3Fhh : feathered 3 ff H : feathered 1 ffhh : not feathered ratio = 15 : 1

4. Cryptomere (9 : 3 : 4)Hidden nature when influenced by certain factors. The factor is dominant, as hidden by the other dominant factor and seen when it is the same with closing factor. Example: on flower Linaria maroccona

Mendel & Hereditary14M = red color (Antosianin exist) m = white color (No antosianin) A = acidic a = base if M + A = purple m + A = white M + a = red m + a = white P : MMaa x mmAA (red) (white) F1 : MmAa (purple) P2 : MmAa x MmAa (purple) (purple) F2 :9MA: purple 1 m m a a : white 3 M a a : red purple : red : white = 9 : 3 : 4 3 m m A - : white

II. Gene Linkage- gene linkage occurs in the genes that lie in the same chromosome with locus which is close to each other - The statement of mendelian segregation law starting that every allele will segregate in dependently during gamete formation isnt applied - The gene are said to be linked, so its called gene linkage

III.

Sex Linkage

Sex linkage is the genes that are set in sex chromosomes. Therere 2 types of sex linkage, X linkage and linkage. X linkage are the genes that are only found in X sex chromosomes, such as color blindness, hemophilia, and brown teeth. Then genes found in Y linkage webbed fingers, hypertricosis. a. Color blindness There are 2 types of color blindness, total color blindness and partial color blindness. The percentage of total color blindness patient between male and female is the same because the genes reside in X and Y chromosomes. b. Hemophilia Hemophilia is also caused by X linkage recessive gene. The heredity pattern is also similar c. Brown Teeth Is a genetic disorder caused by a defect in the formation email layer on teeth. Caused by X linkage dominant B gene d. Drosophila melanogaster The gene that determines the formation of eye color in fruit fly is X linkage gene

IV.

Crossing over

process of exchanging genes between chromatids than their partner on a pair of homologous chromosomes. Place a cross of two chromatids called Chiasma, and occurs in meiotic events

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Result new offspring formation, either in parental type or recombinant type. So it also has a role in increasing diversity in living organism

The several factor causing crossing over: Distance between gene. The farther the distance, the bigger the chance for crossing over to occur Age. The older the age of the person, the smaller the chance for crossing over to occur Temperature. The lower or higher the temperature, the bigger the chance for crossing over to occur X-ray. The x-ray can increase the possibility for crossing over to occur Sex type. Generally, crossing over occurs to both male & female

V. Sex Determination~ Inherited independently by parental gametes to the offspring in the event of meiosis. ~ Each organism has a form of sex chromosome with different patterns, theyre XY, XO and ZWa. XX XY System

This system is found in plants, animalsand humans. Genosom X larger than Y. genosom XX is female, XY is maleb. XO XX System

This system is found in insects (grasshoppers) and other orthoptera. Genotype XO is male Genotype XX is female

c. ZZ - ZW System

This system is found in the poultry, fish and butterflies. Genotype ZZ is male ZW is female genotype

d. Sistem Haploid - diploid (Ploidi)

Mendel & Hereditary16 This system of sex determination is not determined by sex chromosomes, but the body chromosomes (autosomes). Found in the group of ants and termites. Females develop from a fertilized egg cell so its diploid Males develop from unfertilized egg cells, so its haploid

VI.

Nondisjunction

Fail to separate or nondisjunction is the failure of one, some, or all chromosomes to separate during meiosis I or II. It can cause a change in chromosomes quantity within genital gene. The change depends on the quantity of non-disjunctive chromosome. If nondisjunction occurs only in certain number of chromosomes, for instance, number 5, then, the change of chromosome quantity only occurs in number 5.

VII. Lethal Gene

Lethal gene is a gene that causes death to the organism in homozygous condition. Therere 2 types of lethal gene, namely recessive & dominant lethal genea. Dominant Lethal Gene

Dominant lethal gene causes death in homozygous dominant condition. In the heterozygous state, generally only have abnormality Examples are the dominant lethal gene in creeper chickens. Creeper chicken is chicken that has legs and short wings. In the homozygous dominant state, the chicken die. If heterozygous, chickens alive but have abnormalities in the legs and short wings. While in homozygous recessive the chicken is normal

Lethal phenotype ratio: redep: normal = 1: 2: 1 Ratio is the ratio deviates from marriage monohybridb. Recessive Lethal Gene

-

Lethal recessive genes cause death if it is in the homozygous recessive state. In the heterozygous state the individual is normal but the carry the

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