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Section III The Basic Rules of Genetics 1 、 law of segregation 2 、 law of independent assortment 3 、 Law of Linkage And Crossing-over.

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Presentation on theme: "Section III The Basic Rules of Genetics 1 、 law of segregation 2 、 law of independent assortment 3 、 Law of Linkage And Crossing-over."— Presentation transcript:

1 Section III The Basic Rules of Genetics 1 、 law of segregation 2 、 law of independent assortment 3 、 Law of Linkage And Crossing-over

2 of The basic rules of monogenic inheritance Mendel ( )

3 Mendel About Mendel ( 1 ) Born on July 22th,1822 Like to ask a questions 1843,enter the seminary 1857,begain to study pea’s seven pairs of contrast character 1865, achievements were reported on Brunn science association released “plant hybridization experiment”,describes the transmission characteristics of characters in the hybrid process - the first and second law of genetic.

4 successful experience of Mendel ( 1 ) Choose a suitable test materials - peas ( 2 ) First study only on one pair of characters, as far as possible to simplify the problem, after acquire the results and conclusions, and then from simple to complex, study on two pairs and more pairs of characters. ( 3 ) Mendel applied the statistical methods to genetic analysis. Mendel is the first one of observer groups and use statistical methods for genetic analysis. This is also the first break of mathematics in biology field. About Mendel ( 2 )

5 About Mendel ( 3 ) Mendel The materials that Mendel choosed -peas

6 The seven character differences studied by Mendel About Mendel ( 4 )

7 Relative Terms character , relative character – (dominant character 、 recessive character ) phenotype , genotype allele (homozygote,heterozygote ) Test cross About Mendel ( 5 )

8 When the heterozygote to form the gametes, one pair of alleles separated from each other respectively, go into the different reproductive cells, form two types of gametes of equal number. The cytology basis of this -homologous chromosome separate in meiosis Law of segregation ( 1 ) Conditions must matched : Equal gametes of F1 Random fertilization The same survival rate of offspring Completely dominant

9 Round ( RR ) Wrinkle ( rr ) Round ( Rr ) Wrinkle ( rr ) R rr r Round ( Rr ) Wrinkle ( rr ) F1F1 F2F2 11 Law of segregation ( 2 )

10 When the organisms to form the reproductive cells, the alleles that control different characters act independently, go into a reproductive cells through random combination. Law of independent assortment ( 1 )

11 two pairs of relative character genetic : F1 dominant character ; F2 four types of phenotype : 2 parental types + 2 recombination types ( this two has a certain proportion ) Law of independent assortment ( 2 )

12 Morgan ( )

13 Important model organisms —— Drosophila ( 1 )

14 Important model organisms —— Drosophila ( 2 ) Drosophila genome

15 Aristotle first provide a written description for the Drosophila, he had mentioned that there is a adult that hatch from the mucus larvae called Drosophila. People put it in Oinopta ( 嗜酒者 ) genera, it originated from Southeast Asia, perhaps in 1871 they attached to a bunch of bananas, and came to the United States. Woodward, an entomologist at Harvard University has cultivated this Drosophila, after 2 years both the eye color, shape of the wings have not found any mutation, he recommend the Drosophila to Kasi Er. Kasi Er training for five years and had not found any mutation too. Kasi Er recommend the Drosophila to Lutz. Lutz at least found a mutation of the phenomenon, again the Drosophila were recommend to Morgan. Important model organisms —— Drosophila ( 3 )

16 white-eye male red-eye female male red-eye male white-eye male 50% female red-eye female 100% sex-linked inheritance : Important model organisms —— Drosophila ( 4 ) "eye color gene (R) and the sex determination gene is combined on the X chromosome."

17 the forecast results of Drosophila hybrid experiment gray long ( BbVv ) black deficient ( bbvv ) ( bv ) BV F1 F2 BvbVbv BbVv gray long Bbvv gray deficient bbVv black long bbvv black deficient 1111 Important model organisms —— Drosophila ( 5 )

18 Important model organisms —— Drosophila ( 6 ) ——complete linkage Drosophila hybrid experiment——complete linkage

19 ——incomplete linkage Drosophila hybrid experiment——incomplete linkage 灰长( BbVv )黑残( bbvv ) ( bv ) BV F1 F2 BvbVbv BbVv 灰长 Bbvv 灰残 bbVv 黑长 bbvv 黑残 41.5%8.5%41.5%8.5% Important model organisms —— Drosophila ( 7 )

20 1 、 Discover and confirmed the Law of linkage and crossing-over linkage group: gene on the same chromosome linked each other to transmission. 2 、 Use linkage to determine the relative position of genes in chromosome chain, and the establishment of Drosophila gene map 2 allele gene of the same linkage group can occur exchange and rearrangement, rearrangement rates could reflect the relative distance of the two genes on chromosome. We use rearrangement rates as map distance to measured distance of the two genes on genetic. It was define that when the rearrangement rates is 1%, the relative distance is 1 Moldovan (cM) Morgan's contribution ( 1 )

21 Morgan's laboratory used Drosophila to continue to do this kind of research as early as the 1930s. Their experimental results show the material that decides fly’s eye color of has a transformation process, and they can analyzed out which eye color mutation is the lack of enzyme of which response step. But they were unable to test and separated the relative material, the experiment can not be go on. For this genetic research based on biochemical experiments, Drosophila is not the appropriate experimental materials. The materials replace the status of Drosophila is the micro- organisms whose structure is very simple : mould, bacteria, viruses. Genetics thus gradually entering the stage of molecular genetics, the historical role of Drosophila in the genetics has been completed. Morgan's contribution ( 2 )

22 However, from 1970 people found that Drosophila has special status in the formation of embryo development pattern : It’s trunk which consists of 14 individual sections is completely symmetrical, a set of genes control the somite morphogenesis from top to bottom. Later research has proved that this set of genes Commonly found in genomes from insects to human,and is basic elements to determine the symmetrical layout of the body. Therefore, Drosophila again aroused great interest, its status as a model organisms in development and genetic research become important. Morgan's contribution ( 3 )

23 The reflect of the three law in human genetic (1) Human PTC tasting ability Independent assortment of human blood type ABO genotypes gene on chromosome 9 and MN blood group genes on chromosome 4 Linkage inheritance of NP and IA on chromosome 9

24 The reflect of the three law in human genetic (2)

25 Section IV genetic and human diseases Monogenic disorders polygenic disease Chromosome disease Somatic inherited disease

26 Human monogenic disorders (Mendelian inheritance disorders) ( 1 ) disease of autosomal dominant, AD disease of autosomal recessive, AR disease of X-linked dominant inheritance, XD disease of X-linked recessive inheritance, XR disease of Y-linked inheritance

27 pedigree analysis : Human monogenic disorders (Mendelian inheritance disorders) (2)

28 symbols used in pedigree : Human monogenic disorders (Mendelian inheritance disorders) ( 3 )

29 genetic characteristics : one of the parents of the patients sickness 1/2 will onset in siblings of the patients , and the onset chance is equal in male and female About 1/2 individual will onset in the children of the parents Exit patients in a family for several generations,that is, continuous transmission Autosomal dominant inheritance disease (1)

30 Autosomal dominant inheritance disease (2)

31 Autosomal dominant inheritance disease(3)

32 Autosomal dominant inheritance disease (4)

33 Several types : 1. incomplete dominance /semidominance : The phenotype of heterozygous is between pure patients and normal. Such as: achondroplasia disease. 2. codominance : a pair of alleles don’t have the distinction as dominant or recessive. When they are heterozygous,they expression gene products respectively, and form the corresponding phenotype. Such as: ABO, MN blood type. 3.irregular dominance : in different conditions, heterozygote can be expressed as dominant or recessive. Such as: polydactyly. 4. delayed dominant : the pathogenic gene of heterozygote expressed when reach a certain age. Such as: Huntington disease. Autosomal dominant inheritance disease (5)

34 Question : Why do a female with O blood type and a male with A blood type have a child of AB blood type ? Autosomal dominant inherited disease (6)

35 Genetic characteristics : Both parents of the patients are generally disease-free, but are carriers 1/4 will onset in siblings of the patients, and the onset chance is equal in male and female There is no patient in the children of patients. This disease don’t transmit continuously. It is often sporadic. Disease risk in the children of consanguineous mating is higher than the children of consanguineous mating Autosomal recessive inherited disease ( 1 )

36 Autosomal recessive inherited disease ( 2 )

37 Autosomal recessive inherited disease ( 3 )

38 Autosomal recessive inherited disease ( 4 )

39 X linkage dominant inherited disease ( 1 ) Genetic characteristics : Female patients are more than male patients in pedigree and the illness state of female is often light than male patients one parents of the patients sickness exist Cross-genetic. the daughters of male patients are patients , but the son is normal ; the children of female patients each have 50% disease risk It can successive transmit in every generations

40 X linkage dominant inherited disease ( 2 )

41 X linkage recessive inherited disease ( 1 ) Genetic characteristics : Male patients are far more than female patients When the parents disease-free, the son may be ill, the daughter had no disease, the disease gene of patient children came from the mother, there are also cross-genetic

42 Britain's Queen Victoria has the hemophilia gene, and passed on to her children. Hemophilia is a hereditary coagulation disorder disease, the patient may be death due to the small wound and unremitbleeding. Hemophilia are generally recessive genetic in female, less onset; and performed dominant genetic in male. Queen Victoria's granddaughter, Alexandra (21) marrid with the Russian Czar Nicholas II, leading to their son with hemophilia. Britain's Queen Victoria has the hemophilia gene, and passed on to her children. Hemophilia is a hereditary coagulation disorder disease, the patient may be death due to the small wound and unremit bleeding. Hemophilia are generally recessive genetic in female, less onset; and performed dominant genetic in male. Queen Victoria's granddaughter, Alexandra (21) marrid with the Russian Czar Nicholas II, leading to their son with hemophilia. X linkage recessive inherited disease ( 2 )

43 Ireland Germany RussianSpain X linkage recessive inherited disease ( 3 )

44 ——All male genetic Testicular decision factor (TDF) and azoospermia factor(AZF) Y linkage genetic disorder


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